2. GSI-EA 21 March 2005 Decay Studies of Exotic Nuclei with RISING & the GSI Fragment Separator Spokesperson for the Stopped Beam RISING collaboration: P.H.Regan GSI contacts: J.Gerl & H.J.Wollersheim Part of the ‘Stopped Beam’ RISING experimental campaign at GSI. PARTICIPANTS CENBG Bordeaux, France: B. Blank GSI-Darmstadt, Germany: J.Gerl, H.J.Wollersheim, F.Becker, H.Grawe, M.Gorska, P.Bednarczyk, N.Saitoh, T.Saitoh IKP Koeln, Germany: J. Jolie, P. Reiter, N. Warr, A. Richard, A. Scherillo, N. Warr TU Munchen: R. Krücken, T. Faestermann University of Camerino, Italy: D. Balabanski, K.Gladnishki, IFJ PAN Krakow, Poland: A. Maj, J. Grebosz, M. Kmiecik, K. Mazurek Warsaw University, Poland: M. Pfűtzner Universidad Autonoma de Madrid, Spain: A. Jungclaus Universidad de Santiago de Compostela, Spain: D. Cortina Gil, J. Benlliure, T. Kurtukian Nieto, E. Caserejos IFIC Valencia, Spain: B. Rubio INFN-Legnaro, Italy: A. Gadea, G. deAngelis, J.J. Valiente Dobon, N. Marginean, D. Napoli, INFN-Padova, Italy: E. Farnea, D. Bazzacco, S. Lunardi, R. Marginean University and INFN-Milano: A. Bracco, G. Benzoni, F. Camera, B. Million, O. Wieland, S. Leoni University of Surrey, UK: Zs. Podolyàk, P.H. Regan, P.M. Walker, W. Gelletly, W.N.Catford, Z. Liu, S. Williams University of York, UK: M.A. Bentley, R. Wadsworth University of Brighton, UK: A.M. Bruce University of Manchester, UK: D.M. Cullen, S.J. Freeman University of Liverpool, UK: R.D. Page University of Edinburgh, UK: P. Woods, T. Davinson CLRC Daresbury, UK: J. Simpson, D. Warner Uppsala University, Sweden: H. Mach Lund University, Sweden: D. Rudolph Lawrence Berkeley National Lab, USA: R.M. Clark University of Notre Dame, USA: M. Wiescher, A. Aprahamian Youngstown State University, Ohio, USA: J.J. Carroll Debrecen, Hungary: A. Algora

3. GSI-EA 21 March 2005 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 original implanted ion, and / or -excited states in  -daughter nucleus.

4. GSI-EA 21 March 2005 Fragmentation at relativistic energies abrasion ablation fragmentation

5. GSI-EA 21 March 2005 1. N~126 2. 190 W - 170 Dy 3. 128,130 Cd 4. 71 Kr 5. 62 Ga 6. 50 Fe

6. GSI-EA 21 March 2005 Fragmentation at relativistic energies - ion-by-ion identification using FRS. - -decay out from the isomers/betas time correlated with fragments (flight time through FRS: ~300ns) Initial population in spin/energy plane reasonably well known from isomer ratio work. Good estimates of isomer population using ABRABLA and (neutron-rich) production cross-section with COFRA

7. GSI-EA 21 March 2005 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 beam Pb @ 1GeV/u Production target Central focus, S2 Final focus, S4  E(Z 2 ) catcher degrader dipole, B  scint 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.

8. GSI-EA 21 March 2005 Higher spins for greater  A. M. Pfützner et al., Phys. Rev. C65 (2002) 064604; K. Gladnishki et al., Phys. Rev. C69 (2004) 024617

9. GSI-EA 21 March 2005 208 Pb 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

10. GSI-EA 21 March 2005 370 ions!. Useful information can be obtained with very low production rates, e.g., Fragmentation of 1 GeV/u 238 U to populate  g 9/2 2 isomer in 212 Pb. Pfützner et al., Phys. Lett. B444 (1998) 32

11. GSI-EA 21 March 2005 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

12. GSI-EA 21 March 2005 197 Au+ 9 Be 5p 4p Cold fragmentation (protons out) to produce neutron-rich nuclei is well modelled by theoretical estimates.

13. Charge states in the FRS: A/Q identification Difference between B  1 and B  2 with a degrader and a stripper at S2 O-1 O-2 1-O O-O  E MUSIC  E degrader

14. Charge states in the MUSICs: Z identification Correlated measurement with two MUSICs with a stripper in between  E Music 1  E Music 2  E Music 1  E Music 2 EE

15. GSI-EA 21 March 2005 Fragmentation of 1 GeV/u 208 Pb, M. Caamano et al., Eur. Phy. J A23 (2005) p201 fully-stripped H-like 184 Lu, H-like fully-stripped 188 Ta

16. GSI-EA 21 March 2005 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.

17. GSI-EA 21 March 2005 RISING set-up with stopped beams RISING Ge Cluster Array. MUSIC Sci41 MW41 MW42 degrader beam

18. GSI-EA 21 March 2005 5 at 51 0, 5 at 90 0 and 5 at 129 0 all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV 8 BaF 2 detectors (185-220mm)

19. GSI-EA 21 March 2005 5 at 51 0, 5 at 90 0 and 5 at 129 0 all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV 8 BaF 2 detectors (185-220mm)

20. GSI-EA 21 March 2005 Implantation detector double sided silicon strip detector active area 50x50 mm 2 thickness 1 mm 16 strips in x- and y-direction Active stopper = 3 x DSSSD Active area, 15cm x 5 cm

21. Implantation range Monoenergetic degrader at S2: larger implantation surface at S4 smaller dispersion in the implantation range Achromatic degraderMonoenergetic degrader

22. Implantation range Estimated implanted isotopes for a setting centered on 192 W in 1 mm thickness silicon with a monoenergetic degrader at S2 Silicium thickness (  m) charge states

23. Detector setup for  half lives measurement Implantation-decay correlations with large background (half lifes similar to the implantation rate): implantation-decay time correlation: active catcher implantation-decay position correlation: granularity implantation of several ions: thickness and area energy of the implanted ion and the emitted  Active catcher for implantation-decay correlations 3 double-side silicon-strip detectors - surface 5x5 cm 2 - thickness 1 mm - 2 x 16 3.125 mm strips - manufactured by MICRON

24. GSI-EA 21 March 2005 Count Rate Limitations with Active Stopper 3 x 16 x 16 = 3 x 256 = 768 total pixels. -Assume upper limit for  -half-life of ~30 seconds -Each pixel hit every 5 half-lives (150 secs) Max. rate of ~768/150 = 5 per sec ( = 50 per 10s spill). Rate increases directly with decreasing half-life -(e.g., T 1/2 = 10 seconds -> 150 per 10 s spill cycle) Dual gain pre-amps on DSSSD to get energies of implanted ion and  -particle All events time stamped with MHz clock.

25. Implantation procedure Setting centered on 186 Lu Produced Implanted MUSIC 1 SC4 SC42 SC43 MUSIC 2 MUSIC 3 Sc43Sc42

26. GSI-EA 21 March 2005 The GSI FRS γ-Ray Spectroscopy Campaign S210 (2001) ProposalsNuclei of Interest ProposersBeam time approved (days) status Evolution of shell structure outside doubly magic 132 Sn Around 132 SnM. Hellstrom, M. Miveva 4 Isomer decay probe of shape coexistence Lead isotopes N <104, Pb, Po, Rn R. Page, R. Wadsworth 5 Shape coexistence in neutron rich Po - > Th nuclei A~230, Po - Th Z. Podolyak5 Isomer spectroscopy of fission fragments close to 78 Ni Around 76 NiM. Bernas, H. Grawe 7 Effective charge near 56 Ni 54 Ni, Tz = -1D. Rudolph4 Isomer spectroscopy of the odd-odd Tz=0 nuclei 82 Nb, 86 TcP. Regan, B. Blank 5 Along the N=126 closed shell: Nuclei below 208 Pb S299 N~126 south of 208 Pb (isomers) Z.Podolyak7 Shape co-existence and the possibility of X(5) behaviour in neutron-rich A~110 nuclei S300 106 ZrA.M.Bruce7

27. GSI-EA 21 March 2005 RISING: Stopped Beam Campaign ProposalsNuclei of Interest ProposersBeam time request (days) sta tus ß-decay lifetimes, ß-decay spectroscopy studies and collective evolution "south" of 208 Pb S312 N~126 south of 208 Pb J. Benlliure, P.H.Regan 7 Nuclear dynamical symmetries and shape evolution in K-isomeric nuclei from 190 W to the 170 Dy valence maximum S313 190 W- 170 Dy P.H. Regan, J.Benlliure 8 Search for the 8 + (πg 9/2 ) -2 isomer in N=82 130 Cd populated via the 6 proton knockout channel in the fragmentation of 136 Xe S305 130 CdA. Jungclaus7 Exotic ß-decays near the proton-drip line: study of the ß-ecay of 70,71 Kr S314 70,71 KrA.Algora, B.Rubio, B.Gelletly 7 Proton-neutron pairing effects in the ß- decay of 62 Ge S315 62 GeA.Gadea, G.deAngelis 6 Isospin symmetry of transitions probed by weak and strong interactions: the ß-decay of 54 Ni, 50 Fe, and 46 Cr S316 54 Ni, 50 Fe, 46 Cr Y.Fujita, W.Gelletly, B.Rubio 7 100 Sn: Gamov-Teller strength in its decay, search for its isomer, and particle stability of heavier nuclei LOI41 100 SnT.Fästermann

28. GSI-EA 21 March 2005 Proposal A:1 (S312)  -Decay Lifetimes,   -Delayed Spectroscopy Studies and Collective Evolution ‘South’ of 208 Pb J. Benlliure, P.H. Regan et al., Universidade de Santiago de Compostela, Spain Department of Physics, University of Surrey, Guildford, GU2 7XH, UK IKP, University of Cologne, 50937 Cologne, Germany Planckstrasse 1, GSI, Germany TU Muenchen, Germany Warsaw University, Poland Uppsala University, Sweden Dept. of Physics, University of Liverpool, UK Dept. of Physics and Astronomy, University of Manchester, UK CLRC Daresbury Laboratory, Cheshire, UK University of Camerino, Italy Universidad Autonoma de Madrid, Spain STOPPED BEAM CAMPAIGN - A

29. GSI-EA 21 March 2005

31. Proposal A:2 (S313) Nuclear Dynamical Symmetries and Shape Evolution in K-isomeric Nuclei from 190 W to the 170 Dy Valence Maximum. P.H. Regan, J. Benllliure et al., Department of Physics, University of Surrey, Guildford, GU2 7XH, UK University of Santiago de Compostela, Spain IKP, University of Cologne, 50937 Cologne, Germany Planckstrasse 1, GSI, Germany Warsaw University, Poland Uppsala University, Sweden CLRC Daresbury Laboratory, Cheshire, UK University of Camerino, Italy University of Manchester, UK Youngstown State University, Ohio, USA IJF, PAN Krakow, Poland STOPPED BEAM CAMPAIGN - A

32. GSI-EA 21 March 2005 Effect of Nuclear Deformation on (K) isomers 50 g 9/2 g 7/2 d 5/2 s 1/2 d 3/2 h 11/2 (8) (6) (2) (4) (12) h 9/2 (10) 82 (10) Spherical, harmon. oscilator H = h  +al.l+bl.s, quantum numbers j  m j Nilsson scheme: Quadrupole deformed 3-D HO. where h  -> h  x +h  y +h  z axial symmetry means  x =  y quantum numbers [N,n x,  ]   K  = sum of individual   values. z x  High-  (DAL) orbit z x  Mid-  (FAL) z x Low- , (RAL) > prolate  2

33. GSI-EA 21 March 2005 82 126 50 82 Expect to find K-isomers in regions where high-K orbitals are at the Fermi surface. Also need large, axially symmetric deformation (      Conditions fulfilled at A~170-190 rare-earth reg. High-  single particle orbitals from eg. i 13/2 neutrons couple together to give energetically favoured states with high-K (=  i ).

34. GSI-EA 21 March 2005 Search for long (>100ms) K-isomers in neutron-rich(ish) A~180 nuclei. low-K high-K mid-K j K Walker and Dracoulis Hyp. Int. 135 83 (2001) (Stable beam) fusion limit makes high-K in neutron rich hard to synthesise Alaga, Alder, Bohr and Mottelson, Mat. Fys. Medd. 29 no 9 (1955)

35. GSI-EA 21 March 2005 Podolyak et al., Phys. Lett. 491B (2000) 225; Caamano et al., EPJ A23 (2005) 201 Discontinuity (change of structure) observed for 190 W following GSI isomer (K  =10 - ) spectroscopy.

36. GSI-EA 21 March 2005 E(2 + ) is signature of deformation. Possible shape change identified from 190 W data point (N=116). Proposal to identify first 2 + state in 192 W (N=118) 188,190 Hf (N=116,118) 186,188 Yb (N=116,118) Decays from I  =10 - isomers and/or  - decay of  - decay of 192 Ta 188,190 Lu and 186,188 Tm t 1/2 ~1-5 secs

37. GSI-EA 21 March 2005 Constrained HF calculations (Stevenson) suggest prolate-oblate shape change/competition at N=116 isotones, 188 Hf, 190 W, etc. Physics interpretation consistent with O(6) ‘critical point’ in extended ‘Casten triangle’ at phase transition between prolate and oblate axially symmetric shapes. See Jolie and Linnemann, Phys. Rev. C68 (2003) 031301(R)

38. GSI-EA 21 March 2005 170 Dy, 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 170 Dy... K  =6 + isomer K  =0 + band

39. GSI-EA 21 March 2005 Apparent underlying SU(3) dynamical symmetry for N=104. (see Casten et al., Phys. Rev. C31 (1984) R1991) Is 170 Dy nature’s best SU(3) nucleus too ? 168 Tb-> 168 Dy, T 1/2 =8 s Asai et al., Phys. Rev. C59 (1999) 3060

40. GSI-EA 21 March 2005 Primary 198 Pt beam @ 1GeV/u, intensity of 10 9 particles per spill, 10 second spill cycle. 2.5 g/cm 2 thick Be target, 5.1g/cm 2 Al. degrader at S2, plus a 108mg/cm 2 Niobium stripper. Cross-section estimates from the COFRA.Estimated values for transmission per eight hour shift are: Setting 1: Centred on 191 W 190 W 1x10 7 191 W 0.4x10 7 192 W 0.4 x10 7 Setting 2: Centred on 187 Hf 187 Hf 3.7x10 5 188 Hf 9x10 4 189 Hf 1x10 4 Setting 3: Centred on 185 Yb 184 Yb 2x10 4 185 Yb 6x10 3186 Yb 240 20%  -ray efficiency for 662 keV, (~50%) prompt-flash, isom. ratio (~5%), Yield estimates for observed photopeak  rays per 8 hour shift of 190 W 250,000 ; 192 W 100,000 ; 188 Hf 2,250 ; 184 Yb 500 ; 186 Yb 6 Setting 4: Centred on 170 Dy 170 Dy 1.4x10 5 170 Tb 4,500 168 Tb 4.9x10 4 Assuming  -ray (0.2) and  -detection (0.5) efficiency for decays of 170 Tb gives 450 photopeak  rays from the decay of the first 2 + state in 170 Dy 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, 191 W setting: Total beam request of 24 shifts (8 days).

41. GSI-EA 21 March 2005 Proposal A:3 (S305) Search for the 8 + (  g 9/2 ) -2 isomer in N=82 130 Cd populated via the 6 proton knockout channel in the fragmentation of 136 Xe A. Jungclaus et al., Universidad Autónoma de Madrid, Spain Institute of Nuclear Research, Debrecen, Hungary Universidad de Santiago de Compostela, Spain GSI Darmstadt, Germany Uppsala University, Sweden University of Surrey, UK Universität zu Köln, Germany University Warsow, Poland IFIC Valencia, Spain Lund University, Sweden STOPPED BEAM CAMPAIGN - A

42. GSI-EA 21 March 2005 Search for the 8 + (  g 9/2 ) -2 isomer in N=82 130 Cd populated via the 6 proton knockout channel in the fragmentation of 136 Xe Why study 130 Cd ? astrophysical reasons: 130 Cd 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=50 130 Cd 132 Sn

43. GSI-EA 21 March 2005 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 124 Cd) there is a series of other nuclear structure puzzles in the 132 Sn region Is this behaviour really a “signature of a weakening of the N=82 shell structure already one proton-pair below 132 Sn” as suggested by the authors of the experimental study ?  -decay @ ISOLDE Kautsch et al., EPJ A9 (2000) 201 Sn Te Cd Pd

44. GSI-EA 21 March 2005 Is there an alternative explanation ? mean-fieldafter angular momentum projection 132 Sn curve much broader than that for 208 Pb fluctuations in  2 much more important in 132 Sn indicating that a higher degree of collec- tivity remains in 132 Sn as compared to 208 Pb after angular momentum projection, 126 Cd and 128 Cd show deep prolate minima already at I=2ħ constrained HFB+AMP with Gogny force, J.L. Egido Does quadrupole collectivity persists close to N=82 in the chain of Cd isotopes ? 208 Pb 132 Sn 130 Cd 128 Cd 126 Cd (Remember: 32 Mg is spherical at mean field level, but deformed after projection !)

45. GSI-EA 21 March 2005 A=128 A=126  -decay study of heavy Cd isotopes at ISOLDE In general: Problems due to beam intensity and dominating In and Cs isobaric activities ! Kautsch et al., Eur. Phys. J. A9 (2000) 201 Sn Te Cd Pd Can probably not be done better at ISOLDE at the moment ! “… has to be considered speculative …” “… close to the present limit that can be achieved with RILIS and GPS-ISOLDE.”

46. GSI-EA 21 March 2005 8 + isomer with (  g 9/2 ) -2 con- figuration expected in 130 Cd in analogy to the one in 98 Cd Study of 8 + isomer decay in 130 Cd (and 128 Cd) already searched for without success at LOHENGRIN and FRS (Mineva, Hellström et al.) Advantage compared to  -decay: possible observation of whole se- quence up to the 8 + state lifetime of the isomer itself contains valuable information

47. GSI-EA 21 March 2005 Production of 130 Cd @ FRS 238 U fission cold fragmentation of 136 Xe implantation rate at the focal plane: I [sec -1 ] =  [cm 2 ] · d[g/cm 2 ] · A -1 [mol/g] ·  [sec -1 ] · T tot · N A [mol -1 ] cross section  target thickness d primary beam current  total transmission  0.1  b calc. !  0.154 nb measured ! 1 g/cm 2 2.5 g/cm 2 10 9 /spill (15s)5·10 9 /spill (5s)  3.5%  95% 1.4 (2000)0.9 (1300) implanted 130 Cd/min(d) for Be target Mineva et al.:  =2·10 7 sec -1 in total 700 implanted 130 Cd measured  easier beam easier exp.

48. GSI-EA 21 March 2005 130 Cd setting 131 In setting Transmission simulations with the Lieschen code known isomers in 127 Cd and 130 In will be observed at the same time in the setting optimized for 130 Cd 130 Cd 127 Cd 130 In N N ZZ 132 Sn 129 In this setting could be used for a quick calibration using the known isomers in the strongly populated nuclei 132 Sn and 129 In

49. GSI-EA 21 March 2005 Proposal A:4 (S314) Exotic Beta decays near the proton-drip line: study of the beta decay of 70,71 Kr. A. Algora, B. Rubio, W. Gelletly et al., Institute of Nuclear Research, Debrecen, Hungary IFIC, CSIC, Valencia, Spain University of Surrey, Guildford, UK University Santiago de Compostela, Santiago, Spain Osaka University, Osaka, Japan Universidad Autonoma de Madrid, Madrid, Spain CIEMAT, Madrid, Spain GSI, Darmstadt, Germany LNL, Legnaro, Italy STOPPED BEAM CAMPAIGN - A

50. Exotic decays near the proton-drip line: study of the beta decay of 70,71 Kr 71 Kr case: Motivations Study of mirror T=1/2 pairs Identification of IAS of 71 Kr g.s. (not known) N~Z region around Z=36-38: shape effects, shape coexistence, shape transitions, isospin symmetry Determination of the ground deformation of 71 Kr

51. GSI-EA 21 March 2005 71 Kr case II Ref. Oinonen et al PRC 52 (1997) 745

52. GSI-EA 21 March 2005 Motivation: Search for states populated in the beta decay of 70 Kr, which may indicate the existence of the proton-neutron condensate Background:  Validity of the IBM-4 classification scheme in light nuclei ( 18 Ne  18 F, P. Halse, et al. NPA 417 (1984) 301)  Existence of some examples in medium-heavy and heavy nuclei that can be explained using this scheme. Transitions with small log ft, that can not be explained because of large hindrance factors in fermion transitions but can be explained assuming boson transitions. ( 130 Sn  131 Sb, Iachello et. al).  Necessity to study systems in the vicinity of the N~Z line 70 Kr case I

53. GSI-EA 21 March 2005 (0+) T=1 T=0 0+ (1+ ?) 2+ 0+ (  700 keV)? 4.0? 3.5? 3.5 74 Sr 70 Kr 62 Ge 58 Zr 66 Se Tz = -1 Franco Iachello, private comunication 70 Kr case II

54. GSI-EA 21 March 2005 (0+) T=1 T=0 (1+ ?) 0+ (  700 keV)? 4.0? 3.5? Franco Iachello, private comunication 70 Kr case II If the 1 + condensate exists, then the GT strength can be very large because may pairs can participate

55. GSI-EA 21 March 2005 Primary beam: 10 9 ions/s of 92 Mo Target: Be (4000 mg/cm 2) Expected Yields (LIESCHEN) 70 Kr: 1.1 x 10 3 ions/h 71 Kr: 6.3 x 10 4 ions/h Implantation area: 5 x 5 cm 2 DSSD detector with 16 x 16 strips Beam requirements: 1 week (6 days measurement + 1 day preparation) Measurements Assuming a feeding of 50 % at an excitation energy of ~ 700 keV, a production of 0.3 atoms/s and a  detection efficiency of 15 % for a  ray of 700 keV  2000 counts/day in the  -  coincidence spectrum 70 Kr: 2 days 71 Kr: 4 days Assuming a production of 18 atoms/s, a feeding of 1 % to the level that decays consequently with a  cascade of 2  -s with energies of 200 keV and 1.0 MeV (  detection efficiency of 30 % and 10 % respectively)  500 counts/day in the  -  coincidence spectrum

56. GSI-EA 21 March 2005 Proposal A:5 (S315) Proton-Neutron Pairing Effects in the Beta Decay of 62 Ge A.Gadea, G.deAngelis et al., INFN-Laboratori Nazionali di Legnaro, Padova, Italy University and INFN-sezione di Padova, Italy University and INFN-sezione di Milano, Italy University of Surrey, UK GSI-Darmstadt, Germany University of Lund, Sweden University of Santiago de Compostela, Spain IFIC Valencia, Spain Institute of Nuclear Research, Debrecen, Hungary STOPPED BEAM CAMPAIGN - A

57. GSI-EA 21 March 2005 Proton-neutron pairing effects in the  -decay of 62 Ge Study of the p-n condensate through  -decay experiments. Low lying 1 + states in odd-odd nuclei have components corresponding to a proton-neutron T=0 condensate. Collective transitions of correlated pairs will lead to “superallowed” GT transitions. Large B(GT) to 1 + T=0 states observed in light nuclei  -decay (18Ne). Single fermion GT transitions in medium mass nuclei are highly retarded logft > 4. If p-n pairing survives small logft (large G(GT) values are expected. Boson space of correlated nucleon pairs in IBM-4 62 Ga N=3

58. GSI-EA 21 March 2005N=Z Sequential decay: 62 Ge (129ms) → 62 Ga (116ms) → 62 Zn (9.1h) 62 Ge (129ms) → 62 Ga (116ms) → 62 Zn (9.1h) With active catcher the sequence of 129ms + 116ms decays (Q EC >9 MeV for both  + -  + ) can help to identify the 62 Ge surviving implantation F.Iachello

59. GSI-EA 21 March 2005 D.Rudolph et al., Phys. Rev.C69(2004)034309 LNL-GASP in beam experiment Theory: Shell model pf 5/2 g 9/2 Shell model pf 5/2 g 9/2 S.M.Vincent, et al., Phys. Lett. B437(1998) 264 O.Juillet, et al., Phys. Rev. C63 (2001)054312 Deformed shell model A.Juodagalvis et al., Nucl. Phys. A683(2001)207 Deformed shell model R.Sahu,et al.,Phys. Rev. C66 (2002)024301 Cranked Nilsson-Strutinsky A.Juodagalvis et al., Nucl. Phys. A683(2001)207IBM-4 O.Juillet, et al., Phys. Rev. C63 (2001)054312 Low lying states level scheme 40 Ca( 24 Mg,pn) Added value: spectroscopy of the low lying low spin states (calculated more than 10) 4.6ns Lifetime 3 + →1 + 4.6ns B(E2) ≈ 14W.u. S.M.Vincent et al. Phys.Lett. B437(1998)264 Calculated CNS g.s. deformation:  ≈0.17

60. GSI-EA 21 March 2005 62 Ge Q EC ≈9.7 SpSpSpSp O.Juillet et al., Phys.Rev.C(2001)054312 0+ T=1 S=1 IBM-4 62 Ga N=3

61. GSI-EA 21 March 2005 Beam Time request The 62 Ge is produced by 78 Kr beam (400 MeV/u) fragmentation. EPAX  ~10-7 barns - 20% transmission of the FRS - primary 78 Kr beam of ~10 9 atoms/s - 1.6g/cm2 Be target. 62 Ge rate at the implantation site ~ 2 atoms/s, (~150 MeV/u). The efficiency of the RISING array is 11% for E  =1.33 MeV and 20% for 662 keV. Approximately 95% of the 62 Ge atoms will survive implantation and will partially decay to the 0+ ground state in 62 Ga and partially to excited states and in particular to the 1+, at 571 keV The precise measurement of the 571 keV transition intensity, compared with the total number of decays of 62 Ge nuclei will give the logft of the GT transition to the low lying 1+, and this value will allow to extract important information on the nature of the state. In the same experiment we will explore the population of other 1+ states that might carry also a consistent fraction of the expected collectivity. The investigation of the decay level scheme will require a minimum of ~10 5 - 10 6 decays and a beam time of 5 days (15 shifts) of measurement will be necessary. One extra day necessary for the setup of RFD and detectors. TOTAL BEAMTIME REQUESTED 18 shifts (6 days)

62. GSI-EA 21 March 2005 Proponents A.Gadea, G.deAngelis, N.Marginean, D.R.Napoli, J.J.Valiente-Dobón, Q.Zhong INFN-Laboratori Nazionali di Legnaro, Padova, Italy E.Farnea, D.Bazzacco, S.Lunardi, R.Marginean University and INFN-sezione di Padova, Italy A.Bracco, G.Benzoni, F.Camera, B.Million, S.Leoni, O.Wieland University and INFN-sezione di Milano, Italy Zs.Podolyàk, P.H.Regan,W.Gelletly, W.N.Catford, S.Williams University of Surrey, UK M.Gorska, J.Gerl, H.J.Wollersheim, F.Becker, H.Grawe, L.Caceres, P.Bednarczyk, N.Saitio, T.Saito GSI-Darmstadt, Germany D.Rudolph, L.L.Andersson,E.K.Johansson University of Lund, Sweden J. Benlliure, D. Cortina Gil University of Santiago de Compostela, Spain B.Rubio IFIC Valencia, Spain A.Algora Institute of Nuclear Research, Debrecen, Hungary

63. GSI-EA 21 March 2005 Proposal A:6 (S316) Isospin Symmetry of Transitions Probed by Weak and Strong Interactions: the beta decay of 54 Ni, 50 Fe, 46 Cr Y. Fujita, B. Rubio, W. Gelletly, A. Algora et al., Osaka University,Osaka,Japan IFIC, CSIC, Valencia, Spain University of Surrey,Guildford,UK Inst.for Nuc.Phys.,Debrecen,Hungary Universidad Autonoma de Madrid,Spain CCLRC,Daresbury,UK University of Santiago de Compostela,Santiago,Spain University of Leuven,Leuven,Belgium GSI, Darmstadt, Germany STOPPED BEAM CAMPAIGN - A

64. GSI-EA 21 March 2005 Isospin Symmetry of Transitions Probed by Weak and Strong Interactions: the  decay of 54Ni, 50Fe, 46Cr. Osaka, Valencia, Surrey, Debrecen, Leuven, Madrid, Daresbury, Santiago and GSI. Aim:- A test of Isospin symmetry from a comparison of beta decay and charge exchange at 0 0 Background:- Charge independence means that Isospin should be a good quantum no. In the absence of isospin mixing, Gamow-Teller decays from mirror parents to common daughter states should be identical. Here we propose to measure the beta decays of 54 Ni, 50 Fe and 46 Cr with the RISING setup with an active stopper to determine the B(GT) values to levels in the daughter nuclei for comparison with the same quantities measured at 0 0 in the ( 3 He,t) reaction at Osaka with the Grand Raiden spectrometer. The charge exchange reactions have already been studied and are being analysed. Spokespersons:-Y.Fujita,B.Rubio and W.Gelletly

65. GSI-EA 21 March 2005 0+ T Z = 0 T = 1 A schematic illustration of the transitions to levels in the N = Z nucleus 54 Co by beta decay and charge exchange reactions. A typical example of an isobaric triplet to be studied

66. GSI-EA 21 March 2005 Typical example of the Charge Exchange Spectra Spectrum taken with the Grand Raiden spectrometer at Osaka Uni. The energy resolution is ~ 30 keV with a 3 He beam energy of 150 MeV. This spectrum was taken at zero degrees. As a result only the  L = 0,  S = 0 transitions are observed.

67. GSI-EA 21 March 2005 Further Examples of the Charge Exchange Spectra ● All of the charge exchange studies of interest in the present work have already been made. ● The spectra are all of high quality and have similar resoluton. ● The spectra shown are all taken at 0 0. ●Analysis of all these spectra is already underway.

68. GSI-EA 21 March 2005 Measurements Primary Beam: 0.1 pnA of 58 Ni ions at 600 MeV/u Target: Be of 4000 mg.cm -2 thickness Expected yields from LISE++ 54 Ni: 280 ions per sec. 50 Fe: 240 ions per sec. 46 Cr: 190 ions per sec Active Target: Si DSSD of 5 x 5 cm 2 area with 16 x 16 strips Total Beam requirement: 1 week(3x2 = 6 days measurement + 1 day preparation/setup) e.g. 54 Ni: 2 days We assume that we have 290 ions per sec on DSSD and 10% eff. for gammas at 1MeV. We also assume preliminary value of B(GT) from Charge exchange. Gives an estimate of 1500 counts in decay of 2010 keV level.