Nuclear and Particle Physics Colloquium 53
Place: Room 513(big), Main Building, Beihang University
Time: 10:00-12:00, April 11, 2018 (Wedesday)
Title: On the Z=6 magic number in neutron-rich carbon isotopes
Speaker: Dr. Ong Hooi Jin (王惠仁), RCNP, Osaka University, Japan
The nuclear magic numbers, as we know in stable nuclei, consist of two different series of numbers. The first series -- 2, 8, 20 -- is attributed to the harmonic oscillator potential, while the second one -- 28, 50, 82, and 126 -- is due to the spin-orbit (SO) interactions. Besides these known magic numbers, possible SO-originated magic numbers (subshell closures) at 6 and 14 had been suggested by Mayer in 1963 . Theoretical and experimental studies on unstable nuclei in recent decades have revealed a possible subshell closure at N=6 in very neutron-rich 8He isotope. For Z=6 and 14, possible subshell closures have been suggested in the semi-magic 14C and 34Si.
In this talk, we will present experimental evidence for a prevalent subshell closure at proton number Z=6 in the neutron-rich carbon isotopes. We investigated (i) the point-proton density distribution radii, combining our recent data for Be, B and C isotopes measured at RCNP, Osaka University and GSI, Darmstadt, with the data from the literature, (ii) the atomic masses, and (iii) the electromagnetic transition strengths for a wide range of isotopes. Our systematic analysis revealed marked regularities which support a prominent proton subshell closure at Z=6 in 13-20C. The results are consistent  with the predictions by Shell-Model calculations and Coupled-Cluster calculations with chiral NN and 3NFs interactions.
 M. Goeppert-Mayer,“The shell model”,(1963) Nobel Lectures, Physics, 20–37(1963).
 D.T.Tran, H.J.Ong et al.,“Evidence for prevalent Z=6 magic number in neutron-rich carbon isotopes”,accepted for publication in Nat. Comm.; arXiv1709.03355 [nucl-ex].