[Triumf-seminars] TRIUMF Nuclear Physics Seminar today at 10:00

[TRIUMF Seminars]

Date/Time: Thu 2017-12-14 at 10:00

Location:  MOB Conference Room 

Speaker:   Iwasaki, Hironori (Michigan State University and National Superconducting Cyclotron Laboratory)

Title:     Electromagnetic Responses of Weakly-bound Nuclei Studied by Lifetime Measurements

Abstract: Collective motions in atomic nuclei at low excitation energies have often been described in terms of rotation and vibration with respect to the ground-state shape. This picture can be altered in exotic nuclei with unusual proton-to-neutron ratios, where shape and shell effects can induce a delicate interplay between different structures. In self-conjugate nuclei at N=Z, proton and neutron shape (deformed shell) effects can be amplified, leading to shape coexistence phenomena pronounced in the A=70-80 region. On the neutron-rich side with large isospin asymmetry (N>>Z), the shell structure is significantly modified, which results in a competition between the normal and intruder configurations at the conventional magic numbers and induces the halo formation in weakly-bound nuclei. As a way to observe unique forms and dynamics of exotic isotopes which are often produced in very low amounts, the advanced gamma-ray tracking array GRETINA (Gamma-Ray Energy Tracking In-beam Nuclear Array) has been employed in physics campaigns with fast rare isotope beams at NSCL. This talk will provide an overview of the lifetime measurement program at NSCL and present the implementation of gamma-ray Doppler-shift techniques with GRETINA. Recent physics highlights on the neutron-rich C, Ne, and S isotopes will be shown and discussed in terms of a possible interplay between halo and deformation at the limit of stability.



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