rare isotope investigation at gsi notre dame, lbnl, youngstown (usa), anu (australia), …… +...
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Rare ISotope INvestigation at GSI
+ Notre Dame, LBNL, Youngstown (USA), ANU (Australia), ……Notre Dame, LBNL, Youngstown (USA), ANU (Australia), ……
Decay Studies of Exotic Nuclei with RISING & the GSI Fragment Separator
Part of the ‘Stopped Beam’ RISING experimental campaign at GSI.
PARTICIPANTS CENBG Bordeaux, France: B. BlankGSI-Darmstadt, Germany: J.Gerl, H.J.Wollersheim, F.Becker, H.Grawe, M.Gorska, P.Bednarczyk, N.Saitoh, T.SaitohIKP Koeln, Germany: J.JolieJ.Jolie, P. Reiter, N. Warr, A. Richard, A. Scherillo, N. Warr TU Munchen, Germany: R. Krücken, T. FaestermannUniversity of Camerino, Italy: D. Balabanski, K.Gladnishki, IFJ PAN Krakow, Poland: A. Maj, J. Grebosz, M. Kmiecik, K. Mazurek Warsaw University, Poland: M. PfűtznerUniversidad Autonoma de Madrid, Spain: A.JungclausA.JungclausUniversidad de Santiago de Compostela, Spain: D. Cortina Gil, J.BenlliureJ.Benlliure, T. Kurtukian Nieto, E. CaserejosIFIC Valencia, Spain: B. RubioINFN-Legnaro, Italy: A. Gadea, G. deAngelis, J.J. Valiente Dobon, N. Marginean, D. Napoli, INFN-Padova, Italy: E. Farnea, D. Bazzacco, S. Lunardi, R. MargineanUniversity and INFN-Milano, Italy: A. Bracco, G. Benzoni, F. Camera, B. Million, O. Wieland, S. LeoniUniversity of Surrey, UK: Zs.PodolyàkZs.Podolyàk, P.H.ReganP.H.Regan,, P.M. Walker, W.GelletlyW.Gelletly, W.N.Catford, Z. Liu, S. WilliamsUniversity of York, UK: M.A. Bentley, R. WadsworthUniversity of Brighton, UK: A.M.BruceA.M.BruceUniversity of Manchester, UK: D.M. Cullen, S.J. FreemanUniversity of Liverpool, UK: R.D. PageUniversity of Edinburgh, UK: P. Woods, T. DavinsonCLRC Daresbury, UK: J. Simpson, D. WarnerUppsala University, Sweden: H. MachLund University, Sweden: D.RudolphD.RudolphLawrence Berkeley National Lab, USA: R.M. ClarkUniversity of Notre Dame, USA: M. Wiescher, A. AprahamianYoungstown State University, Ohio, USA: J.J. CarrollDebrecen, Hungary: A. Algora
Overall Physics Aims and Technical Background
• Use of FRS and RISING gamma-ray spectrometer to study internal structure of extremely exotic nuclei.
• Relativistic projectile fragmentation to populate – Heavy, neutron-rich nuclei (cold fragmentation). – N~Z nuclei approaching the proton drip-line.
• Active, position sensitive, pixellated stopper to correlate implanted ions (mother) with -decay.
• Measure rays (internal structure) from decays of– ns-ms isomeric states in implanted ion, and / or– excited states in -daughter nucleus.
Fragmentation at relativistic energies
abrasion ablation
fragmentation
Rare Isotope Production at GSI
relativistic energies: 0.2 – 1 GeV/amu
- fragmentation reactions
- fission after peripheral collisions
1. N~1261. N~126
2. 2. 190190W - W - 170170DyDy
3. 3. 128,130128,130CdCd4. 4. 7171KrKr5. 5. 8282Nb, Nb, 8686TcTc
7. Zr, Mo, A~1107. Zr, Mo, A~1106. 6. 5454NiNi
N=Z line
eg. R. Grzywacz et al. Phys. Rev. C55 (1997) p1126 LISE M. Pfützner et al. Phys. Lett. B444 (1998) p32 FRS Zs. Podolyàk et al. Phys. Lett. B491 (2000) p225 FRS M. Pfützner et al. Phys Rev. C65 (2002) 064604 FRS M. Caamano et al., Eur. Phys. J. A23 (2005) p201 FRS
primary beamPb @ 1GeV/u
Production target
Central focus, S2Final focus, S4
E(Z2)
cu
eB
Q
A
FTO
catcher
degrader
degrader
dipole, B
scintscint
MW=x,y
scint(veto)
In-Flight Technique Using Projectile Fragmentation
Use Fragment Separator to ID individual nuclei. Transport some in isomeric states (TOF~ x00ns).Stop and correlate decays with nuclei id.
C. Chandler et al. Phys. Rev. C61 (2000) 044309
67Ge
69Se
76Rb
92Mo fragmentation on natNi target
Heaviest odd-odd,N=Z gammas, isobaric analog states ? N=Z=43; 86Tc, C. Chandler et al. Phys. Rev. C61 (2000) 044309
~500 86Tc in ~ 1 week
208Pb beam at 1 GeV/u showed production of heavy, neutron-rich (A>170-200) high-spin (>35/2 h) isomers.
Pfützner et al. Phys Rev. C65 (2002) 064604
High spins (>35/2) populated
Walker, Dracoulis et al., Nuc. Phys. A568 (1994) 397
Higher spins for greater A.
M. Pfützner et al., Phys. Rev. C65 (2002) 064604; K. Gladnishki et al., Phys. Rev. C69 (2004) 024617
14.3 ns
M. Caamano et al., Eur. Phy. J A23 (2005) p201
Stripping the ions of electrons lengthens the apparent isomeric decay half-life by ‘switching off’ conversion electron decay branch
Fragmentation of 1 GeV/u 208Pb, M. Caamano et al., Eur. Phy. J A23 (2005) p201
fully-stripped H-like
184Lu, H-like fully-stripped
188Ta
Prompt ‘flash’ can be a limiting problem for fragmentation isomer spectroscopy.
Can reduce the effective Ge efficiency factors of 3-4 for close geometry….
but 105 (15 x 7) detectors in RISING will improve this.
RISING set-up with stopped beams
RISING GeCluster Array.
MUSIC MUSIC
Sci
41
MW
41 MW
42
deg
rad
er
beambeam
5 at 510, 5 at 900 and 5 at 1290 all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV
8 BaF2 detectors (185-220mm)
5 at 510, 5 at 900 and 5 at 1290 all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV
8 BaF2 detectors (185-220mm)
Stopped Beam RISING Campaign Accepted Proposals
Nuclei interest
Spokespersons
ß-decay lifetimes, ß-decay spectroscopy studies and collective evolution "south" of 208Pb S312
N~126 south of 208Pb
J. Benlliure, P.H.Regan
Nuclear dynamical symmetries and shape evolution in K-isomeric nuclei from 190W to the 170Dy val. max. S313
190W- 170Dy
P.H. Regan, J.Benlliure
Search for the 8+ (πg9/2)-2 isomer in N=82 130Cd via 6 proton knockout from 136Xe fragmentation S305
130Cd A. Jungclaus
Shape co-existence and X(5) behaviour in neutron-rich A~110 nuclei S300
106Zr A.M. Bruce
Along the N=126 closed shell: Nuclei below 208Pb S299
N=126Z<82
Z. Podolyak
Isospin symmetry of transitions probed by weak and strong interactions: the ß-decay of 54Ni, 50Fe, and 46Cr S316
54Ni, 50Fe, 46Cr
Y.Fujita, W.Gelletly, B.Rubio
+ ‘old’
N=Z=41-43(Regan, Blank, Rudolph Wiescher)
+
54Ni/54Fe mirrorSymmetry (Rudolph et al.,)
197Au+9Be
5p
4p
Cold fragmentation (protons out) to produce neutron-Cold fragmentation (protons out) to produce neutron-rich nuclei is well modelled by theoretical estimates. rich nuclei is well modelled by theoretical estimates.
B. Fornal et al., Phys. Rev. Lett. 87 (2001) 212501
208Pb -> 206Hg (2p knockout)I= 10+ = 0.25mbI= 8+ = 0.20mb I= 7- = 0.20 mbI= 5- = 0.15mb
N=126, Z=80 206Hg(idealised 2hole system)
Seniority (h11/2)-210+ probes knock-out theory (see Jeff Tostevin Fri.)
more ways of knocking out a pair of high-j orbitals than low-j ones. Isomeric RatioIsomeric Ratio gives test of reaction mechanism / spin population.
Proposal A:2 (S313)
Nuclear Dynamical Symmetries and Shape Evolution in
K-isomeric Nuclei from 190W to the 170Dy Valence Maximum.
P.H. Regan, J. Benllliure et al.,
Department of Physics, University of Surrey, Guildford, GU2 7XH, UKUniversity of Santiago de Compostela, Spain
IKP, University of Cologne, 50937 Cologne, GermanyPlanckstrasse 1, GSI, Germany
Warsaw University, PolandUppsala University, Sweden
CLRC Daresbury Laboratory, Cheshire, UK University of Camerino, ItalyUniversity of Manchester, UK
Youngstown State University, Ohio, USA IJF, PAN Krakow, Poland
STOPPED BEAM CAMPAIGN - A
Podolyak et al., Phys. Lett. 491B (2000) 225;Caamano et al., EPJ A23 (2005) 201
Discontinuity (change of structure)observed for 190W following GSI isomer (K=10-) spectroscopy.
0
50
100
150
200
250
300
350
400
450
Yb (70) Hf (72) W (74) Os (76) Pt (78)
108
110
112
114
116
118
120
122
E(2E(2++) is signature of deformation. Possible shape change ) is signature of deformation. Possible shape change identified from identified from 190190W data point (N=116).W data point (N=116).
Proposal to identify Proposal to identify first 2first 2++ state in state in 192192W (N=118)W (N=118)188,190188,190Hf (N=116,118)Hf (N=116,118)186,188186,188Yb (N=116,118)Yb (N=116,118)
Decays from IDecays from I=10=10- -
isomers and/orisomers and/or -- decay of decay of 192192TaTa188,190188,190Lu andLu and186,188186,188Tm Tm
tt1/21/2 ~1-5 secs ~1-5 secs
Constrained HF calculations (P.D.Stevenson)suggest prolate-oblate shape change/competition at N=116 isotones, 188Hf, 190W, etc.
Physics interpretation consistentwith O(6) ‘critical point’ in extended ‘Casten triangle’ at phase transitionbetween prolate and oblate axially symmetric shapes.See J. Jolie and A. Linnemann, Phys. Rev. C68 (2003) 031301(R)
170Dy, double mid-shell, nature’s purest K-isomer ? P.H. Regan et al. Phys. Rev. C65 (2002) 037302
Reduced hindrance correlated with N.N…max. at 170Dy...
K=6+ isomer
K=0+ band
Primary 198Pt beam @ 1GeV/u, intensity of 109 particles per spill, 10 second spill cycle. 2.5 g/cm2 thick Be target, 5.1g/cm2 Al. degrader at S2, plus a 108mg/cm2 Niobium stripper. Cross-section estimates from the COFRA.Estimated values for transmission per eight hour
shift are: Setting 1: Centred on 191W
190W 1x107 191W 0.4x107 192W 0.4 x107
Setting 2: Centred on 187Hf 187Hf 3.7x105 188Hf 9x104 189Hf 1x104
Setting 3: Centred on 185Yb 184Yb 2x104 185Yb 6x103 186Yb 240
20% -ray efficiency for 662 keV, (~50%) prompt-flash, isom. ratio
(~5%), Yield estimates for observed photopeak rays per 8 hour shift of 190W 250,000 ; 192W 100,000 ; 188Hf 2,250 ; 184Yb 500 ; 186Yb 6 Setting 4: Centred on 170Dy
170Dy 1.4x105 170Tb 4,500 168Tb 4.9x104
Assuming -ray (0.2) and -detection (0.5) efficiency for decays of 170Tb
gives 450 photopeak rays from the decay of the first 2+ state in 170Dy per
shift. Setting 1: 3 shifts (1 day) ; Setting 2: 3 shifts (1 days)Setting 3: 6 shifts (2 days) ; Setting 4: 6 shifts (2 days)2 days (6 shifts) primary beam tuning and particle id. calibrations, 191W
setting:Total beam request of 24 shifts (8 days).
Proposal A:3 (S305)
Search for the 8+ (g9/2)
-2 isomer in N=82 130Cd populated via the 6 proton knockout channel in the
fragmentation of 136Xe
A. Jungclaus et al.,
Universidad Autónoma de Madrid, Spain Institute of Nuclear Research, Debrecen, Hungary
Universidad de Santiago de Compostela, SpainGSI Darmstadt, Germany
Uppsala University, SwedenUniversity of Surrey, UK
Universität zu Köln, Germany University Warsow, Poland
IFIC Valencia, Spain Lund University, Sweden
STOPPED BEAM CAMPAIGN - A
Search for the 8+ (g9/2)-2 isomer in N=82 130Cd populated
via the 6 proton knockout channel in the fragmentation of 136Xe
Why study 130Cd ?
astrophysical reasons:
130Cd is the most important waiting-point nucleus before the r-process breakout of the N=82 shell
relation between N=82 shell closure and the A~130 peak of the solar r-process abundance distribution
r-process path
N=82
Z=50
130Cd
132Sn
nuclear structure reasons:
unexpected behaviour of the 2+ excitation energies of even Cd isotopes towards the N=82 shell closure (change of curva- ture starts already at 124Cd)
there is a series of other nuclear structure puzzles in the 132Sn region
Is this behaviour really a “signature of a weakening of the N=82shell structure already one proton-pair below 132Sn” as suggestedby the authors of the experimental study ?
50 54 58 62 66 70 74 78 82
400
800
1200
1600 Pd Cd Sn Te
E(2
+ ) [k
eV]
neutron number N
-decay @ ISOLDEKautsch et al., EPJ A9 (2000) 201
Sn
TeCd
Pd
NiZn
Ge
Gd
54 56
524846444240383634323028
Sr
Mo
Ru
Pd
Cd
100Sn Te
Xe
Ba
Ce
Nd
Sm
58 60 62
68 70
72
7476 78
8082
Z
50
50
N=Z
132Sn
98Cd 102Sn 134Sn 130Sn134Te130Cd
(g9/2)-2 (d5/2 g7/2)2 (g9/2)-2 (f7/2)2 (g7/2)2 (h11/2)-2
0+
8+
0+
6+
0+
6+
165 ns
1.6 s
80 ns
480 ns
1.0 s
0+ 0+0+
6+
4+
2+
2+
2+
4+
4+
4+6+
2+
4+6+
2+
8+10+
?
N
8+ isomer with (g9/2)-2 con-figuration expected in 130Cdin analogy to the one in 98Cd
Study of 8+ isomer decay in 130Cd (and 128Cd)
already searched for withoutsuccess at LOHENGRIN andFRS (Mineva, Hellström et al.)
Advantage compared to -decay:• possible observation of whole sequence up to the 8+ state• lifetime of the isomer itself contains valuable information
Production of 130Cd @ FRS
238U fissioncold fragmentation
of 136Xe
implantation rate at the focal plane:
I [sec-1] = [cm2] · d[g/cm2] · A-1[mol/g] · [sec-1] · Ttot · NA[mol-1]
cross section
target thickness d
primary beam current
total transmission
0.1 bcalc. !
0.154 nbmeasured !
1 g/cm2 2.5 g/cm2
109/spill (15s) 5·109/spill (5s)
3.5% 95%
1.4 (2000)0.9 (1300)implanted 130Cd/min(d)
for Be target
Mineva et al.:=2·107 sec-1
in total 700implanted 130Cd measured
easier beameasier exp.
University of SurreySCHOOL OF ELECTRONICS AND PHYSICAL SCIENCES
Department of PhysicsPost-Doctoral Research Fellow in Experimental Nuclear Physics
JOB(Ref: 5077)Salary: Up to £24,820 per annum
(subject to experience and qualifications) Applications are invited for the position of Research Fellow in the Nuclear Physics Group to undertake research to study the structure of atomic nuclei with highly exotic proton to neutron ratios following their production via projectile fragmentation reactions at the GSI laboratory in Germany as part of the RISING collaboration. You will be expected to help perform research with initiative and a reasonable degree of independence with particular focus on the physics arising from isomer and beta-delayed spectroscopic studies of heavy, neutron-rich nuclei as part of the Stopped Beam RISING collaboration. Experience in structural studies of exotic nuclei with particular emphasis on the production of nuclei with projectile fragmentation reactions and/or gamma-ray spectroscopy following decays from beta-decays/isomeric states would be an advantage with a PhD in experimental nuclear physics or expect to receive such an award in the near future.You will need to spend a significant period of the initial part of the project at the GSI facility in Darmstadt, Germany, providing technical expertise to the successful running of the experiments of the RISING Stopped Beam Campaign. Later in the grant period, you will lead the development of a new pixellated silicon detection system for the measurement of beta particles following the implantation of exotic projectile fragments at the focal plane of the GSI Fragment Separator. This post is initially for 2 years, with the prospect of renewal for a further two years, subject to performance. The post is available from October 2005 so we are looking for you to start as soon as possible. For further information about the Department of Physics visit http://www.ph.surrey.ac.uk/ Informal enquiries can be made to Dr Paddy Regan by e-mail: [email protected] For full job and application details visit http://www.surrey.ac.uk/ and click on ‘Working at UniS’ or contact Becky McTigue on Tel: +44 (0) 1483 686126 or email [email protected] Please quote Post Ref No. 5077, supply your postal address and where you saw this advertisement. Closing date for applications is: Thursday 15 September 2005
The University is committed to an Equal Opportunities Policy
GREAT
GREAT
JOB !!
!!
JOB !!
!!GREAT
GREATJOB !!!!
JOB !!!!
Isomer Spectroscopy of 91Zr
B.A. Brown et al., Phys. Rev. C13 (1976) 1900Expt. s.p.e. for N=51 and Z=41well known.
Simple 88Sr core allows max. spins of
(g9/2)28+ x d5/2
= 21/2+ (Ex= 3.17 MeV) (g9/2)2
8+ x g7/2 = 23/2+ (Ex ~ 5 MeV) (g9/2)2
8+ x h11/2 = 27/2- (Ex ~ 5.5 MeV)
Allowing 4 protons in (g9/2) gives extra4 ħ, ie. (g9/2)2
12+ x d5/2 = 29/2+
(g9/2)212+ x g7/2 = 31/2+
(g9/2)212+ x h11/2 = 35/2-
Higher spins require N=50 core breaking.
I=21/2+,=6s
Experimental Details
• 13C beam @ 50 MeV, 200g/cm2 82Se target
• s detected with 10 Clovers + 2 LEPS
• 91Zr (+4n) predicted to have ~500 mb
• Faraday cup acted as 'stopper' for isomer(s).
5 cm
92Zr data agrees with data from fusion-fission data from Fotiades et al., Phys. Rev. C65 (2002) 044303 and Pantelica et al., Phys. Rev. C72 (2005) 024304
178Hf (Z=72) + 27Al (Z=13) Z=85, N=110 fusion-fission to 91ZrG.A. Jones, private communication. (from GS expt. at ATLAS).
305
1545901
2170 keV delayed gate
Projected earlies on double delayed {2170}.{859} keV gate below 21/2
+ isomer in 91Zr…candidates for transitions above!
90 keV859 keV
290 keV
transitions identifiedbelow 21/2+ isomer in 91Zr, B.A.Brown et al., PR C13 (1976) 1900.
Simple 88Sr core allows max. spins of
(g9/2)28+ x d5/2
= 21/2+ (Ex= 3.17 MeV)
(g9/2)28+ x g7/2 = 23/2+ (Ex ~ 5 MeV)
(g9/2)28+ x h11/2 = 27/2- (Ex ~ 5.5 MeV)
Allowing 4 protons in (g9/2) gives extra
4 ħ, ie. (g9/2)212+ x d5/2 = 29/2+
(g9/2)212+ x g7/2 = 31/2+
(g9/2)212+ x h11/2 = 35/2-
Higher spins require N=50 core breaking.
25/2+ ?
27/2+ ?27/2- ?
23/2+ ?23/2+ ?
88Se core sen. 3 val.max.
29/2 35/2 ?
Seniority 5 Val. Max ?
> 35/2 N=50 core breaking
P.H. Regan1, N.J. Thompson1,2, A.B. Garnsworthy1,2, H.C. Ai2, L. Amon2,3, R.B. Cakirli2,3, R.F. Casten2, C. Fitzpatrick1,2, S.J. Freeman4,
G. Gurdal5, A. Heinz2, G.A. Jones1, E.A. McCutchan2, J. Qian2, V. Werner2, S.J. Williams1, R. Winkler2
1Dept. of Physics, University of Surrey, Guildford, GU2 7XH, UK2WNSL Yale University, 272 Whitney Avenue, New Haven CT 06520 , USA
3Dept. of Physics, Istanbul University, Istanbul, Turkey4School of Physics and Astronomy, The University of Manchester,
Manchester, M13 9PL, UK 5Clark University Worcester, Mass. 01610, USA