The Scientific and Educational Impact

of the University-Based Accelerator Laboratories ARUNA

A white paper submitted to NSAC in January 2015

Executive Summary

ARUNA, the Association for Research at University Nuclear Accelerators, consisting of 10 institutions and176 registered users, is an association of university-based accelerator laboratories and the scientists performingnuclear research at them. This white paper was produced as the outcome of a workshop held June 12 and13, 2014 on the campus of the University of Notre Dame. The workshop was attended by 59 registeredparticipants from 20 institutions and centered its discussion around 34 plenary presentations. The programis available at http://aruna.physics.fsu.edu/Workshop.html. The goal of the meeting was to documentthe scientific impact of the programs at the university-based accelerator laboratories and formulate a visionof their future role for the scientific community.

The university-based ARUNA laboratories pursue research programs in nuclear astrophysics, low energynuclear physics, fundamental symmetries, and a rapidly growing number of nuclear physics applications,building bridges to other research communities. Their efforts are advancing the priorities for low-energynuclear science as expressed in the NSAC long-range plans, and are also pioneering new initiatives, newscientific directions and developments in the field.

The ARUNA laboratories span a range of sizes and comprise a very diverse portfolio of research instrumentsand programs. All ARUNA facilities benefit from their location on university campuses, where a large fractionof the research is carried out. The faculty and scientists at these facilities represent an important intellectualresource for the national nuclear program. They not only provide new ideas for their local facilities, butrepresent a large fraction of the user community for the national laboratories. ARUNA facilities are thetesting ground for new ideas and new technical developments; the nation’s first radioactive beam facilitieswere developed at ARUNA laboratories, ARUNA facilities provide now the design for critical instrumentationfor FRIB as the major new tool for low energy nuclear physics.

Some ARUNA laboratories have developed unique capabilities in mono-energetic neutrons, high intensitymono-energetic γ–photon beams, providing new ideas for large scale international facilities such as ELI inEurope. ARUNA laboratories have also developed techniques for generating and utilizing high-intensitylow-energy beams, which will be an important asset towards the development of the next generation ofunderground accelerator laboratories. Utilization of these probes is essential for addressing many of thescientific goals and challenges in low energy nuclear physics and astrophysics. The facilities are characterizedby their flexibility to perform long term experiments or experimental programs that are not possible withinthe environment of the national user facilities.

ARUNA laboratories provide an important fraction of the nuclear workforce. Through their location onuniversity campuses, they attract undergraduate and graduate students into the field, and they provide aunique training environment for students and postdocs from a very early stage on. A large fraction of today’snuclear physics research community has been trained at university facilities. The ARUNA laboratories playa major role in the workforce rejuvenation of the national nuclear science endeavor and are often the flagshipfacilities at their host institutions.

To maintain this role for the broader community continuing support for university based laboratories isessential.

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Resolution

In order to ensure the long-term health of the field and the education of the next generation of scientists, it iscritical to maintain a balance between funding of major facilities and the needs of university-based programs,for their research operations, science and new initiatives.

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1 Introduction

ARUNA (Association for Research at University Nuclear Accelerators) is an association of the acceleratorlaboratories at Florida State University, Hope College, Ohio University, Texas A&M University, TUNL (DukeUniversity, University of North Carolina at Chapel Hill, North Carolina State University), Union College,the University of Kentucky, the University of Massachusetts Lowell, the University of Notre Dame and theUniversity of Washington. It was founded in 2011 to enhance communication and exchange between thepartner institutions and to strengthen the research and educational opportunities at these laboratories.

The ARUNA research programs presented in this white paper are characterized as nuclear astrophysics, low-energy nuclear physics, fundamental symmetries and applications. In cases, overlap with research questionsand needs of other science communities exists. ARUNA scientists are primarily funded through DOE andNSF for the nuclear physics core program. Most ARUNA groups operate their facilities as a means toachieve the grant-funded scientific goals, with the exceptions of the Texas A&M cyclotron, TUNL and theUniversity of Washington. These three are operated as DOE Centers of Excellence. Currently (FY 2014),the ARUNA groups receive 15.5 million dollars in grant funding, of which between 20 and 30% are usedto support the accelerator operations, a total of around 3.7 million dollars. The grant funding to ARUNAlaboratories is strongly leveraged by the hosting universities, which, almost everywhere, over-match theoperations budgets by providing staff positions, utilities, and other contributions. The universities considertheir respective ARUNA laboratories as scientific flagships with a big role in innovative and independentresearch developments and a unique role in graduate and, even more so, undergraduate student training.

The National Science Foundation has traditionally made education and training a cornerstone of theirresearch support. The topic of workforce development and its impact on the DOE mission has also becomea primary focus at the DOE Office of Science and has been addressed in a report to NSAC [2]. Severalchallenges in fulfilling the workforce needs of fundamental and applied nuclear science were identified. Thereport concludes that early exposure of undergraduate students to nuclear methods is a big factor in addressingthese needs. All ARUNA laboratories support undergraduate research projects, many are hosts to groups fromundergraduate colleges and two ARUNA accelerator labs are located at undergraduate institutions. Throughthese links, ARUNA laboratories are playing an important role in rejuvenating the nuclear workforce.

During the last four years, the Holifield Radioactive Beam Facility (HRIBF) at Oak Ridge National Labora-tory and the Wright Nuclear Structure Laboratory at Yale University have ceased operations. These facilitieswere supporting internal and external user programs with around 7500 hours of experiment time per year.Access to experimental facilities in low-energy nuclear science has reached a critically low level, which, if itcontinues, will endanger scientific progress, the quality of education and the number of experimental nuclearPh.D’s. ARUNA laboratories are needed to alleviate the impact of the nationwide reduction in experimentalfacilities for low-energy nuclear science and nuclear astrophysics.

ARUNA scientists provide intellectual and scientific leadership, not only at their own institutions. Theyalso play a leading role for the nation’s nuclear physics endeavor, as users and innovators at national researchfacilities and through developments for these programs. Many of the scientific goals and developments inthe low energy nuclear physics and astrophysics community have been spearheaded, tested, and developedat ARUNA institutions.

The intellectual potential at work in ARUNA provides great benefits for the national nuclear physicsprogram. ARUNA laboratories and their broader intellectual and scientific networks provide the link betweendisciplines that foster new ideas and innovations. Without their continuous and strengthened support, nuclearphysics may well disappear as an academic field from many university campuses.

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2 The Scientific Impact of

ARUNA: Nuclear Astro-

physics

2.1 Introduction

Nuclear Astrophysics is a field where ARUNA labo-ratories have made fundamental contributions overthe last two decades. ARUNA facilities presentlyassume a leading role in the nuclear astrophysicscommunity. They have pioneered the developmentof radioactive beams, they are leading in the use ofhigh-intensity stable beams and pioneered new in-direct techniques and methods complementing thedirect study of nuclear reactions at quiescent andexplosive burning. They have initiated a worldwidenetwork of experimentalists, theorists and observersto identify the scientific goals and priorities, and totest the results against predictions and observations.

Figure 1 demonstrates the key role that nuclearphysics plays in the universe and in the developmentof the isotopic and elemental abundances from thefirst minute to the present time. It shows a snapshotof the distribution of γ radiation from the radioiso-tope 26Al, a fingerprint of the ongoing nucleosyn-thesis distributed over the galactic plane. ARUNAscientists lead the laboratory effort for explainingvarious quiescent and violent nucleosynthesis pro-cesses. Their work is not limited to their “home”facilities, but they provide essential contributionsto the scientific plan and agenda of FRIB as theworld’s leading radioactive beam facility.

The following sections will specify the contribu-tions of ARUNA based research in investigating thecontributions to stellar burning and in exploring thefar-off stability reaction sequences that drive stel-lar explosion. In addition, this section provideson overview of achievements and long-term researchplans at ARUNA laboratories that cannot be per-formed anywhere else in the United States.

Stellar Burning and Stellar Evolution

Stable-beam experiments have been a major con-tributor to our understanding of nuclear astro-physics since the field began in the 1930s. Photon

beams are a relative newcomer but also have signif-icant impact. Here, we focus on quiescent burningin stars and explosive nucleosynthesis, where signif-icant progress using stable and γ-photon beams isanticipated. This is not to say that these approachesare not useful in other scenarios, for example Big-Bang Nucleosynthesis (BBN). In the case BBN, it isalready a triumph of stable-beam experiments thatthe important reactions have been measured in theGamow window, although some experimental datastill requires re-measurement with higher accuracyand precision. Further experimental work in thearea of BBN could be motivated by high-precisionprimordial abundance measurements, e.g., of deu-terium.

Planned stable and γ-photon beam experimentsdirectly address two of the key questions for nuclearscience identified in the 2007 Long Range Plan:

• What is the origin of the elements in thecosmos?

• What are the nuclear reactions that drivestars and stellar explosions?

How Do Stars Work?

Almost all questions in astrophysics ultimately re-quire a detailed understanding of stars and stellarproperties, thus challenging stellar models to be-come more sophisticated, quantitative and realisticin their predictive power. Such improvements de-mand a more detailed understanding of the inputphysics, such as thermonuclear reaction rates andopacities. Experimental efforts to measure crosssections and related spectroscopic information ad-dress the question of reaction rates and will pro-vide significantly more accurate rates in the future.Ultimately, the improvement of our understandingof stars requires systematic studies from many sub-fields of science, including: observations, theoreticalastrophysics, nuclear experiment, and nuclear the-ory (e.g., to guide extrapolations of cross sectionsto lower energies). Observations are taken broadlyhere to include the entire electromagnetic spectrumas well as neutrino and meteoritic abundances mea-surements, and are essential for validating stellarmodels. The systematic nature of this work implies

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Roland Diehl ALMAP

Figure 1: Map of the Galaxy in radioactive 26Al gamma-rays as obtained from the NASA Compton Obser-vatory mission and its COMPTEL telescope (Plueschke et al. 2001).

that a broad range of isotopes is considered and thatcareful error analysis is undertaken for all ingredi-ents of the models as well as for the observations.

Key areas of interest for stable beams are the ppchain and CNO reactions that occur in our sun,due to the continuing interest in the solar neutri-nos produced by these processes. The measure-ments of solar neutrinos (e.g., via the Borexino ex-periment) have entered a phase of high-precisionspectroscopy, making it imperative that the nuclearphysics be understood at a comparable level. In gen-eral, these reaction rates can be improved via twoapproaches: (1) improved precision or (2) measure-ments at lower energies. Measurements at low en-ergies are made difficult by the small cross sectionsand it should be noted that a lower-energy measure-ment with poor precision compared with other datais not helpful. What is thus required are dedicatedfacilities which can supply the beam time and lumi-nosity required to perform the measurements withsmall statistical and systematic uncertainties. Suchfacilities are discussed in more detail below. Spe-cific reactions where improvements are desired in-clude 3He(α, γ)7Be, 12C(p, γ)12N, 14N(p, γ)15O, and17O(p, γ)18F.

Hydrogen burning is of fundamental importancein essentially all stars. In addition to the CNO reac-tions already mentioned, quiescent hydrogen burn-ing can affect abundances all the way up to A = 40,

and important questions remain to be answered.

After the hydrogen fuel in the core of a star is ex-hausted, the star enters the helium burning phase.The key reactions here are the triple-alpha pro-cess which burns three α particles into 12C and the12C(α, γ)16O reaction. In massive stars, which un-dergo type-II supernova explosions and are largelyresponsible for enriching the interstellar medium inheavy elements, the rates of these reactions have sig-nificant impact on the nucleosynthesis of elementsin the A = 12 − 40 range and also have impor-tant consequences for understanding the masses ofthe post-supernova remnant of these stars (neutronstar or black hole). The 12C(α, γ)16O reaction isparticularly uncertain, due to a complicated reso-nant reaction mechanism near zero α + 12C energy.This reaction rate can be most directly addressedvia stable beam measurements at low energies us-ing a specialized and dedicated facility. It shouldalso be noted that this is a reaction where γ-photonbeams can be fruitfully applied to study the inversereaction. Indirect information is also very helpful forthis reaction. For example, measurements of crosssections and angular distributions at higher energiesthan presently available would be very helpful forconstraining the so-called background terms whichaffect the extrapolation of the cross section to as-trophysical energies.

The slow neutron capture process (s process), to-

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gether with the rapid neutron capture process, areresponsible for the synthesis of the majority of el-ements heavier than iron. The neutron sources forthe s process are the 13C(α, n) and 22Ne(α, n) reac-tions. The thermonuclear reaction rates for theseprocesses are not known for the needed tempera-tures of (1− 3)× 108 K, depending on the reaction.These reaction rates are an essential ingredient fora complete understanding of the s process, whichmust explain the astrophysical sites, neutron den-sities, and temperatures where this occurs. Themost straightforward approach is improved directmeasurements, which demand dedicated facilities,with intense beams and low-background detectiontechniques. Indirect methods are also helpful; forexample recent (γ, γ′) measurements using photonbeams have supplied valuable spectroscopic infor-mation that constrains the 22Ne(α, n) reaction.

Near the final stages of the evolution of mas-sive stars, the heavy-ion burning reactions, such as12C + 12C and 16O + 16O are responsible for en-ergy generation and nucleosynthesis. The 12C + 12Creactions are particularly poorly understood, dueto the presence of resonances in the cross section.Improved measurements of this reaction, includingcharged-particle exit channels, are planned for thefuture.

Explosive Nucleosynthesis

There is considerable current interest in the nuclearphysics associated with explosive events such as no-vae, x-ray bursts, type Ia supernovae (explosions ofwhite dwarfs), and core-collapse supernovae. Exper-iments with stable and γ-photon beams contributein several ways to our understanding of these events.In some cases, the important reactions involve sta-ble isotopes, and thus direct measurements, simi-lar to those discussed in the previous section, arepractical. An excellent example of this approachis provided by the 17O(p, γ)18F reaction. Classi-cal novae are thought to be the dominant sourceof 17O in our galaxy, and this reaction significantlyimpacts the quantity produced. In Fig. 2, some re-cent experimental results are displayed along witholder data. It is seen that the new results have muchsmaller error bars and reach significantly lower en-

ergies. One attractive aspect of this case is that,due to the higher temperatures involved, it is possi-ble to perform the measurements within the Gamowwindow. Another example is again the 12C + 12Creaction, which also determines the ignition condi-tions for type Ia supernovae and the ignition of therecently discovered superbursts in accreting binarysystems.

Many of the reactions involved in explosive nucle-osynthesis involve radioactive nuclei. In these cases,stable beam facilities are able to make significantadvances in our understanding using indirect ap-proaches. Most of the reaction rates for A < 40are dominated by a few resonances, making statis-tical approaches inapplicable. However, it is oftenpossible to measure the spectroscopic properties ofthe resonant states (excitation energy, spin, parity,and partial widths) using indirect approaches. Infavorable cases, the needed reaction rates can bedetermined with the required precision solely us-ing indirect methods. Many of these reactions willalso be studied in the future using radioactive ionbeams at large national facilities. The indirect mea-surements taking place at university facilities arehighly complementary to these efforts. The indirectapproaches can identify the locations of the reso-nances with high precision, often with spin and par-ity information. Thus, the valuable radioactive ionbeam time can be devoted to measurements of thestrength of resonances at known locations, greatlyincreasing the efficiency of the process. In addition,some resonances will likely never be possible to mea-sure directly, due to the weak resonance strength, soindirect methods will be the only approach availablein some cases.

In novae and x-ray bursts, chains of (p, γ), (p, α),and (α, p) reactions occur on the proton-rich sideof the stability line. Transfer reactions on stabletargets can often be utilized to probe the relevantresonance states. Excellent energy resolution is of-ten required, due to the relatively close spacing ofthe levels. The best resolution is typically availableusing reactions with light projectiles and ejectiles,such as (p, t), (p, n), (3He, d), (3He, t), and (3He, n).In addition, more exotic multi-nucleon transfer re-actions, such as (12C, 16C) and (12C, 6He), can beused to study the structure of nuclei farther off the

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Figure 2: Plot of the world-wide data of the astrophysical S-factor for the 17O(p, γ)18F reaction as a functionof the proton beam energy in the c.m. system. The solid red circles are the new data from the LENA facilityat TUNL and the hashed area is the Gamow window.

stability line, which is applicable for reactions oc-curring in x-ray bursts. Also, the proton transferreactions (3He, d) and (d, n) are of special interestas they can supply information about the protonwidths of resonances using well-established transferreaction theory. It should be noted that indirecttechniques are not limited to resonances but canalso be used to study non-resonance cross sections;the Asymptotic Normalization Coefficient (ANC)method or the Trojan Horse Method (THM) aretwo implementations in this case. Two particularlycompelling cases of resonant reactions where indi-rect techniques are being utilized are studies of the18F(p, α)15O reaction (involving states in 19Ne) andthe 25Al(p, γ)26Si reaction (involving states in 26Si).

2.2 Direct Measurements

Specialized Facilities: At TUNL-LENA and Uni-versity of Notre Dame:This experimental program in nuclear astrophysics

Figure 3: The planned reconfiguration of the FSUexperimental hall with the Enge split-pole spectro-graph.

requires specialized and dedicated facilities. Fordirect measurements, high beam currents, efficientand low-background detection methods, and longrunning times are required. Backgrounds can bereduced by utilizing pulsed beams, ultra-pure tar-gets, passive and active shielding, coincident detec-tion techniques, and/or by performing the measure-

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ments deep underground. The existing Laboratoryfor Experimental Nuclear Astrophysics (LENA) atTUNL is presently performing such measurementswith normal kinematics and is planning an up-grade which will increase the available beam in-tensity. An underground accelerator, called CAS-PAR, is presently being developed at the Univer-sity of Notre Dame. This facility plans to studythe s-process neutron source reactions, which arecases where the background reduction coming frombeing underground is particularly compelling. An-other approach to direct measurements is inversekinematics, where a heavy ion beam bombards agas target of hydrogen or helium and the heavy re-action products are detected in a recoil separator.The recently-completed heavy-ion accelerator andrecoil separator (St. Ana and St. George) at theNotre Dame Nuclear Science Laboratory (NSL) isan example of this approach, which is designed tomeasure alpha induced reaction processes of rele-vance for late stellar burning scenarios using inversekinematics techniques.

pp-reactions: At University of Notre DameCritical measurements for reducing the uncertaintyin the 3He(α, γ)7Be reaction have been performedat Notre Dame. The experimental results allow aself-consistent r-matrix simulation of the entire crosssection curve, which translates into a more reliableextrapolation of the experimental data in the solarenergy range and limits the uncertainties in the pro-duction rate of the solar neutrinos from the secondand third pp-chain. Future efforts at Notre Damewill focus on the study of proton capture reactionson lithium isotopes which still suffer from substan-tial uncertainties in the low energy range.

CNO reactions: At University of Notre Dame andTUNL-LENA:The CNO cycle in the sun is of limited relevance forthe solar energy budget but it may provide a newand independent measure of the solar core metal-licity through the analysis of the CNO neutrinosat Borexino and other neutrino detectors. This re-quires an improved understanding of the low en-ergy reaction cross sections of the CNO reactions.The Notre Dame group has systematically stud-ied the radiative capture processes that lead to theproduction of CNO neutrinos through the β de-

cay of the reaction product such as 14N(p, γ)15O,15N(p, γ)16O, and 17O(p, γ)18F. The measurementswere performed over a wide energy range and werecomplemented by an extensive set of elastic scat-tering experiments. A multi-channel multi-level R-matrix has been developed to analyze all the data,taking into account the new measurements as well asexisting data for all reaction channels has been per-formed for all these processes. The results demon-strate in some cases substantial deviations to long-accepted values for low energy extrapolation.

These studies are being expanded to the measure-ment of 12C(p, γ)1 and 16O(p, gγ to study the con-tribution of 13N and 17F decay neutrinos to the solarCNO neutrino flux.NeNa reactions: At University of Notre Dameand TUNL-LENA:The NeNa cycles play a role in shell hydrogen burn-ing of massive stars and in explosive nova eventsthat correspond to thermonuclear runaways at thesurface of accreting white dwarfs. The Notre Damegroup reinvestigated the slow 20Ne(p, γ reaction andthe possible contribution of a subthreshold state inthe 21Na compound nucleus. This reaction deter-mines the cycle period for the NeNa cycle.

At the LENA facility at TUNL, the 23Na(p, α)has been measured using the high intensity ECRplatform.HI fusion At Florida State University, with a groupfrom Indiana University, at University of NotreDame, at Texas A&M UniversityFusion reactions between carbon and oxygen iso-topes dictate the fate of the star during its last burn-ing phases. Heavy ion fusion experiments at ANLhave indicated a possible hindrance mechanism thatreduces the fusion probability at very low energies.These energies are only available at university accel-erator facilities. A number of stellar fusion reactionstudies such as 12C + 12C, 12C + 13C and 12C + 16Oare being pursued at Notre Dame. Complementarytransfer reactions for probing the 12C cluster struc-ture in the compound nuclei have been and are beingmeasured at FSU and Texas A&M.

2.3 Indirect Methods

At the University of Notre Dame, at Ohio Univer-

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sity, at TUNL-HIγS, at Florida State University

The Notre Dame group introduced a program formapping critical resonant states for reactions in theαp-reaction path using (p,t) and (4He,8He) reac-tions at the Grand Raiden Spectrometer at RCNPOsaka. The program was completed, mapping theentire αp-process from 18Ne to 48Cr and a completeset of resonance data is now available for directmeasurement at radioactive beam facilities such asCARIBU using the HELIOS detector, or at ReA3using ANASEN. The Grand Raiden experimentswere complemented by (3He,n) reaction studies atthe Notre Dame tandem accelerator using the timeof flight techniques for neutron spectroscopy andmeasuring the decay channels of the populated res-onance states. The TwinSol facility was modifiedto serve as a medium-resolution spectrometer to de-termine the strength of break-out reactions such as15O(α, γ)19Ne from the hot CNO cycles by using co-incidence techniques between 19F(3He, t)19Ne trans-fer reactions and subsequent α and γ decay prod-ucts. This method is presently being refined by con-verting TwinSol into a HELIOS type spectrometerdevice to increase the efficiency of transfer reactionstudies.

The above example shows the power of indirectmethods and stable ion beams, relying upon spe-cialized detection systems. In the case of charged-particle reaction products, the best resolution is pro-vided by magnetic spectrometers, a capability whichis presently lacking in North America. However,two laboratories have plans to rectify this situation;the John D. Fox Accelerator Laboratory at FloridaState University (FSU) is planning to install theEnge split-pole spectrograph that was previous uti-lized at Yale University and TUNL is planning toupgrade and refurbish their Enge split-pole spectro-graph. The planned configuration the split pole atFSU is shown in Fig. 3. For the cases of neutrons inthe final state, high-resolution neutron spectroscopyis carried out using pulsed beams and long flightpaths at Ohio Universitys Edwards Accelerator Lab-oratory.

Photon beams are becoming increasingly impor-tant for nuclear astrophysics. The High-Intensityγ-ray Source (HIγS) at TUNL provides quasi-

monoenergetic γ-photon beams that can be utilizedto bombard suitable samples. Direct measurementsof radiative capture cross sections can be obtainedby measuring the reverse reaction and applying thereciprocity theorem. An excellent example is the16O(γ, α)12C reaction, which can be studied to de-termine the 12C(α, γ)16O cross section. In addition,nuclear resonance fluorescence, i.e., the (γ, γ′) reac-tion, can be utilized to locate potential resonancesand determine their quantum numbers.

2.4 In-flight Radioactive Beam Ex-periments: TWIN-SOL andRESOLUT

At University of Notre Dame and Florida StateUniversity

The university laboratories at Notre Dame andFlorida State University have developed in-flight ra-dioactive beam capabilities.

TwinSol is a facility for producing beams of lightradioactive ions at energies near the Coulomb bar-rier. Commissioned in 1998, it is one of the first in-struments to produce intense radioactive beams inthis energy region. Seven Physical Review Lettersand over 50 other papers in refereed journals haveso far been published based on research done withTwinSol. One of the early PRLs was the subject ofa short article in the CERN Courier, and several ofthe papers have received 150 or more citations. Acollaboration between the University of Notre Dameand the University of Michigan, TwinSol also has anactive national and international user community.

The most recent work with TwinSol has uti-lized novel detectors, such as the prototype active-target time projection chamber (pTPC) developedat Michigan State University, and deuterated liquidscintillators that produce a neutron energy spec-trum without the need for time-of-flight measure-ments. The neutron detectors were recently used tostudy (d,n) reactions on 7Be and 17F.

The pTPC has been used to study proton andalpha-particle elastic and inelastic scattering fromradioactive nuclei, to measure an entire near- andsub-barrier fusion excitation function at a rate of

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only 100 particles per second, and to investigate theangular correlation of alpha particles from the de-cay of the Hoyle state by visualizing their tracks.Planned future experimental programs with this de-vice include the study of charged-particle-inducedtransfer reactions in inverse kinematic using 1H ,2H and 4He targets.

Florida State University has been operating theRESOLUT in-flight radioactive beam facility since2006. This facility, like TwinSol, uses two supercon-ducting solenoids to focus reaction products onto asecondary target, but uses in addition a supercon-ducting RF resonator and a large-acceptance mag-netic spectrometer to sharpen the beam energy andselect the beam isotopes more cleanly. RESOLUThas recently been used to perform a series of (d,n)transfer reactions to study the resonance spectrumfor (p,γ) reactions, an indirect technique which cansupply information about the partial proton widths,in addition to the excitation energy, spin, and parity.RESOLUT has also been used to measure protonand α–resonance scattering using the new ANASENactive–target detector, see also 2.7. ANASEN willbe used at RESOLUT and ReA3 to measure ex-citation function cross sections of (α, p) reactionswith the aim of calibrating the astrophysical reac-tion rates of the αp process.

2.5 Neutron Source Reactions

At University of Notre Dame and TUNL-HIγSThe identification and understanding of stellar neu-tron sources and neutron poisons is critical for areliable model description of the s-process which isresponsible for the production of about 50% of theheavy elements. The s-process is a major signaturefor mapping and understanding the chemical evolu-tion of our universe through the chemical analysisof meteoritic inclusions. Both direct and indirectmeasurement techniques can be profitably appliedto the neutron source reactions.

There has been a combined effort by the UNC andND groups using the HIγS facility at TUNL to un-derstand critical resonance states in 22Ne(α, n) neu-tron source through 26Mg(γ, γ′) nuclear resonancefluorescence measurements.

Direct measurements are planned using inverse

kinematic techniques at the Notre Dame St. Georgeseparator and forward kinematics at the futureCASPAR underground accelerator facility. Di-rect measurements have already been performed atNotre Dame on the 17O/18O(α, n) as well as on the25Mg/26Mg(α, n) reactions, which showed substan-tial differences from tabulated results that have sofar been used in s-process site simulations.

2.6 Unambiguous Identification ofthe Second 2+ State in 12C

At TUNL-HIγSLate-stage red giant stars produce energy in theirinteriors via helium (α) burning. The outcome ofhelium burning in red giant stars is the formationof the two elements: carbon and oxygen. The ratioof carbon to oxygen at the end of helium burninghas been identified as one of the key open questionsin nuclear astrophysics. Helium burning proceedsthrough the 3α process to produce carbon, whicheventually burns to oxygen via the 12C(α, γ)16O re-action.

Figure 4: Typical image of three alpha par-ticles detected recorded in the the opticaltime-projection chamber from the reaction12C(γ, α0),8 Be(→ α + α). Both α–products ofthe 8Be-decay are contained in the top-left track.

An excited 0+ state in 12C, named the Hoyle Stateafter Fred Hoyle who predicted its existence, plays

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a central role in determining the rate of the 3α pro-cess. This prediction was the first and quite possi-bly still the best example of an application of theanthropic principle in physics. Soon after the dis-covery of this excited state in 12C, predictions of therotational band structure of the Hoyle state led toa fifty-year search for an excited state built uponthe Hoyle state. An excited state having the prop-erties of the Hoyle state excitation was unambigu-ously identified at the HIγS laboratory TUNL andwas reported in a letter publication. The state wasidentified using the 12C(γ, α)8Be reaction. The al-pha particles produced by the photodisintegrationof 12C were detected using an optical time projec-tion chamber (OTPC). Data were collected at beamenergies between 9.1 and 10.7 MeV using the in-tense nearly monoenergetic γ-photon beams at theHIγS facility. The measured angular distributionsdetermine the cross sections and the E1-E2 relativephases as a function of energy leading to an unam-biguous identification of the second 2+ state in 12Cat 10.13(60) MeV. This work was a collaborativeeffort which includes TUNL, the University of Con-necticut, Yale University, Physikalisch-TechnischeBundesanstalt, Germany, and the Weizmann Insti-tute of Science, Israel. In Figure 4, a γ ray of 9.5million electron-volts (MeV) (not seen in the image)breaks apart a carbon nucleus into a helium frag-ment and a 8Be fragment. The 8Be immediately de-cays into two α particles and appears as two tracksmerged into each other. A fast, high-resolution, andimage intensified camera creates this image. Othercomponents of the OTPC gather information on theenergy of these fragments and the angles at whichthey are ejected to provide a complete picture ofthis reaction.

W.R. Zimmerman, M.W. Ahmed, B. Bromberger,S.C. Stave, A. Breskin, V. Dangendorf, Th. Delbar,M. Gai, S.S. Henshaw, J.M. Mueller, C. Sun, K. Tit-telmeier, H.R. Weller, and Y.K. Wu UnambiguousIdentification of the Second 2+ State in C12 and theStructure of the Hoyle State Physical Review Let-ters, 110, 152502 (2013).

2.7 Detector and Method Develop-ment: ANASEN

At Florida State University, with groups fromLouisiana State University and Texas A&M Uni-versity

The Array for Nuclear Astrophysics Studies withExotic Nuclei (ANASEN) is a charged-particle de-tector array developed specifically for experimentswith radioactive ion beams, primarily to measurethe nuclear reactions important in stellar explo-sions. ANASEN is a collaborative project betweenscientists at Louisiana State University, FloridaState University (FSU) and Texas A&M Univer-sity. ANASEN was constructed and commissionedat the FSU accelerator laboratory, using more than12 weeks of beam-time. The completed array hasbeen in operation since Summer 2012, performingmeasurements with beams of radioactive ions fromthe RESOLUT facility at FSU. ANASEN was alsoused in the commissioning exotic beam experimentat the new ReA3 facility of the National Supercon-ducting Cyclotron Laboratory of Michigan State,measuring the elastic proton scattering from a beamof 37K.

ANASEN is a universal device that can be usedin active target mode (target gas serving as an ac-tive medium for tracking detectors) and also in solidtarget mode. ANASEN has three major compo-nents: An array of resistive strip and double-sidedsilicon strip (DSSD) detectors, backed by an ar-ray of CsI(Tl) scintillators with PIN-diode readout.The active target is realized through a position-sensitive proportional counter of more than 40 cmactive length. The readout is performed by Appli-cation Specific Integrated Circuits (ASICs) coupledwith conventional electronics. A schematic repre-sentation of ANASEN is shown in Fig. 5. ANASENhas cylindrical geometry around the beam axis, witha proportional counter and silicon barrel array ar-ranged as concentric cylinders. A photo of the com-ponents is shown in Fig. 6

The ANASEN active target detector system (seesect. 2.7) will be used to create a very sensitive sys-tem to study transfer reactions of the (d, p) type.ANASEN can operate with an effective target thick-

11

ness of ≈ 2 mg/cm2, without losing substantiallyin resolution, which is more than a factor ten in-crease in luminosity over fixed targets of deuteratedpolyethylene.

ANASEN will be used as a traveling device, per-forming experiments and developing its capabilitiesat the FSU radioactive beam facility RESOLUT anddelivering a very high sensitivity for the most ex-otic beams available at the re-accelerated beam pro-grams of the NSCL and FRIB.

Figure 5: Schematic representation of ANASEN.The beam enters from the left, proceeding throughthe gas-filled chamber. Light charged particles aretracked through the position-sensitive proportionalcounter and silicon detectors.

Figure 6: ANASEN being prepared for experi-ments. Two rings of Silicon-CsI detector rings sur-round the multi-wire proportional counter.

3 The Scientific Impact of

ARUNA: Nuclear Struc-

ture and Reactions

Today’s experiments in low energy nuclear scienceare characterized by a diversity of experimentalmethods. Some experimental programs describedin the next sections are based on unique experi-mental capabilities available at ARUNA laborato-ries, such a mono-energetic neutron or γ–photonbeams. Even in the coming era of FRIB, the bigquestions of the field will be studied in the contextof individual nuclides and a variety of methods, re-quiring individually optimized experimental setups.The energy range and diversity of the experimentsenvisioned for the re-accelerated beam program atFRIB is commensurate with many of the ARUNAlaboratories, which makes them ideal places to de-velop new experimental equipment and methods.

The area of nuclear structure and nuclear reac-tions examine the complexity of the nuclear many-body problem and how its properties can be un-derstood from first principles. In the past decade,the topics of nuclear structure and nuclear reac-tions have become understood as two closely re-lated aspects of the same scientific topic, a devel-opment that is represented within the programs ofARUNA laboratories described below. These cou-pled research areas are the foundation for the manyapplications of nuclear physics, especially in the con-text of astrophysics, which was described in Section2. These topics were summarized as the following“big questions” of nuclear science in the 2007 Nu-clear Science and Nuclear Astrophysics White Pa-per, which are quoted to introduce the followingparagraphs and sections.

How does shell structure evolve with neutronnumber ?How do NNN forces impact structure and re-action properties of nuclei ?Many features of near-stable nuclei relate to the con-cept of “single-particle orbits” that group to formclosed shells at certain “magic” numbers of neutronsand protons. These shells arise naturally in a mean-field picture and are due to energy gaps betweenthe single-particle orbits. A central question is how

12

shell closures along these so-called magic numbersare modified in the presence of a large neutron ex-cess.

While the forces between pairs of protons andneutrons are relatively well known and were summa-rized as nucleon-nucleon (NN) potentials, the samecannot be said for the forces between larger groupsof nucleons. Recent results in theoretical nuclear sci-ence show that the experimental properties of lightnuclei cannot be entirely derived from the knownNN potentials alone. The presence of three-bodyforces, or NNN potentials, manifests itself in thestability of light “Borromean” nuclei like 6,8He, 9Be,and 11Li. Studies at ARUNA laboratories relatingto the topic of the relation of the nuclear mean fieldto the fundamental nucleonic interactions are de-scribed in Sections 3.1 and 3.4.

What is the impact of the continuum on nu-clear properties?As we probe exotic nuclei near the neutron drip line,the neutron separation energy decreases, and therole of open channels increases. A consistent de-scription of the interplay between scattering states,resonances and bound states in a weakly-bound nu-cleus requires an “open quantum system” formula-tion of the many-body problem, such as the con-tinuum extension of the nuclear shell model. Thereare many examples of the impact of many body cor-relations and continuum coupling on the structuralproperties of neutron-rich nuclei. Nuclear halos withtheir low-energy decay thresholds and cluster struc-tures are obvious examples. This convergence of nu-clear reaction methods with nuclear structure the-ory, the communication between the inside and out-side of the nuclear system, will be a central themeof nuclear science in the coming decade. ARUNAlaboratories are pursuing research programs on thephysics of open quantum systems, as described inSect.3.2.

What is the origin of simple patterns in com-plex nuclei?One overarching theme in nuclear science is theemergence of collective, coherent phenomena out ofthe inherent complexity of the nuclear multi-particlesystem. Collective modes like vibrations and ro-tations are common examples. Often, such simplepatterns reflect underlying symmetries of the many-

body system. For instance, the collective excitationsof the proton-neutron system are an expression ofthe underlying isospin-symmetry of the nuclear in-teraction. As the interest of nuclear structure sci-ence is focused on nuclei with very large neutronexcess, such proton-neutron excitations can be usedto investigate the resulting changes in the collectivewave functions. Research on the emergence of sim-ple patterns is described in Sections 3.5 and 3.6.

What is the equation of state (EOS) of nu-clear and neutron matter?The bulk properties of nuclear systems play a keyrole in several areas of physics. Of obvious impor-tance is the equation of state of nuclear and neu-tron matter, which governs the properties of neutronstars, plays an important role in core-collapse su-pernovae, and may be measurable in intermediate-energy heavy-ion collisions. At present, large uncer-tainties in the pairing interaction and the bulk sym-metry energy lead to substantially unconstraineddescriptions of neutron matter. From a purely mi-croscopic point of view, it remains an open questionif ab initio based calculations can be performed forneutron matter with NNN interactions. Also, ba-sic questions about the EOS above saturation den-sity remain open, since non-relativistic descriptionsin terms of neutrons and protons are expected tobreak down at a certain point. As a result, thresh-old densities for the appearance of strange baryonsand/or partially deconfined quarks, their effect onthe EOS, and the consequences for neutron star andsupernova models, need to be understood. Investi-gations of the bulk properties of nuclear matter aredescribed in Section 3.10.

In the area of nuclear structure and reactionphysics, the ARUNA laboratories pursue the samescientific goals as the national community and areoften tightly linked to programs at national user fa-cilities. In the following, examples of results fromARUNA laboratories pursuing the above listed top-ics are given and their plans for near-future projectsdescribed.

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3.1 Investigation of the Nucleon-Nucleon Force: First Measure-ments of Spin-Dependent CrossSections for the Photodisinte-gration of 3He

At TUNL-HIγSDetermination of the nucleon-nucleon force is at

the very basis of developing a comprehensive the-ory of the atomic nucleus. To this end, experimentsestablishing direct observables for few-nucleon dy-namics are essential for advancing ab initio nuclearreaction and structure calculations. Recently, thedouble polarization (polarized beam and polarizedtarget) cross section for photodisintegration of 3Hewas measured at HIγS for the first time.

These new data provide stringent tests of state-of-the-art three-nucleon calculations that use realis-tic nucleon-nucleon and three-nucleon interactions.The measurements were performed at 12.8 and 14.7MeV using a 3He target polarized by the spin-exchange optical pumping technique and the cir-cularly polarized mono-energetic gamma-ray beamat HIγS. The measured spin-dependent double-differential cross sections are compared to state-of-the-art three-body calculations in Figure 7. Thegood agreement between the data and calculationsgives confidence in the theoretical treatment of thisreaction. Furthermore, these data are used to deter-mine the integrand for the Gerasimov-Drell-Hearn(GDH) sum rule for 3He which relates the dynamicsof the photoabsorption process to the static mag-netic moment of the nucleus.

This work was published in G. Laskaris et al.,Phys. Rev. Lett. 110, 202501 (2013).

TUNL is developing a new program to measureprecision data on the neutron-neutron quasi-freescattering and search for the di-neutron bound stateby studying the γ–induced γ+t→ n+n+p breakupof tritium.

3.2 Nuclei as Open Systems –Super-radiance in CompetingDecay Channels

At Florida State University, with a group from

Figure 7: (Top) Schematic of the experimental ap-paratus: The movable 3He target system is sur-rounded by 16 liquid scintillator detectors.(Bottom)Spin-dependent double-differential cross sections forparallel (left panel) and anti-parallel (right panel)states as a function of the neutron energy. Thedata are compared with two theoretical calcula-tions made with (dashed curves) and without (solidcurves) the Coulomb interaction. The band at thebottom shows the systematic uncertainties.

14

Louisiana State UniversityA new research program at FSU is designed to

study the presence of the super-radiant or doorway-state mechanism in the presence of competingparticle-decay channels. The phenomenon of super-radiance is based on the mixing interaction of mul-tiple unbound quantum states through the contin-uum part of their wave functions, which in effectconcentrates the respective decay strength in onestate. The effect is based on a general mechanismand has been studied in the context of quantum op-tics, atomic and nuclear scattering.

An interesting facet of the super-radiant mech-anism for the stability of exotic nuclei is the pres-ence of multiple, competing particle-decay channels.It can be speculated that the mechanism of super-radiance will, in effect, separate neutron– from α–resonances in the spectrum.

In the coming years, the details of the super-radiance effect in nuclei will be studied using thenew split-pole spectrograph setup at the FSU labo-ratory (see also Sect.2.3), in conjunction with neu-tron detectors and a silicon-detector array. Themechanism of super-radiance is a natural ingredi-ent of the continuum shell model, which has beensuccessfully applied to sd-shell nuclei.

3.3 Cross-shell Excitations Investi-gated by γ–Spectroscopy

At Florida State UniversityThe shell model using the USD, USD-A, and USD-B interactions provides the best description of thepositive-parity excitations of the shell orbits overa wide range of nuclei between 16O and 40Ca. Agroup at the FSU laboratory is studying a rangeof moderately exotic nuclei between mass 20 and40 through γ–ray spectroscopy. The experimentshave established a set of negative-parity cross-shellintruder excitations, which was used to test differ-ent cross-shell interactions of the shell-model. TheWBP-a interaction describes one-particle-one-holecross-shell excitations quite well, but does not agreewith some other states, which presumably involveeither multi-particle-multi-hole states or excitationsacross more than one shell.

A wider range of moderately neutron-rich nuclei

will be investigated in the coming years at FSU,with the goal of anchoring the spectrum of cross-shell excitations, which also determine the proper-ties of exotic nuclei. This research program is di-rectly connected to studies of exotic nuclei at theNSCL and at Argonne National Laboratory, usingthe SEGA, Gammasphere and GRETINA γ-ray de-tector arrays.

3.4 Shell-Modification Studies usingTransfer Reactions on Radioac-tive Beams

At Florida State University, with a group fromLouisiana State University

The modification of shell structure at the limits ofnuclear binding and interaction with the continuumof unbound states will gain center stage at frib.The excitations of neutrons in particular can be ex-pected to deviate from the behavior found in ordi-nary nuclei, as they are solely confined by the strongforce. As an example, the location of the neutrondrip-line in 24O has been attributed to the presenceof three-body forces, which raise the neutron d3/2

orbital to be unbound and influence the excitationspectra of less exotic isotopes.

The experimental methods required for such stud-ies are being developed today and are already beingused in experiments at ARUNA laboratories, andthe re-accelerated RIB facility ReA3. The spectrumof bound states in 20O was studied at Argonne Na-tional Lab with HELIOS, establishing good agree-ment of the experimental data with the wave func-tions predicted by the phenomenological USD-Aand USD-B shell-model interactions, while the d3/2

strength is almost entirely expected to be unbound.The anasen detector (see Sect.2.7) is being devel-oped by this group as a highly efficient spectrom-eter for (d,p) reactions on exotic nuclei, with theaim to establish the systematic behavior of the d3/2

strength in moderately neutron-rich nuclei of the sdshell. The development of neutron-resonance spec-troscopy through the (d,p) reaction at the FSU ac-celerator laboratory aims at a program investigatingthe shell structure of exotic nuclei with ReA3 and

15

frib.

3.5 Microscopic Origin of Deforma-tion Coexistence

At Florida State UniversityThe high-spin structure of nuclei in the f-p-g shell

(28 ≤ N,Z ≤ 50) has been studied for its rich spec-trum of well formed rotational bands and exhibitscoexistence of prolate and oblate deformations. Arenewed interest in nuclei of this mass region comesfrom the vastly increased capability of large-spaceshell-model calculations.

In exploratory calculations, several rotationalbands are predicted, as a result of microscopic pre-dictions. Many other characteristics can also be in-ferred from the wave functions with the additionof small amounts of additional code. The promis-ing ability to achieve a better understanding of themicroscopic structure of apparently collective rota-tional bands will strongly motivate further experi-mental study and will be a future focus of the γ–rayspectroscopy program at FSU.

3.6 “Scissors Mode”, Mixed-Symmetry States and Multi-Phonon Excitations

At University of Kentucky, and at TUNL-HIγSThe lowest collective nuclear excitations with

proton-neutron degrees of freedom are the so-called mixed-symmetry states, which contain bothproton-neutron symmetric, and proton-neutronanti-symmetric components in their wave-functions.In these excitations, the isovector character isthought to be limited to the valence nucleons only.These excitations, characterized by their enhancedM1 decays, lie between 2 and 3 MeV (see Fig.8)and have been established in many medium-massand heavy nuclei, most prominently through nuclearresonance fluorescence studies of the 1+ “scissorsmode”.

An active research program into these excitationsis pursued at the TUNL-HIγS facility, which de-livers the worlds most intense mono-energetic, tun-able γ-photon beam, produced by inverse Compton-

scattering of photons from a free-electron laser. Thephoton beam is used to selectively excite collective1+ and 1− states and observe their decay throughhigh-resolution γ-ray spectroscopy. The capabilityto produce polarized beams and the direct electro-magnetic excitation mechanism makes these studiesvery sensitive, selective, and of high precision in themeasurement of ground-state electromagnetic ma-trix elements.

A complementary technique of inelastic neutron-scattering is used at the University of Kentucky Ac-celerator Laboratory (UKAL), taking advantage ofmono-energetic, tunable neutrons, which are pro-duced by intense proton and deuteron beams ongaseous deuterium and tritium targets. The inelas-tic neutron scattering reaction generally excites lev-els with spins up to I=6 at energies up to the inci-dent neutron energy. Their decays can be observedusing high-resolution γ–ray spectroscopy. The de-cay lifetimes are measured through Doppler-shiftmethods and γ–ray multipolarities are determinedthrough angular distribution measurements. Thismethod has proven to be well suited to study thespectrum of 2+ states of mixed-symmetry charac-ter, as well as multi-phonon states.

The UKAL group has recently performed a seriesof measurements with solid, isotopically enrichedXeF2 targets, which were used in experiments atboth UKAL and HIγS, filling an important gap innuclear structure information of these nuclides andstudying nuclear excitations with potential impacton neutrinoless double–β decay studies, describedin Section 3.8.

3.7 Fine Structure of the Giant M1Resonance in 90Zr

At TUNL-HIγS

Understanding the magnetic dipole and Gamow-Teller responses in nuclei are long-standing chal-lenges in nuclear physics. Because of the close re-lationship between the M1 excitation and neutrino-nucleus processes, knowledge of the M1 excitation isparticularly important for the estimate of neutral-current cross sections in supernova explosions andterrestrial detection of supernova neutrinos.

16

Sn

P, n

p n

() (,Xn)

M1 E1

p,n n

Xλ ? E1

Ex

Cro

ss S

ectio

n

10 2051

Figure 8: Schematic representation of collective nuclear excitations studied by real photon probes. The“scissors mode” around 2..3 MeV, two-phonon excitations around 4 MeV, the “pygmy” dipole resonancearound 5-10 MeV and the giant dipole resonance above 10 MeV.

As a general observation, measurements find con-siderably less magnetic strength than theoreticallyexpected. This is known as the “quenching” phe-nomenon of the nuclear spin-flip magnetic response.Explaining the dynamics of quenching means un-derstanding the coupling of the two-quasiparticledoorway states to many-quasiparticle configura-tions. The M1 excitations in 90Zr were studied in aphoton-scattering experiment with mono-energeticand 100% linearly polarized photon beams from 7 to11 MeV. The results of the experiment are displayedin Fig.9. More than 40 1+ states were identified fromobserved ground-state transitions, revealing the finestructure of the giant M1 resonance for the firsttime. The concentration of M1 strength around9 MeV is further confirmed in three-phonon quasi-phonon model calculations and explained as frag-mented spin-flip excitations. The observed stronglyfragmented M1 strength and its absolute value canbe explained only if excitations more complex thanthe single particle-hole excitations are taken into ac-count. The theoretical investigations of the frag-mentation pattern of the M1 strength indicate astrong increase of the contribution of the orbitalpart of the magnetic moment due to coupling ofmultiphononon states. The effect is estimated toaccount for about 22% of the total M1 strength be-low threshold.

This work was published in G. Rusev, N. Tsoneva,F. Donau, S. Frauendorf, A. S. Adekola, S. L. Ham-mond, C. Huibregtse, J. H. Kelley, E. Kwan, H.Lenske, R. Schwengner, A. P. Tonchev, W. Tornow,and A. Wagner. Phys. Rev. Lett. 110, 022503(2013).

3.8 Nuclear Structure Studies for0νββ Decay

At TUNL-HIγS, University of KentuckyA research program using multiple instruments

at TUNL is in progress to study the nuclearphysics context of neutrinoless double–β decay(0νββ). Quasiparticle random phase approximation(QRPA) theory is used to calculate the matrix ele-ments of 0νββ decays. The validity of such calcu-lations is tested by measuring the fragmentation ofthe pygmy dipole strength using nuclear resonancefluorescence spectroscopy in mass 40-150 nuclides.A new program has been initiated at the TUNLtandem laboratory with the aim to study the samedecay matrix elements through the (3He, n) reac-tion, measuring neutron time-of-flight with a pulsed3He beam. The studies, which connect the sameinitial and final states as the 0νββ decay include76Ge(3He, n)76Se and similar experiments on 74Ge,74Se, 76Se, 126Te, 128Te,130Te,132Xe,134Xe, 136Xe.

17

Figure 9: Results for (a) the measured B(M1)strength of discrete levels in 90Zr compared with thedetection limits (red solid line) and (b) predictionsfrom the quasiparticle phonon model. A compari-son of the measured and calculated QPM cumula-tive M1 strength is shown in panel (c). The shadedarea gives the uncertainty of the experimental val-ues.

Another study at the University of Kentucky isaimed at characterizing background signals in neu-trinonless double–β decay experiments. The Uni-versity of Kentucky Van de Graaff accelerator wasused to produce fast, mono-energetic neutrons tomeasure γ-ray spectra following (n, n′γ) reactionson 76Ge, 134Xe and 136Xe, which may create neutron-induced background signals in 0νββ experiments.In 76Ge, two excited states were identified, whichdecay by the emission γ-rays, within the detectorresolution of the 0νββ Q-value. A similar resultwas obtained in 134Xe, where a 2485-keV γ ray couldcreate background signals for the EXO experiment,which contains 20% of 134Xe in its liquid xenon TPC

detector.

3.9 Statistical Nuclear Physics

At Ohio University and University of Notre-Dame

Hauser-Feshbach (HF) theory of compound nu-clear reactions is the main tool to calculate crosssections at low energies for middle- and high- massnuclei. Despite the fact that the underlying physicsis simple and well understood, the accuracy of suchcalculations does not reach the predictive power re-quired for many astrophysical problems. Uncertain-ties can reach the factor of two for nuclei close to thestability line and even higher for radioactive nuclei.

The accuracy of HF theory is determined by theaccuracy of its input parameters, namely the opticalpotential parameters, level densities and γ–strengthfunctions. A very active program at the EdwardsAccelerator Laboratory of Ohio University is pur-suing research to determine these input parame-ters, using systematic studies of particle evaporationspectra obtained from experiments with deuteron,3He, and 6,7Li projectiles. The objective is to es-tablish reliable information on the behavior of theHF input parameters for nuclei off stability and de-formed nuclei. Another objective of the researchis an independent determination of the γ–strengthfunctions, which are studied in collaboration withthe Cyclotron Laboratory of Oslo University. Oneimportant recent finding is that the γ-strength func-tion experiences a considerable enhancement in thelow energy region (Eγ < 3 MeV) for nuclei in themass range 50-60 and around 90. This is in con-tradiction with current theoretical models and hasa very large impact on (n, γ) cross sections off thestability line.

Although these parameters have been determinedexperimentally for some stable nuclei, they are com-pletely unknown for nuclei off of the line of stabil-ity. This motivates studies with radioactive beamsfrom the next generation of nuclear physics facil-ities (NSCL/FRIB/Atlas etc. . . ). Development ofsuch an experimental program will also provide thenecessary experimental ground for refining nuclearreaction codes such as EMPIRE and TALYS usedfor the evaluations of nuclear reaction data for the

18

U.S. nuclear data program and for the prediction ofastrophysical cross sections.

Results from this program were published inA. V. Voinov, S. M. Grimes, C. R. Brune, M. J.Hornish, T. N. Massey, and A. Salas, Phys. Rev.C76, 044602 (2007).S. M. Grimes, Phys. Rev. C88, 024613 (2013).A. Voinov, S. M. Grimes, C. R. Brune, M. Gut-tormsen, A. C. Larsen, T. N. Massey, A. Schiller,and S. Siem, Phys. Rev. C81, 024319 (2010).A. Voinov, E. Algin, U. Agvaanluvsan, T.Belgya, R.Chankova, M. Guttormsen, G. Mitchell, J.Rekstad,A. Schiller, and S. Siem, Phys. Rev. Lett. 93,142504 (2004).

A research program which is actively pursued atthe Nuclear Structure Laboratory of Notre Dameconcerns the effects and implications on cross sec-tion calculations arising from HF input models. Re-cent r-process simulations, performed using ratesobtained from the TALYS and NON-SMOKERcodes, have indicted that model dependent features,such as those originating from nuclear input pa-rameters in Hauser-Feshbach calculations, can prop-agate through to abundance predictions. Thesemodel differences stem from two primary sources,including code-dependent numerical effects, and in-put parameter implementation details. An activeeffort at Notre Dame has been focused on examiningthese two aspects. This has involved developing twonew HF codes, CIGAR (Capture Induced GAmma-ray Reactions) and SAPPHIRE (Statistical Anal-ysis for Particle and Photon capture and decay ofHIgh energy REsonances). The codes have been de-veloped to contain an overlapping set of identicallyimplemented nuclear model input parameters, al-lowing the effects of numerical approximations andtruncation on HF calculations to be directly inves-tigated.

The investigation of cutting edge input models onHF cross section calculations is also a very activeresearch area at the NSL. The objective is to re-fine HF cross sections with the latest available dataand models in order to produce high quality cal-culations for other applications. Current theoreti-cal efforts are centered on three main aspects. Thefirst is the origin and modeling of the low energy γ-

strength function enhancement, indicated by shell-model calculations to be M1 in nature, which hasbeen observed for some nuclei. An ongoing effortis focused on including a new M1 γ-strength func-tion model into HF calculations. The second aspectis investigating the effects of a new, state-of-the-artspin and parity-dependent shell-model level-densitytreatment for HF calculations. The third area of re-search being actively pursued at the NSL is the in-clusion and investigation of a new global α-particleoptical-model potential on HF calculations.

Results from the HF research program have beenpublished in M. Beard, E. Uberseder, R. Crowterand M. Wiescher, Phys. Rev. C 90, 034619 (2014).

3.10 Nuclear Equation of State

Studies of the Nuclear Compressibilitythrough Measurement of the BreathingMode State : At Texas A&M UniversityThe compressibility of nuclear matter (KNM)and the asymmetry behavior (KSYM) is studiedthrough measurements of the breathing mode, Gi-ant Monopole Resonance (GMR) state. In the lastfive years, an experimental program at the TexasA&M cyclotron laboratory has shown (1) that theresults for 24Mg and 28Si agree with a KNM fromheavier nuclei (KNM ≈ 230 MeV) but (2) the po-sition of the breathing mode state in some nuclei(particularly in 92Zr and 92Mo but also in Ca andNi isotopes) is NOT explained by mean field calcu-lations (Figure 10), suggesting a significant nuclearstructure effect. This effect might alter the presentlyaccepted KNM extracted from breathing mode ener-gies using mean field calculations. Understandingthe nuclear structure effects will provide a betterbasis for KNM and KSYM.

With the ongoing progress of the T-Rex labora-tory upgrade for re-accelerated exotic ion beams,similar experiments will be performed on exotic nu-clei at Texas A&M, with the goal to study the sys-tematic dependence on the neutron-proton asymme-try. The experiments will be performed with newlight-particle detectors covering the full solid anglein coincidence with the residual heavy nucleus, to bemeasured in the Multipole-Dipole-Multipole Spec-trometer.

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Figure 10: Squares: HFB-QRPA: Sly4 with pair-ing, KNM=252 MeV, Kτ=-500 MeV, P. Vesely et al.PRC 86, 024303(2012). Circles: KA from TAMUGMR data. Colors correspond to particular isotopesas shown, while for the color brown no correspond-ing calculations are given.

First Observation of the Asymmetry De-pendence of the Caloric Curve :At Texas A&M UniversityThe nuclear equation of state (EOS) is of funda-mental importance in describing properties of nu-cleonic systems, and as such is a recurring themein the Long Range Plan (LRP). The EOS, whichdescribes the relationship between the thermody-namic parameters and the bulk nuclear properties,is relevant in heavy ion collisions and environmentsof nucleosynthesis. The nuclear EOS is well char-acterized near beta-stability, so the neutron-protonasymmetry is increasingly studied in relation to theEOS. The lack of understanding in how the asym-metry impacts the caloric curve represented an op-portunity to make a leap forward in understandingthe nuclear equation of state.

We have studied the decay of isotopically recon-structed quasi-projectiles (QPs) produced in heavyion collisions at 35 MeV/u. The excitation energyis determined from charged particle kinetic energies,neutron multiplicities, and the Q-value of the QPbreakup. The neutron-proton asymmetry of the QPis calculated directly from the charged particles andneutrons attributed to the decay of the QP. Thetemperature of the QP is calculated using severalcharged particles as probes and multiple methods

of temperature determination.

Figure 11 shows the≈1 MeV decrease in tempera-ture with increasing asymmetry. For all probes, thetemperature rises with increasing excitation energyas expected and decreases significantly with increas-ing asymmetry. The strength of this measurementlies in the knowledge of the composition of the ex-cited system (via isotopic reconstruction of the QP),which allows this measurement to succeed whereothers had failed. In this way, we have measuredfor the first time a clear asymmetry dependence ofthe nuclear caloric curve, which represents a leapforward toward understanding the nuclear equationof state.

Confirmation of this seminal observation ought toprobe the caloric curve in an independent manner,avoiding the necessity of a free neutron measure-ment. For these measurements, the system com-position must be fully constrained by the entrancechannel and the reaction mechanism. By measur-ing the evaporation residue and evaporated particleswithout reliance on free neutrons, the temperaturemay be extracted with minimal systematic uncer-tainty. Moreover, the density and pressure will beextracted to gain a larger perspective of the asym-metry dependence of the relations between the ther-modynamic parameters.

The recently commissioned QTS Spectrometerat the Texas A&M University Cyclotron Instituteis ideally suited to measuring the heavy residueswith good efficiency and resolution. The focusingspectrometer may be used in conjunction with thecharged-particle detector FAUST to measure theevaporated particles with good energy resolutionand position resolution. Such a detector suite iswell poised to take advantage of heavy rare-isotopebeams when they become available.

Effects of Clusterization on the Low-Density Equation-of-State :At Texas A&M UniversityConventional theoretical calculations of nuclearmatter properties based on mean-field approachesfail to give the correct low-temperature, low-densitylimit, which is governed by correlations, in partic-ular by the appearance of bound states. New datafrom heavy-ion collisions have been used to probeclusterization at temperatures and densities compa-

20

Figure 11: Caloric curves for isotopically recon-structed sources extracted with the momentumquadrupole fluctuation method using protons as theprobe particle. Each curve corresponds to a narrowrange in source asymmetry (ms).

rable to those expected for the neutrinosphere in asupernova explosion. These data are being used totest astrophysical equations of state at low density.From the data, in-medium cluster binding energiesfor d, t, 3He, and α-clusters, produced in low densitynuclear matter and the free symmetry energy andthe internal symmetry energy at sub-saturation den-sities and temperatures are extracted. The symme-try energy of nuclear matter is a fundamental ingre-dient in the investigation of exotic nuclei, heavy-ioncollisions, and astrophysical phenomena. A recentlydeveloped quantum statistical (QS) approach thattakes the formation of clusters into account predictssymmetry energies that are in very good agreementwith the experimental data. Proper treatment of in-medium effects in astrophysical equations of stateshould improve the utility of those for modeling as-trophysically interesting events.

K. Hagel, J.B. Natowitz and G. Roepke, Theequation of state and symmetry energy of low-density nuclear matter European Physical JournalA 50 39-1 - 39-16 (2014) and references therein.

3.11 Prospects for Discovering NewSuper-Heavy Elements

At Texas A&M University

In the last 15 years, several super-heavy elementshave been discovered using a single, exceptional pro-jectile: 48Ca. These discoveries used nuclear re-actions where two nuclei fuse together to form a“compound nucleus” containing all of the protonsand neutrons originally in the two reacting nuclei.48Ca has an unusually high neutron-to-proton ratio,and this impacts its ability to form super-heavy el-ements. Unfortunately, all possible reactions whichcould potentially produce new elements using 48Cahave already been studied, so a new projectile willbe needed. Experiments at Texas A&M Universityhave been evaluating whether 45Sc and 50Ti couldbe used as projectiles to produce new super-heavyelements. The data suggest that these projectilescreate compound nuclei which are more likely tofission (to split back into two nuclei) rather thanstay fused. As a result, forming new super-heavyelements will likely be extremely difficult, possiblyrequiring upgrades to existing facilities.

D. A. Mayorov, T. A. Werke, M. C. Alfonso,M. E. Bennett, and C. M. Folden, III Productioncross sections of elements near the N=126 shell inCa48-induced reactions with Gd154,Tb159,Dy162,and Ho165 targets Phys. Rev. C 90, 024602 (2014)

3.12 Surrogate Reactions for n-Induced Fission

Texas A&M University, with a group from the Uni-versity of RichmondThe Richmond group carries out an active programon surrogate reactions for neutron-induced fissionand inelastic neutron scattering on actinide targets,performed with the STARLITER array at TexasA&M University. The surrogate reaction programaims to test the efficacy of the surrogate reactiontechnique to extract (n,f) and (n,xnγ) cross sec-tions for unstable nuclei. Direct measurements ofsuch cross sections are difficult or impossible forshort-lived species. The surrogate reaction producesthe same compound system as the direct neutron-induced reaction but exploiting a stable beam andtarget combination. A measurement of the de-cay probabilities and a calculation of the forma-tion probability yields the cross section of interest,assuming the system is equilibrated and that the

21

spin/parity/excitation energy distributions are sim-ilar.

The primary apparatus for these investigationsat Texas A&M University is the STARLITER ar-ray. STARLITER, developed and commissioned bya group at LLNL, consists of a highly segmented Sidetector array (STARs, the Silicon Telescope Arrayfor Reaction studies) to detect light charged-particleand fission fragments coupled to the 5-6 Compton-suppressed Ge detectors of the LITER (LIvermoreTExas Richmond) array. Typical detection efficien-cies are 20% for light charged particles, 30% forfission fragments and 5% (200 keV) and 1.5% (1.3MeV) for γ rays.

The results for (n,f) cross sections show remark-able agreement with the evaluated databases: agree-ment is typically within 5-10% of the accepted val-ues for multiple different reactions and nuclei. Thelatest results, 236Pu,237 Pu and 238Pu(n, f) measure-ments based on a recent experiment at the TexasA&M Cyclotron Laboratory, have been published.The results for 237,238Pu(n, f) show good agreementwith the database values. However, the surrogatecross section for 236Pu(n, f) deviates significantly, inboth magnitude and trend, from the ENDF values.It is of note that in this case there are essentially nodata to guide the database (model) values.R.O. Hughes, C.W. Beausang, T.J. Ross,J.T. Burke, R.J. Casperson, N. Cooper, J.E. Es-cher, K. Gell, E. Good, P. Humby, M. McCleskey,A. Saastimoinen, T.D. Tarlow, and I.J. Thompson,Pu236(n,f), Pu237(n,f), and Pu238(n,f) cross sec-tions deduced from (p,t), (p,d), and (p,p) surrogatereactions, Phys. Rev. C 90, 014304 (2014).

4 The Scientific Impact of

ARUNA:

Fundamental Symmetry

Studies

Many groups working on studies of fundamental in-teractions or searches for physics beyond the Stan-dard Model have found the ideal environment, com-plementary to that of the national laboratoriesand large nuclear physics facilities, at some of the

ARUNA labs. These experiments usually need ex-tended experimental studies to understand and min-imize systematic uncertainties, which can take longperiods of on-line beam time. Thus, in many cases itis difficult to run these experiments at large facilitieswhere beam time is limited and setups need to bedisassembled to yield space for other experiments.

4.1 Testing CVC and CKM Unitar-ity via Superallowed 0+ → 0+

Nuclear Beta Decay

At Texas A&M UniversityConservation of the vector current (CVC) andthe unitarity of the Cabibbo-Kobayashi-Maskawa(CKM) matrix are fundamental pillars on which theStandard Model was built. Tests of their validitymake it possible to exclude potential scenarios fornew physics. For several decades, measurements onsuperallowed 0+ → 0+ nuclear β transitions havetested CVC and been the source of the most pre-cise value for Vud, which in turn has yielded themost demanding test of CKM unitarity. The uncer-tainties on all these results have been substantiallyand continuously reduced over that period of time.In addition, the observed constancy of the effectivecoupling with respect to the β-decay Q values forthe superallowed transitions has been used to putthe most sensitive limits so far on possible Scalarcontributions to weak decays.

During the last 5 years, the group of John Hardyand collaborators (Texas A&M) have measured pre-cise half-lives (±0.03%) for the superallowed emit-ters 26Si, 26Alm, 30S, 38Km, 38Ca and 46V, QEC values(±80 eV) for the superallowed emitters 10C, 34Ar,38Ca and 46V and branching ratios (±0.1%) for thesuperallowed transitions from 34Ar and 38Ca. Inall cases, the precision they have achieved is unsur-passed by any other group worldwide and, in mostcases, it is also unmatched by any other group. Asa long-term goal, they plan to complete all fouraccessible mirror pairs, 26Si → 26Alm → 26Mg,34Ar → 34Cl → 34S, 38Ca → 38Km → 38Ar and42Ti → 42Sc → 42Ca. Depending on the results,these cases could constrain the calculated isospin-symmetry-breaking corrections enough to reduce

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Figure 12: The extraction of Vud and the verificationof the conservation of the vector current have beenconstrained using data from ARUNA labs. The topleft shows the measured ft values. When correctedfor isospin-symmetry breaking and radiative effects,the Ft values show independence of Z. This is usedto put limits on the violation of CVC and gives con-fidence in the isospin-breaking corrections. (Cour-tesy: John Hardy).

the systematic uncertainty on Vud, and thus improvethe unitarity sum.

New test of Isospin Symmetry BreakingAt Texas A&M UniversityA new and powerful test of isospin-symmetry-breaking effects in nuclear beta decay has beendemonstrated at the Texas A&M Cyclotron Insti-tute by a precise measurement on the decay of 38Ca,a nucleus with a half-life of only 444 ms. Onemode of decay for 38Ca is a so-called “superallowed”branch, which exclusively occurs via the vector weakinteraction. By determining the fraction of 38Ca de-cays that follow this path, the experimenters estab-lished the overall strength of the transition, referredto as its ft value, with ±0.2% precision. They thencompared that result with the ft value for a similartransition in the decay of 38mK. These two transi-tions are described as mirrors of one another becausethe nuclear structure of their initial and final statesis very similar and, indeed, would be identical if theneutron and proton were identical particles. It turnsout that the small difference between the ft valuesfor such a pair of transitions is a sensitive measure ofthe effects of the proton-neutron differences them-

Figure 13: Dan Melconian and students near theTAMUTRAP setup.

selves, i.e., isospin symmetry breaking. This result,once combined with planned future comparisons ofmirror superallowed transitions, is expected to re-sult in an improved test of the unitarity of the CKMmatrix. This has deep implications since any exper-imentally observed deviation from unitarity wouldsignal the existence of new physics beyond the Stan-dard Model.

H.I. Park, J.C. Hardy, V.E. Iacob, M. Bencomo,L. Chen, V Horvat, N. Nica, B.T. Roeder, E. Sim-mons, R.E. Tribble, and I.S. Towner, β Decay ofCa38: Sensitive test of Isospin Symmetry-BreakingCorrections from Mirror Superallowed 0+ → 0+

Transitions, Physical Review Letters 112, 102502(2014).

Addional Techniques for the study of super-allowed β–decaysAt Texas A&M UniversityThe group of Dan Melconian and collaborators(also at Texas A&M) is setting up an ion trap(TAMUTRAP) to do precision determination ofbeta-delayed proton decays of the A = 4n T = 2nuclei and test isospin symmetry breaking correc-tions which affect the extraction of Vud.

Lynn Knutson (Madison, Wisconsin), ElizabethGeorge and Paul Voytas (Wittenberg University)and collaborators have set up an iron-free spectrom-eter and performed precise determinations of theshape of beta spectra. They have published workfrom 66Ga and are presently working on the determi-nation of the 14O spectrum, which could potentially

23

affect the extraction of Vud.

4.2 Precision Determination of Cor-relations in Nuclear Beta Decaysto Search for Scalar and TensorCurrents

At University of Washington, with groups fromArgonne National Laboratory, etc. At Texas A&MUniversity. At Lawrence Berkeley National Labora-tory (Not an ARUNA member)

Conservation of angular momentum combinedwith the left-handedness of the weak interactionyield clear prescriptions for angular correlations in-volving the electron and neutrino. Scalar and tensorcurrents, with chiralities opposite those of the Stan-dard Model, would produce effects on these corre-lations and on the shape of the spectra which al-low for sensitive searches in particular nuclei. Sev-eral groups are working at ARUNA labs using noveltechniques for improving sensitivity.

Figure 14: Graduate students David Zumwalt andYelena Bagdasarova at work at the laser setup at theUniversity of Washington, Seattle. David Zumwaltcontributed to developing a source for producing6He which currently is the most intense in the world.

In order to determine the correlations it is neces-sary to detect the slow recoiling nuclei, so it helps touse ion or atom traps to have minimal interferenceon the decaying particles.

Yuan Mei, Brian Fujikawa, and collaborators atLawrence Berkeley National Laboratories are work-ing on an electrostatic ion beam trap (EIBT) that

should allow them trapping of 19Ne and 6He and de-termination of the electron-antineutrino correlation.

The group of Dan Melconian and collaborators(at Texas A&M) is setting up the largest open Pen-ning ion trap (TAMUTRAP mentioned in the pre-vious section) to do precision determination of cor-relations in beta-delayed proton decays of A = 4nT = 2 nuclei.

A collaboration (P. Muller, A. Garcia, spokeper-sons) between Argonne National Laboratory, Uni-versity of Washington (Seattle), LPC (CAEN,France), and Michigan State University is workingon the determination of the electron-antineutrinocorrelation from 6He.

All these experiments are presently working to-wards determinations of the correlations at the sub-percent level, aiming for a goal of ∼ 0.1%, compet-ing worldwide with the most sensitive experiments.

5 The Scientific Impact of

ARUNA:

Applications of Nuclear

and Radiation Methods to

Other Fields of Science

The majority of the ARUNA laboratories support“applied” programs, meaning the use of acceleratorfacilities and methods of particle and radiation de-tection for other areas of science. These programsare natural for the unversity-based ARUNA labo-ratories, since a wide variety of scientific and engi-neering expertise is concentrated on university cam-puses. ARUNA facilities provide opportunities forcross fertilization of ideas and suggestions and areideally situated for applications in the nuclear andradiation sciences.

The applied programs also play an important rolein the educational mission of ARUNA laboratories,which will be described in more detail in Section 6.The campus presence of ARUNA facilities, togetherwith the opportunity to participate in applied sci-ence, is attractive to students. As natural hosts tointer-disciplinary research programs, ARUNA labo-ratories are the first point of contact with the nu-

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clear science field for many undergraduate students.The importance of applied programs for the scienceeducation of undergraduate students is exemplifiedin the two undegraduate institutions, Hope Collegeand Union College, who are members of ARUNA.

5.1 Ion Beam Analysis:

At Hope College, Union College, University ofNotre Dame, TUNL, Florida State University

The α-scattering experiment that Rutherford in-terpreted to establish the existence of the nucleus,founding our field, is used in the ARUNA labora-tories, as it is around the world, to characterizematerials. In addition to Rutherford backscatter-ing (RBS), proton-induced X-ray emission (PIXE),proton-induced gamma-ray emission (PIGE), andother techniques are used in our laboratories as re-search and teaching tools. These relatively simplemethods allow for projects that are well adaptedto undergraduate research. At the Hope CollegeIon Beam Analysis Laboratory, a research programtakes undergraduate students from the analysis oftrace elements in glasses for art and archeology stud-ies to characterization of metalloproteins. System-atic studies of consumer products also have beenperformed to evaluate the usage of flame-retardentchemicals in car seats or perfluorinated compoundsin cosmetics and food containers. In addition to ex-citing scientific results and a significant number ofpublications, the undergraduate students are learn-ing the key elements of the scientific method.

At the University of Notre Dame, an applied pro-gram in art analysis has been developed in collab-oration with the Department of Anthropology, andinvolves undergraduate students from that Depart-ment. Through this program, which is supported bythe University, pottery samples from the US South-west Anasazi sites have been analyzed using PIXEtechniques, see Fig.15. Of particular interest wasthe pigment composition of the painted pottery sur-face. Through the organization of this program andthe development of a special multidisciplinary sem-inar, strong communication links have been estab-lished with the non natural science academic com-munity at Notre Dame.

This program has now expanded into a collabora-tion with the rare book collection of the Notre Damelibraries to study and identify medieval book paint-ing techniques and monastery artists and paintingschools.

Figure 15: (a) Exposing an artifact to UV lightreveals the location of pigments invisible to theunassisted eye (b) Proton-induced x-ray emission(PIXE) provides quantitative details of the pigmentcomposition; in particular, it reveals the iron andmanganese content of the paint.

At the Triangle Universities Nuclear Laboratory,characterization of membranes for water purifica-tion by RBS and elastic recoil detection (ERD) anal-yses have been performed, and a publication withan undergraduate student as first author has beensubmitted.

At the Triangle Universities Nuclear Laboratory,a multidisciplinary study of the impact of increasedCO2 concentrations in the atmosphere due to hu-man activities is being performed. 11C is producedat the TUNL Tandem laboratory, 11CO2 is then in-jected into growth chambers for corn plants. Aninnovative method, called PhytoPET developed atJefferson Laboratory, is being used to dynamicallyfollow the path taken by the 11C in the plants.

At Hope College, a method is being developed forisotope harvesting of 67Cu from the beam stop of theFacility for Rare Isotope Beams (FRIB). This iso-tope can be used for positron emission tomographybut more importantly, it is used to target specificcancerous tumors while imaging them at the sametime using the single-photon emission computed to-mography (SPECT).

At the University of Notre Dame, a program to

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systematically study the Mo(p,Xn)mTc is underwayto evaluate the dosimetric contamination that mayoccur in the accelerator-based production of 99Tcm.This isotope is used in 90% of nuclear medicine pro-cedures in the US. There is currently a risk of short-age as the standard method of production, whichuses highly enriched Uranium, is being phased out.

An accelerator mass spectrometry (AMS) pro-gram has been developed at the University of NotreDame. While standard 14C AMS techniques are pri-marily used for undergraduate student training, newAMS probes from 44Ti to 60Fe have been developedfor geological, hydrological, and meteorological ap-plications.

5.2 Homeland Security and Na-tional Nuclear Security

Much of the equipment used by border control agentoriginates from developments in nuclear science.ARUNA laboratories are investigating new methodsfor security.

At the Triangle Universities Nuclear Laboratory,studies are performed to provide crucial data to anon-intrusive active interrogation system using nu-clear resonance fluorescence (NRF). The objectiveof the measurement is to demonstrate that key el-ements (240Pu, 237Np, 233U) have states that canbe excited by the proposed source. The source pro-duce gamma rays between 2 and 4 MeV. In addition,TUNL is studying photo-fission induced by polar-ized γ rays as a new material analysis method.

5.3 Neutron Physics and InertialConfinement Fusion (ICF)

At Ohio University, with a group from SUNY Gene-seo and University of Notre DameAt the Ohio University Edwards Accelerator Labo-ratory, a unique national facility for neutron science,the applied program is centered around the 4.5-MV tandem accelerator designed to support highbeam intensities. The majority of the applied nu-clear physics work at this laboratory involves neu-tron production and/or detection. The combinationof continuous and mono-energetic neutrons togetherwith a well-shielded 30-meter fight path does not

exist anywhere else in North America. This com-bination of equipment permits measurements withhigh resolution and low background.

Two ongoing projects in the lab are the study offast neutron transmission in iron. Other projects,which are led by outside users, include neutronimaging, neutron detector calibration, studies ofneutron damage of electronics, and a measurementof the 12C(n, 2n)11C cross section. The latter projectis part of an effort to develop a high-energy neutrondiagnostic for inertial confinement fusion (CF) fa-cilities, led by external users involving a dozen un-dergraduate students from the State University ofNew York in Geneseo, NY. In the same context, themeasurement of the 3H(d,γ) and 3H(d, n) branchingratio important for understanding ICF diagnosticsis underway.

5.4 Radiation chemistry

At University of Notre DameThe radiation chemistry program at the Universityof Notre Dame Nuclear Science Laboratory focuseson the fundamental physical and chemical processesinvolved in the passage of ionizing radiation throughmatter. Although the research examines basic pro-cesses involved in radiolysis, the information is di-rectly applicable to a wide variety of scenarios inthe fields of medicine, engineering, and environmen-tal studies. Specific progress made in the nuclearpower industry includes addressing problems in re-actor water chemistry, waste storage and fuel repro-cessing. The goal of these particular studies is toderive fundamental information on radiation effectsto allow for the safe and economical developmentand management of nuclear power. Secure storageof radioactive waste is one of the main elements ofthis program to ensure a pristine environment andpublic safety. Other applications related to medicaltherapy, space exploration, and homeland securityare being explored.

The group at the University of Notre Dame isin the process to develop new nuclear probes formapping the temperature density conditions for theNIF shot environment using the 10B(p, α)7Be reac-tion. Simulations have shown that reaction rate issufficient to produce observable quantities of 7Be at

26

NIF. First tests are being in preparation. If suc-cessful the program will be expanded to the studyof plasma effects on nuclear reaction rates that arepresently only estimated.

5.5 Detector development

At University of Massachusetts Lowell, Universityof Kentucky

The combination of a research reactor next to a5.5-MV Van de Graaf accelerator allows for the de-sign and a construction of the next generation neu-tron detectors and high-granularity germanium γ-ray detectors. The characterization of neutron de-tectors based on the Cs2LiYCl6 (“CLYC”) scintilla-tor is being performed in experiments at the UMassLowell research reactor and the University of Ken-tucky accelerator laboratory. The development ofplanar, pixellated high-purity germanium detectorsis performed at the UMass Lowell accelerator. Bothprojects are leveraged with private industry throughSBIR-grants.

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6 Education and Workforce

Development

The ARUNA facilities play an important role in theresearch and education missions of the field of nu-clear science. The important contributions to re-search have been outlined already. In this section,we concentrate on the contributions in terms of edu-cation and outreach. The research programs at theARUNA facilities are conducted in an environmentthat is optimized for graduate education in exper-imental nuclear science, mentoring young scientistsand providing research opportunities for undergrad-uate students.

Faculty at ARUNA facilities are dedicated tomaintaining an environment that engages studentsin all aspects of research from concept development,experimental preparation and execution, throughdata interpretation to the dissemination of results.The small-group environments at these facilitiesprovides opportunities for graduate students andundergraduates to work closely with postdocs andfaculty, to have hands-on research experiences, andultimately to provide leadership on thesis projects.The on-campus presence of the ARUNA laborato-ries is an important factor in attracting the brighteststudents to the field of nuclear science.

The location of these facilities at universitiesmakes the educational reach very broad, impact-ing the undergraduate students, graduate students,postdocs, faculty and administrators within the uni-versity, as well as the general public in the commu-nities in which the universities exist.

The report on the implementation of the 2007Long-Range Plan [1] lists the number of Ph.D. grad-uates, distinguished by research area, year and insti-tution. This report shows that, during the periodof 2006-2012, close to 40% of the Ph.D’s in low-energy nuclear science and nuclear astrophysics weregranted by the institutions of the ARUNA labora-tories (including the Yale University group). Themajority of those Ph.D. dissertations include ex-periments from ARUNA laboratories, where manyprojects were connecting local experiments with ex-periments at national user facilities. A table of theARUNA Ph.D. graduates 2006-2015 is given at the

end of this section. The seven largest ARUNA fa-cilities (FSU, Kentucky, Notre Dame, Ohio, TUNL,TAMU, UMass) currently host 75 undergraduate re-searchers and 37 postdocs.

6.1 Undergraduate Students get In-volved

Undergraduate students are the lifeblood of a uni-versity and of an ARUNA laboratory. The researchgroups at ARUNA facilities routinely involve under-graduate students in their work as undergraduateresearch assistants (URA). The URA positions areusually funded by research grants of the groups or bythe universities, and many undergraduate studentswork on research projects throughout the year.

Additionally, a number of the ARUNA labora-tories have research experience for undergraduates(REU) programs in the summer or connectionswith predominantly undergraduate institutions thatbring students for the summer for research experi-ences. For example, Texas A&M has had a nuclearscience REU program for over 10 years, exposingover 120 students to nuclear science, predominatelyfrom schools where they would have limited or noexposure to nuclear science in their undergraduatecurriculum. The ND REU program, funded formore than 25 years, involves an average of 5-10 stu-dents in the nuclear lab. At TUNL an NSF-fundedREU program involves 8 students in a 10-week re-search experience.

In many cases the connections to these undergrad-uate institutions are scientists, who came throughthe ARUNA laboratories. One example of the roleARUNA labs play beyond their own students isthe 30 undergraduate students from the Univer-sity of Dallas that Prof. Sally Hicks has brought tothe University of Kentucky Accelerator Laboratory(UKAL) to engage in research over the past 20+years. Professor Sally Hicks herself came throughUKAL and now shares her knowledge of and excite-ment for nuclear physics with students that other-wise would likely have no exposure to this field ofscience. Of the undergraduate students who partic-ipated, 42% received a physics or engineering Ph.D.

Professor Shelly Lesher is beginning a similar tra-dition of bringing undergraduate students from the

28

University of Wisconsin at La Crosse with her to theUniversity of Notre Dame and the UKAL for sum-mer research experiences. These students are notonly learning nuclear physics, but they are gainingvaluable skills.

Benefits of undergraduate researchexperience:

• Technical skills

• Creative problem solving skills

• Scientific communication skills

• Dealing with frustrations / persever-ance

• Self-confidence

• Time management

• Project planning

• Working within a collaboration

• Leadership development

In addition to the students who make the com-mitment to do an undergraduate research project,there are other undergraduates who get exposedto nuclear physics by working at the laboratory invarious capacities. At many ARUNA laboratoriesyou can find undergraduates involved across the fullspectrum of the laboratory. Some may work onconstruction projects, others as part of the com-puter group, some on the accelerator, and othersare imbedded in the research groups. In the caseof the applied programs, non-science undergraduatestudents get exposed to nuclear physics techniques.All of these are valuable contributions to educationand increase the understanding and acceptance ofnuclear science in a broad group of individuals.

6.2 Teaching is Impacted by theARUNA Facilities

Faculty at ARUNA facilities teach classes at thehost university. This results in many more people

being exposed to nuclear science. We bring our re-search into the classroom and we bring the studentsthrough the facilities.

For example, the 1.1-MV Pelletron tandem accel-erator at Union College is used for PIXE and RBSexperiments in two physics courses and for under-graduate research projects in ion-beam analysis eachyear. It is also used in an annual workshop for highschool students and physics teachers. In the last tenyears, over 230 undergraduate students, 110 highschool students, and 40 high school teachers havegained experience with the accelerator.

Additionally, there is often unique curriculardevelopment both in terms of components withina general physics or chemistry course and specialtycourses that take place at universities with ARUNAfacilites. At Hope College students in generalchemistry might be challenged to think throughthe implications of food irradiation when they dothe case study of a “Benign Hamburger” (ref: G.F. Peaslee, J. M. Lantz, M. M. Walczak; “TheBenign Hamburger”; J. College Sci. Teaching, 2821 (1998)). At the University of Notre Dame, manystudents learn about nuclear concepts in a coursecalled Physics Methods in Art & Archaeology. (Refhttp://isnap.nd.edu/Lectures/phys10262 2011/)Imbedding nuclear concepts into existing coursesand developing specialized courses are ways toimprove students’ science and nuclear scienceliteracy.

6.3 Graduate Students are Pushingthe Frontiers of Science

Graduate students are the future of the field and thefeedstock for the workforce needed by the nationallaboratories. Graduate students at ARUNA labo-ratories get an unparalleled educational experience,learning everything from tuning accelerator beamsthrough cutting edge nuclear physics. They learneverything from conceiving and planning an exper-iment through building of experimental equipment,in some cases repairing the accelerator and beam de-livery, to analyzing data. ARUNA laboratories pro-vide training in vacuum technology, accelerator op-eration, detector design, electronics, and data acqui-sition at a level that is not possible at larger national

29

user facilities, where access is limited and technicalstaff is often responsible for setting up and aligningexperiment and experimental equipment. Addition-ally, graduate students at ARUNA laboratories alsolive among the larger physics community in their de-partments, thus increasing the appreciation for ourfield in a larger community.

6.4 Examples of Recent Graduates

Mary Kidd is an an assistant professor at the Ten-nessee Technological University in 2012. Mary re-ceived a B.S. in physics in 2004 from TennesseeTechnological University and a Ph.D. in physicsfrom Duke University in 2010. Her research spe-cialty is experimental nuclear physics. She con-ducted her Ph.D. dissertation research on two-neutrino double-beta decay measurements at theKimballton Underground Research Facility underthe supervision of Professor Werner Tornow. Af-ter completing her degree in 2010, she conductedresearch at Los Alamos National Laboratory as apostdoc in the weak-interactions group.

Daniel Sayre is currently a research staff memberat Lawrence Livermore National Laboratory, work-ing on nuclear diagnostics for the National IgnitionFacility. Daniel received is B.S. in physics from OhioUniversity in 2005 and a Ph.D. in Physics from OhioUniversity in 2011. His thesis research on the fusionof 4He and 12C was performed with the tandem ac-celerator at Ohio University under the supervisionof Carl Brune.

Matthew Kiser is a Senior Scientist at NationalSecurity Technologies, LLC, and is stationed atthe Remote Sensing Laboratory located at AndrewsAirforce Base in Maryland. Matthew received B.S.degrees in physics and mathematics from King Col-lege in 2002. He received a Ph.D. in physics fromDuke University in 2008 with specialty in exper-imental nuclear physics. His Ph.D. dissertationproject was the development of techniques to studyplant physiology using tracking of short-lived ra-dioisotopes. His thesis research was carried out inthe tandem laboratory at TUNL under the supervi-sion of Calvin Howell.

30

John Cesaratto is currently a Toohig Fellow in Ac-celerator Science at SLAC in the LHC AcceleratorResearch Program. John received a B.S. with majorin physics from John Carroll University in 2005 anda Ph.D. in physics from the University of North Car-olina at Chapel Hill in 2011. He conducted his thesisresearch at the LENA facility on developing beamcapabilities to enable measurements of nuclear re-action rates important to understanding elementalvariations in globular cluster stars. Art Champagneand Thomas Clegg supervised his dissertation re-search.

Calem Hoffman is an Assistant Physicist at Ar-gonne National Laboratory. His research interestsare the shell structure of exotic nuclei. Calem re-ceived a B.S. in physics from Florida State Univer-sity in 2003, and a Ph.D. in Physics from FloridaState University in 2009 on research performed atthe NSCL, on the magic character of 24O. His Ph.D.dissertation was awarded the Dissertation Award inNuclear Physics American Physical Society Divisionof Nuclear Physics, February 2010. His thesis advi-sor was Samuel L. Tabor.

6.5 Postdocs are Junior Colleaguesand Future Researchers

ARUNA laboratories educate postdocs, often treat-ing them as junior colleagues. It is not uncommonfor postdocs at ARUNA facilities to also get expe-rience teaching to help prepare them to transitioninto faculty positions, should they decide on thatcareer path.

6.6 ARUNA Facilities Provide forWidespread Visibility

Many members of the public visit the ARUNA fa-cilities. From members of Congress who are havingface time at their local university, to the undergrad-uate students mentioned above, to parents of stu-dents, to students from local school districts and tothe general public, the ARUNA laboratories play animportant role in raising the nuclear science literacyof the general public. Because these facilities aredistributed throughout the country, it is much morelikely that there will be an ARUNA facility, withan enthusiastic tour guide, close by for a teacher totake his/her students than a national facility.

Researchers at ARUNA facilities are active in sci-ence education in the schools and of the generalpublic in their local areas. Through combinationsof personal contacts and established institutional re-lationships, faculty, postdocs and graduate studentscreate opportunities for people in the region to learnabout nuclear physics and more generally about thescience of the physical world. Educational outreachactivities include giving presentations and demon-strations in the classrooms of local K-12 schools,providing tours of the research facilities for studentsand teachers in the local schools, and participat-ing in the Nuclear Science Merit Badge program ofthe Boy Scouts of America. As an example, overthe last four years researchers at TUNL have giventours of the accelerator laboratories to more than200 students attending local schools and 400 under-graduate students. The High Intensity Gamma-raySource (HIγS) and the Laboratory for ExperimentalNuclear Astrophysics (LENA) are the main attrac-tions for many of the tours. An example of a visitby a boy scout troop is given below. As part of its

31

participation in the Nuclear Science Merit Badgeprogram, TUNL provides boy scouts troops withscience presentations, hands-on activities and toursof the research facilities that are appropriate for awide age range (7th grade through high school stu-dents). See Figs. 16 and 17.

Figure 16: The scouts are exploring the large targetroom at HIγS.

Figure 17: The scouts in the control room of theTandem Laboratory analyzing data.

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6.7 ARUNA Experimental Ph.D. Graduates 2006-1/2015

Year Name Ph.D. Research Facility Current Position (if known)

Florida State University2006 Pipidis, Paschalis Akis FSU/Gammasphere (ANL) Post Doctoral Researcher, INFN Legnaro (Italy)2006 Roeder, Brian T. FSU Accelerator Physicist, Texas A&M University2007 Diffenderfer, Eric S. FSU Assistant Professor of Radiation Oncology, U. of Pennsylvania2008 Aguilar, Aaron Gammasphere(ANL)/FSU Staff Physicist, LLNL2008 Cluff, Warren FSU Dept. of Homeland Security, Customs and Border Protection2008 Hinners, Trisha FSU/NSCL (MSU) Systems Engineer at Northrop Grummnan Corporation2008 Johnson, Eric FSU Deputy Director, Florida Office of Insurance Regulation2008 Lee, Sangjin FSU Research Fellow at Indiana University, Institute for Basic Science2009 Hoffman, Calem R NSCL (MSU) Assistant Physicist at Argonne National Laboratory, Physics Division2009 Peplowski, Patrick FSU Staff Scientist at Johns Hopkins U., Applied Physics Laboratory2009 Teal, Charles FSU/Gammasphere(ANL) Officer, Nuclear Regulatory Commission2010 Reynolds, Robert R., Jr NSCL (MSU)2011 Bender, Peter C. FSU/Gammasphere(ANL) Postdoctoral Researcher at TRIUMF, Vancouver (Canada)2011 Rojas, Alexander FSU Postdoctoral Researcher at TRIUMF, Vancouver (Canada)2012 Mitchell, Joseph FSU Postdoctoral Researcher at Cero Observatory2014 Santiago-Gonzalez, Daniel NSCL (MSU)/FSU Postdoctoral Researcher, Louisiana State University2014 Avila-Coronado, Melina FSU Postdoctoral Researcher, Argonne Natl. Lab.2014 Kuchera, Anthony FSU Postdoctoral Researcher, NSCL, Michigan State University, NSCLOhio University2006 Matel, Catalin Ohio U/TRIUMF Staff Scientist, ELI-NP (Romania)2008 Shukla, Shaleen Ohio U Physics Instructor, UNC Greensboro2009 Oginni, Babatunde M Ohio U Research Scientist at Canberra Industries (CT)2009 Adekola, Aderemi HRIBF(ORNL) Research Scientist at Canberra Industries (CT)2011 Sayre, Daniel Ohio U Staff, Lawrence Livermore National Laboratory2013 Cooper, Kevin Ohio U Assistant Professor, Lincoln Memorial University2013 Byun, Youngshin Ohio U/Oslo C High School Teacher in South Korea2014 Divaratne, Dilupama NSCL(MSU) Physics Instructor, Miami (OH)2014 Ramirez, Anthony Paul Ohio U U. of Kentucky, PostdocTexas A&M University2006 Pochivalov, Oleksiy Grigorievich TAMU Oil Company in Houston, TX2007 Al-Abdullah, Tariq TAMU Assistant Professor of Physics, Hashemite University of Jordan2007 Fu, Changbo TAMU Distinguished Research Fellow, Dept. of Physics & Astronomy,

Shanghai Tia Tong U.2007 Keksis, August Lawrence TAMU Scientist at Los Alamos National Lab2007 Peng, Yong TAMU Medical Physics2007 Vuong, Au Kim TAMU Oil Company in Houston, TX2007 Zhai, Yongjun TAMU Asst. Professor at Cooper Medical School of Rowan University, USA2008 Chen, Xinfeng TAMU Medical Physics2008 Qin, Lijun TAMU Hewlett- Packard Co., Houston, TX2009 Wuenschel, Sara Katherine TAMU Post-Doc. at Texas A&M University2010 Zhao, Xingbo TAMU Post-Doc. Dept. of Physics at Iowa State University2010 Kohley, Zachary Wayne TAMU Faculty at MSU2010 Sarah, Soisson TAMU Scientist at Sandia National Lab2011 McCleskey, Matthew Edgar TAMU Nuclear Scientist at Baker Hughes2011 Park, Hyo-In TAMU Post-Doc at Texas A&M University2012 Goodwin, John TAMU Faculty at Blinn CollegeTUNL Duke University2006 Sabourov, Amanda TUNL-Tandem Health Physicist, SLAC2007 Blackston, Matthew TUNL-HIGS Scientist, ORNL2008 Hutcheson, Anthony TUNL-Tandem Staff Scientist, Naval Research Lab, Washington, DC2008 Kiser, Matthew TUNL-Tandem Germanium Detector Physicist, PHDs Co.2009 Sun, Changchun TUNL-HIGS Postdoc, LBL2010 Henshaw, Seth TUNL-HIGS National Security Technologies, LLC2010 Kidd, Mary TUNL-KURF Physics Dept., Tenn. Tech Univ.2010 Perdue, Brent TUNL-HIGS Postdoc, LANL2010 Zong, Xing TUNL-HIGS Trivest Advisors, Shanghai, China2011 Jia, Botao TUNL-HIGS Financial Advisor, BLACKROCK2012 Broussard, Leah KVI(Groningen) Postdoc, LANL2012 Esterline, James TUNL-Tandem2012 Wu, Wenzhong TUNL-HIGS2013 Mueller, Jonathan TUNL-HIGS Postdoc, NC State Univ., nuclear engineeringNorth Carolina State University2006 Xu, Yan-Ping LANSCE(LANL) Associate Research Scientist, Columbia University2007 Poole, John TUNL-Tandem2007 Sheets, Steven DANCE(LANL) Scientists, LLNL2009 Chyzh, Andrii DANCE(LANL) Postdoc, LANL

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Year Name Ph.D. Research Facility Current Position (if known)2009 Kephart, Jeremy Postdoc, PNNL2010 Baramsai, Bayarbadrakh DANCE(LANL) Financial Advisor, Goldman & Sachs2010 O’Shaughnessy, Christopher NIST Postdoc, UNC2012 Holley, Adam LANSCE(LANL) Postdoc, Indiana Univ.2012 Pattie, Robert LANSCE(LANL) Postdoc, NCSU2013 Schelhammer, Karl LANSCE(LANL)2013 Walker, Carrie DANCE(LANL) Postdoc, LANL2014 Gooden, Matthew TUNL-Tandem Postdoc, LANL2014 Leviner, Lance Private Industry2014 Palmquist, Grant PULSTAR-Reactor Private IndustryTUNL University of North Carolina2007 Boswell, Melissa TUNL-HIGS Postdoc, LANL2008 Angell, Christopher TUNL-HIGS Japan Atomic Energy Agency2009 Bertone, Peter TUNL-LENA NASA, science research office2009 Daniels, Timothy TUNL-Tandem Mechanical Eng., SLAC2009 Newton, Joe TUNL-LENA Duke University Med. Center2010 Longland, Richard TUNL-LENA Asst. Prof., NC State Univ.2011 Arnold, Charles TUNL-HIGS Staff Scientist, Los Alamos National Laboratory2011 Cesaratto, Johnny TUNL-LENA Postdoc, SLAC/CERN, Accelerator Research2011 Couture, Alexander TUNL-Tandem Staff scientist, Savannah River Lab, Aiken, SC2012 Hammond, Samantha TUNL-HIGS Postdoc, Penn. State Univ. (assigned to DTRA)2012 McMulllin, Sean TUNL-Tandem Postdoc, Purdue Univ.2012 Tompkins, Jeromy TUNL-HIGS Staff Scientist, FRIB2013 Daigle, Stephen TUNL-LENA2013 Finnerty, Padraic TUNL-KURF Staff Scientist at Applied Rsearch Associates, Inc (defense & space)TUNL Students from other Universities, supervised by TUNL faculty2009 Zhang, Jianfeng TUNL-HIGS2009 Leber, Micheller TUNL-HIGS Physics education, high school, southern calif.2012 Schubert, Alexis Postdoc2013 Zimmerman, William TUNL-HIGS Postdoc, DukeUniversity of Kentucky2007 Choudry, Sadia Naeem UK Teacher, Jefferson County Public Schools, Louisville KY2008 Mukhopadhyay, Sharmistha UK Assoc. Prof. and Head of Department at Institute of Mathematical

Sciences, CIT, Chennai, India2008 Elhami, Esmat UK Assistant Prof. at University of Winnipeg2014 Crider, Benjamin Patrick Sledd UK Postdoctoral Researcher at NSCL, MSU2014 Peters, Erin Elizabeth UK Postdoc/Part-time Instructor at University of KentuckyUniversity of Massachusetts Lowell2006 Roldan, Carlos Gammasphere (ANL)2007 Ji, Chuncheng Gammasphere (ANL)2009 Shirwadkar, Urmila Gammasphere (ANL) Scientist, Radiation Monitoring Devices, Inc., Watertown, MA2010 Alimeti, Afrim Gammasphere (ANL)2012 Hota, Sankha Gammasphere (ANL) Postdoc, Australian National University, Canberra2014 D’Olympia, Nathan U Mass Scientist, Passport Systems, Inc., Billerica, MAUniversity of Notre Dame2006 Couture, Aaron UND Staff member2006 Lee, Hye Young Louvain (Belgium)/UND Staff member Los Alamos National Laboratory2007 Skorodumov, Boris B. UND Asst. Vice President Barclays Capital, New York2007 Strandberg, Elizabeth UND Lockheed Martin Aeronautics Company2007 Triambak, Smarajit CENPA(UW) SARChI Chair Professor, University of the Western Cape, South

Africa2007 Wang, Xiaofeng Gammasphere (ANL) Adjunct Lecturer at California Polytechnic in San Luis Obispo, CA2008 Couture, Jennifer UND Homemaker2008 Li, Tao Quantitative Researcher Knight Capital2009 Palumbo, Annalia UND Vist. Asst. Professor Central Michigan University2010 LeBlanc, Paul UND/LUNA (Gran Sasso) CSE Icon2010 O’Brien, Shawn Patrick RCNP (Osaka) Central Intelligence Agency, Washington, DC2010 Quinn, Matthew A. NSCL(MSU) Radiation Safety, Fermi National Laboratory2010 Robertson, Daniel J UND Research Professor, University of Notre Dame2010 Schmitt, Christopher J. UND Asst. Professor, Oak Ridge Community College2011 Almaraz Calderon, Sergio Jesus UND Asst. Professor, Florida State University2011 Best, Andreas Christian UND Research Associate, INFN Gran Sasso, Italy2011 deBoer, Richard James, II UND Research Associate, University of Notre Dame2012 Kontos, Antonio UND Research Associate, MIT2013 Bowers, Mathew UND Industry, Bechtel National, Inc2013 Uberseder, Ethan UND Research Associate, Texas A&M University2013 Ayangeakaa, Akaa Daniel Gammasphere(ANL) Research Associate, Argonne National Laboratory2014 Bucher, Brian T. UND Research Associate, Lawrence Livermor National Laboratory2014 Smith, Karl UND Research Associate, University of Tennessee2015 Li, Quan UND Actuarial Analyst, Windhaven Insurance

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Year Name Ph.D. Research Facility Current Position (if known)2015 Patel, Darshana RCNP(Osaka) Medical Physicist, MS Anderson Cancer CenterUniversity of Washington2006 Bacrania, Minesh CENPA(UW) Private Bussiness, self employed in Santa Fe, NM2008 Sjue, Sky CENPA(UW) LANL staff (scientist 2)2008 Mohrmann, Erik CENPA(UW) Department Chair, DigiPen Institute of Technology, Seattle WA2010 Sallaska, Anne L. CENPA(UW) NIST staff at Gaithersburg, MD

Table 1: ARUNA Ph.D. Graduates 2006–1/2015 in experimental low-energynuclear physics, nuclear astrophysics, fundamental symmetries (as far as con-nected to accelerator-based research) and applications. Their current positionand institution is listed where known.

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7 The ARUNA facilities

ARUNA facilities provide a unique set of nuclear probes that are often not available at national facilities.They offer flexibility and quick response to new research developments and challenges.

The connection of research goals at the ARUNA facilities to the goals of the national community allowsfor a synergy of scales, where new detector and methodological developments can be pursued at ARUNAfacilities, which in turn lead to new opportunities at the national user facilities. ARUNA facilities havea history of developing new techniques, from the first in-flight radioactive beam facility, Twinsol at NotreDame, to the currently highest sensitivity cross section measurements for astrophysics at LENA (TUNL).In many other examples, ARUNA labs have been used to push the boundaries of scientific inquiry and havegreat opportunities to continue to do so in the future.

Major upgrades are ongoing or proposed at ARUNA laboratories;

• The stopped and re-accelerated radioative beam facility (T-Rex) at Texas A&M university, with sufficientenergy and beam quality for multi-fragmentation reaction studies is approaching completion.

• A high-intensity heavy-ion accelerator and recoil separator, St. ANA / St. George, are nearing produc-tion phase at the Notre Dame facility.

• A high-resolution high-acceptance magnetic spectrograph is being installed at Florida State University.

• HIγS at TUNL is pursuing a staged intensity and quality upgrade for the monoenergetic γ–ray beam.

• The CASPAR underground accelerator at the Sanford Underground Research Facility in South Dakotathat is being developed by Notre Dame and will be operated by a collaboration of ARUNA groups.

Florida State University, John D. Fox AcceleratorLaboratory

• 9-MV FN tandem accelerator, Pelletron charged• 9-MV Superconducting Linear Accelerator as booster,

using 14 split-ring niobium on copper cavities• Ion beam mass range and maximum energy: A≤7: 10

MeV/u, A≤16: 8 MeV/u, A≤40: 5 MeV/u• In-flight radioactive beam facility RESOLUT; exotic

beams between mass 6 and 30• Germanium detector array, 3 Clover + 10 conventional,

anti-Compton detectors• New project: split-pole spectrograph• Planned linac upgrade to 14 MV, extending RIB reach

to mass 50

Hope College, Ion Beam Analysis Laboratory

• 1.7-MV tandem accelerator for ion beam analysis• Programs in materials analysis

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Ohio University, John E. Edwards Laboratory

• 4.5-MV T-type tandem accelerator, Pelletroncharged• Beams of p,d, 3He, 4He, heavy ion beams• 2 target rooms• 30-m long, time-of-flight tunnel• Particularly well equipped for time-of-flight exper-

iments and neutron detection

Texas A&M Cyclotron

• K-150 cyclotron• K-500 superconducting cyclotron• ECR ion sources• Negative ion source• Mars recoil spectrometer, production and separa-

tion of radioactive beams• Nimrod high-efficiency multi-particle detector• Precision on-line β-decay γ-detector system• MDM spectrometer• FAUST-QTS• Radiation effects facility• STARLiTeR array• Upgrade-project, ongoing: T-REX, Gas-stopping

and re- accelerated RIB facility• New project: TAMU-trap, studying delayed pro-

ton decays• New project: Sassyer / Aggie gas-filled spectrom-

eter for super heavy element studies

TUNL-HIγS

• World’s most intense accelerator-driven γ–raysource• 1.2-GeV e-storage ring free electron laser (FEL)• γ-ray beam through Compton-backscattering of

FEL photons• Linear and circular polarized mono-energetic γ-

ray beams• Program for γ-induced astrophysical reaction

rates• Program in nuclear structure (high-resolution nu-

clear resonance fluorescence, photofission andCompton scattering)• Upgrade-project: Increase capacity of FEL-

wigglers, increase photon energy to 120 MeV• Upgrade-project: HIγS2, x100 increase in γ-ray

beam intensity with optical cavity pumped withexternal laser

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TUNL-LENA, Laboratory for ExperimentalNuclear Astrophysics

• 2 High-intensity low-energy accelerator systems• LENA I, JN van de Graaff accelerator, 1 MeV, 0.3

mA beam current• LENA II, 200-kV platform, ≤ 1 mA beam current• High-resolution Ge–detector, inside NaI calorime-

ter• Program to measure (p, γ) reactions for stellar

evolution and Nova- and X-ray burst nuclear re-action rates• Upgrade-project: RF-Pulsing ECR source, im-

proved accelerator tube• Upgrade-project: replacement of JN accelerator

TUNL-Tandem Laboratory

• 10-MV FN tandem accelerator, Pelletron-charged• p,d, 3He, 4He beams• Secondary neutron beams• Upgrade-project: re-commissioning of split-pole

spectrograph

Union College, Ion Beam Analysis Laboratory

• 1.1-MV tandem accelerator for ion beam analysis

University of Kentucky, Accelerator Laboratory

• 7-MV single-ended Van de Graaff accelerator• p,d,3He, 4He beams• Terminal and post-acceleration bunching system,

sub-ns resolution• In-flight production of mono-energetic neutrons• Shielded setup for high-resolution γ–ray spec-

troscopy after inelastic neutron scattering; neu-tron time-of-flight capabilities

University of Massachusetts-Lowell, RadiationLaboratory

• 5.5-MV single-ended Van de Graaff accelerator• 100µA DC beam• Terminal bunching system, sub-ns resolution• In-flight production of mono-energetic, pulsed

neutron-beam• Programs in neutron detector development• 1-MW research reactor, hot-cell with remote ma-

nipulators• 100-kCi 60Co source for γ irradiation• Programs in neutron and segmented-Ge detector

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University of Notre Dame, ISNAP, Institute forStructure and Nuclear Astrophysics

• 11-MV FN tandem accelerator, Pelletron charged

• TwinSol in-flight radioactive beam facilty

• Accelerator mass spectrometry with ion sourceand gas-filled spectrometer

• 250 kV accelerator for implantation and low en-ergy studies.

• Recent project: 5-MV single-ended Pelletron withECR source (St. Ana) is operating

• Recent project: St. George recoil seperator for As-trophysical reaction rate measurements

• New project: Move 1-MV CASPAR acceleratordeep underground, to Sanford Underground Re-search Facility

• Planned project: Isotope production with 24-MeVmedical cyclotron for ion-trap mass measurements

University of Washington, CENPA, Centerfor Experimental Nuclear Physics and Astro-physics

• 10-MV FN tandem acclerator, Pelletron-charged

• World-record production of 6He isotope, used forβ–decay measurement in Laser-trap

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8 Summary

ARUNA laboratories have active and innovative programs in low-energy nuclear science and nuclear astro-physics, with a focus on the big questions of the field. The ARUNA laboratories of today have re-inventedtheir experimental programs many times over and, in doing so, have often defined the forefront of methodicaldevelopments, such as in-flight radioactive beam facilities. ARUNA laboratories have leadership programsin the areas of nuclear astrophysics and fundamental symmetries. The programs in nuclear structure andnuclear reactions are complementary to, or synergistic with, the efforts at the two national user facilitiesof low-energy nuclear science and nuclear astrophysics. The scientists of ARUNA operate the acceleratorfacilities because of the multiple scientific opportunities and the scientific flexibility they offer for innovativeresearch and development.

The ARUNA laboratories provide an ideal environment to develop new experimental techniques for researchwith exotic beams. Present examples for such development projects include the ANASEN active-targetdetector developed at FSU, and techniques for a direct measurement of astrophysical reaction rates at St.Ana / St. George, which can be applied directly to the measurements with the to-be-developed SECARseparator for FRIB. Another example is the development of high intensity low energy beams, which can beutilized for the underground accelerator project.

During the period of 2006-2012, 40% of the doctoral degrees in low-energy nuclear science and nuclearastrophysics were granted at the groups of the ARUNA laboratories (including the Yale University group)[1].With their flexible scheduling and fast turn-around, ARUNA laboratories are ideal places to provide graduateeducation on the full depth of experimental science, encompassing development projects at the accelerator,experiments, data analysis and scientific interpretation.

Early exposure of undergraduate students to fundamental and applied nuclear methods is a big factorin addressing the workforce needs in nuclear science and nuclear applications. The presence of ARUNAlaboratories on university campuses make them ideal places for undergraduate research projects. All ARUNAlabs support undergraduate research and most are hosts to external groups from undergraduate colleges.The broad range of applied programs creates collaborations with non-nuclear and non-science faculty andstudents, leading to a broader appreciation for the benefits of nuclear science. ARUNA labs are naturalplaces to rejuvenate the nuclear workforce and represent nuclear science in society.

References

[1] NSAC Subcommittee Report on the Implementation of the 2007 Long-Range Plan, January 18, 2013http://science.energy.gov/˜/media/np/nsac/pdf/20130201/2013 NSAC Implementing the 2007 Long Range Plan.pdf

[2] NSAC Workforce Subcommittee Report, July 18, 2014 J. Cizcewski (chair)http://science.energy.gov/˜/media/np/nsac/pdf/docs/2014/NSAC workforce jul-18-2014.pdf

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