The study of neutron-rich nuclei production in the region of the closed shell N=126 in the multi-nucleon transfer reaction 136Xe+208Pb

[摘要] The unexplored area of heavy neutron rich nuclei is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleogenesis. For the production of heavy neutron rich nuclei located along the neutron closed shell N=126 (probably the last "waiting point" in the r-process of nucleosynthesis) the low-energy multi-nucleon transfer reaction136Xe+208Pb at Elab=870MeV was explored. Due to the stabilizing effect of the closed neutron shells in both nuclei, N=82 and N=126, and the rather favorable proton transfer from lead to xenon, the light fragments formed in this process are well bound and the Q-value of the reaction is nearly zero. Measurements were performed with the PRISMA spectrometer in coincidence with an additional time-of-flight (ToF) arm on the +20 beam line of the PIAVE-ALPI accelerator in Legnaro, Italy. The PRISMA spectrometer allows identification of the A, Z and velocity of the projectile-like fragments (PLF), while the second arm gives access to the target-like fragments (TLF). Details on the experimental setup and preliminary results are reported.

[发布机构] Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Russia^1;Instituto Nazionali di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro, Italy^2;Dipartamento di Scienze Fisiche, INFN (INFN-Na), Napoli, Italy^3;Dipartimento di Fisica, Universit di Padova, Instituto Nazionale di Fisica Nucleare, Padova, Italy^4;GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, Caen Cedex 5; F-14076, France^5;Ruer Bokovi Institute, University of Zagreb, Croatia^6;GSI Helmholtzzentrum Fr Schwerionenforschung, Darmstad, Germany^7;Cyclotron Institute, Texas A and M University, College Station; TX; 77843-3366, United States^8;Accelerator Laboratory of University of Jyväskylä (JYFL), Jyväskylä, Finland; (10) Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering (IFIN-HH), Bucharest- Magurele, Romania; (11) Facultatea de Fizica, Universitatea Din Bucuresti, Bucharest, Romania^9

[效力级别] 天文学 [学科分类] 天文学(综合)

[关键词] Closed shells;Neutron shells;Neutron-rich nuclei;Nuclear astro-physics;Stabilizing effects;Target-like fragments;Time of flight;Transfer reaction