1. R. Krücken Physik Department E12 Technische Universität München & Maier-Leibnitz Laboratorium für Kern- und Teilchenphysik Nuclear Structure Studies at REX-ISOLDE and the HIE-ISOLDE project

2. Introduction Recent results – Island of inversion at N=20 – N=50 shell closure – collectivity near 132 Sn New developments – transfer experiments – HIE-ISOLDE project MINIBALL at the FRS middle focus

3. Introduction

4. Long Standing Questions of Nuclear Structure Physics What are the limits for existence of nuclei? –Where are the proton and neutron drip lines situated? –Where does the nuclear chart end? How does the nuclear force depend on varying proton-to- neutron ratios? –What is the isospin dependence of the spin-orbit force? –How does shell structure change far away from stability? How to explain collective phenomena from individual motion? –What are the phases, relevant degrees of freedom, and symmetries of the nuclear many-body system? How are complex nuclei built from their basic constituents? –What is the effective nucleon-nucleon interaction? –How does QCD constrain its parameters? Which are the nuclei relevant for astrophysical processes and what are their properties? –What is the origin of the heavy elements?

5. Superheavy elements Nuclear Structure at the extremes Halos New shell gaps through residual interaction Shell quenching by diffuse surface New shell gaps through residual interaction harmonic oscillator + spin-orbit +centrifugal diffuse surface neutron rich + spin-orbit

6. Superheavy elements Nuclear Structure at the extremes Halos New shell gaps through residual interaction Shell quenching by diffuse surface

7. Magic Numbers – Benchmarks of Nuclear Structure Our interest: Test of existing shells ( 56 Ni, 100 Sn, 132 Sn, 208 Pb, 270 Hs) Changes of shell structure (vicinity of 32 Mg, 54 Ca) towards r-process nuclei (vicinity of 78 Ni and 132 Sn)

8. Selected spectroscopic tools to probe single-particle and collective properties of low lying state

9. - measurement of excitation energy E(2 1 + ) - measurement of cross section  electromagnetic matrix elements  collectivity, deformation, test of shell closures  ~ B(E2) Coulomb-excitation g-factor measurement following Coulomb-excitation (or transfer) - perturbed angular distribution / correlation  magnetic moments  sensitivity to neutron and proton single-particle contributions  B-field 0+0+ 2+2+ Coulomb- excitation  -decay Spectroscopic tools

10. Single nucleon transfer  single-particle energies  quantum numbers (orbital and total angular momentum L,J=L+S, parity)  spectroscopic factors (overlap with shell-model wave-function) Spectroscopic tools typical Reactions: (d,p), ( 9 Be,2  ) Pair-transfer  spectroscopic factors  sequential and simultaneous transfer  pairing correlations  shape coexistence Z,N Z,N+1 Z,N+2 0+0+ 0+0+ Z,N Z,N+2 0+0+ 0+0+ 0+0+ 32 Mg 30 Mg proposed Reactions: (t,p), ( 10 Be,2  )

11. measure: Identification of residual nucleus Momentum of residual nucleus gamma-detection for excited states Adopted from J. Al-Khalili & D. Cortina Gil theoretical approximation best at GSI energies: Eikonal approximation: semi-classical trajectories Sudden approximation:slow/frozen inner degrees of freedom Spectroscopic tools ground state of exotic projectile occupation probability State in residual nucleus valence nucleon model prediction: (e.g. shell model) | P  = ∑ CS 2 ( | C  n  ) Single-particle knock-out

12. REX-ISOLDE and MINIBALL

13. 1.4 GeV REX-ISOLDE MINIBALL

14. - 8 clusters à 3 6-fold segmented crystals -total MINIBALL efficiency ~8% at 1.3 MeV -digital electronics, on-board online pulse shape analysis (PSA) for better position resolution - 8 clusters à 3 6-fold segmented crystals -total MINIBALL efficiency ~8% at 1.3 MeV -digital electronics, on-board online pulse shape analysis (PSA) for better position resolution

15. Set-up for safe Coulomb-excitation - beam B(E2) measured relative to known target B(E2) - DSSSD Univ. of Edinburgh Particles angle energies    Beam- monitor PPAC TU Darmstadt Beam- purity Beam Dump Detector Gamma- spectroscopy MINIBALL 

16. Recent Results from REX-ISOLDE

17. REX-ISOLDE Physics Program Coulomb-excitation of - 30,32 Mg (MPI Heidelberg)

18. Evolution of effective single particle energies from H. Scheit

19. Collectivity of the Mg isotopes H. Scheit

20. Comparison with theoretical predictions Adopted values: weighted averages without Ganil data H. Scheit

21. REX-ISOLDE Physics Program Coulomb-excitation of - 74,76,78 Zn - isomeric 68m Cu (Univ. Leuven)

22. Reduced N=50 shell gap at 78 Ni Presented by H. Grawe at ENAM 04 EPJA 25 S01, 357 (2005)

23. 74 Zn 120 Sn 74 Zn (606 keV, 2 +  0 + ) 120 Sn (1174 keV, 2 +  0 + ) 76 Zn 76 Zn (600 keV, 2 +  0 + ) 120 Sn 14.5h measuring time  Zn/total  = 68% 3·10 5 pps Zn 12.5h measuring time  Zn/total  = 80% 7·10 5 pps Zn Coulomb excitation of 74,76,78 Zn 108 Pd (434 keV, 2 +  0 + ) 78 Zn 108 Pd 78 Zn (730 keV, 2 +  0 + ) 23.5h measuring time  Zn/total  = 59% 8·10 3 pps Zn

24. Towards the doubly magic 78 Ni - evolution of collectivity in 74,76,78 Zn - J. Van de Walle et al., to be published Large scale shell model calculations Lisetskiy (MSU,GSI) Ni Ge Zn  74 Zn: agreement with intermediate energy Coulex (GANIL)  Steep drop in B(E2) towards N=50  Good agreement with large scale shell model calculations E. Padilla-Rodal et al., PRL94, 122501(2005)

25. 6-6- 1+1+ U. Koester et al., NIM B 167 (2000) 528 1+1+ (2 + ) (6 - ) 68 Cu T 1/2 =30 s T 1/2 =3.7 min -- -- LASER 68m Cu: production of isomeric beams

26. 140 160 180 200 220 E [keV] 68 Cu (4 -  3 - ) 178 keV 68 Ga (2 +  1 + ) 174 keV 68m Cu (2.86 MeV/u) @ 120 Sn (2.3 mg/cm 2 ) Y MB ( 68m Cu) ~ 3 · 10 5 pps Coulomb excitation of isomeric beam: 68m Cu 6 - 3 - 4- 4- 5-5- 0 63 409 768 Shell-model ** (e p =1.9; e n =0.9; 56 Ni core) B(E2)=6.5 W.u. **N. Smirnova, Private Communication  p 3/2  g 9/2 J  =3 -, 4 -, 5 -, 6 - Good agreement with large scale shell model calculations 6 - (3 - ) 4 - (5 - ) 0 56 235 628 EXP. B(E2)=6.7± 0.7 W.u. I. Stefanescu et al., to be published

27. REX-ISOLDE Physics Program Coulomb-excitation of 122,124 Cd, 138,140,142 Xe (TU München)

28. B(E2) systematic – improved Grodzins rule reduced B(E2) 148 Ba program for REX-ISOLDE Raman systematics + isospin dependence (Habs, Krücken ) Minimum of Weizsäcker mass parabola for given mass number A

29. Coulomb excitation of 140 Xe 140 Xe 2 + FWHM ~9 keV 96 Mo FWHM ~10 keV running time: ~11 h beam intensity: ~5·10 5 part/s 140 Xe 4 + T. Behrens TUM dissertation

30. B(E2) values around 132 Sn Two values published

31. B(E2) values around 132 Sn g-factor experiments planned in 2006/2007 No evidence for further deviations from systematics further experiments for 126 Cd, 144 Xe, 138,148,150 Ba

32. Future perspectives for REX-ISOLDE

33. Transfer-Experiments H. Lenske, G. Schrieder Eur. Phys. Jour. A 2 (1998) 41 Cross sections peak at low energy

34. 2 H( 30 Mg,p  ) at REX-MINIBALL Calculations by H. Lenske G. Neyens et al, PRL 94(2005)22501 H.Mach et al, ENAM 2004 proc. Population of high-lying states? Experiment not conclusive Data from M. Pantea, T. Nilsson (TU Darmstadt)

35. Issues Transfer Reactions at the Coulomb barrier –Energy resolution Kinematic broadening does not allow to do spectroscopy using recoils Light particles allow for some spectroscopy (≥150 keV resolution) –Angular distributions At low energies the distributions are more flat (Problem for high L)  need full angular coverage –Identification of reaction products Gamma-particle coincidences (also provides high resolution) Above fusion barrier for target carrier: swamped by fusion protons  Recoil spectrometer needed EMMA (TRIUMF) B. Davids et al.

36. New detector setup for transfer experiments V. Bildstein, TUM dissertation TUM-Leuven collaboration laboratory angle Simulation for the

37. t( 40 Ar,p) 42 Ar @ 2.25 MeV/u at HMI Berlin L=4 L=2 L=0 3.096 MeV 1.208 MeV Ground state 4+4+ 2+2+ 0+0+ DWBA calculations (CHUCK3) M. Mahgoub TUM dissertation  cm Beam intensity: 6·10 8 pps Tritium loaded Ti foil: ~ 40 µg/cm 2 3 H 12 hrs data taking 40 Ar 42 Ar p DSSD t

38. The HIE-ISOLDE project

39. HIE-ISOLDE (2007-2012) Higher energies and increased currents –Upgrade of REX in tow stages to 5.5 MeV/u and 10 MeV/u –Improvements of the REX low-energy stage Higher intensities –Faster cycling of PS booster (1.9  6.4  A) –New ISOLDE targets, target stations, target handling system Improved beam quality –Smaller emittance (RFQ cooler and buncher after preseparator) –Higher charge states (ECR source, improved REX frontend) –Better mass resolution (New High Resolution Separator) –Upgrade of Laser Ion Source system

40. RILIS ECR RFQ cooler Targetry SC LINAC charge breeder

41. Suggested option: Superconducting LINAC Recommended by International Advisory Board A. Müller (IN2P3), R. Laxdal (TRIUMF), O. Kester (GSI)

42. MINIBALL @ FRS middle focus: Spectroscopy in one-nucleon knock-out reactions

43. Gamma-spectroscopy in knock-out experiments MINIBALL 9 Be 500 MeV/A 86 Kr 56 Ti 55 Ti Gamma-spectroscopy New transition at ~950 keV Energy [keV] Counts / 10 keV Online spectrum 55 Ti Momentum distribution

44. Gamma-spectroscopy in knock-out experiments MINIBALL 9 Be 500 MeV/A 86 Kr 48 Ca 47 Ca Gamma-spectroscopy 47 Ca 2013 565 7/2- 3/2+ 3/2- 452 MeV/A 48 Ca Online spectrum Unique combination of reaction at relativistic energies (Eikonal) high resolution gamma-spectroscopy high resolution momentum measurement

45. 74 Zn  73 Cu + p Counts / 20 keV Energy [keV] Online spectrum

46. NuSTAR@FAIR: The R3B set-up Kinematical complete reaction studies at the highest energies along the drip lines (R 3 B) Wave functions and few body correlations (knock-out, quasifree scattering) Inelastic excitations (soft modes, giant resonances)

47. Summary MINIBALL @ REX-ISOLDE –Evolution of collectivity studied via safe Coulomb excitation 30,32 Mg: border of the N=20 island of inversion 74,76,78 Zn, 68m Cu: probing large scale shell model near 78 Ni 122,124 Cd, 138,140,142 Xe: evolution of collectivity around 132 Sn –Good agreement with shell model (N=20,50) or systematics (A~140) –Study of single-particle structure via for transfer reactions (d,p) and (t,p) reactions at the Coulomb barrier possible New detector set-up under development, recoil spectrometer needed HIE-ISOLDE –Energy upgrade to 5.5 MeV/u and 10 MeV/u –Improvement of beam purity and intensity MINIBALL @ FRS middle focus: towards R3B –High resolution spectroscopy in relativistic knock-out reactions –Measurement of recoil momentum –Successful measurements for 47 Ca, 55 Ti, 73 Cu  ISOL and Fragmentation facilities allow for complementary investigations of nuclear shell structure and collectivity

48. Beam composition for 74,76,78 Zn: laser ON/OFF measurements; Ionization chamber – Si detector; beam dump decay detector; 78 Rb 78 Ga 78 Zn Proton beam on target: p+ 238 U  E (a.u.) E total (a.u.) REX- ISOLDE  E-E detector Proton beam on converter: n+ 238 U 78 Ga 78 Zn 78 Rb  E (a.u.) Producing “clean” Zn beams – the neutron converter TUM ionization chamber

49. Backup

50. Coulomb excitation of 138 Xe 138 Xe 2 + FWHM ~9 keV 96 Mo FWHM ~10 keV running time: ~9 h beam intensity: ~5·10 5 part/s 138 Xe 4 + T. Behrens TUM dissertation

51. Evidence for gamma-ray in 55 Ti

52. KU Leuven Towards the doubly magic 78 Ni - evolution of collectivity in 74,76,78 Zn - N J. Van de Walle et al., to be published  74 Zn: agreement with intermediate energy Coulex (Ganil)  Steep drop in B(E2) towards N=50  Shell-model: E. Padilla-Rodal, PRL 94, 122501(2005) 0 Shell-model: N. Smirnova Private communications  Seniority: I. Deloncle Irina Stefanescu, Trento, 8-12 May 2006

53. T 1/2 =44.5 s (6 - ) 70 Cu (3 - ) (4 - ) (5 - ) T 1/2 =33 s Neutron-rich even-A Cu isotopes - 68,70 Cu- J.D. Sherman et al. PLB67 (77) 257 T. Ishii et al., Jaeri-Review, 2002-029, 25  p 3/2 - g 9/2  p 3/2 – p 1/2 1+1+ (2 + ) (3 + ) 6 - (4 - ) (3 - ) (5 - ) 68 Cu T 1/2 =30 s T 1/2 =3.7 min T 1/2 =7.84 ns  p 3/2  g 9/2  p 3/2  p 1/2 KU Leuven Irina Stefanescu, Trento, 8-12 May 2006

54. Coulex of 68,m Cu, 70,g Cu 68 Cu 6 - (3 - ) 4 - (5 - ) 0 56 235 628 EXP. 6 - 3 - 4- 4- 5-5- 0 63 409 768 Shell-model (e p =1.9; e n =0.9; 56 Ni core) B(E2)=6.7±o.7 W.u. B(E2)=6.5 W.u. 6 - 3 - 4- 4- 5-5- 0 87 336 582 6 - 3 - 4- 4- (5 - ) 0 101 228 506 B(E2)=5.6 W.u. B(E2)=7.2±0.9 W.u. 70 Cu **N. Smirnova, Private CommunicationI. Stefanescu et al., to be published Irina Stefanescu, Trento, 8-12 May 2006

55.  p 3/2  g 9/2 (J  =3 -,4 -,5 -, 6 - )  p 3/2  p 1/2 (J  =1 +, 2 + ) 1+1+ (2 + ) 6 - 68 Cu T 1/2 =30 s T 1/2 =3.7 min T 1/2 =7.84 ns f 7/2 p 1/2 f 5/2 p 3/2 sd-shell 28 g 9/2 40  p 1/2 f 5/2 p 3/2 g 9/2 40 28 T. E. Ward et al., PR88, 1802(1969) L. Hou et al., PRC68, 054306(2003) (3 - ) 0.7 <T 1/2 < 4 ns N=40: Coulomb Excitation of 68m Cu isomer odd-A and odd-odd nuclei around 68 Ni  nuclear wave function dominated by single-particle configurations Coulex of 67,68,69,70,71 Cu  strength of the N=40 subshell closure  evolution of collectivity around 68 Ni  testing ground for shell model calculations July 2005: Coulex of 68,70 Cu

56. Detaillierte Gliederung Intro –Questions for nuclear physics –Nuclear reactions: Tools for probing single-particle and collective degrees of freedom Coulomb excitation Single- and two-nucleon transfer reactions Knock-out reactions (and quasi-free scattering) Recent results –Studying the island of inversion (Coulex 30,32 Mg, Transfer 31 Mg) –Probing the N=40 and 50 shelle closures (Zn, CU Coulex) –Evolution of collectivity around 132 Sn: Cd, Xe Coulex (g-factor) New developments –Transfer reactions New set-up under development Stable beam studies (Fe(d,p) & Ar(t,p) –HIE-ISOLDE project MINIBALL at GSI –S277 and S245 experiments

57. t( 40 Ar,p) 42 Ar @ 2.25 MeV/u at HMI Berlin Q (keV) Ring # E p (keV) 0 1.208 2.41 +2.49 +2.51 4.01 3.10 5.0 MeV Q (keV) Beam intensity: 6·10 8 pps Tritium loaded Ti foil: ~ 40 µg/cm 2 3 H 12 hrs data taking 40 Ar 42 Ar p DSSD t