nuclear physics - nupecc · 2019-10-17 · editorial vol. 16, no. 4, 2006, nuclear physics news 3...

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NewsNuclear Physics News is published on behalf of theNuclear Physics European Collaboration Committee(NuPECC), an Expert Committee of the EuropeanScience Foundation, with colleagues from Europe,America, and Asia.

Volume 16/No. 4

Vol. 16, No. 4, 2006, Nuclear Physics News 1

Editor: Gabriele-Elisabeth Körner

Editorial BoardJ. D’Auria, Vancouver R. Lovas, DebrecenR. F. Casten, Yale S. Nagamiya, TsukubaA. Eiró, Lisbon H. Ströher, JülichM. Huyse, Leuven (Chairman) T. J. Symons, BerkeleyM. Leino, Jyväskylä C. Trautmann, Darmstadt

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CorrespondentsArgentina: O. Civitaresse, La Plata; Australia: A. W. Thomas, Adelaide; Austria: H. Oberhummer, Vienna; Belgium:C. Angulo, Lauvain-la-Neuve; Brasil: M. Hussein, São Paulo; Bulgaria: D. Balabanski, Sofia; Canada: J.-M. Poutissou,TRIUMF; K, Sharma, Manitoba; C. Svensson, Guelph: China: W. Zhan, Lanzhou; Croatia: R. Caplar, Zagreb; CzechRepublic: J. Kvasil, Prague; Slovak Republic: P. Povinec, Bratislava; Denmark: K. Riisager, Årnus; Finland: M. Leino,Jyväskylä; France: G. De France, GANIL Caen; B. Blank, Bordeaux; M Guidal, IPN Orsay; Germany: K. D. Gross, GSIDarmstadi; K. Kilian Jülich; Greece: E. Mavromatis, Athens; Hungary: B. M. Nyakó, Debrecen; India: D. K. Avasthi,New Delhi; Israel: N. Auerbach, Tel Aviv; Italy: E. Vercellin, Torino; M. Ripani, Genova; L. Corradi, Legnaro;D. Vinciguerra, Catania; Japan: T. Motobayashi, RIKEN; H. Toki, Osaka; Malta: G. Buttigieg, Kalkara; Mexico:J. Hirsch, Mexico DF; Netherlands: G. Onderwater, KVI Groningen; T. Peitzmann, Utrecht; Norway: J. Vaagen, Bergen;Poland: T. Czosnyka, Warsaw; Portugal: M. Fernanda Silva, Sacavém; Romania: V. Zamfir, Bucharest; Russia: Yu.Novikov, St. Petersburg; Spain: B. Rubio, Valencia; Sweden: P.-E. Tegner, Stockholm; Switzerland: C. Petitjean, PSIVilligen; United Kingdom: B. F. Fulton, York; D. Branford, Edinburgh; USA: R. Janssens, Argonne; Ch. E. Reece,Jefferson Lab; B. Jacak, Stony Brook; B. Sherrill, Michigan State Univ.; H. G. Ritter, Lawrence Berkeley Laboratory;S. E. Vigdor, Indiana Univ.; G. Miller, Seattle.

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NuclearPhysics

News

2 Nuclear Physics News, Vol. 16, No. 4, 2006

Volume 16/No. 4

Contents

Editorial .............................................................................................................................................................. 3

Feature ArticlesAnalysis of Art Works and Nuclear Physics at the Laboratory of Centre de recherche et de restauration des musées de France

by Jacques Castaing and Michel Menu......................................................................................................... 4

Probing the Standard Model with Superallowed Nuclear Beta Decayby J. C. Hardy and I. S. Towner .................................................................................................................... 11

Double Beta Decayby Petr Vogel ................................................................................................................................................ 18

The Rationale for Nuclear Energy: A Canadian Perspectiveby J. S. C. (Jasper) McKee ............................................................................................................................ 22

Facilities and Methods

by Robert Laxdal .......................................................................................................................................... 27

Meeting Reports9th International Conference on Nucleus-Nucleus Collisions, NN2006, August 28–September 1, 2006, Rio de Janeiro, Brazil

by M. S. Hussein, A. Szanto de Toledo, C. A. Bertulani and P. R. S. Gomes................................................ 31

International Workshop on Stopping and Manipulation of Ions (SMI-06)by Peter Dendooven ..................................................................................................................................... 32

EXON-2006by Yu. E. Penionzhkevich .............................................................................................................................. 32

News and Views ................................................................................................................................................ 36

Obituary ............................................................................................................................................................ 39

Calendar ............................................................................................................................................................ 40

editorial


The views expressed here do not represent the views and policies of NuPECC except where explicitly identified.

News and Issues from Japan

In recent years, nuclear physics hasagain become popular in Japan. Thereare three major reasons for this. First,the funding for individual scientists hasgrown significantly due to the steadygrowth of research funds for researchersat universities and institutes. During thepast ten years the federal support forbasic science, called the Grants-in-Aidfor Scientific Research, has grown by afactor of two. Second, several new facil-ities for nuclear physics have beenfunded and constructed in Japan. Theyare (1) the RI Beam Factory (RIBF) atRIKEN to provide 100 kW radioactiveisotope beams and (2) J-PARC at Tokai(managed by KEK and JAEA) for theacceleration of MW-class proton beamsthat will provide intense kaon and neu-trino beams, in addition to pulsed neu-tron and muon beams for materialstudies and life sciences research. Thesefacilities will be completed in 2006(RIBF) and 2008 (J-PARC), respec-tively. Third, applications of nuclearphysics techniques, such as radiationtherapies, are highly appreciated in soci-ety. Therefore, many accelerators formedical usage and other applications areunder construction in Japan.

At the same time, however, I feelthat Japan is facing an important andcritical issue concerning the usage ofthese facilities, in particular, for inter-national users. The most importantissue is how to create mechanisms toallow easy and friendly access ofinternational users to these facilities.Unfortunately, the system in Japan hasnot been well designed in this respect.For example, the fraction of non-Japa-nese employees in universities and

institutes is extremely small. Also, theinfrastructure to support temporaryforeign visitors has not been wellestablished at most institutes andtowns. Furthermore, in spite of theexistence of a strong need of Asianscientists to use Japanese facilities,very little discussion between Asianscientists has thus far taken place forthe usage of RIBF and J-PARC. Theestablishment of some mechanism foraccess by non-Japanese scientists istherefore an urgent issue in Japan.

At RIBF a new organization forthe operation of the accelerator, calledthe Nishina Center for Accelerator-Based Science, started in April 2006.About the same time, in February2006, a new organization called the J-PARC Center was born. In both placesthe internationalization of the facilitiesis one of most important items to beimplemented in the organizations.

In 1999 the Working Group onNuclear Physics at the OECD Mega Sci-ence Forum published its report. It statesthat four important accelerator facilitieswould be needed for future nuclearphysics research in the world: (1) high-intensity radioactive nuclear beam facil-ities, (2) intense high-energy electronbeam facilities, (3) multi-purpose had-ron facilities with a wide variety of sec-ondary particle beams, and (4) facilitiesfor heavy-ion collisions at very highenergies. Among those it was recom-mended that high-intensity radioactivenuclear beam facilities should be builton a regional base, whereas the multi-purpose hadron facility should be builtat only one place. Clearly, the former isthe RIBF facility at RIKEN and the lat-

ter is the J-PARC facility. The importantmessage from this OECD WorkingGroup was that, although the style ofinternational usage could be differentbetween RIBF (regional center) and J-PARC (international center), Japan muststart to make serious efforts to acceptworld users for both these new Japanesefacilities.

In the fall of 2005 the IUPAP (Inter-national Union of Pure and AppliedPhysics) created a new Working Groupcalled the “International Cooperation inNuclear Physics.” Also, the OECD Glo-bal Science Forum created the “Work-ing Group on Nuclear Physics” in thespring of 2006. Both Working Groupshave a common goal to discuss and pro-mote international worldwide coopera-tion and collaboration in nuclearphysics. Japan would like to utilize thesetwo Working Groups as a tool for solv-ing the issue of internationalization ofthe Japanese facilities.

At the same time, while I was writingthis article I discovered that this journal,Nuclear Physics News, is a unique jour-nal in nuclear physics in the world,which could play an important role, sim-ilar to the CERN Courier in high-energyphysics, for the acceleration of commu-nications among nuclear physicists in theworld. Thus, I feel that we would like toutilize this journal more often to informthe world community of the progress ofnuclear physics facilities in Japan, inorder to achieve true internationalizationof the forthcoming two facilities.

SHOJI NAGAMIYA

J-PARC CenterKek and Jaea

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Analysis of Art Works and Nuclear Physics at the Laboratory of Centre de recherche et de restauration des musées de France

JACQUES CASTAING AND MICHEL MENU Laboratoire du Centre de recherche et de restauration des musées de France (C2RMF)-UMR 171 C.N.R.S., Palais du Louvre, 14, quai François Mitterrand, 75001 Paris, France

Introduction Human societies have never considered that it was impera-

tive to preserve objects and artefacts as part of a heritage. Inour present time, the destruction of goods is the engine of theeconomy; it allows production growth and social stability.However, simultaneously to the industrial revolution of the19th century, it has become essential to collect and protect anincreasing variety of traces from the past [1]. This includes notonly objects kept in museums (remains of living species, arte-facts, works of art, etc.), but also people-made structures (pal-aces, churches, industrial buildings, etc.) and even largerfractions of our environment as can be seen in the list of theUNESCO “world heritage.” To preserve the past productionof human activity, one must understand the knowledge and theskills associated to the objects; hence, the development ofmany disciplines such as history, archaeology, conservation,life science, physics, chemistry, and so on are applied to heri-tage. Many institutions have been involved and during the20th century research laboratories have been created, such asthe laboratory [2], located in the Louvre museum, that wedescribe in the following. The laboratory of centre de recher-che et de restauration des musées de France (C2RMF) is incharge of studying the collections at the request of the publicmuseum system or of other authority. Multidisciplinary inves-tigations are currently performed by curators/art historians,chemists, physicists, geologists, restorers/conservators, and soon Together, they aim at helping the restoration and the con-servation of objects as well as improving the understanding oftheir fabrication, the strategy developed by the ancient artistsor craftsmen, and finally their use. Specific analytical tech-niques have been implemented, many of them involvingnuclear physics. We focus on the latter in the following.

Examination of Works of Art Multidisciplinary and multi-scale examinations of

objects are a prerequisite to any detailed investigation.Indeed, the aspect, and the social and historical contexts of

objects as long as they are known, are the first steps. This isthe domain of historians and curators. In addition to directvisual observation, these specialists are helped by the use ofvarious electromagnetic radiations such as infra red, ultraviolet, and X-rays [2]. The radiography of paintings hasbeen performed more than 10,000 times since it began inthe 1920s [3]. These techniques give information beyondthe surface and allow discovering details about the fabrica-tion of the objects or about their deterioration or theirancient restoration. Resulting from these investigations,many questions often are raised concerning the origin andthe processing of the materials, the date of manufacture, thealteration of the object, and so on. To attempt bringinganswers, it is necessary to use various types of analyticaltechniques to determine detailed characteristics of thematerials, such as chemical compositions, atomic arrange-ments in molecules or in crystals, lattice imperfections, andso on. The strategy of analysis depends on many parame-ters such as the question to be answered, the nature of thematerials (organic, mineral), their alteration with time, thenecessity of non-destructive analysis, and so on; differentpoints of view can be found in publications [4,5].

An example of such multidisciplinary research wasundertaken recently on the Mona Lisa by Leonardo [6]. Allthe partners of the C2RMF associated with a few specialistsof French and Canadian research centers developed a com-mon study of the famous painting.

This approach is at the encounter of art and chemicalscience with the consequence that the laboratory of C2RMFhas been supported by the Chemistry department of theCNRS (UMR 171) for the past 15 years. A large variety ofmaterials are currently studied in the C2RMF, from metals,ceramics, and stones to organic materials. The present arti-cle gives examples related most to inorganic materials.Actually, the techniques used for the analysis of materials(X-ray fluorescence, electron microscopy, X-ray diffrac-tion, infra-red absorption, etc.) derive from physics. Several

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important techniques used at the C2RMF derive fromnuclear physics, involving ion beams and stable or unstableisotopes. The laboratory of C2RMF has been pioneering in ionbeam analysis on art works thanks to the design and con-struction of an attachment to work at atmospheric pressure [7].

Physics Tools in Heritage Investigations

Ion Beam Analysis of Chemical Elements Materials are fully characterized once the chemical

composition, the crystal lattice, and the microstructure ofthe various phases are determined. This requires extensiveinvestigations that cannot always be afforded. Chemicalelement analysis is the most common because it can bedone by the spectrometry of X-rays emitted under theimpact of X-rays (fluorescence; XRF), of electrons gener-ally in a scanning electron microscope (SEM-EDX) or ofparticles (PIXE) in an accelerator such as the one at the lab-oratory of C2RMF (Figure 1 AGLAE for AccélérateurGrand Louvre d’Analyse Elémentaire). XRF and PIXE areperformed directly at atmospheric pressure without takingspecimens from the objects; they are non-destructive andgive information on the superficial layers (10–50 μm fromthe surface). SEM-EDX is routinely used because it com-bines imaging and analysis; small specimens (usually lessthan 1 mm) have to be extracted from the art works whenthe whole object cannot be inserted in the vacuum chamberof the SEM.

AGLAE and its applications have been described inmany publications [7–10]. The equipment is based on a2 MV NEC tandem accelerator 5SDH- (Figure 1) that isused with beams of protons, deuterons, and α-particles, andless frequently of heavier ions such as O or N. The beamsexit to the atmosphere through a 0.1 μm thick windowmade of silicon nitride. These external beams allow per-forming the analysis, usually in a flow of helium, at atmo-spheric pressure, thus preventing from having to introducethe objects in a vacuum chamber with the risk of damagingfragile art works. With this system, beam diameters assmall as 20 μm are currently achieved.

All the IBA techniques are available at AGLAE. PIXEis the most common analysis because it readily gives quan-titative compositions for major elements and it has limits ofdetection (typically 5–10 ppm) much lower than SEM-EDX (0.1%) because of the reduced “brehmstrahlung” forheavy particles. PIX/E and SEM-EDX have the same limi-tations for the analysis of light elements, that is, beforesodium in the periodic table. This difficulty is overcome byusing nucleus transitions associated to γ-ray emission(PIGE) or nuclear reaction analysis (NRA), thus givingaccess to fluorine, boron, nitrogen, and so on in art works atthe cost of extra work.

Depth profiling near the surface can be obtained bythese techniques, for instance using beams inclined at vari-ous angles in PIXE/PIGE or using resonant NRA. How-ever, such profiling is usually made at AGLAE byRutherford back-scattering (RBS), most often with incidentα-particle beams. Hydrogen profiling has also been per-formed by elastic recoil detection analysis (ERDA) with α-particles [11,12].

In the following, we give two examples to illustratethese techniques applied to ceramics, with first a PIGEanalysis of boron in glazes of wares fabricated between themiddle age and the 19th century and second a PIXE/RBSstudy of luster on Hispanic ceramics. An application of thecharacterization of metal point drawings illustrates the effi-ciency of AGLAE applied to precious and fragile works.

i. Boron seems to have appeared in glasses in the 17th–18th century with a massive presence in the 19th due to adecrease of its price after the discovery of large quantitiesof borax in Death Valley (California) [13]. Boron cannot bedetected by PIXE, then, we used PIGE induced by 3 MVprotons. The emission of γ rays corresponds to the reactionsdisplayed in Table 1 spectra are shown in Figures 2 and 3for a glass standard and an ancient ceramic glaze. The reac-tion with the best yield is the one at 429 keV. It cannot be

Figure 1. General view of the AGLAE system. In the backare the source and the Pelletron accelerating system. In theforefront, the beam exit window is surrounded by detectorsand specimen monitoring devices.

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used with specimens containing Li that has a γ peak at thesame energy and it is not convenient in the presence of Na,frequent in glass, that has a peak at 439 keV (Figure 2). Theresults for the three emissions of boron are, then, used toverify that there is no coincidence in γ emission energy,giving thus reliable values for B2O3 concentrations.

The concentration c is determined from the ratio of thepeak areas of the sample (Figure 3) to the standard (Figure2) Y/YS. However, if the standard and the materials underanalysis are different, an approximate calculation is madeby taking into account the stopping powers according to theequation:

c = cS (Y/YS) (S/SS)

where S is the stopping power (in MeV/g/cm2) for the inci-dent protons. The units used in that equation are importantand cannot be changed without changing the whole equation.We have examined, by PIGE, 33 ceramic wares coveredwith glaze produced between the Middle Ages and the 19thcentury to check for the presence of boron. Each object wassubmitted to one or two PIGE measurements. An exampleis given in Figure 3 where the presence of boron confirms

that the ceramic platter is not from the renaissance, but verylikely a 17th century fabrication.

Indeed, among the 33 wares, there were medieval tilesfrom the “châteaux de Vincennes” and objects from Arras.From the Renaissance, PIGE was performed on fragmentsof objects from the Della Robbia’s active between 1450 and1550, tiles made by Masséot Abaquesne who died in 1564,and shards of Palissy (1510–1590) wares found at the timeof excavations made near the Louvre museum in the 1980s.In none of these objects, the concentration of B2O3 is abovethe detection limit that is around 0.05%. A number ofglazes on ceramic wares from followers of Palissy containB2O3 concentrations between 0.2% and 0.75% [14].Finally, PIGE was performed on various colors of twoglaze palettes made by Avisseau (19th century) [14]; B2O3

concentrations between 3% and 15% have been found in 7cases out of 35 PIGE measurements. Clearly, the drop inthe price of boron has induced 19th century potters to intro-duce boron in the glazes.

ii. In the ultimate years, there has been a renewed inter-est in luster pottery that has been investigated using SEM,transmission electron microscopy (TEM), EXAFS, and soon [15–19]. Luster is a ceramic decoration that appeared inthe 9th century in the Middle East and spread around theMediterranean basin in the following centuries. Lustergives a metallic aspect that is due to copper and silver nano-particles distributed into a thin layer under the glaze sur-face. These particles are revealed by TEM and the nature ofthe chemical bond of copper or silver can be determined byEXAFS. However, these techniques require samplesadapted to the measurements that are very expensive. RBS

Table 1. PIGE conditions for the analysis of boron.

g energy 429 keV 718 keV 2125 keV

Reaction 10B (p, α1 γ) 7Be 10B (p, p1 γ) 10B 11B (p, p1 γ) 11B

Yields at 3.1 MeV 7.2 × 106 1.3 × 106 4.8 × 106

PIGE NIST 93a

1

10

100

1000

10000

600 1100 1600 2100 2600 3100 3600

channel

spc

2125keV B

Si

Na

Si

Al718keV

B

429keVB Na

Figure 2. PIGE spectrum for a standard referenceborosilicate glass (NIST 93a) containing 12.5% B2O3,80.8% SiO2, 4% Na2O, 2.3% Al2O3 as major components.The energies of g rays is indicated for boron.

PIGE E. Cl 1141

1

10

100

1000

10000

600 1100 1600 2100 2600 3100 3600

channel

cps

Figure 3. PIGE spectrum from the glaze of a ceramicplatter in the style of Bernard Palissy. The glaze is rich inlead; it is grey and covers a snake. The concentration ofB2O3 is 1.1%.

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provides an alternative that is fast to obtain concentrationprofiles of copper and silver; it is non-destructive and iscurrently performed on valuable luster ceramic wares at thelaboratory of C2RMF. A study has been recently performedon 15th century shards excavated from a workshop inSeville that was unknown for any production of lusterceramics [20]. The chemical composition of the glazes,determined by PIXE, is typical of the Iberian productionwith 50% SiO2, 35% PbO, and 7% SnO2. Concentrationprofiles have been determined by RBS. In places, the pro-files show a loss of lead due to surface weathering duringthe centuries underground; metallic luster seems to providea protection [20]. The luster layers are revealed by the Agand Cu peaks (Figure 4), both elements being present in allthe luster objects. Quantitative profiles are obtained withthe SIMNRA simulation code. The layers containing themetallic particles are particularly thin (100–200 nm) andgenerally not covered by a 20–100 nm glass layer, as com-monly found in other productions; they are rich in Cu. Theratio of Ag to Cu concentration is found to vary consider-ably with the origin of the wares, luster ceramics rich in Agbeing yellow and those rich in Cu being red. External beamRBS is a very convenient non-destructive technique toobtain characteristics of sub-surface layers in luster ceram-ics [20]; it is presently used to investigate a large number ofobjects from several national museums.

iii. Metal point drawings belong to the most preciousand rarest treasures of graphical collections. They weremainly realized during the Renaissance period by Italianand Northern European artists. These drawings are charac-terized by extremely thin grey-brown strokes. Until now,only little chemical information was provided because ofthe very delicate character of the works. However, the anal-ysis is difficult to perform without damaging the drawings.

The metal point was known as early as the Romanperiod and was used more extensively during the MiddleAges. From the 14th century, the metal point became anindependent drawing instrument until the mid-16th century,when it was progressively replaced by black or red pencils.Lead, silver, and gold were the principal metals used, butmore rarely copper and its alloys. More recently, lead, tin,or bismuth alloys were prepared. The famous early 15thcentury Cennino Cennini’s treatise recommended only twometals: a lead-tin (2/1) alloy and silver. Lead and tin pointmight be used directly on paper or parchment and had theuseful quality to be rubbed out. On the other hand, silverpoint, with a higher hardness, was used on a support with aspecial bone white preparation. When sketched, the trace isnot erasable. Basically, analyses of the chemical composi-tion provide additional information in the knowledge of thegenesis of the creation: identification and provenance of thematerials, revealing the artistic knowhow. By evaluatingthe chemical fingerprint (determination of the chemical ele-ments: major, minor, and trace elements), one can deducethe origin of the materials used, the processing and the stor-age conditions.

The analysis should overcome three principal con-straints: First, the precious character of the works impliesthat the analysis has to be absolutely non-destructive: adirect analysis without sampling and any damage. Second,the tracks of the metal point consist of a dispersion of tinyparticles on the support. The contribution of the supportshould be deduced in the final analysis, which is not alwayseasy because of the heterogeneity of the composition andthickness of the track itself. Finally, the amount of thedeposited matter is small: if the area of the analysis isaround 100 square micrometers, the mass of the analyzedmatter is about 1 μg. Quantitative analysis of 1 μg of matteron an infinite thick support is a real challenge. The sensitiv-ity of induced X-ray spectrometries is particularly favor-able for the goals to be achieved.

As a second analytical technique, we applied spatiallyresolved X-ray fluorescence spectroscopy induced by synchro-tron radiation (SR-XRF), a method totally nondestructive

Figure 4. RBS spectra obtained, in 1 atmosphere helium,on three locations of the RFM 5 lustre ceramic from Seville.A 50 mm diameter beam of 3 MeV a particles was used. Thesimulation gives atomic concentrations of about 5% Ag and20% Cu in a 70 nm thick layer at the surface [19].

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and very sensitive. Ina Reiche (C2RMF-UMR171) per-formed the analyses at the BAMline of the BESSY syn-chrotron in Berlin [21]. The high energy (5–90 keV) mono-chromatic X-rays are collimated in ca 100 μm.

As an application the drawingbook of Albrecht Dürerwas analyzed. The German painter created this book duringhis trip to the Netherlands in 1521. Dispersed in severalmuseums, mainly in Paris (Chantilly) and Berlin (Kupfer-stichkabinett), the different sheets were studied. All wereexecuted on a paper covered by a preparation based onbone white. All the drawings show the same chemical com-position: 90 w% silver, 10 w% copper, and minor traces ofzinc (Figure 5). Only one has another composition: 83 w%silver, 12 w% copper, 5 w% zinc: The Portrait of youngman with a fur hat was realized with another silver point(Figure 4), which does not appear in the travel notebook. Itis most probable that the portrait is not contemporary withthe other drawings.

Synchrotron Radiation The use of synchrotron radiation has grown very

quickly during the past decade. The laboratory of C2RMFhas been involved in investigations at LURE (Orsay, nowclosed), ESRF (Grenoble), BESSY (Berlin) [22,23] andBrookhaven National Laboratory; scientists of the C2RMFare active in the CNRS GDR 2762 set up to organize theconnection between the heritage community and the newSOLEIL facility due to start operating at the end of 2006.The investigations have used infra red (IR) absorption,which provides high resolution microscopy particularlyuseful for mixtures of organic and inorganic matter, andalso X-rays that provide unique performance for XRF andX-ray diffraction (XRD) on small volumes as well as thepossibility to determine the local environment of atoms byabsorption (XANES, EXAFS). Examples are brieflydescribed in what follows.

Lead sulphide is a major component in ancient Egyptianeye make-up. Other compounds such as lead carbonate(PbCO3), as well as unexpected constituents (laurionitePbOHCl; phosgenite Pb2Cl2CO3) have been identified byXRD [24]. The microstructure of lead sulphide was evalu-ated by analyzing the XRD peak broadening in terms ofdislocation densities and crystallite sizes in relation to thepowder processing for the cosmetic manufacture [25].Focused X-ray micro-beam has been used to identify byXRF the trace elements in powder grains of cosmetics inorder to identify the provenance of the minerals; XANESallowed us to check that the impurities are in the lead

sulphide fraction of the make-up [26]. The same techniquehas been used to identify the minerals in black pigmentsused in Labastide prehistoric cave (around 14500 B.P.);they contain the unexpected Mn rich birnessite that is prob-ably due to micro-organism activity [27].

Specimens of Egyptian mummy skin have been exam-ined with IR microscopy with apertures adjusted down to3 μm × 3 μm thanks to synchrotron radiation [28]. Compari-son with modern skin indicates that the structure and thecomposition of the skin have been deeply modified due todegradation; some aspects of the degradation mechanisms

Figure 5. Albrecht Dürer: Drawings from the sketchbookduring his trip to the Netherlands. Berlin. Top/Musée deChantilly, analyzed by PIXE/AGLAE; bottom/Berlinanalyzed by SR-XRF/BAM BESSY. The drawing of the“young man with a fur hat” presents a particular elementalcomposition: silver ally with 13 wt% Cu and 5.3 wt% Zncompared with the other drawings, 90 wt% Ag/10 wt% Cu.

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have been uncovered [29]. Such sets of measurementswould have been impractical without the help of synchrotronradiation.

Dating Nuclear physics is at the base of a large number of dat-

ing techniques. Applications to heritage studies are usefulmostly for the past 20–30,000 years and exceptionally forolder times. For such a time span (14C half life is 5,730years), 14C dating is particularly suited to organic materialsleft by living species when they stop being in chemicalequilibrium with their environment. The decay of 14C con-centration gives a direct access to the age of the death ofanimals or plants. It requires measuring 14C/12C ratios infe-rior to 10−12; accelerator mass spectroscopy (AMS) is par-ticularly adapted to this type of measurement. AMS givesdates with very small amounts of carbon (1 mg) and hassuch a sensitivity that it can give ages as old as 50,000years.

A new AMS machine has been purchased, the costsbeing shared by the Ministry of Culture, CNRS, CEA, andIRD. It is a 3 MV Pelletron tandem accelerator 9SDH-2,manufactured by NEC-USA designed for 14C concentrationmeasurements. The machine is located in Saclay, south ofParis, and is part of the laboratory LMC14, managed in theframe of the CNRS UMS 2572. The laboratory of C2RMFis involved in 14C dating of heritage objects. The productionof 14C dates is currently becoming a routine process.

In complement to the previous technique, thermolumi-nescence (TL) dating is applied to minerals; it has beenused at the laboratory of C2RMF to date ancient ceramicsfor the last 30 years [30]. TL is a universal tool for dosime-try. It applies to heated minerals giving the possibility ofdating by measuring the total dose of natural radiationrecorded since the last temperature increase (T > 350 °C).This dose is measured by TL or by optically stimulatedluminescence (OSL). In order to calculate the age, theannual dose rate must be known for the whole life of theartefact after the thermal event. The dose rate comes fromradio-elements (uranium, thorium, potassium) inside theobject and from the environment. The first contribution canbe deduced from the measurements of the concentrations ofradio-elements. The second contribution is less knownbecause it may fluctuate depending on the conditions ofstorage as shown by a recent survey of the radiation back-ground in various buildings [31]. Errors on ages can be assmall as 5–10% in the best cases. Additional sources ofuncertainty are the unknown humidity level in the objects

during their storage and also the possible application of ion-izing radiation to the objects, mostly X or γ rays, thatinduce an artificial ageing (laboratory study, airport safety,etc.) [31]. In spite of these limitations, TL and OSL datingare largely used, not only in archaeology, but also formuseum collections and in the art market where the resultsshould be considered with some caution. On the occasionof a recent exhibit of the Tanagra terracottas of the Louvre,the laboratory of C2RMF has performed an investigationwith the aim to verify the authenticity of the statuettes.Luminescence dating has been applied to 140 Tanagra figu-rines, which were all found to have an age of 2,300 ± 400years, except 9 of them having an age of 150 ± 50 years.Obviously, the Louvre collection includes a small numberof fakes, a common situation for the Tanagra statuettes [32].

Conclusions and Perspectives The aims of heritage research are to understand the past

through the studies of objects, establishing details of date,place, technology, materials, and so on. We have shownthat in all these aspects, analysis based on nuclear physicsplays an important role. The efforts in investigating andpreserving the heritage are steadily growing in our societ-ies. A network of laboratories has been created by the Euro-pean Union to promote “Access, Research and Technologyfor the Conservation of European Cultural Heritage” (EU-ARTECH). In this network, the laboratory of C2RMF is incharge of providing access to AGLAE for IBA studies ofart work; details are given on the websites of EU-ARTECHor of C2RMF.

AGLAE allows nondestructive measurements of elemen-tal compositions of specimens or of objects when they can becarried to the accelerator. The cost of transportation is a limi-tation to the use of IBA for the studies of art work. Hence,portable equipment is being developed that can be carriedeasily to the sites of measurements (museum, monument,excavation). Various systems are commercially availablesuch as Raman spectroscopy or X-ray fluorescence. Othersystems exist as laboratory prototypes; an example is a porta-ble PIXE using a 210Po source of α-particles [33].

Numerous techniques are available for elemental analy-sis. For identification of materials, it is necessary to identifythe crystal structure of the phases. The laboratory ofC2RMF is developing two XRD equipments. A portablelightweight system, supported by EU-ARTECH, will beable, when completed, to characterize by combined XRFand XRD objects that cannot be moved. Another system isunder construction with the financial support of the

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“Conseil Régional Ile de France”; it will give XRD patternsof surfaces of art works with a spatial resolution of less than0.2 mm in combination with elemental analysis withAGLAE; this system will give access to the identificationof small inclusions or to the mapping of mineralogical com-position of the surface of objects. Progress in the knowl-edge and the conservation of heritage depends not only onthe availability of complementary analytical techniques,but also on the narrow collaboration of many disciplinesfrom physics, geology, chemistry to curators, art historians,conservators, archaeologists, and so on.

References 1. M. Guillaume, Techne 13–14, 14–19 (2001). 2. J. M. Dupouy, Bulletin de la SFP 107, 21–26 (1996). 3. D. Dubrana, Histoire secrète des chefs-d’oeuvre, ed.

Barthélémy, Paris, 2001. 4. M. Regert, M.-F. Guerra, I. Reiche, Techniques de l’Ingénieur

3 partie 1: P3780, 1–35 & partie 2: P3781, 1–20. 5. M. Menu, Microelectr. Eng. 83, 597–603 (2006). 6. J. P. Mohen, M. Menu, B. Mottin, Mona Lisa: Inside the

painting by Leonardo, Harry N. Abrams Incl., 2006. 7. T. Calligaro et al., Nucl. Inst. And Meth. B 161–163, 328–333

(2000). 8. J. C. Dran, Bulletin de la SFP 136, 12–17 (2002). 9. T. Calligaro et al., Nucl. Instr. and Meth. B 226, 29–37 (2004). 10. J. C. Dran etal., Nucl. Instr. and Meth. B 219–220, 7–15 (2004).

11. T. Calligaro et al., Nucl. Instr. and Meth. B 181, 180–185(2001).

12. I. Reiche et al., Nucl. Instr. and Meth. B in press, availableonline (2006).

13. E. Speel and H. Bronk, Berliner Beiträge zur Archaeometrie,18, 43–100 (2001).

14. A. Bouquillon et al., Techne, 20, 83–91 (2004). 15. D. Oger and A. Bouquillon, Techne, 16, 26–32 (2002). 16. J. Perez Arantegui et al., J. Amer. Ceram. Soc. 84, 442–446

(2001). 17. S. Padovani et al., Appl. Phys. A 79, 229–233 (2004). 18. D. Hélary et al., J. Amer. Ceram. Soc. 88, 3218–3221 (2005). 19. J. Roqué et al., J. Europ. Ceram. Soc. in press, available online

(2006). 20. A. Polvorinos, J. Castaing, M. Aucouturier, Nucl. Instr. and

Meth. B in press (2006). 21. I. Reiche et al., Nucl. Instr. and Meth. B 226, 83–91 (2004). 22. P. Martinetto et al., Bulletin de la SFP 138, 4–7 (2003). 23. I. Reiche, Bulletin de la SFP 153, 11–17 (2006). 24. P. Walter et al., Nature 397, 483–484 (1999). 25. T. Ungar et al., J. Appl. Phys. 91, 2455–2465 (2002). 26. P. Martinetto etal., Nucl. Instr. and Meth. B 181, 744–748 (2001). 27. E. Chalmin et al., Appl. Phys. A 83, 213–218 (2006). 28. M. Cotte et al., Vibrat. Spectro. 38, 159–167 (2005). 29. A. Bouquillon, G. Querré, Techne 2, 62–67 (1995). 30. J. Castaing et al. J. Cult. Herit. 5, 393–397 (2004). 31. J. Castaing and A. Zink, Techne 19, 130–133 (2004). 32. A. Zink and E. Porto, Geochronometria 24, 21–26 (2005). 33. G. Pappalardo et al., J. Cult. Heritage 5, 83–188 (2004).

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Probing the Standard Model with Superallowed Nuclear Beta Decay

J. C. HARDY AND I. S. TOWNER* Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA

Introduction Central to the Electroweak Standard Model is the

Cabibbo-Kobayashi-Maskawa (CKM) matrix, a unitary3 × 3 matrix that relates the weak- to the mass-eigenstates ofthe three generations of quarks. The Standard Model itselfdoes not prescribe the values of the individual matrix ele-ments—they must each be determined experimentally—butit does insist that the full matrix must satisfy all conditionsof unitarity. Thus, any conclusive experimental demonstra-tion that the unitarity conditions are not met would provethe need for “new physics” extending beyond the currentStandard Model. Conversely, if the experiment wereinstead to confirm unitarity, this result would circumscribethe scope of any possible new physics to an extent limitedonly by the quoted experimental uncertainties on the unitar-ity sum. Either way, there is compelling motivation here forprecision measurements of the CKM matrix elementsaimed at the most demanding tests possible of the matrix’sunitarity.

It is nuclear physics measurements that form the key-stone of what is by far the best test of CKM unitarity that iscurrently possible.

Superallowed 0+ → 0+ nuclear beta decay is a singularlyvaluable tool in probing many properties of the weak inter-action, not just CKM unitarity. Ironically, its value for thispurpose follows from its relative insensitivity to the effectsof nuclear structure, effects that are notoriously difficult toaccount for with high accuracy. To understand why theseparticular decays are so insensitive to nuclear structure weneed to examine some of the general properties of betadecay.

To a good approximation—the “allowed approxima-tion”—the two leptons emitted in beta decay, e+ and νe (ore− and e), do not carry any orbital angular momentum. Thelepton spins can be antiparallel (total S = 0) or parallel (totalS = 1). For the former to occur (a process referred to as vec-tor, or Fermi, decay) there can be no change in the nuclear

spin between the parent and daughter states: ΔJ= | Ji −Jf | = 0.For the latter (referred to as axial-vector, or Gamow-Teller,decay), the leptons carry away one unit of angular momen-tum, which means that the parent and daughter nuclearspins may differ by as much as one unit: Δ J = 0 ± 1. How-ever, what is most important in the present context is thatangular-momentum conservation does not permit an axial-vector transition to occur between states with Ji = 0 andJf = 0. When such a transition occurs, it must be uniquely ofthe vector type.

Calculation of the decay rate for a beta transitionrequires knowledge of the wave functions for the initial andfinal nuclei and of a transition matrix element connectingthem; in general, this is a complicated and difficult proce-dure, producing results that are certainly not expected to beaccurate to the percent level. For one special class ofdecays, however, the calculation is simplified and its reli-ability is increased enormously. These are the vector decaysbetween “analogue” states. Without charge-dependent forcesin nuclei, analogue states would be completely identical instructure (including spin and parity) except for the inter-changed roles of a neutron and a proton. Although, in fact,charge-dependent effects do exist, they are comparativelysmall and the wave functions of analogue states remainnearly identical to one another. For that reason, beta transi-tions between analogue states are among the strongestknown, and are called “superallowed.” Furthermore, if theanalogue initial and final states have spin 0+, then we have apure-vector superallowed transition, and the transitionmatrix element turns out to be nearly independent of thedetailed structure of the states involved.

If we ignore small charge-dependent effects for themoment, the parent and daughter analogue states differonly in their z-component of isospin. This is a critical pointbecause the transition operator for vector beta decay is theisospin ladder operator, exactly the operator that acts tochange the z-component of isospin. Thus, the transition

*Present address: Department of Physics, Queen’s University, Kingston, Ontario K7L 3N6, Canada

v−

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matrix element between analogue states is simply a Cleb-sch-Gordan coefficient of isospin algebra, which for T = 1states has the value . The actual structure of theanalogue states does not affect this transition matrix ele-ment at all so long as both states are identical. As we willsee, it is only when charge-dependent effects are incorpo-rated that nuclear structure enters, and then only at the per-cent level.

The measured strength of a beta transition is expressedin terms of an “ft value,” where f is the “statistical rate func-tion,” a phase-space integral that depends strongly on thetotal measured decay energy; and t is the partial half-life,which depends on two other measured quantities, the totalhalf-life of the parent and the branching ratio for the super-allowed transition. For superallowed 0+ → 0+ transitionsbetween T = 1 analogue states, the measured ft value can bewritten in simple form as

where = 8120.271(12) × 10−10

GeV−4s, and GV is the weak-interaction coupling constant. By referring to GV as a “constant,” we have already

made an assumption, rather an important one in fact. Inmost applications a nucleon embedded inside a nucleusdoes not behave as a free nucleon but is affected by its sur-roundings, primarily the cloud of mesons that engulfs it asit participates in exchange interactions with its neighbors.The hypothesis that Fermi beta decay is an exception, withGV being unchanged by the mesons surrounding a decayingnucleon, is known as the Conserved Vector Current (CVC)hypothesis. The term “vector” refers to the Lorentz trans-formation properties of the operator responsible for thedecay. The CVC hypothesis for the weak interaction can beunderstood by analogy with the electromagnetic interac-tion. The proton’s electric charge is not changed by itsbeing embedded in a nucleus and interacting with mesons.This is true because the electromagnetic interaction is gov-erned by a conserved vector current. The CVC hypothesisis that the weak vector current is just an isospin rotation ofthe electromagnetic vector current. In this context then, thevector coupling constant, GV, plays the same role for theweak interaction that charge plays for electromagnetism,and it is likewise independent of its environment.

We arrive then at the first important application ofsuperallowed 0+ → 0+ beta decays: testing the CVC hypoth-esis experimentally. According to Eq. (1), the measured ft

values for all such transition must be the same, regardlessof the parent nucleus involved, providing that GV is con-stant as CVC hypothesizes.

The second important application of superalloweddecays only follows if the first is successful. If the mea-sured ft values are found to be the same, indicating that GV

is truly constant, then the value for GV is automaticallydetermined from the average. Once we know the value ofGV, we can turn to the test of CKM unitarity and the light itsheds on physics beyond the Standard Model. If we denotethe weak eigenstates of the quarks in the three-generationStandard Model as d, s′, and b′, and their mass eigenstatesas the corresponding unprimed quantities, then the CKMmatrix connects the two,

and must consequently be unitary. There are many relation-ships among the nine experimentally determined matrixelements that could be used to test whether this requirementis met, but the one that currently provides the most preciseresult is the top-row sum:

By far the dominant term in this sum is Vud, which dependsdirectly on GV via the relationship Vud = GV /GF, where GF

is the well-known weak-interaction constant for the purelyleptonic decay of the muon. The result for GV obtainedfrom superallowed beta decay is thus the linchpin of thiscritical test of CVC unitarity.

Before examining the nuclear data to see how well CVCand CKM-matrix unitarity stand up to these tests, we mustfirst add some small correction terms to Eq. (1).

Decay in the Nuclear Environment Although CVC hypothesizes that GV does not change in

the nuclear environment, other small effects are expected tooccur there. First, there are radiative corrections that arisebecause the beta-decaying nucleon is doing so in the pres-ence of the electromagnetic field of all the other nucleonsand, for example, the decay positron may emit abremsstrahlung photon, which goes undetected in theexperiment. Second, isospin is not an exact symmetry innuclei; so the nuclear matrix element is slightly reduced

⟨ ⟩ =MV 2

ftK

G MV V

=⟨ ⟩2 2

, (1)

K c m ce/( ) ln /( )� �6 3 2 52 2= π

′′′

⎛

⎝

⎜⎜

⎞

⎠

⎟⎟ =

⎛

⎝

⎜⎜⎜

⎞

⎠

⎟⎟⎟

⎛

⎝

⎜d

s

b

V V V

V V V

V V V

d

s

b

ud us ub

cd cs cb

td ts tb

⎜⎜

⎞

⎠

⎟⎟ , (2)

V V Vud us ub2 2 2

1+ + = (3)

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from its ideal value, leading us to write ,where δC is the isospin-symmetry-breaking correction.

Because of these various corrections, the expression forthe ft value in Eq. (1) is modified, and the ft value isreplaced by a “corrected” value, written F t [1,2]:

Here, δ′R and δNS comprise the transition-dependent part ofthe radiative correction and Δ1

R is the transition-indepen-dent part. The first of these terms, δ′R, is a function only ofthe electron’s energy and the Z of the daughter nucleus. Ithas been evaluated by standard QED to order Zα2 and esti-mated in order Z2α3 [3,4]; its values [1] are around 1.4%and can be considered to be very reliable. The second term,δNS, is affected by nuclear structure and its evaluationdepends on a detailed shell-model calculation. Although itsvalues [5] are thus much less certain, they are quite small,being of order 0.2% for transitions from nuclei with Tz =½ (N–Z)=−1, and of order 0.04% for those from Tz=0 nuclei.

The third radiative-correction term, Δ1R, is somewhat

larger (2.4%) and is nucleus independent; it is thus placedon the right-hand side of Eq. (4). It plays no role in the testof CVC, which only requires the F t values to be constant,but its value is needed before the CKM matrix element,Vud, can be determined. Marciano and Sirlin recently re-computed Δ1

R by a new method [6] and after careful scru-tiny reduced its uncertainty to 0.04%, half its previousvalue [7].

The isospin symmetry-breaking correction, δC, is alsosmall but, because it depends most strongly on nuclearstructure, it requires considerable attention. Although theCVC hypothesis makes the tacit assumption that isospin isan exact symmetry, this can never be strictly true in nuclei,where the Coulomb and other charge-dependent forces cer-tainly play some role. Thus a sound evaluation of the isos-pin-symmetry-breaking correction, δC, is required and overthe years there have been many calculations of theseeffects. Here we choose to retain only two—those ofTowner and Hardy [5], and of Ormand and Brown [8]—because these calculations were constrained to reproduce avariety of other properties of the nuclei involved. Typicalvalues for δC in nuclei with A ≤ 54 are around 0.4%, but forcases in the upper pf shell, where the extra node in the 2porbital plays a critical role, the correction jumps to around1.2%. There is a small systematic difference between the twocalculations, however, presumably due to Towner–Hardy’s

use of Woods-Saxon functions and Ormand–Brown’s useof Hartree-Fock functions for the appropriate nuclear radialfunctions. This does not affect the CVC test but, in evaluat-ing Vud, we correct for this discrepancy and assign a sys-tematic uncertainty equal to half the spread between them.Unfortunately, this assigned error emerges as one of thelarger contributors in the total error budget for Vud.

The four correction terms we have introduced into Eq.(4) are all small, about 1% or less. Their uncertainties donot exceed 0.05%. This means, in principle, that CVC andCKM unitarity can both be tested to a few parts in 104 if thenuclear measurements of the ft values of superallowed 0+

→ 0+ beta decays can reach the 0.1% level of precision orbetter. This is a challenging goal but it is one that hasalready been met—for nine separate transitions!

Status of World Data Last year, a new critical survey of world data on super-

allowed 0+ → 0+ beta decays was published [1]. All for-mally published measurements were included, even thosethat were based on outdated calibrations if enough informa-tion was provided that they could be corrected to modernstandards. In all, more than 125 independent measurementsof comparable precision, spanning four decades, made thecut. The evaluated survey results for half-lives, branchingratios and QEC values were then used to obtain ft and cor-rected F t values, which ultimately were applied to funda-mental weak-interaction tests.

It is beyond the scope of this brief overview to describeany of these experiments in detail. However, we will give afew of the many possible references, and encourage theinterested reader to seek them out because many of thetechniques used in these precision measurements are inge-nious extensions of, or substitutes for, familiar nuclearmethods in a very different regime. For example, whereelse has a decay Q value been measured with a voltmeter?

For half-life measurements, the most important experi-mental criteria are that the source be pure, the signal-to-noise ratio high, pulse pile-up eliminated, circuit dead-timecontrolled and appropriate statistical techniques used inanalysis. The most precise measurements have been madewith isotope-separated samples and a 4π gas counter todetect the positrons [9,10], although recently a precise mea-surement has been reported with a plastic-scintillator tele-scope [11].

Until recently, branching-ratio measurements were the leastexperimentally demanding of the quantities required forprecise ft values because most of the best known superallowed

MV C2 = 2(1 )− δ

Ft ftK

GR NS C

V RV

≡ + ′ + − =+

( ) ( )( )

1 12 12

δ δ δΔ

(4)

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transitions were from relatively light Tz = 0 parent nuclei,from which the superallowed branching ratios are typicallyvery close to 100%. In such cases, the intensity of the fewweak competing branches could be measured with modestprecision and subtracted from 100%, leaving the superal-lowed branching ratio determined with high precision [12].However, in the past decade it has become possible to studysuperallowed decays from heavier Tz = 0 parents (A ≥ 62),as well as from Tz = −1 parents. The former are plagued bythe so-called Pandemonium effect [13,14]: so many weakcompeting transitions that they are difficult, if not impossi-ble, to fully characterize. The latter offer competingGamow-Teller branches that are as strong, if not strongerthan, the superallowed branch, thus affording no shelterfrom a direct ±0.1% measurement on the transition of inter-est. In both cases, experiments focus on the beta-delayed γrays. With a combination of careful spectroscopy on thevisible γ rays and shell-model calculations to account forthose too weak to see, the Pandemonium effect appears tohave been overcome [15]; and the direct measurements ofbranching-ratios from Tz = −1 parents are inching closer andcloser to the 0.1% goal. In one case, the key was a γ -rayarray and alternating reactions to provide internal calibra-tion [16]; in another, it was a single HPGe detector that hadbeen painstakingly efficiency-calibrated to 0.15% [17].

Historically, the QEC value was the most challengingproperty of a superallowed transition to measure with suffi-cient precision. Because f depends on the decay energy tothe fifth power, these Q values have to be determined toabout ±0.01%, or ±500 eV for a 5-MeV β decay. Until lastyear, the only measurements to meet these standards wereof reaction Q-values, typically obtained from a (p, n) or(3He, t) reaction in which the β-decay daughter nucleus wasused as the target. For the (p, n) reaction (e.g., Ref. [18]), itsthreshold was determined with the target placed at the focalplane of a magnetic spectrometer and the incident protonbeam tightly constrained through the spectrometer by slits.Cesium ions from an ion source were later passed throughthe same slits, and the required accelerating voltage mea-sured against a 1-V standard in order to determine the orig-inal proton beam energy. In the case of the (3He, t) reactionmeasurements [19], two superallowed transitions werestudied simultaneously, with a composite target made up ofboth daughter nuclides, and the outgoing tritons were ana-lyzed in a magnetic spectrometer. A periodic voltage wasimposed on the target, causing the triton peaks to shiftbetween two positions on the focal plane. The voltage neededto overlap a peak from one reaction with an unshifted peak

from the other corresponded to the Q-value differencebetween the two reactions. This voltage was then measuredwith a precision voltmeter.

The whole situation has changed very recently as onlinePenning traps have begun to achieve astonishing precisionin atomic mass measurements. For the first time, it has nowbecome possible to measure parent and daughter massesindividually and obtain the difference between them to aprecision of a few hundred eV in light nuclei [20–22]. Thisis a very active research area at the moment, with a fewmeasurements published and numerous other ones inprogress or in the process of being published.

CVC Under the Microscope The top panel of Figure 1 shows the up-to-date situation

for the ft values of the superallowed 0+ → 0+ decays. Mostdata come from our recent survey [1] but we have alsoincluded new results that have been published since the sur-vey, or that we know to have been submitted for publication.

The middle and bottom panels of Figure 1 show the effectsof successively incorporating the correction terms shown inEq. (4): first the transition-dependent radiative term, (1+δ′R),and then the nuclear-structure-dependent one, (1+δNS – δC). Acomparison of these two panels shows how effective the struc-ture-dependent corrections are in removing the considerablescatter that is apparent in the ft values and is completely absentin the F t values. It is especially important to recognize that theorigins of the structure-dependent corrections are completelyindependent of the superallowed decay data; so the consis-tency of the corrected F t values is a powerful validation of thecalculated corrections used in their derivation.

The agreement among the F t values for transitions froma wide range of nuclei 10 ≤ A ≤ 74) is just what CVC led usto expect—but the extent of agreement is truly impressive!The data presented in the bottom panel of the figure yieldan average value of (F t)av = 3073.2(8) s, with a normalizedchi-squared of 0.94. Because F t is inversely proportional tothe square of GV, this result confirms the constancy of thelatter to a part in 104, the tightest limit ever set.

A second implication of the CVC hypothesis is that the“induced” scalar term in the vector part of the weak interac-tion must be zero. If this term were non-zero, it would man-ifest itself as a curvature, either upward or downward, inthe F t-value line at low Z. There is no hint of any such cur-vature in the bottom panel of Figure 1, and a careful analy-sis of the 2005 survey results confirmed the absence of anyinduced-scalar term at the level of 13 parts in 104, again thetightest limit ever.

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CKM Unitarity With a mutully consistent set of F t values, the test of

CVC is passed and we can confidently proceed to determin-ing the value of GV and, from it, the up-down element of the

CKM matrix, Vud. The procedure is straightforward and hasbeen described recently [1]: it incorporates some provisionfor possible systematic uncertainty in the nuclear-structure-dependent corrections and also employs the Particle DataGroup value for GF. The result is

where the contribution of experiment to the quoteduncertainty is only ±0.00007. The result in Eq. (5) is consistentwith, but considerably more precise than, other determina-tions of Vud obtained from neutron or pion decay. Both ofthese sources are free from the charge-dependent correc-tions that are a serious concern in nuclear β decay, but bothare fraught with experimental difficulties that have so farlimited their precision.

Unlike the 0+ → 0+ superallowed decays, neutrondecay includes axial-vector as well as vector contribu-tions. Thus, to isolate GV, not only a lifetime measurementis required, but also a correlation measurement to deter-mine λ, the ratio of axial-vector to vector coupling con-stants. Both measurements present serious experimentalchallenges—and serious issues in reconciling the results.For the neutron mean life, the Particle Data Group (PDG)[23] actually excludes the most recent gravitational trapmeasurement [24] because it differs by 5.6 standard devi-ations from the previous most precise result [25]; that waythey arrive at seven consistent measurements and aweighted average of τn = 885.7 ± 0.8 s. The PDG’s recom-mended value for λ is a weighted average of five results,not all mutually consistent, so they scale the uncertaintyby a factor of two, yielding λ = −1.2695 ± 0.0029. Fromthese results, the PDG obtains

Here the uncertainty is dominated by experiment—the cor-relation measurements—and furthermore, if the recent dis-crepant lifetime measurement had not been excised by thePDG at an earlier stage, experiment would have caused theuncertainty on Vud to increase even more.

Pion beta decay is a pure vector transition between twospin-zero members of an isospin triplet and is thereforeanalogous to the superallowed nuclear decays. Its majordisadvantage is that it is a very weak branch (~10−8) in thedecay of the pion and, even the recently completedPIBETA experiment [26], which succeeded in reducing the

10C

14O26mAl 34Cl

38mK42Sc

46V50Mn

54Co

tf

3090

3030

3040

3050

3060

3070

3080

74Rb22Mg

34Ar

Z of daughter

t

3070

3080

3090

3100

5 3025201510 353060

3100

3110

3120

3130

3140

3080

3090

tf)

+1(R’

62Ga

Figure 1. The uncorrected ft values for the 13 well knownsuperallowed transitions (top); the same ft values correctedonly for the transition-dependent radiative correction, d¢R(middle); and the fully corrected F t values (bottom). Thedifference between the middle and bottom panel illustratesthe effects of the nuclear-structure-dependent corrections,dC and dNS. The grey band in the bottom panel is the averageF t value including its uncertainty.

Vud = ±0 97370 0 00027. . , [nuclear] (5)

Vud = ±0 9746 0 0019. . , [neutron] (6)

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branching-fraction uncertainty by a factor of six, still onlyreached a precision of 0.5%. This experiment measured thebeta-decay branching fraction relative to the two-body π+

→ e+νe branch. Taking the precisely determined theoreticalprediction for the latter, the PDG obtains

where almost all the uncertainty comes from experiment. With the value of Vud currently coming entirely from the

dominant nuclear superallowed decays, we can now turn tothe two other matrix elements required for the CKM unitar-ity test presented in Eq. (3). The value of |Vub| is not knownvery precisely but, at (4.31 ± 0.30) × 10−3, it plays no statis-tically significant role when squared in the unitarity sum.That just leaves Vus, an element that has undergone majorupheaval in the last few years.

The value of Vus is mainly derived from the Kl3 decays,K0 → π−l +νl and K+ → π0l +νl, where the leptons l are eitherelectrons or muons. Prior to the 2004 Particle Data Groupcompilation [27], the accepted value for Vus contributed to aunitarity sum that was less than one by more than two stan-dard deviations, a nagging problem that has persisted forover a decade. Prompted by this discrepancy, a new roundof Kl3 experiments was undertaken, from which the resultshave now been published [28–31]. The new results, all con-sistent with one another, are 2.6% higher than the old mea-surements and yield f+(0) |Vus| = 0.2169 ± 0.0009, wheref+(0) is a form factor whose departure from unity is a mea-sure of the SU(3) symmetry breaking in the octet mesons.A number of calculations for f+(0) have appeared recently,but the one preferred by the PDG is an older result byLeutwyler and Roos [32], which has been corroboratedrecently by a quenched lattice QCD calculation [33]. Thisissue has certainly not been completely settled yet but, forthe time being, we follow the PDG in using|Vus| = 0.2257 ± 0.0021.

With the values just presented for all three matrix ele-ments, the unitarity sum becomes

where the first uncertainty is the contribution from |Vud|2,

the second from |Vus|2. It should be stressed, though, thatboth uncertainties are dominated by theory and not byexperimental precision. Clearly, unitarity is well satisfied

by the result. Even so, if we had adopted a different calcula-tion [34] for f+(0) in deriving Vus, the unitarity sum wouldagain have fallen short by two standard deviations. Thenagging problem has not entirely gone away.

Directions for the Future With CVC verified to high precision and CKM unitarity

in all likelihood satisfied, one could be forgiven for askingif any more work needs to be done on these questions. Havethe results described here now become material only for thetextbooks?

Not yet. Whether the unitarity sum is consistent withunity or not, its value and the uncertainty on that value setimportant constraints on physics beyond the StandardModel. Obviously, if the CKM matrix is shown not to beunitary, then we will know that new physics is definitelyrequired; but, even if the sum equals one, its uncertaintywill strictly delimit what new physics is possible. Both arefundamentally important outcomes! As long as improve-ments are possible in the unitarity sum, they will continueto have a significant impact on our understanding ofnature.

Certainly some of these improvements must comefrom theory because it is the theoretical correction termsthat currently dominate the uncertainty budget. Straight-ening out the SU(3) symmetry-breaking correctionrequired to extract Vus from kaon decay heads the list, butfurther improvements in Δv

R, the radiative correctionrequired for Vud, wousld have a significant effect on theoverall uncertainty too. Third in order of significance arethe nuclear-structure-dependent corrections, δC and δNS.So long as the 0+ → 0+ nuclear decays provide the bestaccess to Vud, these corrections will need to be tested andhoned. Here is where nuclear experiments can continue toplay a critical role.

The approach is best illustrated by Figure 1. We havealready noted in discussing that figure that the calculated cor-rections are seen to completely remove the considerable scat-ter present in the experimental ft values. This alreadyvalidates the calculations at the level of current experimentalprecision. However, improvements in experimental precisionwould test the calculations even more severely, as wouldnew cases of 0+ → 0+ transitions, specifically selected forhaving larger calculated corrections. The reasoning is that ifthe ft values measured for cases with large calculated correc-tions also turn into corrected F t values that are consistentwith the others, then this must verify the calculations’ reli-ability for the existing cases, which have smaller corrections.

Vud = ±0 9749 0 0019. . , [pion] (7)

V V Vud us ub2 2 2

0 9991 0 0005 0 0009+ + = ± ±. . . (8)

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In fact, the cases of 34Ar, 62Ga, and 74Rb, which have onlyrecently been measured, were chosen for this reason. Manymore are possible, either among the light even-even Tz = −1nuclei like 34Ar or among the heavier odd-odd Tz = 0 oneslike 62Ga. These new cases were inaccessible to precisionstudies in the past but, with the increasing availability ofradioactive beams, their time has certainly come.

Acknowledgment This work was supported by the U.S. Department of

Energy under Grant No.~DE-FG03-93ER40773 and by theRobert A. Welch Foundation under Grant No.~A-1397.

References 1. J. C. Hardy and I. S. Towner, Phys. Rev. C 71, 055501 (2005). 2. J. C. Hardy and I. S. Towner, Phys. Rev. Lett. 94, 092502

(2005). 3. A. Sirlin, Phys. Rev D 35, 3423 (1987); A. Sirlin and R.

Zucchini, Phys. Rev. Lett. 57, 1994 (1986). 4. W. Jaus and G. Rasche, Phys. Rev D 35, 3420 (1987). 5. I. S. Towner and J. C. Hardy, Phys. Rev. C 66, 035501 (2002). 6. W. J. Marciano and A. Sirlin, Phys. Rev. Lett. 96, 032002

(2006). 7. W. J. Marciano and A. Sirlin, Phys. Rev. Lett. 56, 22 (1986). 8. W. E. Ormand and B. A. Brown, Phys. Rev. C 52, 2455

(1995); Phys. Rev. Lett. 62, 866 (1989); Nucl. Phys. A 440,274 (1985).

9. V. T. Koslowsky et al., Nucl. Instrum. & Meth. In Phys. Res A401, 289 (1997).

10. G. C. Ball et al., Phys. Rev. Lett. 86, 1454 (2001). 11. P. H. Barker and A. P. Byrne, Phys. Rev. C 73, 064306 (2006). 12. E. Hagberg et al., Phys. Rev. Lett. 73, 396 (1994) 13. J. C. Hardy et al., Phys. Lett. B 71, 307 (1977); Phys. Lett. B

135, 331 (1984). 14. J. C. Hardy and I. S. Towner, Phys. Rev. Lett. 88, 252501

(2002). 15. B. Hyland et al., Phys. Rev Lett. in press. 16. G. Savard et al., Phys. Rev. Lett. 74, 1521 (1995). 17. J. C. Hardy et al., Phys. Rev. Lett. 91, 082501 (2003). 18. N. R. Tolich et al., Phys. Rev. C 67, 035503 (2003). 19. V. T. Koslowsky et al., Nucl. Phys. A 472, 419 (1987). 20. F. Herfurth et al., Eur. Phys. J. A 15, 17 (2002). 21. G. Savard et al., Phys. Rev. Lett. 95, 102501 (2005). 22. T. Eronen et al., to be published. 23. W.-M. Yao et al. (Particle Data Group), J. Phys. G 33, 1

(2006). 24. A. Serebrov et al., Phys. Lett. B 605, 72 (2005). 25. S. Arzumanov et al., Phys. Lett. B 483, 15 (2000). 26. D. Poani et al., Phys. Rev. Lett. 93, 181803 (2004). 27. S. Eidelman et al. (Particle Data Group), Phys. Lett. B 592, 1

(2004). 28. A. Sher et al., Phys. Rev. Lett. 91, 261802 (2003). 29. T. Alexopoulos et al. (KTeV Collaboration), Phys. Rev. Lett.

93, 181802 (2004); Phys. Rev. D 70, 092006 (2004). 30. A. Lai etal. (NA48 Collaboration), Phys. Lett. B 602, 41 (2004). 31. F. Ambrosino et al. (KLOE Collaboration), Phys. Lett. B 632,

43 (2006); Phys. Lett. B 636, 173 (2006). 32. H. Leutwyler and M. Roos, Z. Phys. C 25, 91 (1984). 33. D. Becirevic et al., Nucl. Phys. B 705, 339 (2005). 34. V. Cirigliano et al., JHEP 0504, 006 (2005).

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Double Beta Decay

PETR VOGEL Kellogg Radiation Lab., Caltech, Pasadena, California 91125, USA

Introduction In the last few years our understanding of neutrino intrin-

sic properties has expanded in a revolutionary and unex-pected way. The results of experiments with solar,atmospheric, reactor, and accelerator neutrinos are all (oralmost all) consistent and lead to the inescapable conclusionthat neutrinos are massive but very light particles and thatthey are mixed. By that we mean that the electron, muon, andtau neutrinos νe, νμ, ντ that are produced in the weak decaysare not particles with a definite mass (in fact, perhaps for thatreason we should not call them elementary particles at all),but rather superpositions of particles with a definite mass,usually just denoted ν1, ν2, ν3. And, unlike the analogousmixing involving quarks where the Cabibbo-Kobayashi-Maskawa unitary mixing matrix is nearly diagonal, the anal-ogous neutrino mixing matrix is nearly “democratic” witheight out of nine matrix elements almost equal in magnitude.These discoveries opened a window to the “Physics beyondthe Standard Model” and ultimately should guide us to for-mulation of a new more general theory that would includesuch phenomena together with all previous successes of theStandard Model. Despite these triumphs there are questionsthat ought to be answered before we might be able to formu-late such a new all encompassing theory:

• Are neutrinos Majorana particles or Dirac particles likethe other fermions?

• What is absolute neutrino mass (oscillation experimentssupply only mass squared diffences)?

• Is CP symmetry violated in the lepton sector? • Is there a relation between all of this and the baryon

asymmetry of the Universe?

Study of neutrinoless double beta decay could, and hope-fully will in a foreseeable future, help answering the firsttwo questions on the aforementioned list.

What is double beta (ββ) decay? ββ decay is a nucleartransmutation, typically involving the ground states ofeven-even nuclei (Z, A) and (Z + 2, A) in which two neu-trons are simultaneously transformed into two protons andtwo electrons (and perhaps something else). Such process is

potentially observable because even-even nuclei are morebound than odd-odd ones with the same number A of nucle-ons, as illustrated in Figure 1. The transition changing pro-tons into neutrons, with the emission of positrons or withelectron captures, is also possible as could be deduced fromFigure 1, but in the following we concentrate on the decaywith the emission of electrons. Note that the depicted situa-tion is not unique, there are eleven “candidate nuclei” pairs,analogous to the 136Xe → 136Ba ββ decay, with the Q value,that is available kinetic energy, in excess of 2 MeV.

There are two modes of ββ decay. In the 2νββ modetwo electrons and two electron antineutrinos are emittedsimultaneously, and in the 0νββ mode only the two elec-trons and nothing else is emitted. The 2νββ decay is a standardallowed process that does not violate any conservation laws,but it is very slow because it is a second order weak transition.It has been observed in a number of cases by now, with thetypical half-life of t1/2 ~1020 years. The sum-electron kineticenergy spectrum of the 2νββ decay is continuous, peakedbelow the midpoint of the Q value.

Figure 1. Masses of nuclei with 136 nucleons, with the y-axis shifted arbitrarily. The two faint parabolas connect theeven-even and odd-odd nuclei, respectively. 136Xe and 136Ceare stable against ordinary beta decay, but can decay byemission of two electrons (136Xe) or two positrons (136Ce).

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In contrast, the 0νββ decay violates the lepton numberconservation law that is a symmetry of the Standard Model.Hence, its observation would signal a presence of “newphysics,” namely that neutrinos are massive Majorana parti-cles, and it would answer the first question on the earlier list.That existence of the total lepton number violation and thestatement that neutrinos are massive Majorana particles areequivalent follows from the theorem initially formulated bySchechter and Valle years ago [1]. In view of this, the searchfor the 0νββ decay is among the top recommendations ofthe APS study of the future of neutrino physics [2].

Study of the ββ decay has a long history and went throughup and down periods of interest several times. The first esti-mate of the 2νββ decay rate was made by Maria Goeppert-Mayer [3] in her thesis under the guidance of Eugene Wigneralready more than seventy years ago. This was followed by thework of Furry [4] who realized that the phase space argumentsgive preference to the 0νββ decay. However, the discovery ofparity violation in weak interactions led to the realization thatthe 0νββ decay is possible only for massive neutrinos and thusis suppressed by the smallness of neutrino mass, and hencemuch more difficult to observe. Although this was considereda drawback fifty years ago, it is the main reason for the presententhusiasm for the search for 0νββ decay.

It took about 50 years since the calculation of Maria Goep-pert-Mayer [3] to observe the 2νββ decay in a laboratory [5].Why it took so long? The problem is that the 2νββ decay has acontinuous spectrum with energies similar to the natural radio-activity governed by half-lives ~1010 times shorter. Hence, theexperimental study of both modes of ββ decay is, first of all,an art of background suppression. At the present time, theobservation of 2νββ decay mode is more or less routine, andthe emphasis is on the search for the 0νββ decay with presentsensitivity to t1/2 ~1025 years, and attempts to extend it soon byone or two orders of magnitude. Many theorists believe thatneutrinos are massive Majorana particles, because that wouldmake it possible to understand the extreme smallness of theirmasses (~106 times lighter than the lightest charged fermion,the electron) without invoking unnatural fine tuning.

Double Beta Decay and Neutrino Oscillations The elementary amplitude of the 0νββ process involves a

six fermion vertex nn → ppee or on the quark level dd →uuee. The two initial neutrons and the two final protons arecorrelated. That correlation may be caused by a virtualexchange of the light Majorana neutrinos, the same neutrinosthat are observed in the oscillation experiments. However,that is not the only possibility. The transition may be caused

also by a virtual exchange of various as yet hypotheticalheavy particles, for example, heavy neutrinos, heavy inter-mediate bosons that could be responsible for the right-handed weak interactions, various supersymmetric particles,and so on. It turns out that this heavy particle exchange couldlead to potentially observable 0νββ decay if the heavy parti-cle mass is ~TeV. That is a mass range that will be exploredsoon with LHC. In addition, there appears to be a relationbetween the 0νββ decay (or lepton number nonconservationin general) and charged lepton flavor violation in processeslike μ → e+γ or μ conversion into e in nuclear field. Obser-vation of the lepton flavor violation in the forthcoming moresensitive searches could be used as a diagnostic tool for themechanism of the 0νββ decay [6].

Lets assume that the simplest scenario is the correctone, that is, that the 0νββ decay is caused by the exchangeof light Majorana neutrinos. In that case the decay rate is:

1/t1/2 = G0ν (Q,Z) |M0n|2<mββ>2,

where G0ν (Q, Z) is the easily and accurately calculablephase space factor, M0ν is the nuclear matrix element, dis-cussed later, and <mββ> is the effective neutrino Majoranamass, the quantity that we would like to determine. <mββ>depends on the absolute neutrino masses, on the mixingangles, and on new and totally unknown so-called Majo-rana phases through the relation

<mββ> =Σ |Uei|2 mie

iα(i)

Here Uei are matrix elements of the first row of the neutrinomixing matrix, mi are the masses (nonnegative) of the neu-trinos νi and α(i) are the Majorana phases that cannot bedetermined in the neutrino oscillation experiments(α(i) ≠ 0,π signifies CP violation).

Thus, if the 0νββ decay rate can be measured, and<mββ> determined, we will have an important constraint onthe absolute neutrino mass. (From oscillation experimentsone can determine only the mass differences Δmij

2 = mi2 −

mj2). The other well-known probe of neutrino mass is the

shape of the β spectrum in tritium β decay that involves thequantity <mβ>2 = Σ |Uei|2 mi

2 and is independent on theMajorana (or Dirac) nature of the neutrinos. In addition,from the study of the cosmic microwave background,galaxy surveys and other cosmological/astrophysical data,one can determine or constrain the sum of neutrino massesM = Σmi. The relation between <mββ> and these otherobservables is illustrated in Figure 2.

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One can see that for the so-called inverted hierarchy,that is, when m3 < m1 < m2 the effective mass <mββ> isalways finite, and larger than about 20 meV (~10 meVwhen the error bars are included). Above ~50 meV the twohierarchies result in indistinguishable value of <mββ> andthe corresponding mass pattern is degenerate, that is,mi >> (Δmij

2)1/2 for all i and j. If the hierarchy is normal,m1 < m2 < m3, the quantity <mββ> might vanish even thoughall three neutrinos νi are massive Majorana particles. How-ever, to have <mββ> = 0 in that case implies either a finetuning or some as yet unknown additional symmetry.

Nuclear Matrix Elements Clearly, if the goal is a determination of the effective

mass <mββ> then any uncertainty in the nuclear matrix ele-ments M0ν causes a corresponding uncertainty in <mββ>.

Unfortunately, the nuclear many-body system does not allow(at least not now) exact solutions, and approximations mustbe used. There are two common methods used in the evalu-ation of M0ν, the quasiparticle random phase approximation(QRPA) and the nuclear shell model (SM). They representalmost opposite extremes in the approximations used. InSM only a narrow interval around the Fermi level (one shellor less) can be used, but all (or almost all) configurations ofthe valence nucleons are included, in QRPA an arbitrarynumber of single particle states can be included, but onlysimple particle-hole (or two-quasiparticle) configurationsand their iterations are included. Because QRPA is muchsimpler computationally, most of the published calculationsuse that method or its modifications. The issues involvedare reviewed in Refs. [7,8].

Alas, the published results often do not agree with eachother. If we were to use the spread of calculated values ofM0ν as a measure of uncertainty, as some people suggest,we would have to conclude that the error in M0ν is quitelarge, a factor of 3–5. What is causing such a large spreadin calculated M0ν within QRPA and its modifications?There is a lively debate among the practitioners on this sub-ject (see, e.g., Refs. [9,10]). Some of it is related to thechoice of the parameters of the effective hamiltonian. Mostof it, however, is caused by including (or not) correctionsfor the short range nucleon-nucleon repulsion and inducedweak currents (primarily pseudoscalar). In any case, thespread of calculated values is not a good measure of uncer-tainty. Instead, a consensus should be reached, and justi-fied, on the proper way of treating these and other effects;the true uncertainty caused by the uncertainties inherent toQRPA and related to the input explicit and implicit parame-ters is considerably less.

When using the M0ν of [10] we conclude that in order toexplore the degenerate neutrino mass region one needs toreach sensitivities to t1/2 ~1026–27 years, corresponding toexposure of several hundred kg-years with negligible back-ground. And, in order to explore the inverted mass hierar-chy region, one would need 1–10 ton-years exposure.

Near-Term Prospects At present, the most sensitive experiments used

enriched 76Ge. The Heidelberg-Moscow [11] and IGEX[12] experiments used ~10 kg of the source each andreached a lower limit t1/2 > 1.9 × 1025 years [11] based on~70 kg-years exposure. Subsequently, a subset of theHeidelberg-Moscow collaboration reanalyzed the data

Figure 2. The relation between the effective neutrino mass<mbb> and other absolute neutrino mass relatedobservables. mmin is the mass of the lightest neutrino,M=Σmi is the sum of neutrino masses, constrained ordetermined by “observational cosmology,” and <mb> isobservable in b decay. Shaded bands are for the best valuesof Uei, lines include the 95% CL errors. The width of theshaded bands reflects the uncertainty related to theunknown Majorana phases. The dashed blue vertical linesin the second and third panel indicate the anticipated limitsin sensitivity of the planned experiments. The horizontal redlines are explained in the text.

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obtained in the experiment, and concluded that the peak atthe Q-value corresponding to the 0νββ decay is in factpresent, and determined the half-life as t1/2=1.5+7.55

0.71×1025 y[13]. If that claim could be independently verified, wewould have to conclude that the neutrino mass pattern is thedegenerate one (see the red horizontal lines in Figure 2).Clearly, such an extraordinary claim requires detailed scru-tiny, and eventual independent verification. Several experi-ments are poised to not only accomplish that (and if truereduce the error bars substantially), but to explore fully andindependently of each other the degenerate neutrino massregion.

Four proposed experiment, CUORE, EXO, GERDA,and Majorana hope to reach sensitivity to 0νββ decay half-life near or in excess of 1026 years, an improvement byabout an order of magnitude. This is accomplished byincreasing the mass of the sample to ~100 kg and at thesame time decreasing the background per unit mass accord-ingly. All of them are also potentially scalable to a ~tonsize experiments, provided the envisioned background sup-pression is achieved in the first phase. The results areexpected by ~2010. (There are other proposed experimentsbut these four seem to be most advanced.)

Thus, within this decade, we should be able to fullyexplore the degenerate neutrino mass region, <mββ> > 50–100 meV. The strength of this program is based on usingseveral different methods and different candidate nuclei,

thus reducing the dependence on the nuclear matrix ele-ments and systematic errors. If the 0νββ decay is found inthis phase, we would have answers to the first two ques-tions listed in the Introduction. If not, larger, ton-sizeexperiments are needed. The experience gained with the~100 kg experiments will then serve as a guide for theselection and funding of those even more challenging tasks.

References 1. J. Schechter and J. W. F. Valle, Phys. Rev. D 25, 2951 (1982). 2. APS study on the future of neutrino physics, http://arxiv.org,

physics/0411216. 3. M. Goeppert-Mayer, Phys. Rev. 48, 512 (1935). 4. W. H. Furry, Phys. Rev. 56, 1184 (1939). 5. S. R. Elliott, A. A. Hahn, and M. K. Moe, Phys. Rev. Lett. 59,

2020 (1987). 6. V. Cirigliano, A. Kurylov, M. J. Ramsey-Musolf, and

P. Vogel, Phys. Rev. Lett. 93, 231802 (2004). 7. S. R. Elliott and P. Vogel, Ann. Rev. Nucl. Part. Sci. 52, 115 (2002). 8. S. R. Elliott and J. Engel, J. Phys. G30, R183 (2005). 9. V. A. Rodin, Amand Faessler, F. Simkovic, and Petr Vogel, Phys.

Rev. C68, 044302 (2003); Nucl. Phys. A766, 107 (2006). 10. O. Civitarese and J. Suhonen, Nucl. Phys. A761, 313 (2005);

Phys. Lett. B626, 80 (2005). 11. H. V. Klapdor-Kleingrothaus etal., Nucl. Phys. A694, 269 (2001). 12. C. E. Aalseth et al., Physics of Atomic Nuclei 63, 1225 (2000). 13. H. V. Klapdor-Kleingrothaus, O. Chkvoretz, I. V. Krivosheina,

and C. Tomei, Nucl. Instr. Meth. A511, 355 (2003) and addi-tional references therein.

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The Rationale for Nuclear Energy: A Canadian Perspective

J. S. C. (JASPER) MCKEE Department of Physics and Astronomy, University of Manitoba, Winnipeg MB R3T 2N2 Canada

Nuclear science is a young science, less than a hundredyears old, but the one that may in the end save the worldfrom self-destruction; particularly if James Lovelock’sGaia Hypothesis is correct[1]. The current reliability,safety, life-capacity, and overall capability of nuclearpower reactors signify that here hangs the key to a securefuture for society including energy availability, predictablefuel costs, and a non-toxic environment.

If it is energy you want, it is electricity that you need!Electricity for your comfort at home, for the expansion ofyour industry or business, and your communication with acomplex and eclectic global market place. It is of courseessential that the electrical source be continuous in opera-tion, and reliable in performance.

As outlined in Ref.[2] only three energy sources meetthis need today, namely fossil fuels, hydraulic power, andnuclear energy. The purpose of this article is to demonstratethat the only complete baseload solution lies with thenuclear option.

It is of course a fact of life that many in society are sus-picious and skeptical about most advances in scientificunderstanding and technology. Because this is so, it isincreasingly important that scientists and physicists in par-ticular explain and quantify realistically the significanceand value of new discoveries as they appear, and act asinterpreters of science to the community at large.

It may be useful to recall that for a time in the earlynineteenth century organized teams of craftsmen existedwho destroyed textile machinery in a vain attempt to haltthe development of industrialization and technology. Themovement began in England, and the activists issued warn-ings and proclamations in the name of their mythical leaderNed Ludd, or “King Ludd” of Sherwood Forest. The nameLuddites stuck, but the movement never spread effectivelyto other countries, although in France, certain workers inthe shoe industry threw their wooden shoes, sabots, into themachinery to damage the equipment; an act that led to thenew word “sabotage.” So, with this historical footnote asbackground, the advent of a comparatively recent Internetwebsite for Luddites-on-Line, must be seen as the most

oxymoronic means of communication ever invented, andwe, as scientists, must wonder at the absence of “innova-tion-on-line” or “inventors-on-line”; alternative addressesthat might draw attention to the latest advances in technol-ogy and reflect the ever growing optimism of science.Instead we find wishful ostriches and nostalgic dreamers of“the good old days” cluttering the network while those whobelieve in a limitless future for science and technologylargely ignore the value of a medium that they themselveshave created. Physicists for one reason or another havenever been so complacent in relation to their impact onsociety as at the present time.

In reviewing the three energy sources mentioned earlierthe first fact to note is that fossil fuels emit large quantitiesof greenhouse gases into the atmosphere, particularly car-bon dioxide, the leading contributor to climate changeaccording to the Intergovernmental Panel on Climatechange of the United Nations Environmental Program(1988). The burning of fossil fuel also produces sulphurand nitrogen oxides, which add acid rain to the fly ash andradioactive emissions from coal-fired power stations.

Water generated “hydro” power at less than 10% of theworld’s current energy supply, has little opportunity toincrease in Canada. Most of the resource in Ontario, Que-bec, and British Columbia is already harnessed, and Mani-toba, apart from two major projects on the Nelson River,has already delivered on its promise. Flooding large areasof land above a hydro dam can be an environmental andsocial challenge because of loss of forest, habitat, fertileland, and the displacement of population to make way forpower generation, so the societal impact of hydro develop-ment can be considerable. It has also been demonstratedthat greenhouse gas emissions from biological decay due tosuch flooding can be similar to those from a coal-firedpower station over a 25-year period.

Nuclear Power plants, on the other hand, release no pol-lutants to the atmosphere. They do not contribute to globalwarming, smog (smoke and fog), or acid rain. On the con-trary, Canada’s existing nuclear plants avoid the emissionof 100 million tons of CO2 per year that would result from

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fossil fuel burning as an alternative. In addition, the foot-print of a nuclear station is small and a plant benefits frombeing sited close to a major center of population. Thisremoves the local need for long electrical transmission linesfrom generator to consumer base.

The Timely Renaissance of Nuclear Power Nuclear power plants currently provide around 20% of

the world’s total electricity production. However, the situa-tion will change because the only way to meet an increasingdemand for electricity, while cutting both the emission ofgreenhouse gases and dependency on oil from the MiddleEast, is to build more nuclear-generating plants.

Canada has had the most effective program in the West-ern world in terms of electricity produced for nuclearresearch dollars spent. From 1952 to 1992, the federal gov-ernment invested $4.7 billion in nuclear research, and dur-ing this time, the nuclear industry contributed at least $23billion to Canada’s gross domestic product (GDP). Cur-rently, Canada’s nuclear industry provides a $6 billionstimulus to the GDP per year and generates more than30,000 Canadian jobs, many of them in the high-tech area,in support of this program. A great social benefit also lies inthe clean air resulting from nuclear power and the resultantgain in human health and environmental protection thatCanadians can enjoy. This is at the core of this article. Also,the improved safety and reliability of nuclear reactorsworldwide is having a significant impact. In the UnitedStates, for example, where the average capacity factor forlarge reactors was 58% in 1980; by 1990 it had increased to66%. Now it has actually leveled off at 90% and it wouldbe imprudent to take it higher because maintenance has tobe done. So, operating nuclear power stations is becoming anormal business and a welcome one.

It is also worth noting that in the United States in partic-ular, although no new plants have been built since 1990, theimproved performance of existing plants between 1990 andtoday has produced an increased output equivalent to thebuilding of 19 new 1,000 MW(e) Megawatt (electric) reac-tors. This is a dramatic figure. In the same context, a coupleof salient facts of a global nature are worth mentioning.Nuclear plants have been generating electricity now for halfa century, with almost 8,000 reactor years of experience.France relies on nuclear power for almost 78% of its elec-tricity (2005); Sweden, 45% Belgium, 55% Switzerland,40% Japan, 34% and Ontario Canada, 55%. In not one ofthese jurisdictions has there ever been one nuclear-relateddeath or injury related to a commercial nuclear power

generator, and it is widely accepted that the statistical like-lihood of dying in a nuclear accident is about the same asbeing hit by a meteorite—virtually nil. It is interesting tonote that the eminent physicist, Bernard Cohen, has statedthat coal pollution causes 10,000 deaths per year in theUnited States, compared to none for nuclear; so we areweighing the low potential for death from nuclear againstthe certainty of deaths from coal. Also, nuclear power con-tinues to be a competitive choice for new plants in centrallycontrolled electricity markets such as Japan, China, andSouth Korea.

Of course, deregulation, the opening of electricity mar-kets to competition in many developed countries, has givennatural gas–fired plants a momentarily competitive edgeover nuclear power. This is because natural gas plants havea capital cost that is at present about half that of a nuclearplant with the same output. As a result, natural gas–firedplants have shorter payback periods and higher financialreturns for investors. However, future natural gas prices arevery uncertain, and this risk may not be offset by the shortpayback period of such plants. Nuclear plants, on the otherhand, have a lower overall average electricity cost overtheir operating lifetime due to their lower operating cost,although the payback period here may be significantlylonger than for a natural gas–fired plant.

The challenge currently facing the nuclear industry istherefore to reduce nuclear plant capital costs by about25%. It is believed that this target is already reached for theadvanced new generation CANDU plant, the ACR 1000[3],and development work is currently under completion. So in2006 the renaissance of and green-ness of nuclear power issuddenly evident, and we will all benefit from this fact.

In comparing the future of fossil fuel vis à vis nuclearpower generation it is useful to examine the environmentalimpact of the construction of a 700 MW(e) coal and a 700MW(e) nuclear power station. Table 1 shows a comparisonof both, and includes the fuel consumption in tons, thewaste products due to stack emissions, residues of combus-tion and distributed ash deposits. It should also be notedthat one hundred tons of fuel per year for a natural uraniumplant would be of the dimensions of a laboratory filing cab-inet, the density of uranium being 19,000 kg/m3. This is truefor metallic uranium, but the actual fuel used is UO2, whichhas a density of about 10,900 kg/m3. This volume should becompared with the 1.75 million tons of coal required for thefossil fuel–based utility. It is also noted that the waste prod-ucts from the coal-fired power station are huge, comprisinggases going up the stack, metals left in the soil, and very

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significant emissions of carbon dioxide. Also, because fuelis a relatively small fraction of the total energy cost ofnuclear power compared to gas, the fluctuations in the costof nuclear fuel are likely to be insignificant compared withoil, gas, and coal as time moves along.

That even the greatest physicists are not always thegreatest visionaries must be evident from the followingremark, attributed to Ernest Rutherford: “The energy pro-duced by the breaking down of the atom is a very poor kindof thing. Anyone who expects a source of power from thetransformation of these atoms is talking moonshine.”

We, however, who live in the twenty-first century, nowknow better. Nuclear power is an integral part of life inCanada, and essential to Ontario. But similar statements tothat of Rutherford are now heard in relation to the useful-ness of renewable resources, and much mythology sur-rounds the economic and environmental appropriateness ofsuch energy sources and technologies. It is therefore impor-tant to assess realistically their value in each instance, andwith the prohibitive capital cost of some (wind machines)and the fluctuating fuel costs of others (gas and oil in par-ticular), the real benefits of nuclear power become apparent.

Assessing Various Energy Sources In order to assess the relevance of various potential

sources of energy it is important to understand the basicfundamental laws of thermodynamics, and to use them asyardsticks in making any such assessment. When the sci-ence of thermodynamics followed the invention of thesteam engine a century later, three important laws wereidentified that are reproduced in the following list in a wellknown but anonymous form that should be brought to theattention of all who would gamble with energy resources:

1. You cannot win. 2. You cannot break even. 3. You cannot get out of the game.

The first law, basically the principle of conservation ofenergy extended to heat, tells us that it is impossible toextract more work from a system than the energy availablewill allow.

The second law tells us that the situation is worse thanthat. No process is possible whose sole result is to convertheat completely into work. It is possible also to note the dif-ference between degraded energy and useful energy. Twobeakers of water at different temperatures, for example, canbe used to operate an engine between the two temperatures.The efficiency of the engine will be determined by applica-tion of the second law. Also, two identical beakers of waterat a common temperature with the same total energy con-tent will on the other hand be incapable of operating anengine between them. The energy in this case is degradedand no longer thermodynamically useful. A further impor-tant point to note is that the flow of heat is irreversible.There is nothing in the first law that forbids heat flow froma cold beaker to a hot beaker, so long as the total energyremains constant. Nature, however, has arranged it differ-ently, and heat flows only from the hotter to the colderbody.

The third law states that it is impossible to reach theabsolute zero of temperature in a finite number of opera-tions, so the extraction of heat from a system has a built-inand fundamental limitation.

In taking a realistic look at the overall usefulness ofenergy sources we also find that, perhaps unexpectedly,energy density and transformation are not all-important,whereas energy flux certainly is. The important relation,P = UVA, where P is the maximum power available, U isthe energy density, V is the velocity, and A the area ofworking surface, serves to illustrate this fact. In this for-mula, physics limits the product UV, whereas economicslimits A. Kapitza [4], illustrated the usefulness of thisformula by assessing the power available from a wind-mill with four sails of total area 80 m2 in a wind veloc-ity of 10 ms−1. As the wind energy is kinetic in thiscase, and air has a density of 1gl−1, U=50 Jm−3, soPmax = 50 × 10 × 80 = 40 kW. An output of 2000 MW, forcomparison with a nuclear power station located typicallyon a 2 km2 site in Canada would require at least 50,000 suchwindmills. According to a prescription given by theNational Research Council of Canada, this number of

Table 1. Environment impact.

Coal Nuclear

Capacity (MWe) 700 700

Fuel (tons) 1,750,000 100

Waste Products

CO2 (tons) 4,200,000 0

SO2 and NO2 (tons) 80,000 0

Toxic metals (tons) ~150 0

Used fuel/ash (tons) 600,000 100

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feature article


windmills would cover a ground area of at least 4000 km2.It is not out of the question to use solar/wind energy in thisway, but whether the solution is environmentally andsocially acceptable or not would depend on local conditionsand in particular the availability of land.

Application of the formula, P = UVA, to other problemsrelated to solar energy conversion can be quite revealing. Itis found in the case of fuel cells, for example, that althoughthe chemical energy of hydrogen oxidation can be directlytransformed into electrical energy with 70% efficiency,there is a very low diffusion rate in electrolytes and there-fore the product UV is small. Indeed, the maximum poweravailable seems to be limited to 200 W for a 1 m2 electrode.

2000 MW would therefore require more than 10 km2 ofelectrodes—a formidable fuel cell system indeed. The sameis also true of the direct biophysical transformation ofchemical to mechanical energy. Here again, flux density islow because of the low rate of diffusion processes acrossmembranes and muscle fiber.

As physicists, who understand all about energy conser-vation, conversion efficiency and flux density, it is almostinstinctive to reject a process whose efficiency is low, asbeing worthless and useless. The first and second laws ofthermodynamics impose a limit on the efficiency of such aprocess through the relationship, η = 1-TC/TH, where η isthe process efficiency, TC and TH the temperatures of thecold and hot reservoirs, respectively. η therefore isregarded as a figure of merit and if it is small it is normal toreject the process. However, even when this quantity issmall, the relevance of the system may be great, particu-larly if it makes use of a readily available and otherwiseuntapped source of energy such as available sunlight. Thereis therefore no reason why humankind should feel weddedto any one particular source of energy or look for a uniquesolution to the energy problem. Assessment of the useful-ness of each energy resource, whether it be solar, tidal, geo-thermal, nuclear, or water power, must involveconsideration of social, regional, political, and economicfactors in addition to the pure physics of the situation. InCanada, wind power is at present viable in the Gulf of St.Lawrence River, on the shores of Hudson’s Bay and at theborder between Alberta and Montana, whereas south Mani-toba and southeast Saskatchewan have a level of solar inso-lation almost equal to that of northern California andArizona, and the prospects of solar electrical power are sig-nificant there. Some provinces are almost self-sufficient inwater power, others in oil. The same diversity can be foundin Europe, where mountain valleys already store water

which has both fallen as rain and been pumped there forstorage of excess nuclear power.

Tidal power is clearly available off some coasts, but notoff others. It therefore seems that the best solution to theenergy problem is to define a mix of energy resources, themix being related to socioregional factors in addition to thephysical usefulness of each system. We should also not for-get that the sun is a self-controlling nuclear fusion reactor,and a part of our environment that we cannot exclude. Itallows us to live and prosper but, unlike the traditional oillamp, we cannot turn up its wick as and when we wish. It isnonetheless a key component of our present and our future.The time-averaged power density from the sun across thesurface of the earth is about 300 watts per square meter, andin principle enough to provide over 200,000 times our aver-age energy needs. The problem is, however, that solar radi-ation cannot be made available at a whim, or at aconcentration appropriate to a particular task.

Firstly, 50% of all solar thermal radiation is reflected orabsorbed by the earth’s atmosphere. Secondly, there areproblems in utilizing solar radiation because of the ineffi-cient conversion of the energy into other forms (e.g., elec-tricity) the intermittent nature of the supply (weather), andthe fact of nighttime. Thirdly, in the absence of an adequatestorage system for solar energy, most of it will continue tobe wasted.

The physicist likes to sum quantities, so it is perhapsappropriate to summarize the argument as follows:E = ΣN

i = Iε1, where ε is an energy resource that may contrib-ute to the need and N is a significant number. There isclearly not one particular road to salvation. However, thenuclear option is certainly favored, as an environmentallyclean, reliable, and versatile source of electricity for thebenefit and quiet enjoyment of modern society.

Summary and Conclusion In order to solve burgeoning electricity supply prob-

lems, Ontario and Canada must maximize conservationand build on its potential in the future, pursue an aggres-sive course for renewable sources within current physi-cal and economic constraints, while looking at ways toreduce these constraints. Adopting a strategy that takesadvantage of the benefits of natural gas–fired generationmust limit exposure to its price and supply risks, as willbe the case for supply options that need long lead times,such as nuclear, large-scale wind generation and hydroimports.

feature article


Ontarians, for more than thirty years, have acceptednuclear power to supply the larger part of their electricityproduction. It peaked in the early 1990s at two-thirds ofproduction, but in the absence of refurbishment of the exist-ing fleet, and any immediate prospect of “new-build,” theoverall problem has now become exacerbated, and the needfor new nuclear is being combined with a societal wish forthe close-down of existing polluting, coal-fired, generatingstations perhaps as early as 2009.

From the financial point of view, the cost of electricityfrom nuclear plants, which incidentally includes decom-missioning of a plant and the management of used fuel, isalready in 2006 comparable with electricity from coal-firedplants, and much lower than that from gas-fired plants.Also, major advances in CANDU technology over the pastthirty years have enabled the capital cost of future powerplants to be reduced. Experience with building flagshipCANDU-6s in South Korea, China, and Romania over thepast decade or so has made this possible, as has the licens-ing and construction of the next generation, AdvancedCandu Reactor [ACR], with greater power capability, andother economic and safety features.

Also, because of the low fuel costs in the nuclear case,the operating costs of nuclear plants will remain belowthose of gas-fired plants for the foreseeable future. It hasbeen noted that one contemporary CANDU fuel bundle10 cm in diameter and 50 cm long can provide the electric-ity consumed by the average household for about 100years. However, as current reactors fission only one percentof the nuclear fuel, an enormous amount of energy remainsin the used bundles, and within a century it is believed thatit will be economical to build new advanced reactors thatwill recycle our “used” fuel (used, but not spent!).

The immediate future of nuclear power generation inCanada is not as yet entirely clear, but it is believed that latein 2006, Ontario will move forward with new-buildnuclear, throwing its weight behind the assessment andcommissioning of the first of a new generation of CANDUreactors, specifically the ACR 1000. This new power gen-erator retains many of the basic proven features of theCANDU-6 fleet, but exhibits many improvements, includ-ing 50% more power than a CANDU 6 from the same sizecore with enhanced passive safety. It will also require onlyone shutdown for maintenance every 3 years, and isdesigned for rapid pressure tube replacement (after 30years), with a lifetime capacity factor of 93%. This reactorwill also—and this is important—withstand grid failures;

remaining in standby mode to supply power once the grid isrestored. Nuclear power can therefore provide a sound eco-nomic future, in a sustainable clean environment, for anycountry taking appropriate advantage of the mature tech-nology involved.

And finally, as Murray Elston, the President and CEOof The Canadian Nuclear Association, has recently writ-ten[2]: “Affordable electricity has helped make Canada apowerhouse among the world’s nations. A reliable supplyof electricity, supplied at low cost, has led to a high stan-dard of living and a competitive economic edge. Nuclearenergy is a vital part of that electricity system.” Becauseuranium contains many thousands of times more energyper unit of weight than fossil fuels, the waste from anuclear power station is very small in volume and is fullymanaged. Unlike fossil-fueled plants there is no ash orsimilar waste product that sometimes ends up in landfill.Nuclear waste is not sent into the atmosphere. It has beensafely and securely stored and managed at reactor sites forover 40 years, and plans for eventual permanent deep geo-logical disposal when appropriate are being developed andexplored at the present time. All in all, the future fornuclear power generation is bright, and the global environ-ment will benefit from it.

References 1. James Lovelock, Speech to the Canadian Nuclear Society

Conference, Ottawa, March 10, 2005. 2. Nuclear Power Generation, Canadian Chemical News. 57, 8,

2005 and references therein. 3. D. Torgerson, Editor, The Advanced CANDU Reactor, Phys-

ics in Canada, November/December 2004. 4. Pyotr L. Kapitsa, in the New Scientist, October 1976.

JASPER MCKEE

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facilities and methods


The initial stage of the ISAC-IIupgrade consisting of the installa-tion of a heavy ion superconductinglinac has been successfully commis-sioned. This milestone makes possi-ble the acceleration of radioactiveions above the Coulomb barrier. Inbrief, the ISAC (Isotope Separatorand Accelerator) facility[1], opera-tional since 1998, includes a 500MeV proton beam (I ≤ 100 μA) fromthe TRIUMF cyclotron impingingon one of two thick targets, anonline source to ionize the radioac-tive products, a mass-separator, anaccelerator complex, and experi-mental areas. The original accelera-tor chain includes a 35 ~ MHz RFQ,to accelerate beams of A/q ≤ 30 from2keV/u to 150keV/u and a post strip-per, 106 MHz drift tube linac (DTL)to accelerate ions of 3 ≤ A/q ≤ 6 to afinal energy fully variable from0.15 MeV/u to 1.5 MeV/u primarilyfor nuclear astrophysics investiga-tions. The ISAC-II initiative isintended to increase the energyrange above the Coulomb barrier. Aswell an ECR-based charge statebooster will be installed in the lowenergy area to increase the availablemass range of the accelerated iso-topes from 30 to at least 150.

An achromatic transfer line trans-ports the beam from ISAC to theISAC-II accelerator vault. The super-conducting linac is composed of bulkniobium, quarter wave, rf cavities,for acceleration, and superconductingsolenoids, for periodic transversefocussing, housed in several cryo-modules. The linac is grouped intolow, medium, and high beta sections.The initial five medium beta cryo-modules described in this article rep-

resent a first stage (Stage 0) with afurther 20MV of high beta supercon-ducting linac to be installed over thenext three years (Stage 1). The ISAC-II accelerator final low beta Stage 2 isforeseen after 2010. A schematic rep-resentation of the expansion is givenin Figure 1.

Many new projects are now beingdiscussed involving a new generationof low beta (5–15%) superconductinglight and heavy ion linacs includingRIA, EURISOL, SPIRAL-II, SOREQ,and REX-ISOLDE. The short, inde-pendently phased cavities provide aflexible, large acceptance machine tosupport a varied nuclear physics pro-gram. Present initiatives take advan-tage of the early developments,production, and operation of niobiumcavities at ATLAS, INFN-LNL, andJAERI. The technology has advanced,spurred by these pioneering labs, andthe parallel developments in the ellip-tical cavity community, to the pointthat high-quality cavities are nowavailable in industry and offer thesmall and medium size labs the ability

to choose superconducting rf technologywithout the added burden of develop-ing an in-house cavity productionexpertise. On-line continuous-wave (cw)operation has been limited historically topeak surface fields of 20–25 MV/m.The new projects are attempting totake advantage of the lessons learnedover the past twenty years and pushthe cw gradients to minimize projectcosts and/or improve facility perfor-mance. The TRIUMF ISAC-II super-conducting linac is the first realizationof this new-generation facility with adesign goal to operate at a peak sur-face field of 30MV/m.

The present installation consistsof twenty 106 ~ MHz quarter wavecavities.

The cavities, originally devel-oped at INFN-LNL[2], consist ofonly two accelerating gaps giving abroad velocity acceptance. Severaldesign and hardware choices weremade in an effort to reach the gradi-ent goal.

The high peak surface field demandsclean rf surfaces so clean assembly

Stage 2

Stage 1

Stage 0

HEBT1−Exp.

HEBT2−Exp.

S1

IH−DTL2

MEBT2

E=0.4Mev/u

S2Low β Mesium β

E=1.5Mev/u

MEBT1 1H−DTL1

A/q≤6E=0.15-1.5Mev/u

High β

3≤A/q≤10 E=6.5Mav/u (A/q=7)

Figure 1. Stages 0, 1, and 2 for the ISAC-II upgrade.

1

2



methods and cavity rinsing wereadopted. The large stored energyrequires an rf system capable of achiev-ing stable performance so a liquid nitro-gen cooled coupling loop and newmechanical tuner were designed. A linaclattice consisting of modules of fourcavities with a single high field (9T)superconducting solenoid in the centeris adopted to compensate the higher rfdefocussing fields. Also unique is theuse of unshielded high field solenoidswith added canceling coils operating inclose proximity to the cavities[3].

All cavities are characterized viacold test in a single cavity test cry-

ostat prior to mounting in the cryo-module[4]. Prior to installation alltwenty cavities met or exceededISAC-II specifications for frequencyand performance. At 7 W rf powerthe average peak surface field forthe cavities is 38 MV/m and corre-sponds to a gradient of 7.6 MV/mand a voltage gain per cavity of1.4 MV. The cryomodule assemblyand commissioning off-line tests areconducted in the clean laboratoryarea in the ISAC-II building. Eachmodule has two main assemblies,the top assembly and the tankassembly. The top assembly shown

in Figure 2 includes the vacuum tanklid, the lid mu-metal, and thermalshield cooled by liquid nitrogen(LN2), the cold mass, and the coldmass support. The tank consists ofthe vacuum tank, the mu-metal liner,and the LN2 box insert.

A 500 W class refrigerator andcold distribution are installed todeliver liquid helium and liquidnitrogen to the new linac. The fivemodules, injection line, and down-stream transport line were installedby the end of March 2006. A view ofthe final vault installation is shownin Figure 3.

Acceleration commissioning isdone using stable beams from theISAC off-line ion source. The beamsare accelerated to 1.5 MeV/u andtransported to ISAC-II via a 25 m S-bend transport line. Accelerationcommissioning runs are scheduledbetween experimental physics beamdelivery periods with a frequency ofabout once per month. A silicondetector 4 m downstream from thelinac monitors ions back scatteredfrom a thin gold foil. The monitor isused for cavity phasing and energymeasurement. A time of flight moni-tor also in the downstream beamlineis used for more precise energy mea-surement. Six different beams havebeen accelerated to date correspond-ing to three different mass to chargeratios; 40 Ca10+, 22 Ne4+, 20 Ne5+,12 C3+, 4 He1+, and 4 He2+ with A/q ratios of 5.5, 4, and 2. Finalachieved energies are shown in Fig-ure 4 (b) compared to expected finalenergies assuming the design gradi-ent of 6 MV/m. Final energies of10.8, 6.8, and 5.5 MeV/u are reachedfor beams with A/q values of 2, 4,and 5.5, respectively. The averagecavity gradients for the three casesas calculated from the accelerationFigure 2. ISAC-II cryomodule top assembly.

2



rate are shown in Figure 4(a). Theaverage gradient in each case is7.2 MV/m corresponding to an aver-age peak surface field of 36 MV/mand an average voltage gain of1.3 MV/cavity. Single cavity rf testresults for each cavity are plotted forcomparison.

The average operating gradient isdown by only 5% from the singlecavity result. Furthermore, over thefirst three months of commissioningthe average gradient has not deterio-rated. During the first year of opera-tion there will be no buncher in thedownstream beam transport. How-

ever, we have successfully demon-strated that for experiments that donot require the full energy, andhence have only a limited number ofcavities “on” starting from thelinac’s upstream end, a downstreamcavity, normally “off,” can be tunedto manipulate the longitudinal phasespace to provide either time-focussed or energy-focussed beamsat the experiment. The transmissionis >90% and the tuning is straight-forward.

The performance represents thehighest accelerating gradient for anyoperating cw heavy ion linac. Initial

commissioning runs have concen-trated on completing measurementsin support of our operating license.Further runs will be devoted to,measuring beam quality and improv-ing application programs in supportof beam delivery. First experimentswith radioactive beams are sch-eduled for November 2006. Theexperiments will study reactions ofradioactive 11 Li nuclei, with ener-gies of 2 and 4 MeV/u, on a hydro-gen gas target to 9 Li, 10 Li, and 12Li final states. The experiment willuse the MAYA detector imported toTRIUMF from GANIL (France)

Figure 3. The ISAC-II accelerator vault.

2



specifically to take advantage of theworld-leading high intensity 11 Libeams available here. The fullISAC-II experimental program isexpected to begin in spring 2007after full operating licensingapproval.

References 1. P. Schmor et al., “Development and

Future Plans at ISAC,” LINAC2004,Lubeck, Germany, August 2004.

2. A. Facco et al., “The Superconduct-ing Medium Beta Prototype forRadioactive Beam Acceleration atTRIUMF,” PAC2001, Chicago, June2001.

3. R. E. Laxdal et al., “Magnetic FieldStudies in the ISAC-II Cryomodule,”Physica C 441, 225–228 (2006).

4. R. E. Laxdal et al., “ISAC-II QWRCavity Characterizations and Investi-gations,” Physica C 441, 193–196(2006).

ROBERT LAXDAL

TRIUMF Vancouver

Figure 4. (a) Average cavity gradients for the three A/q values and for an rf power of 7W/cavity. Results are inferred from the step energy gain per cavity during acceleration. Alsoshown are gradients from initial single cavity characterizations. (b) Final energies for thethree cases compared to expected final energies assuming the design gradient of 6MV/m.

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meeting reports


9th International Conference on Nucleus-Nucleus Collisions, NN2006, August 28–September 1, 2006, Rio de Janeiro, Brazil

The IX International Conferenceon Nucleus-Nucleus Collisions(NN2006) was held in Rio de Janeiro,Brazil on August 28–September 1,2006. The venue was the Rio OthonPalace Hotel, situated at the sea frontof the world famous CopacabanaBeach. It was organized by M. S. Hus-sein, A. Szanto de Toledo, C. A.Bertulani, and P. R. S. Gomes. Spon-sors, including the University of SãoPaulo, the Universidade Federal Flu-minense, the Federal Government ofBrazil, The State Governments of Riode Janeiro, and São Paulo. The ICTP-Trieste and CLAF also supported theevent, which is officially sponsored byIUPAP. The Annual Brazilian NuclearPhysics Workshop, RTFNB, was heldconcommitantly in the same venue.

The last meeting of the series ofthese conferences, NN2003 was heldin Moscow in Russia. The one beforethat, NN200, was held in Strasbourg,France.

More than 300 scientists from 30countries attended the meeting, with asignificant active participation ofgraduate students, young scientists,and women. Many scientists fromdeveloping countries were present aswell. The program was denselypacked for 4 and a half full days with

many excellent contributions fromplenary speakers, invited talks, andselected oral and poster presentations.The topics covered were:

• Accelerator Facilities • Nuclear Structure in Nucleus-

Nucleus Collisions and High SpinPhysics

• Low Energy Nucleus-NucleusCollisions

• Fusion and Fission Dynamics • Superheavy Elements • Nuclear Astrophysics • Reactions and Structure of Rare

Nuclear Isotopes • QCD, Hadrons, and Nuclei • Nuclear Fragmentation and Liquid–

Gas Phase Transitions • Equation of State of Nuclear Matter • Relativistic Heavy Ions, sQGP,

and Beyond • Applications and Technological

Developments

The program of the meeting wasmeant to represent faithfully the cur-rent research in the field of heavy-ion physics, both basic and applied.An excellent summary talk wasdelivered by Professor WalterGreiner in the afternoon of the lastday, Friday, September 1. The con-

ference room was fully packed(more than 150 attendees).

The Conference dinner was at thesteak house Porcão in the Flamengodistrict of Rio. About 350 physicistsand guests attended and had a joyfulmixture of excellent “churrasco” din-ner and samba dance.

A meeting of the InternationalAdvisory Committee was held in theevening on Tuesday, August 29 todecide the site of the next NN confer-ence. The meeting was presided byDr. Walter Henning, the Chair of theNuclear Physics Committee, C12 ofIUPAP. Several proposals were pre-sented and after a lengthy deliberationthe overwhelmimg majority voted infavor of the Chinese proposal. We arethus happy to announce that NN2009will be held in Beijing, China.

More information about NN2006can be found at the site,www.nn2006.com.br

M. S. HUSSEIN, A. SZANTO DE TOLEDO

São Paulo

C. A. BERTULANI

Tucson

P. R. S. GOMES

Rio de Janeiro

meeting reports


International Workshop on Stopping and Manipulation of Ions (SMI-06)

The International Workshop onStopping and Manipulation of Ionsand related topics (SMI-06) was orga-nized by the Kernfysisch VersnellerInstituut (KVI), University of Gronin-gen, on March 27–28, 2006 in Gronin-gen, the Netherlands.

The Workshop was the 9th in aseries of meetings that began in 1986in Finland and have since been held inFrance, Belgium, Poland, Japan, Russia,Germany, and the United States. Theearliest workshops in the series, called“IGISOL workshops,” concentratedon the Ion Guide Isotope SeparatorOn-Line technique. Over time, thescope of the meetings has followed theevolution and expansion of the tech-niques related to the stopping of ener-getic ions in noble gases and the useof noble gases to manipulate ions andatoms, mostly in research involvingunstable nuclides. The many newdevelopments since the last workshopin 2001 in Chicago warrented theorganization of this meeting.

The 50 or so participants includedmost of the leading researchers in thefield as well as representatives frommany of the world’s major nuclearphysics laboratories. Various presen-tations were given on ion catcherfacilities at light-ion, heavy-ion

fusion, and fragmentation facilities, onradiofrequency quadrupole (RFQ) ionbeam cooler/bunchers and on laserionisation and spectrocopy. Plans fornew facilities, ideas, and develop-ments were presented and discussed.The program and most of the presenta-tions can be found at www.kvi.nl/SMI06/; here we highlight a few top-ics related to new developments.

The maximum beam intensity thatcan be handled by a gas catcher orRFQ is limited by space-charge.Recent realistic simulations provide adetailed understanding of the nature ofthe space-charge problem. Simula-tions of the so-called cyclotron ionguide show great promise for high-intensity beams as most of the ioniza-tion happens outside of the regionwhere ions are thermalized. Plans forthe construction of such devices atRIBF-RIKEN and NSCL/MSU werepresented. In order to deal with everincreasing energy at fragmentationfacilities, the use of higher densitystopping media has been investigatedin recent years. The status of thedevelopment of cryogenic gas orsuperfluid helium catchers jointly byKVI and JYFL was reported. Contri-butions by Mainz and JYFL showedhow the Laser Ion Source Trap (LIST)

provides laser-ionized beams withimproved purity and optimal spatialand temporal structure by separatingtarget/catcher and ionization func-tions.

Interesting presentations weregiven by representatives of Linde Gason liquid helium and SAES Getters onhelium gas purification. A tour of rele-vant installations and developments atKVI, notably related to the atomicphysics and fundamental interaction/symmetries (TRIP) research pro-grams, was organized.

Thanks to sponsoring from fund-ing agencies and industry, the organi-zation costs could be taken care of anda reception at the Groningen City Hallfollowed by dinner at a nearby restau-rant could be offered.

Based on comments from the par-ticipants, the goal of providing a statusof the field as well as guidance forfuture developments seems to havebeen achieved. Judging from thedevelopments planned for the nextyears, a new SMI workshop in a fewyears’ time will very likely be useful.

PETER DENDOOVEN

Hans WilschutKVI Groningen

EXON-2006

The International Symposium onExotic Nuclei (EXON-2006) tookplace in the town of Hanty-Man-siysk (West Siberia) on July 17–23,2006. It was jointly organized by

JINR, GANIL (France), GSI (Ger-many), and RIKEN (Japan). Thissymposium, as it has become a tradi-tion, dealt with the latest experimen-tal and theoretical investigations on

the synthesis and properties ofnuclei far from stability, from verylight to very heavy elements. Duringthe last few years this field has beenintensively developing—this is the

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meeting reports


main motivation for organizing suchregular scientific meetings. The pre-vious symposium EXON-2004 washeld in Peterhof near St. Petersburg(Russia).

About 100 scientists from 15countries came to Hanty-Mansiysk.The choice of Hanty-Mansiysk wasbased on the extremely fast exten-sive economic developmentobserved in the Hanty-MansiyskAutonomous District, including itsscientific and educational potential,as well as the commitment of theDistrict government and personallyof the Governor A.V. Fillipenko inthe organization of such scientificactions.

The scope of the Symposiumcovered such topics as light exoticnuclei—their production and proper-ties, superheavy elements—synthe-

sis and properties, rare processesand decays, radioactive ion beams—production and scientific programs,experimental facilities, and newprojects. In addition to these topics,on the request of the hosts, we addedto the symposium scope issues, con-nected to the applications of themethods of fundamental nuclear sci-ence to in interdisciplinary fields ofscience and technology—in medi-cine, ecology, information, andgeology.

Many interesting results havelately been obtained in studies of theinteraction of loosely bound lightnuclei, such as 6He, 8He, 6Li, 11Li,and so on. Here, sub-barrier fusion,as well as enhancement of transferreaction cross-sections below theCoulomb barrier has been revealed.The attempt to explain these phe-

nomena were presented in the theo-retical talks. At this session, the firstexperimental results on the interac-tion of 8He with a deuterium targetand the search for a 7H resonancewere also reported. These experi-ments have been performed at FLNR(JINR) and the new interestingresults have demonstrated that reac-tions with weakly bound nuclei willallow getting new information onthe limits of nuclear stability in theregion of the lightest elements.These problems were discussed alsoat another session, where the resultson the search for the tetraneutron, 6Hand 7H have been carried out at otherscientific centers: the physicistsfrom GANIL (France) reported onthe discovery of 7H and the tetra-neutron using beams of 8He and14Be, respectively.

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meeting reports


The results on the latest achieve-ments in the synthesis of superheavyelements at FLNR JINR, GSI, andRIKEN were reported by representa-tives from these scientific centers.The scientists from Germany ana-lyzed in detail the situation with thestudy of the characteristics of ele-ment 112 and claim to have discov-ered it. The properties of element113 were determined by the col-leagues from Japan, who insist onpriority of discovering this element.Elements from 112 to 118 were pro-duced during the last few years inDubna using hot fusion reactions,and in the reports on these experi-ments the priority of Dubna in dis-covering the island of stability ofsuperheavy elements was convinc-ingly demonstrated. This was con-firmed by the talks on the chemicalexperiments performed at FLNRjointly with chemists from Switzer-land, Germany, and the United

States to study the chemical proper-ties of elements 113 and 115.

One session was dedicated tostudying the decay properties ofheavy elements, including fission. Inthis field new effects have been dis-covered, in particular the manifesta-tion of shell effects at highexcitation energy, the competitionbetween fission and quasi-fission,collinear cluster decay into severalfission fragments. All these pro-cesses are extremely important withregard to the choice of future meth-ods of synthesis of new elements.

It is well known that at presentin the biggest scientific centers newaccelerator facilities are built. Theywill make it possible during thenext 5–10 years to start investiga-tions in the field of heavy ion phys-ics, including exotic nuclei, at acompletely new level. The con-struction of such accelerator “facto-ries” and their scientific programs

were discussed by representativesof several centers—the FAIRproject at GSI, SPIRAL2 atGANIL, RIBF at RIKEN, ALTO in(France), EXYT in Catania (Italy),DRIBs in Dubna, and so on.Because these large-scale facilitiescan be realized only due to the jointefforts of the different world scien-tific centers, of great importanceturned out to be the discussions onthe possible collaborations to buildexperimental setups and work outjoint scientific programs. This infact was the main aim of the Sym-posium and explains the supportthat it got from the leading nuclearphysics centers. The organizationof the future joint work and in par-ticular the possibility of collabora-tion of JINR with the Europeanscientific society was discussed.

One day of the Symposium wasdedicated to applied physics. Ofgreat interest were the talks on the

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meeting reports


development of radiation therapyat heavy ion beams in Japan. Inter-esting were the communications onthe use of track membranes, manu-factured at FLNR for medicalappliances and radio-biologicalinvestigations in JINR. The spe-cialists from the Hanty-MansiyskUniversity presented scientificinvestigations in ecology. Alto-gether this session inspired greatinterest in the local scientists whoare concerned with the ecologicalsituation in their District, which isone of the basic regions deliveringoil to Russia and abroad. Theachievements of the scientists from

Dubna were demonstrated at theexhibition of products made inDubna and by the Firm “ASPECT”in the field of monitoring, nano-technologies, and medicine. Theeffect of these contacts was soonseen. Already in August, the gov-ernor of the Hanty-MansiyskAutonomous District A.V. Fil-lipenko visited Dubna and atFLNR he discussed specific issuesof collaboration in design and con-structing setups for the needs ofthe investigations that arecarried out in the District, includ-ing the construction of a compactaccelerator.

The informal contacts at the site ofthe unique Siberian nature and themodern architecture of Hanty-Man-siysk made it possible to have a suc-cessful meeting and achieve the mainaim facing the participants—the carry-ing out of joint investigations in thisimportant field of nuclear physics—the physics of exotic nuclei.

VICE-CHAIRMAN OF THE ORGANIZING

COMMITTEE

EXON-2006

YU. E. PENIONZHKEVICH

RUMIANA KALPAKCHIEVA

Dubna

news and views


G. N. Flerov Prize

The Joint Institute for NuclearResearch (JINR) announces the G. N.Flerov prize for outstanding research innuclear physics. The contest is for indi-vidual participants only. The prize,established in 1992 in memory of theeminent physicist Georgy NikolaevichFlerov (1913–1991), is awarded for con-tributions in the fields of nuclear physicsrelated to Flerov’s interests.

The prize will be awarded inMarch 2007, the year of the fiftiethanniversary of the Flerov Laboratory

of Nuclear Reactions (FLNR). Entriesfor the 2007 prize (including CV, anabstract of research, enclosing copiesof major contributions) should be sentto the Directorate of the FLNR beforeFebruary 1, 2007 to Dr. Andrey G.Popeko, Scientific Secretary of Fle-rov Laboratory of Nuclear Reactions,Joliot Curie str., 6, 141980, Dubna,Moscow Region, Russia E-mail:[email protected].

Flerov’s main interests were con-nected with the experimental heavy

ion physics including the synthesis ofheavy and exotic nuclei using ionbeams of stable and radioactive iso-topes, studies of nuclear reactions,acceleration technology, and appliedresearch.

ANDREY POPEKO

Dubna

Lise Meitner Prize for Nuclear Science 2006

The European Physical Societyawarded through its Nuclear PhysicsBoard the Lise Meitner Prize forNuclear Science 2006 to ProfessorDavid Brink (Emeritus Fellow, BalliolCollege, University of Oxford, UK)and Professor Heinz-Jürgen Kluge(Gesellschaft für Schwerionenfors-chung, Darmstadt, Germany). Medals,diplomas, and cheques, sponsored byCANBERRA, France, were presentedto the two Laureates at a special cere-mony at the Seventh InternationalConference on Radioactive NuclearBeams (RNB7) in Cortina d’Ampezzo,Italy, on July 7, 2006.

David Brink is honored for hismany contributions to the theory ofnuclear structure and nuclear reac-tions that have helped to shapeNuclear Physics over severaldecades. He is one of a select bandof theorists whose work over morethan forty years has deeply influ-enced the field. His seminal workwith D. Vautherin in 1969–1971 ona theory of nuclear masses using

effective interactions of the Skyrmetype in a mean field approach

proved particularly successful andestablished the ground rules for

Lise Meitner Prize Ceremony from left to right: Ron Johnson, David Brink, Heinz-Jürgen Kluge, HartwigFreiesleben

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thousands of papers in nuclear the-ory. This work introduced densityfunctional methods into nuclearmany-body theory and has beencited over 1150 times, including 30in 2003. His methods are currentlybeing used by theorists all over theworld in the new field of exoticnuclei.

Brink’s 1972 work on transferreactions between heavy ions is alsoheavily cited by both theorists andexperimentalists. Based on semi-classical ideas, this work provided auseful, simple way of understandingand predicting important selectionrules for transfer reactions.

Brink’s ideas and insights havealso helped to clarify a variety of otherphenomena including nuclear giantresonances, clustering in nuclei andquantum mechanical and semi-classi-cal theories of heavy-ion scattering.With C. V. Sukumar and others heshowed how the Feynman Path Inte-gral approach to quantum effectscould be applied successfully tonuclear reactions.

Brink’s work reflects his remark-able intuition, his clarity and ability tosimplify the description of compli-cated phenomena by identifying themost appropriate approximations. Hehas had a large number of students andcollaborators from all over the world.For all of them he has been a source ofscientific and human inspiration andadmiration. His commitment to thevalue of truth and his unselfish atti-tude to sharing knowledge have madehim an outstanding figure in nuclearphysics and one still very active at thefrontline of research.

Heinz-Jürgen Kluge has enrichedour knowledge of the masses, sizes,shapes, and spins of nuclei through anumber of decisive, sophisticated, andbrilliant experiments combining tech-niques of atomic and nuclear physics.He is honored for his key contribu-tions to these developments.

As a young post-doctoralresearcher in the early 1970s he set upan optical pumping experiment on achain of neutron-deficient mercuryisotopes at ISOLDE, CERN, and mea-sured their spins, moments, andcharge radii. Recently, backed by thehuge progress in laser techniques andisotope production, he initiated aheroic experiment to measure the tinyshifts in the atomic spectra of Li-iso-topes produced by the differentnuclear volumes of the isotopes. Thesame technique was used successfullyto measure the size of the very exotichalo nucleus 11Li, so-called because ofthe way some of its neutrons are dis-tributed far outside the protons. Hisapplication of laser spectroscopictrace analysis to the study of environ-mental 90Sr after the Chernobyl disas-ter earned him the prestigiousHelmholtz award in 1990.

Kluge’s development of the ISOL-trap for the precision mass measure-ment of nuclear masses is well known.His exploitation of this method has ledto the readjustment of the nuclearmass scale over large regions of thenuclear chart far from stability, andhis precise determination of betadecay properties led to fundamentaltests of weak interaction theory. Thismethod is now applied worldwide,often by Kluge’s pupils, or with their

support. As head of the relevant GSI-group he has also pushed the compli-mentary Schottky mass measure-ments in the storage ring ESR.

Heinz-Jürgen Kluge’s experimen-tal ideas and achievements have hadan invaluable impact on the art ofexperimental atomic and nuclearphysics, and his results for nuclearground state properties have provideda reliable and indispensable corner-stone for nuclear theory. He hasinspired at least 55 Ph.D. studentswith his physics skill and enthusiasm,many of whom are active in scienceand academia.

HARTWIG FREIESLEBEN

Technische Universität DresdenChairman, Nuclear Physics Board

HONOREE

1

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CALL for Nominations for the IBA-Europhysics Prize 2007 for Applied Nuclear Science and Nuclear Methods in Medicine

The Nuclear Physics Board of theEPS invites nominations for the year2007 for the IBA-Europhysics prize.The award will be made to one or sev-eral individuals for outstanding contri-butions to Applied Nuclear Scienceand specially Nuclear Methods andNuclear Researches in Medicine.

The Board would welcome proposalsthat represent the breadth and strength ofApplied Nuclear Science and NuclearMethods in Medicine in Europe.

Nominations should be accompa-nied by a completed nomination form, a

brief curriculum vitae of the nominee(s),and a list of major publications. Lettersof support from authorities in the fieldthat outline the importance of the workwould also be helpful.

Nominations will be treated inconfidence and although they willbe acknowledged there will be nofurther communication. Nomina-tions should be sent to: SelectionCommittee IBA Prize: ChairmanProf. Ch. Leclercq-Willain, Depart-ment of Theoretical Nuclear Physics—PNTPM—CP 229, Université Libre

de Bruxelles, Bvd. du Triomphe,B1050 Bruxelles, Belgium. E-mail:[email protected]

For nomination form and moredetailed information see the website ofthe Nuclear Physics Division, http://www.kvi.nl/~eps_np and the websiteof EPS, www.eps.org (EPS Prizes,IBA-Europhysics Prize) .

The deadline for the submission ofthe proposals is January 15, 2007.

CHRISTIANE LECLERQ-WILLAIN

Université Libre de Bruxelles

obituary


Obituary

Ziemowid Sujkowski, a long-timedirector of the Institute for NuclearStudies, wierk/Warsaw, Poland, diedon July 9, 2006 after an heroic strug-gle against cancer.

Born in Warsaw in 1933, he stud-ied physics at Warsaw University(1951–1955), obtained his Ph.D. atStockholm University (1961) and aprofessorship at the Institute ofNuclear Research in Swierk (1971)where he spent the rest of his life.

His interest was in atomic, nuclear,particle, and astroparticle physics. Hewas an expert on the use of radiation andcoincidence methods in those fields.

Sujkowski played a significantrole in our scientific life. His eruditionwas much appreciated when he waselected to Nuclear Physics Board ofthe European Physical Society.

Sujkowski was an exceptional men-tor for young scientists. He supervised21 Ph.D. theses in Poland and abroad.He served on advisory committees ofmany international conferences. InPoland he was a chairman of the famousMazurian Lakes Conferences.

Ziemek loved all kinds of watersports: swimming, canoeing, wind-surfing, and sailing. He liked skiing,biking, and also hiking.

We will remember Ziemek forhis many contributions to theprogress of nuclear physics and thepromotion of international collabo-rations for developing new frontiersof science. We will remember himfor his works on a wide range ofnuclear, particle, astro-particle, andatomic physics. Primarily we willremember him for his personal

contributions to generations of phys-icists, his honesty, his cheerfulnessand sense of humor, and his abilityto bring out the best in others.

For Friends and Colleagues fromThe Andrzej Soltan Institue

for Nuclear Studies andWarsaw University

ZIEMOWID SUJKOWSKI

á

calendar


2007 January 14–21

Bormio, Italy XLV InternationalWinter Meeting on Nuclear Physics

http://lxmi.mi.infn.it/bormio/

January 15–19 Orsay, France AGATA Week http://www.agata.org/

January 15–19 ECT* Trento, Italy Workshop on

photoproduction at collider ener-gies: from RHIC and HERA toLHC

http://dde.web.cern.ch/dde/photoprod_ect07/

February 28–March 2 GSI Darmstadt, Germany

Annual NUSTAR Meeting

http://www.gsi.de/forschung/kp/kp2/nustar_e.html

May 20–24 Vico Equense, Italy 9th Interna-

tional Spring Seminar On NuclearPhysics Changing Facets OfNuclear Structure

http://vico07.na.infn.it/

May 30–June 2 RIKEN, Wako-shi, Japan Direct

Reactions with Exotic BeamsDREB2007

http://rarfaxp.riken.go.jp/DREB2007/

June 3–8 Tokyo, Japan International Nuclear

Physics Conference INPC 2007 http://www.inpc2007.jp/

June 24–29 Deauville, France EMIS 2007 http://emis2007.ganil.fr/

July 3–7 Golden Sand Hoi An, Vietnam

International Symposium on Phys-ics of Unstable Nuclei (ISPUN07)

http://www.inst.gov.vn/ispun07

September 3–7 Stratford-upon-Avon, England

Clusters ’07 http://www.iop.org/Conferences/

Forthcoming_Institute_Conferences/event_7938.

September 23–28 Davos, Switzerland TAN 07 3rd

International Conference on theChemistry and Physics of theTransactinide Elements

http://tan07.web.psi.ch/

More information available under: http://www.nupecc.org/calendar.html

nuclear physics - nupecc · 2019-10-17 · editorial vol. 16, no. 4, 2006, nuclear physics news 3...

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