6He Spatial Structure and Spin-Orbit Potential Studied via Proton Elastic Scattering at 200 A MeV

by Sergey Chebotaryov (Ph.D Candidate)

Thursday May 31, 2018, 1:30 PM → 2:30 PM Asia/Seoul

201-4호 (제1과학관)

발표제목: Study of matter density distribution of unstable neutron-rich 6He

Differential cross sections and vector analyzing powers of p–6He elastic scattering were measured in inverse kinematics at the incident energy of 200 A MeV, covering high momentum transfer region of 1.7–2.7 fm−1 at Rare Isotope Beam Factory (RIBF), RIKEN, Japan. The data were analysed using the theoretical framework of relativistic impulse approximation (RIA) which utilized IA2 interaction and nuclear density matrix based on relativistic mean field (RMF) calculations.
Elastic scattering at high momentum transfers of 1.7–2.7 fm−1 shows high sen- sitivity to the inner part of 6He density distribution. RIA calculations were used to deduce the inner part of 6He density from the obtained data. Two phenomenolog- ical density models, assuming α-like core and two-neutron halo structure of 6He were used for this purpose. The radius of the distribution of the α-like core was determined to be 1.87 ± 0.05 fm. The result is in agreement with the radius of point-proton distribution of 6He deduced from the charge radius measurement. The obtained results support the assumption that 6He nucleus consists of a rigid α-like core with two-neutron halo.
Vector analyzing power data were compared to a set of RIA predictions. Results of comparison show that 6He spin-orbit potential has a considerably weaker strength and a more diffuse shape in comparison to stable nuclei. The change is driven by the α-like core of 6He, which in turn is affected by the recoil motion of two valence neutrons. Study of the core-halo correlation in 6He should be valuable to deepen our understanding of its structure.

Thesis Advisor: Prof. Wooyoung Kim