Exploring the evolution of the shell structure by means of deep inelastic reactions

Exploring the evolution of the shell structure by means of deep inelastic reactions G. de Angelis INFN - LNL Grazing reactions as mechanism to study the structure of moderately neutron-rich nuclei Results on n-rich nuclei from N=20 (A~40) to N=82 (A~136) Shell structure at Z=28 and N=50 Lifetime measurements in n-rich Ca nuclei using the differential plunger technique (isospin dependance of the effective charges?) AGATA Demonstrator at PRISMA) and Pre-Spes

+ populating many nuclei in one shot medium and high spin states mainly yrast states spin assignment IC MWPPAC - most of the cases no -coincidences need of complementary experiments

Approximate cross sections [mb] Grazing reactions transferring several nucleons as a tool to study n-rich nuclei 82 Ge ~0.6mb 80 Zn ~2 b Deep-inelastic reactions used since thick target pioneering work of R.Broda et al. (PLB 251 (90) 245) Use of Multinucleon-transfer triggered by the LNL reaction mechanism group. 82 Se + 238 U E=505 MeV Effective Pairing Term Grazing calculations Sequential Transfer L.Corradi et al., Phys.Rev.C59 (99)261, Theory: G.Pollarolo

6m PRISMA: Large acceptance tracking Magnetic Spectrometer Q-D msr Z/Z 1/60 (Measured) A/A 1/190 (Measured) TOF Energy acceptance ±20% B = 1.2 T.m

Evolution of magic numbers and collectivity in n-rich nuclei Proton drip-line Shell Model States in 48 Ca Region - isospin dependance of the effective charges? n-rich nuclei Shell Closures and and shell Neutron evolution in drip-line A~136 nuclei Evolution of the shell gap N=50 protons neutrons Island of Inversion. From N=20 to N=28 Shell Closures and Collectivity in A~60 nuclei towards N=40 Evolution of the Z=28 Shell Gap and effective single particle states n-rich

To do this we have to use of the most neutron-rich beams available 136 Xe 64 Ni 82 Se 70 Zn 22 Ne 40 Ar 48 36 S Ca 26 Mg at energies 10-15% above the Coulomb barrier

Stability n-rich N-reach nuclei: shell closures The qualitative effect of the spin-flip l = 0 proton-neutron interaction is shown for different regions of the chart of nuclides. By comparing the left and right hand sides of the Figure, the removal of protons induces a change in the spacing and possibly ordering of the neutron states. When this interaction is missing, the major Harmonic Oscillator shell gaps N = 8, 20, 40 are reduced to the benefit of new subshell gaps at N = 6, 16, 32, 34. O.Sorlin, M.-G.Porquet, Prog.Part.Nucl.Phys. 61, 602 (2008)

N=34 N=34 Ca Effective interaction for pf-shell nuclei M. Homma et al., Phys. Rev. C65 (2002) 061301 (R) The GXPF1 interaction predicts the appearance of a new magic number N=34 in neutron-rich nuclei Ni

Spectroscopy around the N=32 shell closure A peak in the 2 + energy is observed at N=32 in the Ti and Cr chain. V isotopes First identification of yrast states in heavy odd- A Vanadium isotopes 55 V and 57 V 55 30 57 32 64 Ni(400 MeV) + 238 U 34 The shell closure is confirmed also in the V isotopes.

Prisma-Clara 48 Ca + 238 U at 330 MeV GXPF1A tested: the N=31 nuclei νp 3/2 2 f 5/2 Gammasphere B. Fornal et al., PRC77, 014304 (2008) N=31

48 Ca + 238 U at 330 MeV GXPF1A tested: the N=31 nuclei Prisma-Clara f 7/2 νp 3/22 f 5/2 Gammasphere N=31

No subshell gap at N=34 Gap of 3.6 MeV between p 1/2 and f 5/2 single-particle states at N = 34 and Z = 20. Z=28 g f p p f 9/2 5/2 1/2 3/2 7/2 N=40 N=28 3.6 MeV N=31 Lowering the gap by 0.5 MeV in Ca nuclei would result in a very good description of the 9/2 state in 51 Ca. B. Fornal et al., PRC77, 014304 (2008)

Erosion of shell gaps N=8 N=20 N=40 O.Sorlin, M.-G.Porquet, Prog.Part.Nucl.Phys. 61, 602 (2008)

N=40 and beyond N=40 N=42 70 Zn + 238 U at 460 MeV S.M. Lenzi et al., LNL Annual Report 2007 and to be published

(j p <) (j p >) p 1/2 f p 5/2 3/2 f 7/2 Role of the neutron-proton interactions (tensor) around Z=28 N=40 28 protons neutrons g 9/2 (j n >) before N=40: Vpn(f7/2 ){fp}) > Vpn(p3/2{fp}) due to f7/2- f5/2 interaction after N=40 :Vpn(p3/2g9/2) > Vpn(f7/2g9/2) due to repulsive tensor f7/2-g9/2 shrink of f 7/2 f 5/2 ) spacing Add neutrons in g 9/2 Inversion of the proton f 5/2 p 3/2 orbits 5/2-1214 534 166 Reduction of Z=28 at 78 Ni 3/2-28 28 28 28 28 28 7/2-69 Cu 71 40 Cu 73 42 Cu 44 N=46 N=48 N=50 Cortesy of O. Sorlin S. Franchoo et al. PRC 64 (2001) 054308.

Monopole migration of f 5/2 : 71,73,75 Cu NO low energy transition 5/2 3/2 < 70 kev f 5/2 p 3/2 71 Cu 73 Cu f 5/2 p 3/2 75 Cu Effective single particle orbitals inversion?

Monopole migration of f 5/2 : 71,73,75 Cu NO low energy transition 5/2 3/2 < 70 kev f 5/2 p 3/2 71 Cu p 3/2 2 + f 5/2 p 3/2 73 Cu p 3/2 2 + 75 Cu Effective single particle orbitals inversion?

Monopole migration of f 5/2 : 71,73,75 Cu NO low energy transition 5/2 3/2 < 70 kev f 5/2 p 3/2 71 Cu f 5/2 2 + f 5/2 p 3/2 73 Cu f 5/2 2 + 75 Cu f 5/2 2 + Effective single particle orbitals inversion?

Monopole migration of f 5/2 : 71,73,75 Cu NO low energy transition 5/2 3/2 < 70 kev f 5/2 p 3/2 71 Cu f 7/2-1 f 5/2 2 + f 5/2 p 3/2 73 Cu f 7/2-1 f 5/2 2 + 75 Cu f 5/2 2 + Effective single particle orbitals inversion?

[ f 5/2 2 + ]( ) Tentative level schemes Inversion of the f 5/2 - p 3/2 effective single particle states [ p 3/2 2 + ]( ) [( f 7/2 ) -1 ] ( ) ( ) ( ) ( ) ( ) ( ) [ f 5/2 ] [ p 3/2 ] ( ) ( ) ( ) E. Sahin et al. to be published

Interaction from A.F. Lisetskiy, B.A.Brown, M. Horoy, H. Grawe PRC 70 (2004) 44314, EPJA 25 s01 (2005) 95 (G-Matrix based on Bonn-C)

Shell Quenching? The N=50 shell closure Cortesy of O. Sorlin 78 Ni g 9/2 100 Sn The 7/2 + state found 171keV above the 5/2 + in 100 Sn O. Kavatsyuk, EPJA (2007), D. Seweryniak PRL 99 (2007) V pn (g 9/2 g 9/2 ) < V pn (g 9/2 g 7/2 )

Shell structure around N=50 82 Se+ 238 U @ E = 505 MeV see poster of. E. Sahin Asymmetries Ge 82 Ge ~ 0.6 mb Spin assignments from Asymmetry Ratios Levels up to 8 +82 Ge and 15/2-83 As

Shell structure around N=50 see poster of. E. Sahin Levels up to 8 +82 Ge and 15/2-83 As

N=50 shell gap dependence for medium spin states Low lying states are mainly based on proton excitations Information can be derived from high spin states No excitations across N=50 Excitations across N=50 Only proton excitations X. Ji and B.H. Wildenthal PRC 37 (1988) 1256 Y.H. Zhang et al., PRC 70 (2004)24301

Combined effective interaction based on JJ4B and on two-body matrix elements of SDI (A=0.2 MeV). JJ4B derived for the p and n pfg space (1f 5/2, 2p 3/2, 2p 1/2, 1g 9/2 ) as an extended version of the JJAPN interaction developped in order to reproduce the 78 Ni region. SDI adopted for neutron sdg subspace (2d 5/2, 3s 1/2, 1g 7/2 ) and cross-shell matrix elements between n in 2d 5/2, 3s 1/2, 1g 7/2 and pn in 1f 5/2, 2p 3/2, 2p 1/2, 1g 9/2. Up to 2p2h excitations largest dimension 24 million (Mscheme) for 83 As. ANTOINE code used for diagonalization. A.F. Lisetskiy

The N=50 Energy Gap at Z=28 E νd5/2 E νg9/2 ) = parameter Up to 2p-2h excitations see poster of. E. Sahin Interaction from A.F. Lisetskiy, B.A.Brown, M. Horoy, H. Grawe PRC 70 (2004) 44314, EPJA 25 s01 (2005) 95 (G-Matrix based on Bonn-C)

The N=50 Energy Gap at Z=28 E νd5/2 E νg9/2 ) = 4.7 MeV Up to 2p-2h excitations see poster of. E. Sahin Interaction from A.F. Lisetskiy, B.A.Brown, M. Horoy, H. Grawe PRC 70 (2004) 44314, EPJA 25 s01 (2005) 95 (G-Matrix based on Bonn-C)

E(νd 5/2 νg 9/2 ) = 4.7(2) MeV

E(νd 5/2 νg 9/2 ) = 4.7(2) MeV D1S GT3 SKP SLy4+GCM FRDM masses this work N=50 E(N=50) = 4.7 MeV E. Sahin et al. to be published

E(νd 5/2 νg 9/2 ) = 4.7(2) MeV D1S GT3 SKP SLy4+GCM FRDM masses this work N=50 E(N=50) = 4.7 MeV No weakening of the N=50 shell gap down to Z=28 E. Sahin et al. to be published

E(νd 5/2 νg 9/2 ) = 4.7(2) MeV D1S GT3 SKP SLy4+GCM FRDM masses this work N=50 E(N=50) = 4.7 MeV Good agreement with the Finate Range Droplet Model predictions E. Sahin et al. to be published

From mirror states in 51 Mn 51 Fe EXP: e pol (0) = 0.47 ± 0.01 e pol (1) = 0.32 ± 0.01 THE: e pol = 0.5 + 0.32 z

KB3G No N=34 subshell closure PGPF1 N=34 subshell closure No subshell closure at N=34 N=28 N=32

Lifetime measurements Recoil Distance Doppler Shift method (RDDS) + CLARA-PRISMA Placed at the θ grazing for BLF CLARA E γ E γ PRISMA E γ β 8.0% E γ E γ : Doppler corrected Good Mass Resolution nat Mg Degrader β 10.0% d Plunger setup (Koln) Target 208 Pb Beam 48 Ca E beam =310MeV Multi-nucleon transfer reactions

Lifetimes of the 2 + and 11/2 - states in the N=30 50 Ca - 51 Sc Effective charges in the fp shell J. Valiente Dobon et al. To be published R = I after /(I before + I after ) B(E2 )=7.5(2) e 2 fm 4 2 + 0 + 50 Ca B(E2 )=18(4) e 2 fm 4 11/2-7/2-51 Sc B(E2 )=19.4(2.1) e 2 fm 4 2 + 0 +48 Ca T. Hartmann et al., PRC65 034301 (2002)

Isospin dependance of the core polarization? Large scale shell model calculation using ANTOINE Full fp shell with a 40 Ca core KB3G and GXPF1A interactions 86% ν(f 7/28 p 3/22 ) 50 Ca 74% ν(f 7/28 p 3/22 ) x f 7/2 51 Sc No isovector component IS effective charges : e =1.5e e ν =0.5e IS+IV effective charges : e =1.15e e ν =0.8e e pol (1) = 0 e pol (1) = 0.32

Effective charges in the fp shell Full fp shell with a 40 Ca core e IV = 0.3 e IV = 0 ISOSCALAR + ISOVECTOR: (e eff ) p E2=1.15e (e eff ) n E2=0.8e The obtained effective charges (IS) are different to the ones obtained nearby N Z (IS+IV) Possible isospin dependence of the effective charges.

Effective charges in the fp shell Full fp shell with a 40 Ca core e IV = 0.3 e IV = 0 ISOSCALAR + ISOVECTOR: (e eff ) p E2=1.15e (e eff ) n E2=0.8e The obtained effective charges (IS) are different to the ones obtained nearby N Z (IS+IV) Possible isospin dependence of the effective charges. Isospin and/or orbital dependance of the effective charges?

The AGATA demonstrator array Objective of the AGATA R&D phase 2003-2008 Main issue is Doppler correction capability coupling to beam and recoil tracking devices PRISMA 5 asymmetric triple-clusters 36-fold segmented crystals 555 digital-channels Eff. 3 7 % @ M g = 1 Eff. 2 4 % @ M g = 30 On-line PSA and γ-ray tracking In beam Commissioning First Test Site: Laboratori Nazionali di Legnaro Courtesy E. Farnea and A. Gadea

The AGATA-PRISMA setup The AGATA demonstrator (LNL 2009-2010) Triple cluster detector

The AGATA demostrator at LNL The first subset of AGATA (the Demonstrator Array) will soon start operation at the Laboratori Nazionali di Legnaro. The installation is in progress. AGATA Triple Cluster Telescopic beam line

Data analisys is going on

18-20 Mai AGATA demostrator workshop at LNL

Ex. Lifetime measurements by multinucleon transfer and Differential Plunger method CLARA AGATA 102 o ring (1/2 efficiency) not usable Full demonstrator (6% efficiency) 2 + 0 + 4 + 2 + After degrader Before degrader At v/c ~ 10% lifetimes in the range 1 to 10ps can be measured with target-degrader distances ranging from 30 to 400 m 60 Fe simulation based on existing experimental data

Deep Inelastic reactions with RIBs

Deep Inelastic reactions with RIBs 92 Kr (10 9-10 pps at SPIRAL2 + 238 U at 600 MeV (N. Pollarolo Grazing code) ( 93 Sr)= 1.3 mb ( 94 Sr)= 1.0 mb ( 95 Sr)= 0.1 mb ( 93 Rb)= 27 mb ( 94 Rb)= 3.4 mb ( 95 Rb)= 0.4 mb ( 93 Kr)= 61.0 mb ( 94 Kr)= 6.2 mb ( 91 Br)= 12 mb ( 92 Br)= 19 mb ( 93 Br)= 0.3 mb ( 88 Se)= 0.4 mb ( 89 Se)= 0.3 mb ( 90 Se)= 0.3 mb

Deep Inelastic reactions with RIBs 78 Zn + 238 U at 550 MeV (N. Pollarolo Grazing code) ( 81 Ga)= 2.5 mb ( 80 Ga)= 6 mb ( 79 Ga)= 33 mb ( 79 Zn)= 48 mb ( 80 Zn)= 14 mb ( 81 Zn)= 0.4 mb ( 82 Zn)= 0.4 mb ( 77 Cu)= 13 mb ( 78 Cu)= 3.5 mb ( 79 Cu)= 0.7 mb ( 75 Ni)= 0.6 mb ( 76 Ni)= 0.6 mb ( 77 Ni)= 0.2 mb ( 78 Ni)= 0.05 mb

Conclusions Shell structure studies near closed shells via multinucleon transfer reactions Excited states of the neutron rich isotopes at Z=28 N=32, 34, 50 and the effective single particle energies Stability of the N=50 shell gap at Z=28: No weakening observed Isospin and/or orbital dependance of the effective charges in the fp shell Future perspectives: the Agata demonstrator

Thank You

The CLARA-PRISMA collaboration France IReS Strasbourg GANIL Caen U.K. University of Manchester Daresbury Laboratory University of Surrey University of Paisley Germany HMI Berlin GSI Darmstadt Poland IFJ-PAN Kraków Italy INFN LNL-Legnaro INFN and University Padova INFN and University Milano INFN and University Genova INFN and University Torino INFN and University Napoli INFN and University Firenze University of Camerino Turkey University of Istanbul University of Nigde Spain University of Salamanca Romania Horia Hulubei NIPNE Bucharest