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
Zheng K
(2021)
Rich band structure and multiple long-lived isomers in the odd-odd Cs 118 nucleus
in Physical Review C
Zheng K
(2022)
Candidate revolving chiral doublet bands in $${}^{119}$$Cs
in The European Physical Journal A
Zheng K
(2021)
Complete set of proton excitations in Cs 119
in Physical Review C
Zheng K
(2021)
Neutron excitations in Ba 119
in Physical Review C
Zheng K
(2021)
Evidence of oblate-prolate shape coexistence in the strongly-deformed nucleus 119Cs
in Physics Letters B
Zhang W
(2021)
Identification of excited states in Te 55 52 107
in Physical Review C
Zhang W
(2022)
Observation of the proton emitter $${}_{\,57}^{116}$$La59
in Communications Physics
Watkins H
(2011)
Lifetime measurements probing triple shape coexistence in 175 Au
in Physical Review C
Wang F
(2017)
Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151Lu
in Physics Letters B
Wang F
(2017)
Reinvestigation of the excited states in the proton emitter Lu 151 : Particle-hole excitations across the N = Z = 64 subshell
in Physical Review C
Wady P
(2015)
High-spin states beyond the proton drip-line: Quasiparticle alignments in 113 Cs
in Physics Letters B
Venhart M
(2012)
Determination of a-decay branching ratios for 178, 179Hg
in The European Physical Journal A
Venhart M
(2017)
Application of the Broad Energy Germanium detector: A technique for elucidating ß -decay schemes which involve daughter nuclei with very low energy excited states
in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Venhart M
(2017)
De-excitation of the strongly coupled band in Au 177 and implications for core intruder configurations in the light Hg isotopes
in Physical Review C
Venhart M
(2011)
Shape coexistence in odd-mass Au isotopes: Determination of the excitation energy of the lowest intruder state in 179Au
in Physics Letters B
Thornthwaite A
(2012)
Characterizing the atomic mass surface beyond the proton drip line via a -decay measurements of the p s 1 / 2 ground state of 165 Re and the p h 11 / 2 isomer in 161 Ta
in Physical Review C
Thomson J
(2010)
Competing quasiparticle configurations in W 163
in Physical Review C
Taylor M
(2013)
A new differentially pumped plunger device to measure excited-state lifetimes in proton emitting nuclei
in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Stolze S
(2021)
Single-particle and collective excitations in the transitional nucleus 166 Os
in Journal of Physics G: Nuclear and Particle Physics
Seliverstov M
(2014)
Electromagnetic moments of odd- A Po 193 - 203 , 211 isotopes
in Physical Review C
Seliverstov M
(2013)
Charge radii of odd-A 191-211Po isotopes
in Physics Letters B
Scholey C
(2010)
Isomeric and ground-state properties of 78 171 Pt , 76 167 Os , and 74 163 W
in Physical Review C
Scheck M
(2011)
Combined in-beam electron and ? -ray spectroscopy of Hg 184 , 186
in Physical Review C
Scheck M
(2010)
Lifetimes of odd-spin yrast states in Hg 182
in Physical Review C
Saygi B
(2017)
Reduced transition probabilities along the yrast line in W 166
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
Sandzelius M
(2009)
? -ray spectroscopy of Ta 163
in Physical Review C
Procter M
(2013)
Proton emission from an oblate nucleus 151Lu
in Physics Letters B
Peura P
(2014)
Quasiparticle alignments and a -decay fine structure of 175 Pt
in Physical Review C
Peura P
(2014)
Erratum: Quasiparticle alignments and a -decay fine structure of 175 Pt [Phys. Rev. C 89 , 024316 (2014)]
in Physical Review C
Paul E
(2012)
Four-quasiparticle high-K band in 130Ce
in The European Physical Journal A
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
Pakarinen J
(2009)
Evidence for prolate structure in light Pb isotopes from in-beam ? -ray spectroscopy of Pb 185
in Physical Review C
Pakarinen J
(2014)
The SAGE spectrometer
in The European Physical Journal A
Page R
(2016)
Proton emission - new results and future prospects
in EPJ Web of Conferences
Page R
(2011)
In-beam conversion-electron spectroscopy of 180 Hg
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
O'Donnell D
(2020)
High-spin states of 218 Th
in Journal of Physics G: Nuclear and Particle Physics
O'Donnell D
(2012)
First observation of excited states of 173 Hg
in Physical Review C
O'Donnell D
(2009)
First observation of excited states in Hg 175 95
in Physical Review C
O'Donnell D
(2009)
Spectroscopy of the neutron-deficient nucleus Os 167 91
in Physical Review C
Mistry A
(2017)
In-beam study of 253No using the SAGE spectrometer
in The European Physical Journal A
Mason P
(2014)
Spectroscopy of Hf 161 from low to high spin
in Physical Review C
Lv B
(2022)
Refined description of the positive-parity bands and the extent of octupole correlations in Ba 120
in Physical Review C
Lund M
(2016)
Beta-delayed proton emission from 20Mg
in The European Physical Journal A
Liu Z
(2011)
Structure of the proton emitter 117La studied by proton and ?-ray spectroscopy
in Physics Letters B
Lica R
(2016)
Fast-timing study of the l -forbidden 1 / 2 + ? 3 / 2 + M 1 transition in Sn 129
in Physical Review C
Lica R
(2017)
Identification of the crossing point at N = 21 between normal and intruder configurations
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 |