G5 Doctoral dissertation (article)
The nuances of β-decay : theoretical computations and their applications for beyond the standard model physics (2024)

Ramalho, M. (2024). The nuances of β-decay : theoretical computations and their applications for beyond the standard model physics [Doctoral dissertation]. University of Jyväskylä. JYU Dissertations, 773. https://urn.fi/URN:ISBN:978-952-86-0124-1

JYU authors or editors

Publication details

All authors or editors: Ramalho, Marlom

eISBN: 978-952-86-0124-1

Journal or series: JYU Dissertations

eISSN: 2489-9003

Publication year: 2024

Number in series: 773

Number of pages in the book: 1 verkkoaineisto (50 sivua, 45 sivua useina numerointijaksoina, 14 numeroimatonta sivua)

Publisher: University of Jyväskylä

Publication country: Finland

Publication language: English

Persistent website address: https://urn.fi/URN:ISBN:978-952-86-0124-1

Publication open access: Openly available

Publication channel open access: Open Access channel

Abstract

This dissertation encompasses a series of six articles, accompanied by an introductory discourse, centered on the intricacies of beta decays and the utilization of the nuclear shell model in computational analysis. The overarching objective is to elucidate various beta decay methodologies as pathways to unearth novel insights in the realm of physics beyond the standard model. The initial segment of research delves into an in-depth examination of 92Rb betaspectral shapes, scrutinizing the legitimacy of employing approximations for forbidden non-unique decays within the summation method. This analysis is pertinent to the reactor antineutrino anomaly, suggesting potential resolutions or improvements to the spectral shoulder conundrum and bridging the gap between theoretical summation approaches and observed experimental fluxes. Subsequent investigations are geared towards the implementation of computed beta spectra in calibrating background radiation for rare-event experiments, particularly focusing on the Radon decay chain in subterranean settings. An exhaustive analysis of the 212−214Pb-Bi-Po decay chain has been undertaken, marking significant progress in addressing the challenge of underground background radiation. A notable discovery in this segment is the sensitivity of spectral shapes to the small relativistic nuclear matrix element (sNME), a parameter that poses computational challenges within the confines of the nuclear shell model’s valence space framework. Inspired by this sensitivity, the research extends to study the impact of varying gA and sNME values on 99Tc, an adjacent isotope to potential neutrinoless double beta decay candidates 100Mo and 96Zr. Observations of dependency on the dual solutions of sNME catalyzed further exploration across a spectrum of isotopes linked to the reactor antineutrino anomaly, assessing the predictive accuracy of beta spectral shapes in relation to sNME and weak-axial coupling. The culmination of this work applies the developed methodologies to assist in the quest for determining the (anti)neutrino’s mass, leveraging the nuclear shell model alongside our computational predictions of half-lives. Keywords: beta decay, nuclear shell model, beta spectral shape, forbidden nonunique, weak axial coupling, small nuclear matrix element.

Keywords: nuclear physics; standard model of particle physics; beta radiation; atoms; shell and peel; mass spectrometry; computational science

Free keywords: beta decay; nuclear shell model; beta spectral shape; forbidden non unique; weak axial coupling; small nuclear matrix element

Contributing organizations

Ministry reporting: Yes