Shell-model Investigations in the p1/2g9/2 Space
(2025) FYSK04 20251Particle and nuclear physics
Department of Physics
- Abstract
- The goal of the present work is to investigate possible improvements to established shell-model interactions concerning atomic nuclei in the mass A=90, N=Z regime. These investigations consist of generating energy spectra for the isotopes Pd-94, Cd-94, Ag-95, and Cd-95 close to the proton drip line, as well as an investigation of the transition probabilities between selected states in Ag-95. Data was generated using the shell-model code ANTOINE, and was evaluated for the GF1 interaction as well as for two newly developed p1/2g9/2-model space interactions based on GF1 and the so-called JUN45 interaction, called Dp1g9 and Fp1g9, respectively. The present work was conducted in parallel with this development, based on the minimization of... (More)
- The goal of the present work is to investigate possible improvements to established shell-model interactions concerning atomic nuclei in the mass A=90, N=Z regime. These investigations consist of generating energy spectra for the isotopes Pd-94, Cd-94, Ag-95, and Cd-95 close to the proton drip line, as well as an investigation of the transition probabilities between selected states in Ag-95. Data was generated using the shell-model code ANTOINE, and was evaluated for the GF1 interaction as well as for two newly developed p1/2g9/2-model space interactions based on GF1 and the so-called JUN45 interaction, called Dp1g9 and Fp1g9, respectively. The present work was conducted in parallel with this development, based on the minimization of binding energy shift and mean level deviation for two sets of isotopes in the mass region of interest. Randomized sampling of two-body matrix elements, fundamental in the description of effective nucleon-nucleon interactions, was used to compare the sensitivity of the three shell-model parametrizations. The quality of comparison between predicted and experimental excitation energies was measured using a least square fit. It is shown that the Dp1g9 and subsequent Fp1g9 constitute a satisfying improvement of level descriptions in the four nuclei studied. In light of this improvement, the decay scheme of Ag-95 could successfully be revised, a conclusion supported by a transition-rate analysis. The present work leaves room for the original, now extended goal: to incorporate the lower lying p3/2 and f5/2 orbitals, which would imply a more complete description of medium-mass, neutron-deficient nuclei. (Less)
- Popular Abstract
- More than a century ago, scientists thought they understood the structure of the atomic nucleus. This understanding had been based on several assumptions which shaped our intuition and our methodological approach to nuclear science. However, it turned out that many of these assumptions were inaccurate, or sometimes fundamentally flawed. For example, the picture that the nucleus consists of a cluster of neutrons and protons "glued" together is misleading. Today, we know that the nucleus has a much more complex internal structure than the particles making it up.
The refinement of nuclear models can be compared to the developments which led to our modern understanding of the atom. The view evolved from a "plum pudding" model and an... (More) - More than a century ago, scientists thought they understood the structure of the atomic nucleus. This understanding had been based on several assumptions which shaped our intuition and our methodological approach to nuclear science. However, it turned out that many of these assumptions were inaccurate, or sometimes fundamentally flawed. For example, the picture that the nucleus consists of a cluster of neutrons and protons "glued" together is misleading. Today, we know that the nucleus has a much more complex internal structure than the particles making it up.
The refinement of nuclear models can be compared to the developments which led to our modern understanding of the atom. The view evolved from a "plum pudding" model and an analogy to planetary revolution, where negatively charged electrons exist in distinct orbits outside a positively charged core. It turns out that protons and neutrons, having some of the same characteristics as electrons, must also occupy and move in such orbits. This gave rise to the nuclear shell model, which received the Nobel Prize in Physics in 1963, and which continues to be applied in various variations in contemporary nuclear physics.
Nuclear science continues to be developed to this day, in part motivated by the search for superheavy elements. Currently, scientists are searching for a so-called island of stability - where massive atomic nuclei can exist for surprisingly long periods of time, due to certain quantum effects. These nuclei exist at the edge of the nuclidic chart, far beyond the naturally occurring, and their properties are largely unknown. In order to predict how and when these elements can exist, further refinements of theoretical models are required.
The present thesis represents a contribution to this development. By combining modern shell-model corrections with the recent increase in experimental data, we investigate how shell-model predictions can be improved, especially in the exotic regions of the nuclidic chart. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9202267
- author
- Cerne, Axel LU
- supervisor
- organization
- course
- FYSK04 20251
- year
- 2025
- type
- M2 - Bachelor Degree
- subject
- keywords
- Nuclear shell model, Isospin, Two-body matrix element, single-particle energy, Interaction, Mirror energy difference
- language
- English
- id
- 9202267
- date added to LUP
- 2025-06-24 14:44:38
- date last changed
- 2025-06-25 07:46:19
@misc{9202267,
abstract = {{The goal of the present work is to investigate possible improvements to established shell-model interactions concerning atomic nuclei in the mass A=90, N=Z regime. These investigations consist of generating energy spectra for the isotopes Pd-94, Cd-94, Ag-95, and Cd-95 close to the proton drip line, as well as an investigation of the transition probabilities between selected states in Ag-95. Data was generated using the shell-model code ANTOINE, and was evaluated for the GF1 interaction as well as for two newly developed p1/2g9/2-model space interactions based on GF1 and the so-called JUN45 interaction, called Dp1g9 and Fp1g9, respectively. The present work was conducted in parallel with this development, based on the minimization of binding energy shift and mean level deviation for two sets of isotopes in the mass region of interest. Randomized sampling of two-body matrix elements, fundamental in the description of effective nucleon-nucleon interactions, was used to compare the sensitivity of the three shell-model parametrizations. The quality of comparison between predicted and experimental excitation energies was measured using a least square fit. It is shown that the Dp1g9 and subsequent Fp1g9 constitute a satisfying improvement of level descriptions in the four nuclei studied. In light of this improvement, the decay scheme of Ag-95 could successfully be revised, a conclusion supported by a transition-rate analysis. The present work leaves room for the original, now extended goal: to incorporate the lower lying p3/2 and f5/2 orbitals, which would imply a more complete description of medium-mass, neutron-deficient nuclei.}},
author = {{Cerne, Axel}},
language = {{eng}},
note = {{Student Paper}},
title = {{Shell-model Investigations in the p1/2g9/2 Space}},
year = {{2025}},
}