Seminar（セミナー）2026.10.9 & 2026.10.15 Calvin Johnson (SDSU)
2026年9月26日 | 新着情報
Dr Calvin Johnson will deliver the following two seminars on October 9th and 15th.
Lecturer: Calvin Johnson (San Diego State University)
Date/Time: October 9th/13:00
Place: Meeting Room C, Center for Computational Sciences
Title: Scattering in a shell-model basis
Abstract: Scattering and reactions are important ways to probe the nucleus as well as other small quantum systems. To extract scattering observables such as phase shifts, one needs the asymptotic behavior of scattering states, which is not easy to compute accurately for many-body systems. To address this problem, we combine two methods that may be obscure to the audience: the J-matrix method, which allows for exact representation of scattering states in bound state bases such as harmonic oscillator states, and integral methods, which deduce the asymptotic behavior from an integral or overlap over the interior. With this approach, and using ab initio interactions such as Daejeon16, we are able to reproduce low-energy neutron-nucleus phase shifts and cross-sections for 4He, 12C, 16O, and 40Ca, in tiny model spaces. This demonstrates from first principles that at low energy the mean-field indeed dominates scattering, and lay the groundwork for more ambitious future applications.
Date/Time: October 15th/13:45
Place: Workshop Room, Center for Computational Sciences
Title: Does the ground state of the nucleus have a temperature?
Abstract: The nuclear ground state is a pure quantum state, of course. Yet in dissecting the nuclear wave function, expressed in the configuration-interaction shell model, one finds a distribution of components following a Boltzmann-like distribution over many orders of magnitude, suggesting a temperature. I explore such findings and their trends, as well as discussing resulting applications for many-body calculations.