Jose Javier Valiente Dobón (INFN-LNL, Italy)

On behalf of the CLARA-PRISMA collaboration

Spectroscopic studies of moderately neutron-rich nuclei with the

CLARA-PRISMA setup

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 reactionsTool to populate neutron-rich nuclei

Target

Beam

Grazing Target-like

Grazing Beam-like

LAB.

Substantial kinetic energy damping and mass exchange while retaining partial memory and

entrance-channel masses and charges

82Se + 238U, E=505 MeV

Fission 238U

G.de Angelis, G.Duchêne

Population of states

•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.

X. Liang et al., Eur. Phys. J. A 10, 41 (2001)

Maximum I ≈ 30ħ

37Cl+160Gd 234MeV EUROBALL

Maximum I ≈ 8ħ

160Dy59Mn

70Zn+238U 460MeV CLARA+PRISMAJ.J. Valiente-Dobon et al., PRC 78 024302 (2008)

Thick target

Thin target

PRISMA

The CLARA-PRISMA setup

• Gamma spectrometer

CLARA

• Magnetic spectrometer

PRISMA

CLARA

Laboratori Nazionali di Legnaro (INFN), Italy

The CLARA spectrometer

• 23 Euroball Clover detectors with anti-Compton

• Efficiency ~ 3 % (Eγ= 1.3 MeV)

• FWHM = 0.9% (for β=10%)

spectrumCLARA spectrometer

A. Gadea et al., Eur. Phys. J. A20 (2004) 193.

The PRISMA 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

I C

MWPPAC

I C

MWPPAC

Large-acceptance magnetic spectrometer

S. Beghini et al., NIM A551, 364 (2005)

G. Montagnoli et al., NIM A547, 455 (2005)

Ca

Ti

Cr

Fe

Ni

ZnGa

Mn

Sc

V

Co

Cu

28 32 34 40 5030

Nuclear structure studies using DIC

Shell evolution Cu Shell evolution Cu

New region of deformation New region of deformation Lifetime measurements Lifetime measurements

CLARA-PRISMA setup

82Se@505MeV onto 238U

The Cu isotopes, towards N=50

Investigate the monopole migration and the

evolution of the single-particle levels along

Z=28 line towards N=50.

g9/2

71Cu42 73Cu4475Cu46

f5/2-p3/2 inversion?

1f7/2

2p3/2

1f5/2

2p1/2

1g9/2

Z=28

N=40

p3/2

f5/2

p1/2

3/2-

5/2-

1/2-

7/2-

67Cu38

7/2-(f7/2)-1

69Cu40

B. Zeidman et al., PRC 18, 2122(1978);R. Grzywacz et al., PRL 81, 766 (1998);S. Franchoo et al., PRL 81, 3100(1998).

p3/22+ (A-1Ni)

T. Otsuka et al. PRL 95, 232502 (2005)

[πf5/2]

[πp3/2]

[π f7/2-1]

[πp3/2θ2+]

[πf5/2θ2+] ( )

( )

( )

( )

( ) ( )

( )

( )( )( )

( )

82Se@505MeV onto 238U

The Cu isotopes, towards N=50

E. S

ahin

and

G. D

e A

ngel

is (

to b

e pu

blis

hed)

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 ...

Coming experiments

•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)

French-Italian collaboration

Neutron-rich Fe nuclei64Ni@400MeV onto 238U

S. Lunardi et al., PRC 76, 034303 (2007)

Shell model calculations: Core 48Cavalence space: full fp for protons p3/2,f5/2, p1/2, g9/2 for neutrons

N=40

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.

64

60

2827

26

25

24

363534

62

Ni

Co

Fe

Mn

Cr

37 38

66- 2p +4n

4039

70

66

3029282726

40393837

68

ZnCuNi

CoFe

- 4p

41 42

Beyond N=40 in Fe isotopes Comparison 64Ni and 70Zn onto 238U

64Ni+238U 70Zn+238U

N=40 N=42

S.M. Lenzi et al., LNL Annual Report 2007 and to be published

70Zn@460MeV onto 238U

N=40 and N=42 Fe isotopes

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)).

229

225 // gf 4

29225 // gf

Lifetime measurements

Beam 48Ca

208Pb

natMg

PRISMA

β≈10.0%

β’≈8.0%

Ebeam=310MeVdDegrader Target

Eγ’ Eγ

CLARA

Recoil Distance Doppler Shift method (RDDS) + CLARA-PRISMA

Eγ Eγ’

Eγ’: Doppler corrected

Good Mass Resolution

Multi-nucleon transfer reactions

Placed at the θgrazing for BLF

Plunger setup (Koln)

Lifetime of the 2+ in 50Ca

Iu

Is

Gamma spectra, lifetime

τ = 96 ± 3 ps

J.J. Valiente-Dobón et al., LNL Annual Report 2007 and to be published

48Ca

Effective charges in the fp shell

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.

GQR (isoscalar)

GQR (isovector)

f7/2

p3/2

p1/2

f5/2fp

40CaCORE

Full fp shell with a 40Ca core.

Nuclear Structure, Bohr and Mottelson.

Effective charges in the fp shellFull fp shell with a 40Ca core.

The obtained effective charges (IS) are different to the ones obtained nearby

N≈Z (IS+IV) → Possible isospin dependence of the effective charges.

ISOSCALAR + ISOVECTOR:

(eeff)pE2=1.15e

(eeff)nE2=0.8e

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)

Analys

is on

going

Courtesy A. Goergen

Simulations for AGATA + PRISMACLARA vs. AGATA

CLARA

AGATA

Lifetime τ=100ps Degrader natMg 4 mg/cm2

Degrader

Target

Bea

mPRISMA

Lifetime measurements

•AGATA 0o – 45°

•εAD ≈ 6%

•Cologne Plunger

•γ-γ coincidences

AGATA: Talk by E. Farnea

Plunger setup (Koln) + AD-PRISMA

Courtesy D. Mengoni

• 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.

Summary

•FranceIPHC (IReS) Strasbourg GANIL Caen

•U.K.University of Manchester Daresbury Laboratory University of Surrey University of Paisley

•GermanyHMI BerlinGSI Darmstadt

•PolandIFJ-PAN Kraków

•CroatiaRuder Boskovic Institute

•ItalyINFN 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

•SpainUniversity of Salamanca

•Romania Horia Hulubei NIPNE

The CLARA-PRISMA collaboration

GANIL 75Cu isomers

(1/2-)

(5/2-)

(3/2-)

http://www.ganil.fr/lise/chart/chart/chart32/75cu.gif

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 μsT1/2(M1+E2)(1/2-) ≤ 700 nns

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

82Se@505MeV onto 238U

The N=50 isotones, towards 78Ni

Three protons away from 78Ni

E. Sahin and G. De Angelis (to be published)

Level schemes

The N=50 isotones

The level schemes have been determined based on: •angular distribution as well as systematics•γ-γ coincidences, thick target experiment (GASP, GAMMASPHERE)

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 1g

9/2

1g7/2

2d5/2

3s1/2

N=50

Z=31

Spectroscopy studies around 136Xe136Xe@930MeV onto 238U

The heaviest system performed with the CLARA-PRISMA setup.

Anal

ysis

Ong

oing

Courtesy F. Recchia and A. Howard

Neutron-rich Mn nuclei70Zn@460MeV onto 238U

fpfp fpgfpg

N=38

N=32 N=34

N=36

Full fp-shell calculations with KB3G and GXPF1A effective Interactions.

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)

Higher spins needed

5 asymmetric triple-clusters36-fold segmented crystals555 digital-channels

Eff. 3 – 7 % @ Mg = 1

Eff. 2 – 4 % @ Mg = 30

On-line PSA and γ-ray trackingIn beam CommissioningFirst Test Site:Laboratori Nazionali di Legnaro

Main issue is Doppler correction capability coupling to beam and recoil

tracking devices

PRISMA

The AGATA demonstrator arrayObjective of the AGATA R&D phase 2003-2008

Courtesy E. Farnea and A. Gadea

The first subset of AGATA (the Demonstrator Array) will soon start operation

at the Laboratori Nazionali di Legnaro. The installation is in progress.

The AGATA demostrator at LNL

Telescopic beam line

AGATA Triple Cluster