Fields of interest, tools, perpectives Collective excitations in fermionic systems: giant resonances in exotic nuclei, shell structure evolution, (fermionic

Embed Size (px)

DESCRIPTION

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

Citation preview

Fields of interest, tools, perpectives Collective excitations in fermionic systems: giant resonances in exotic nuclei, shell structure evolution, (fermionic atoms) Pairing: phase transition, Giant Pairing Vibrations Application to astrophysics: r process, neutron star crust, ultra-high energy cosmic rays Mean field + QRPA: Skyrme, coordinate representation Direct reactions : DSSSD, active targets, proton scattering Bubbles in exotic nuclei, detection of the GPV, relativistic approaches, GMR in neutron-rich nuclei, First measurement of the GMR and the GQR in an unstable nuclei : 56 Ni C. Monrozeau, E. Khan, Y. Blumenfeld et al., Phys. Rev. Lett. 100 (2008) 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 E ISGMR along an isotopic chain (unstable nuclei) D.T.Khoa et al. Nucl. Phys. A602 (1996) 98 evolution of incompressibility with asymmetry Neutron stars and neutron excess determination of K (symmetry energy term) : density D.H. Younblood et al, Phys. Rev. Lett 76, 1429 (1996) 58 Ni =240 MeV Inelastic scattering : (d,d) E 25 A.MeV GQR GMR GR in 58 Ni : analysis mixing 0 + and 2 + Experimental probes for isoscalar giant resonances reverse kinematics unstable nuclei 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/cm 2 (6,3 mg/cm 2 CD2 ) deuteron kinematics MeV/A cathod Frisch grid beam amplification wires pads (cathod) detection zone active zone MAYA MeV/A pps July 2005, GANIL SISSI beam Experimental setup Au foil Drift chamber Ionisation chamber Moving flap Si wall CsI wall Diamond 56 Ni ( pps) 50 A.MeV + contaminants GMR+GQR Results 56 Ni excitation energy spectrum recoiling d kinematics Analysis with gaussian fit E* (MeV) Counts/MeV Reaction : DWBA with double folding using HF and RPA 56 Ni gs and transition densities Angular distributions Multipole Decomposition Analysis Isoscalar GMR and GQR measured in the 56 Ni unstable nucleus Use of MAYA active target with d gas 16h of 10 4 pps beam Results compatible with the 58 Ni (stable) data The method works ! Improvements : identification & d breakup, reaction model Next : neutron rich Ni isotopes, 132 Sn ACTAR active target Summary & outlooks first (p,p) experiment in inverse kinematics ! G. Kraus et al. Phys Rev. Lett. 73 (1994) 1773 Collaboration C.Monrozeau 1, E.Khan 1, Y. Blumenfeld 1, C-E.Demonchy 3,W. Mittig 5, P.Roussel-Chomaz 5 D.Beaumel 1, M.Caamao 2,D.Cortina-Gil 2,J.P. Ebran 1 N.Frascaria 1, U.Garg 4, M.Gelin 5, A.Gillibert 6, D.Gupta 1, N. Keeley 6, F.Marchal 7, A.Obertelli 6, J-A.Scarpaci 1 1 Institut de Physique Nuclaire (IN2P3/CNRS), Orsay Cedex, France 2 Univ. Santiago de Compostela, E Santiago de Compostela, Spain 3 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 USA 5 GANIL (DSM/CEA, IN2P3/CNRS), BP 5027, Caen Cedex 5, France 6 CEA/DSM/DAPNIA/SPhN, Saclay, Gif-sur-Yvette Cedex, France 7 Institut de Recherches Subatomiques (IN2P3/CNRS), BP 28, Strasbourg, France Motivations: K Skyrme & Gogny K = 235 12 MeV Relativistic MF K = 250 270 MeV E ISGMR (self-consistent CHF) Energy Functional E[] K in nuclear matter (analytic) (N=Z and no Coulomb interaction) E( , ) = E( ,0) + a sym ( ) Pb neutron excess nucleus G. Col et al. (Phys. Rev. C70 (2004) ) measure E ISGMR 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 56 Ni(d,d) with the active target MAYA 56 Ni unstable (10 6 GANIL) A NEW EXPERIMENTAL METHOD 25cm 20cm 28cm 2 H gas He gas Primary: 58 Ni, 75 MeV/A, 0.7 kW (July 05) target: C (78 mg/cm 2 ) + SISSI Secondary: 56 Ni, 50 MeV/A, pps 56 Ni excitation energy spectrum Maya beam 56 Ni(d,d) First measurement of isoscalar giant resonances in an unstable nucleus