Exploring the limits of nuclear existence for heavy proton-rich nuclei
Lead Research Organisation:
University of Liverpool
Department Name: Physics
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
Parr E
(2018)
Fine structure in the a decay of high-spin isomers in Lu 155 and Hf 156
in Physical Review C
Parr E
(2019)
Fine structure in the a decay of Lu 156 and Ta 158
in Physical Review C
Ding B
(2017)
First identification of excited states in Ba 117 using the recoil- ß -delayed proton tagging technique
in Physical Review C
Li H
(2015)
First identification of rotational band structures in Re 91 75 166
in Physical Review C
O'Donnell D
(2009)
First observation of excited states in Hg 175 95
in Physical Review C
O'Donnell D
(2012)
First observation of excited states of 173 Hg
in Physical Review C
Paul E
(2012)
Four-quasiparticle high-K band in 130Ce
in The European Physical Journal A
Wady P
(2015)
High-spin states beyond the proton drip-line: Quasiparticle alignments in 113 Cs
in Physics Letters B
O'Donnell D
(2020)
High-spin states of 218 Th
in Journal of Physics G: Nuclear and Particle Physics
Ghazi Moradi F
(2011)
High-spin study of 162 Ta
in Physical Review C
Grodner E
(2014)
Hindered Gamow-Teller decay to the odd-odd N=Z (62)Ga: absence of proton-neutron T=0 condensate in A=62.
in Physical review letters
Andreyev A
(2009)
Identification and decay of the 0.48 ms 13 / 2 + isomer in Hg 181
in Physical Review C
Hadinia B
(2009)
Identification of ? rays from Au 172 and a decays of Au 172 , Ir 168 , and Re 164
in Physical Review C
Zhang W
(2021)
Identification of excited states in Te 55 52 107
in Physical Review C
Lica R
(2017)
Identification of the crossing point at N = 21 between normal and intruder configurations
in Physical Review C
Sapple P
(2011)
In-beam ? -ray spectroscopy of the N = 85 isotones 159 W and 160 Re
in Physical Review C
Page R
(2011)
In-beam conversion-electron spectroscopy of 180 Hg
in Physical Review C
Mistry A
(2017)
In-beam study of 253No using the SAGE spectrometer
in The European Physical Journal A
Scholey C
(2010)
Isomeric and ground-state properties of 78 171 Pt , 76 167 Os , and 74 163 W
in Physical Review C
Li H
(2016)
Lifetime measurements in Re 166 : Collective versus magnetic rotation
in Physical Review C
Lewis M
(2019)
Lifetime measurements of excited states in 163W and the implications for the anomalous B(E2) ratios in transitional nuclei
in Physics Letters B
Doncel M
(2017)
Lifetime measurements of excited states in W 162 and W 164 and the evolution of collectivity in rare-earth nuclei
in Physical Review C
Watkins H
(2011)
Lifetime measurements probing triple shape coexistence in 175 Au
in Physical Review C
Scheck M
(2010)
Lifetimes of odd-spin yrast states in Hg 182
in Physical Review C
Page R
(2011)
Limits of observable proton-emitting nuclei between the N = 82 and Z = 82 shell closures
in Physical Review C
Description | Understanding the limits of nuclei that are observable in the laboratory is one of the fundamental questions in nuclear physics. This work has helped to address this question through the discovery of nuclei that decay by proton and alpha-particle emission. |
Exploitation Route | The measurements obtained in this work are being used by theorists to refine their models and provide a better understanding of the limits of observable nuclei. |
Sectors | Education |
Description | Nuclear Physics Consolidated Grant |
Amount | £2,213,696 (GBP) |
Funding ID | ST/L005670/1 |
Organisation | Science and Technologies Facilities Council (STFC) |
Sector | Public |
Country | United Kingdom |
Start | 08/2014 |
End | 09/2018 |
Description | Nuclear Physics Consolidated Grant |
Amount | £2,176,557 (GBP) |
Funding ID | ST/J000094/1 |
Organisation | Science and Technologies Facilities Council (STFC) |
Sector | Public |
Country | United Kingdom |
Start | 08/2011 |
End | 07/2015 |
Description | LISA |
Organisation | Daresbury Laboratory |
Department | Nuclear Physics Support Group |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Intellectual contributions to experimental research programme. |
Collaborator Contribution | Intellectual contribution to experimental research programme. |
Impact | Joint publications. |
Description | LISA |
Organisation | University of the West of Scotland |
Department | School of Physics |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Intellectual contributions to experimental research programme. |
Collaborator Contribution | Intellectual contribution to experimental research programme. |
Impact | Joint publications. |
Description | Research collaborators |
Organisation | Daresbury Laboratory |
Department | Nuclear Physics Support Group |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Intellectual contributions to research programme and joint research papers. |
Collaborator Contribution | Intellectual contributions to research programme and joint research papers. |
Impact | Many joint research papers. |
Description | Research collaborators |
Organisation | University of Jyvaskyla |
Department | Department of Physics |
Country | Finland |
Sector | Academic/University |
PI Contribution | Intellectual contributions to research programme and joint research papers. |
Collaborator Contribution | Intellectual contributions to research programme and joint research papers. |
Impact | Many joint research papers. |
Description | Research collaborators |
Organisation | University of Surrey |
Department | Department of Physics |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Intellectual contributions to research programme and joint research papers. |
Collaborator Contribution | Intellectual contributions to research programme and joint research papers. |
Impact | Many joint research papers. |
Description | Schools lectures, Liverpool |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Type Of Presentation | Keynote/Invited Speaker |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | Many school pupils have attended and asked questions at end of lecture. Not possible to verify. |
Year(s) Of Engagement Activity | 2009,2010,2011,2012,2013 |