measurement of the gmr and the gqr in unstable nuclei using the maya active target

Measurement of the GMR and the GQR in unstable nuclei using the MAYA active target

C. Monrozeau (Ph. D), E. Khan, Y. Blumenfeld

Motivations: exotic modes ?

•Few measurements on GR in unstable nuclei IVGDR•GQR and GMR soft modes are predicted !

Terasaki et al, Phys. Rev. C71 (2006) 34310

Motivations: equation of state

• GMR breathing mode density variation around 0 (few %)

Nuclear equation of state

EISGMR along an isotopic chain (unstable nuclei)

D.T.Khoa et al. Nucl. Phys. A602 (1996) 98

evolution of incompressibility with asymmetry

N Z

A

Neutron stars

and neutron excess

determination of K

(symmetry energy term)

: density

D.H. Younblood et al, Phys. Rev. Lett 76, 1429 (1996)

58Ni ’=240 MeV

Inelastic scattering : (d,d’) ’@ E 25 A.MeV

GQR

GMR

GR in 58Ni : analysis

mixing 0+ and 2+

Experimental probes for isoscalar giant resonances

reverse kinematics

unstablenuclei

good detection efficiency

thick target

low intensity beam

large solid angular coverage

low energy threshold

thin target

ISGMR in unstable nuclei

Time and Charge Projection Chamber

Active target =

target + detector

deuterium gas : 1,6 mg/cm2

(6,3 mg/cm2 CD2 )

deuteron kinematics 56Ni(d,d’) @ 50 MeV/A

cathod

Frisch grid

beam

amplification wires

pads (cathod)

detection zone

active zone

MAYA

56Ni @ 50 MeV/A 5.104 pps

• July 2005, GANIL• SISSI beam

Experimental setup

Au foil

Drift

chamber

Ionisation

chamber

Moving flap

Si wall

CsI wall

Diamond

56Ni (5.104 pps)

50 A.MeV

+ contaminants

Results

d breakup

56Ni excitation energy spectrum

recoiling d kinematics

Analysis with gaussian fit

E* (MeV)

Cou

nts/

MeV

Reaction : DWBA with double folding using HF and RPA 56Ni gs and transition densities

Multipole Decomposition Analysis

• Isoscalar GMR and GQR measured in the 56Ni unstable nucleus• Use of MAYA active target with d gas• 16h of 104 pps beam• Results compatible with the 58Ni (stable) data• The method works !

•Improvements : identification & d breakup, reaction model

• Next : neutron rich Ni isotopes, 132Sn ACTAR active target

Summary & outlooks

first (p,p’) experiment

in inverse kinematics !

G. Kraus et al. Phys Rev. Lett. 73 (1994) 1773

Collaboration

C.Monrozeau1, E.Khan1, Y. Blumenfeld1, W. Mittig5, D.Beaumel1, M.Caamaño2,D.Cortina-Gil2, C-E.Demonchy3, N.Frascaria1, U.Garg4, M.Gelin5, A.Gillibert6, D.Gupta1, N.

Keeley6, F.Maréchal7, A.Obertelli6, P.Roussel-Chomaz5, J-A.Scarpaci1

1 Institut de Physique Nucléaire (IN2P3/CNRS), 91406 Orsay Cedex, France2 Univ. Santiago de Compostela, E-15706 Santiago de Compostela, Spain3 Univ. of Liverpool, Dep. of Physics, Olivier Lodge Lab., Liverpool L69 7ZE, U.K.4 Univ. of Notre-Dame, Dep. of Physics, Notre Dame, IN 46556 USA5 GANIL (DSM/CEA, IN2P3/CNRS), BP 5027, 14076 Caen Cedex 5, France6 CEA/DSM/DAPNIA/SPhN, Saclay, 91191 Gif-sur-Yvette Cedex, France7 Institut de Recherches Subatomiques (IN2P3/CNRS), BP 28, 67037 Strasbourg, France

Motivations: K∞

Skyrme & GognyK = 235 12 MeV

Relativistic MF K = 250 – 270 MeV

EISGMR (self-consistent CHF)

Energy Functional E[ρ]

K∞ in nuclear matter (analytic)(N=Z and no Coulomb interaction)

E(,) = E(,0) + asym() 2 +...

208Pb neutron excess nucleus G. Colò et al. (Phys. Rev. C70 (2004) 024307)

measure EISGMR along an isotopic chain (unstable nuclei)

probe the effect of the symmetry term

N.B. : macroscopic method needs data on the nuclear chart

Microscopic method

56Ni(d,d’) with the active target MAYA

56Ni unstable (106 pps @ GANIL)

A NEW EXPERIMENTAL METHOD

25cm

20cm

28cm

2H gas2H gasHe gas