Chen Sidong "Structural evolution of neutron-rich calcium isotopes"




The 288th RIKEN RIBF Nuclear Physics Seminar
Lecturer: Dr. Chen Sidong 
        (Department of Physics, The University of Hong Kong)

Title: Structural evolution of neutron-rich calcium isotopes
            * The talk will be given in English

Date:  May 26th (Tues.) 2020  15:00-

Place: via Zoom 
     (the URL was distributed in the mailing list and the number of audience is up to 100)

The calcium isotopes, which have 20 protons (Z=20), are one of the most 
interesting isotopic chains to study nuclear structure. Due to the 
closed proton shell, the structural evolution is governed by the 
neutrons. Using the intense radioactive beams at RIBF, the first 
experimental evidence of the N=34 sub-shell closure was found in 54Ca 
[1].  More recent in-beam gamma-ray spectroscopic studies aimed at a 
detailed study on the nature of the N=34 sub-shell closure of 54Ca and 
the nuclear structures in its vicinity.

 More specifically, the N=34 sub-shell closure of 54Ca was investigated 
by quasifree one-neutron knockout reactions. Using the in-beam γ-ray 
technique tagging on the final states of 53Ca, the exclusive cross 
sections and momentum distributions were measured. A significantly 
larger cross section to the p3/2 state compared to the f5/2 state in 
53Ca corroborated the arising of the N=34 sub-shell closure in calcium 
isotopes [2]. Furthermore, spectroscopic information for calcium 
isotopes beyond the N=34 sub-shell closure was obtained for the first 
time by measuring the de-excitation γ rays of 56,58Ca following 
one-proton knockout reactions. The observations were confronted with 
several state-of-the-art theoretical calculations, allowing for a 
prediction of the structure of 60Ca.
  In this seminar, the study on the N=34 sub-shell closure of 54Ca, as 
well as the structural information on 56,58Ca will be discussed in detail.
[1] D. Steppenbeck et al., Nature, 502, 207-210, (2013).
[2] S. Chen et al., Phys. Rev. Lett. 123, 142501 (2019).