Spectroscopic studies of moderately neutron-rich nuclei with the CLARA-PRISMA setup Jose Javier Valiente Dobón (INFN-LNL, Italy) On behalf of the CLARA-PRISMA collaboration

Overview Grazing reactions as a tool to populate neutron-rich nuclei The CLARA-PRISMA setup Neutron-rich Copper nuclei Neutron-rich Fe nuclei Lifetime measurements of n-rich nuclei: RDDS + CLARA-PRISMA Future: AGATA for lifetimes measurements at LNL Summary

Grazing reactions LAB. Tool to populate neutron-rich nuclei Fission 238U Grazing Target-like LAB. Grazing Beam-like Target Beam Substantial kinetic energy damping and mass exchange while retaining partial memory and entrance-channel masses and charges 82Se + 238U, E=505 MeV G.de Angelis, G.Duchêne

Population of states 59Mn 160Dy Population of yrast or near-yrast states. Part of the input of the angular momentum of the reaction goes into intrinsic angular momentum. It is less efficient than fusion-evaporation. The case that converts more transational energy into rotational energy, in a semiclassical picture, is where the projectile and target stick together, and each nucleus rotates around its own centre at the same speed. 59Mn 160Dy Maximum I ≈ 30ħ Thick target Maximum I ≈ 8ħ Thin target 37Cl+160Gd 234MeV EUROBALL 70Zn+238U 460MeV CLARA+PRISMA X. Liang et al., Eur. Phys. J. A 10, 41 (2001) J.J. Valiente-Dobon et al., PRC 78 024302 (2008)

The CLARA-PRISMA setup Laboratori Nazionali di Legnaro (INFN), Italy PRISMA Gamma spectrometer CLARA Magnetic spectrometer PRISMA CLARA

The CLARA spectrometer 23 Euroball Clover detectors with anti-Compton Efficiency ~ 3 % (Eγ= 1.3 MeV) FWHM = 0.9% (for β=10%)  spectrum CLARA spectrometer A. Gadea et al., Eur. Phys. J. A20 (2004) 193.

The PRISMA spectrometer Large-acceptance magnetic spectrometer Formed by 1 Q, 1 D and detectors (MCP,MWPPAC, IC) to track the ions. ΔΩ = 80 msr, ΔZ/Z  1/60, ΔA/A  1/190, Bρ = 1.2 T.m Identifies nuclei produced in the reaction (A,Z,β) event by event S. Beghini et al., NIM A551, 364 (2005) G. Montagnoli et al., NIM A547, 455 (2005)

Nuclear structure studies using DIC CLARA-PRISMA setup Ca Ti Cr Fe Ni Zn Ga Mn Sc V Co Cu 28 32 34 40 50 30 Shell evolution Cu New region of deformation Lifetime measurements

The Cu isotopes, towards N=50 82Se@505MeV onto 238U Investigate the monopole migration and the evolution of the single-particle levels along Z=28 line towards N=50. 1f7/2 2p3/2 1f5/2 2p1/2 1g9/2   Z=28 N=40 (f7/2)-1 7/2- 7/2- p3/22+ (A-1Ni) p1/2 T. Otsuka et al. PRL 95, 232502 (2005) 1/2- f5/2 5/2- f5/2-p3/2 inversion? 3/2- p3/2 67Cu38 69Cu40 71Cu42 73Cu44 75Cu46 g9/2 B. Zeidman et al., PRC 18, 2122(1978);R. Grzywacz et al., PRL 81, 766 (1998);S. Franchoo et al., PRL 81, 3100(1998).

E. Sahin and G. De Angelis (to be published) The Cu isotopes, towards N=50 82Se@505MeV onto 238U From β-decay, Coulex, deep-inelastic we can disentangle the nature of the excitations in neutron-rich Cu isotopes and therefore the shell evolution along Z=28. More information needed ... [πf5/2] [πp3/2] [π f7/2-1] [πp3/2θ2+] [πf5/2θ2+] ( ) ( ) ( ) E. Sahin and G. De Angelis (to be published)

Coming experiments French-Italian collaboration Weakening of the Z=28 gap by the tensor force in neutron-rich copper isotopes. Fragmentation of a 76Ge beam at GANIL to reach the π(f7/2)-1states by means of AZn(d,3He) A-1Cu proton pickup in inverse kinematics Spokepersons: S. Franchoo (Orsay), J.J. Valiente-Dobon (LNL-INFN) 75-77Cu: probing the Z=28 shell gap around doubly magic 78Ni. Deep inelastic reaction using inverse kinematics VAMOS-EXOGAM Spokepersons: E. Sahin (LNL-INFN), G. De France (GANIL)

Neutron-rich Fe nuclei 64Ni@400MeV onto 238U Shell model calculations: Core 48Ca valence space: full fp for protons p3/2,f5/2, p1/2, g9/2 for neutrons Fe isotopes evolve towards more collective structures when approaching N=40 → This could be understood in terms of a decrease in the energy gap between the fp shell and the g9/2 when the f7/2 proton shell is not completely filled and more neutrons are excited to the upper shell. N=40 S. Lunardi et al., PRC 76, 034303 (2007)

Beyond N=40 in Fe isotopes Comparison 64Ni and 70Zn onto 238U 64Ni+238U 70Zn+238U 64 60 28 27 26 25 24 36 35 34 62 Ni Co Fe Mn Cr 37 38 66 - 2p +4n 40 39 70 66 30 29 28 27 26 40 39 38 37 68 Zn Cu Ni Co Fe - 4p 41 42

N=40 and N=42 Fe isotopes N=40 N=42 70Zn@460MeV onto 238U The experimental level schemes seem to be more quadrupole-collective than the calculated ones. This quadrupole collectivity can be produced by including the d5/2 shell in the model space (A. Zuker et al., PRC52 R1741 (1995)). S.M. Lenzi et al., LNL Annual Report 2007 and to be published

Lifetime measurements Recoil Distance Doppler Shift method (RDDS) + CLARA-PRISMA Eγ Eγ’ CLARA Placed at the θgrazing for BLF Eγ’ Eγ Eγ’: Doppler corrected PRISMA β’≈8.0% natMg Beam 48Ca Good Mass Resolution β≈10.0% Ebeam=310MeV d Degrader Target 208Pb Plunger setup (Koln) Multi-nucleon transfer reactions

Lifetime of the 2+ in 50Ca Is Iu 48Ca τ = 96 ± 3 ps Gamma spectra, lifetime τ = 96 ± 3 ps Is Iu 48Ca J.J. Valiente-Dobón et al., LNL Annual Report 2007 and to be published

Effective charges in the fp shell Full fp shell with a 40Ca core. GQR (isoscalar) GQR (isovector) f7/2 p3/2 p1/2 f5/2 fp 40Ca CORE Effective charges take into account the core polarization, that can be understood in terms of the coupling between the particles and the collective oscillations associated with deformations of the core. Nuclear Structure, Bohr and Mottelson.

Effective charges in the fp shell Full fp shell with a 40Ca core. ISOSCALAR + ISOVECTOR: (eeff)pE2=1.15e (eeff)nE2=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.

Collectivity of Fe isotopes (N=40) Two weeks ago it was performed an experiment for lifetime measurments at GANIL, using inverse kinematics of a 238U beam onto a 64Ni target with a natMg degrader (VAMOS+EXOGAM) Study of 62Fe 64Fe, collectivity towards the N=40 Spokepersons: W. Korten (Saclay), A. Gadea (LNL-INFN, CSIC-Valencia) Analysis ongoing Courtesy A. Goergen

Simulations for AGATA + PRISMA CLARA vs. AGATA AGATA: Talk by E. Farnea Degrader Target Beam PRISMA Lifetime measurements AGATA 0o – 45° εAD ≈ 6% Cologne Plunger γ-γ coincidences AGATA CLARA Lifetime τ=100ps Degrader natMg 4 mg/cm2 Plunger setup (Koln) + AD-PRISMA Courtesy D. Mengoni

Summary Grazing reactions are a good tool to populate n-rich nuclei at medium spins Copper siotopes to prove the shell evolution of the Z=28 towards 78Ni. Efforts at LNL and GANIL. Population of medium mass nuclei A≈60 Fe, showing that these structures evolve towards higher collectivity (LNL) → Lifetimes at GANIL Novel method to measure lifetimes that combines the traditional RDDS method with the CLARA-PRISMA spectrometers. Lifetimes of the N=30 isotones 50Ca and 51Sc. Determination of the effective charges in the fp shell. Future at LNL: The AGATA demostrator. Common interests and collaboration among the french-italian community in the study of neutron-rich nuclei.

The CLARA-PRISMA collaboration France IPHC (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 Croatia Ruder Boskovic Institute Italy INFN LNL-Legnaro University of Padova INFN University of Milano INFN University of Genova INFN University of Torino INFN University of Napoli INFN University of Firenze University of Camerino Spain University of Salamanca Romania Horia Hulubei NIPNE

GANIL 75Cu isomers Ganil-Lise Isomeric Chart Data Tentative spin assignments for the two isomers in 75Cu based on lifetimes and extrapolating the collectivity from 73Cu Estimates: T1/2(3/2-)~30 μs T1/2(M1+E2)(1/2-) ≤ 700 ns (1/2-) (3/2-) (5/2-) http://www.ganil.fr/lise/chart/chart/chart32/75cu.gif

Experimental Technique Thick-target measurements: No channel selection Recoiling binary fragments stop inside target Visible γ rays from states with cumulative half-life 1 ps High-resolving power multi-detector Ge array Thin-target measurements: Channel selection using large solid-angle magnetic spectrometer (PRISMA@INFN Legnaro; VAMOS@GANIL) In-beam γ-rays measured with multi-detector Ge array in coincidence with detected binary fragments High efficiency required for γ-γ coincidences

The N=50 isotones, towards 78Ni 82Se@505MeV onto 238U Three protons away from 78Ni E. Sahin and G. De Angelis (to be published)

The N=50 isotones Z=31 2d5/2 1g7/2 1g9/2 Level schemes N=50 The level schemes have been determined based on: angular distribution as well as systematics γ-γ coincidences, thick target experiment (GASP, GAMMASPHERE) 1g9/2 1g7/2 2d5/2 3s1/2 N=50 Shell Model calcuations: 2p-2h excitations across the N=50 shell to 2d5/2-1g7/2-3s1/2 (Lisetsky) for 4.7 MeV of the shell gap value→No reduction of the shell gap

Spectroscopy studies around 136Xe 136Xe@930MeV onto 238U The heaviest system performed with the CLARA-PRISMA setup. Analysis Ongoing Courtesy F. Recchia and A. Howard

Neutron-rich Mn nuclei 70Zn@460MeV onto 238U fp fpg fp fpg Full fp-shell calculations with KB3G and GXPF1A effective Interactions. N=32 N=34 N=36 N=38 Higher spins needed fp+g9/2 shell space are considered in the calculations done with the fpg effective interaction. The fpg calculations improve for N≥36. J.J. Valiente-Dobon et al., PRC 78 024302 (2008)

Courtesy E. Farnea and A. Gadea 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 % @ Mg = 1 Eff. 2 – 4 % @ Mg = 30 On-line PSA and γ-ray tracking In beam Commissioning First Test Site: Laboratori Nazionali di Legnaro Powerful array in its own right Still to decide where to site Still to decide the key test experiments Courtesy E. Farnea and A. Gadea

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