Speaker
Description
An efficient way to explore the nuclear structure is the effective use of transfer reactions. Two different physical aspects are being investigated with the use of transfer reactions on 56Ni, which is a N=Z unstable doubly magic nucleus.
(i)To probe the gap of N=28, we study the spectroscopy of the N=29 and N=27 isotones by the (d,t), (p,d) and (d,p) one nucleon transfer reactions on 56Ni (N=28 isotone) and extract information on the single-particle configuration around the Fermi surface.
(ii)To study the np pairing in the self-conjugate nucleus 56Ni, we have measured the two-nucleon transfer reactions 56Ni(p, 3He)54Co [1] and 56Ni(d,α)54Co. In the (p,3He) reaction, the ratio of the population of the T=0 and T=1 states indicates a predominance of T=1 pairing [1]. The selectivity of the (d,α) reaction enables the investigation of the T=0 channel with better precision.
During spring 2014 the experiment aiming to these studies took place at GANIL-Caen, France. The radioactive beam of 56Ni at 30MeV/u was produced by fragmentation of 58Ni and purification. Measurements were performed in inverse kinematics on CH2 and CD2 targets. The experiment included a 4π coverage for the study of the charged projectiles with the MUST2 and TIARA detectors, while 4 clovers of EXOGAM were also used for γ-particle coincidences in order to identify the populated state of the residue. The analysis of the 56Ni(d,t)55Ni and 56Ni(d,p)57Ni reactions yield the differential cross-section for transfer reaction to the ground state and the excited states of 55Ni and 57Ni giving information about the shell closure and depicting the Fermi surface of 56Ni. I will present the angular distribution and compare with the results for the (p,dγ), (d,tγ) and (d,pγ) reactions, as well as with DWBA calculations. The results for the transfer reaction 56Ni(d,α)54Co will be also presented, completing the information about the strength of the isoscalar np pairing in the closure of the fp shell.
[1]Benjamin Le Crom, Thesis: “Etude de l’appariement neutron-proton dans les noyaux instables N=Z par réactions de transfert.” Physique Nucléaire Expérimentale [nucl-ex]. Université Paris-Saclay, 2016.
