“Characterizing shape and shell evolution in light Sn nuclei: spectroscopy of 110Sn and 111Sn” by Jason Park PhD, Physics

The experimental electric quadrupole transition strengths, B(E2; 01+ → 21+), in light eveneven Sn isotopes are found to be enhanced compared to theory, a discrepancy which has eluded a satisfactory solution for over a decade. In addition, the systematics of the excitation energies and spectroscopic factors of single-particle dominated states in light odd-N Sn isotopes requires more experimental data in order to characterize shell evolution towards the doubly magic 100Sn.

Independent campaigns of safe-energy Coulomb excitation and (d,p) reaction on neutrondeficient Sn nuclei were launched at HIE-ISOLDE, CERN. The obtained gamma-ray statistics on 110Sn using the Miniball high-purity germanium spectrometer allowed the determination of the spectroscopic quadrupole moment of the first-excited 2+ state in 110Sn for the first time, and oblate deformation is suggested. New and more precise B(E2) values in the same nucleus were also measured, and they are compared against MCSM and other SM results.

In a separate experiment with the ISOLDE Solenoidal Spectrometer, population of the ground state and excited states up to 4 MeV in 111Sn from the d(110Sn,p)111Sn reaction was observed. Data analysis for spin-parity assignments and determination of spectroscopic factors is ongoing.

Results from both experiments will be presented.

BIO: Jason Park earned his BS and Ph.D degrees at the University of British Columbia in Canada. His doctoral degree thesis was based on a decay spectroscopy experiment of rare isotopes produced at the Radioactive Isotope Beam Factory, RIKEN Nishina Center in Japan. He continued his career as a researcher in nuclear physics through two postdoctoral fellowships: one at Lund University in Sweden, and another at the Center for Exotic Nuclear Studies, Institute for Basic Science in South Korea. He has visited multiple heavy-ion accelerator facilities around the world to conduct various experiments using accelerated beams of exotic nuclei, and led efforts in detector construction and experiment designs. He is an active member of several international research collaborations using rare isotope beams. He joined Hope College in July 2025 as an assistant professor in physics, and is just starting to engage in full-time teaching and to seek research opportunities with students.