Exploring the limits of nuclear existence for heavy proton-rich nuclei
Lead Research Organisation:
University of the West of Scotland
Department Name: School of Science
Abstract
A fundamental question in nuclear physics is, 'what are the limits on the number of protons and neutrons that can be bound inside an atomic nucleus?' The aim of this research proposal is to answer a vital part of this question by determining more carefully than ever before the precise location of what is known as the proton drip line. The proton and neutron drip lines are the borders between bound and unbound nuclei. Those at the proton drip line have such a large excess of protons that they are highly unstable and try to achieve greater stability through the process of proton emission. We will investigate how nuclear behaviour is affected when protons become unbound. Nuclei along this distant shore of the nuclear landscape should show the greatest deviations from the behaviour expected from predictions of models optimised for more stable nuclei. Our investigations will focus on nuclei close to the proton drip line, for elements between tin (Z=50) and lead (Z=82). Historically, this region has been the primary source of data on proton-emitting nuclei, largely because here the proton emission occurs on an experimentally accessible timescale that still competes effectively with alpha or beta decay. One important feature of the 30 or so proton emitters discovered to date is that they span a wide range of nuclear deformations, ranging from spherical nuclei to others that are rugby ball shaped and are up to 50% longer than they are wide. Proton emission from spherical nuclei is well described using simple models and the simplicity of the theoretical description has allowed a great deal to be learnt about the structure of these nuclei. The theoretical descriptions for proton emission from strongly deformed nuclei are necessarily rather different and several models have been proposed and compared with the available data. We will exploit a new generation of experimental methods to study the most proton-rich atomic nuclei that can be made in the laboratory, spanning the entire range of nuclear deformations. We will search for nuclei presently unknown to science and measure their proton and alpha decays, study excited states in selected nuclei for the first time and extend experimental observations of direct proton emission from heavy nuclei to lifetimes of nanoseconds (billionths of a second!) and even shorter. The results of our experiments will be compared with the theoretical predictions in order to improve our understanding of the complex and fascinating world of the nuclei at the heart of every atom.
Publications
Bree N
(2014)
Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation.
in Physical review letters
Capponi L
(2016)
Direct observation of the Ba 114 ? Xe 110 ? Te 106 ? Sn 102 triple a -decay chain using position and time correlations
in Physical Review C
Chapman R
(2015)
Spectroscopy of neutron-rich P 34 , 35 , 36 , 37 , 38 populated in binary grazing reactions
in Physical Review C
Gaffney L
(2015)
Collectivity in the light radon nuclei measured directly via Coulomb excitation
in Physical Review C
Hodge D
(2016)
Deformation of the proton emitter Cs 113 from electromagnetic transition and proton-emission rates
in Physical Review C
Orlandi R
(2015)
Single-neutron orbits near 78 Ni: Spectroscopy of the N = 49 isotope 79 Zn
in Physics Letters B
Roberts O
(2016)
E 3 and M 2 transition strengths in Bi 83 209
in Physical Review C
Smith J
(2012)
? -ray spectroscopy of neutron-deficient 123 Ce
in Physical Review C
Steppenbeck D
(2012)
Magnetic rotation and quasicollective structures in 58 Fe: Influence of the ? g 9 / 2 orbital
in Physical Review C
Wady P
(2015)
High-spin states beyond the proton drip-line: Quasiparticle alignments in 113 Cs
in Physics Letters B
Description | This grant was to fund a programme of research to study exotic proton-rich nuclei at the University of Jyvaskyla in Finland using the Jurogam-II gamma-ray spectrometer together with other devices such as the RITU recoil-separator and the LISA light-ion spectrometer array. |
Exploitation Route | The results will be of interest to the worldwide community of experimental and theoretical nuclear physicists. Techniques of gamma-ray and charged-particle spectroscopy such as those used in this research could be exploited in various areas of industry and society, such as in medical physics (imaging), environmental monitoring and security (such as nuclear forensics). |
Sectors | Construction Education Energy Environment Healthcare Security and Diplomacy Other |
Description | The results will be of interest to the worldwide community of experimental and theoretical nuclear physicists. |
First Year Of Impact | 2010 |