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
Zhang W
(2022)
Observation of the proton emitter $${}_{\,57}^{116}$$La59
in Communications Physics
Zheng K
(2022)
Candidate revolving chiral doublet bands in $${}^{119}$$Cs
in The European Physical Journal A
Lv B
(2022)
Refined description of the positive-parity bands and the extent of octupole correlations in Ba 120
in Physical Review C
Auranen K
(2022)
Nanosecond-Scale Proton Emission from Strongly Oblate-Deformed ^{149}Lu.
in Physical review letters
Balogh M
(2022)
New collective structures in Au 179 and their implications for the triaxial deformation of the Pt 178 core
in Physical Review C
Stolze S
(2021)
Single-particle and collective excitations in the transitional nucleus 166 Os
in Journal of Physics G: Nuclear and Particle Physics
Zheng K
(2021)
Rich band structure and multiple long-lived isomers in the odd-odd Cs 118 nucleus
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
Zheng K
(2021)
Complete set of proton excitations in Cs 119
in Physical Review C
O'Donnell D
(2020)
High-spin states of 218 Th
in Journal of Physics G: Nuclear and Particle Physics
Ertoprak A
(2020)
Evidence for octupole collectivity in $$^{172}{\mathrm {Pt}}$$
in The European Physical Journal A
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
Ghys L
(2019)
a -decay properties of Fr 200 , 202
in Physical Review C
Parr E
(2019)
Fine structure in the a decay of Lu 156 and Ta 158
in Physical Review C
Hilton J
(2019)
a -spectroscopy studies of the new nuclides Pt 165 and Hg 170
in Physical Review C
Parr E
(2018)
Fine structure in the a decay of high-spin isomers in Lu 155 and Hf 156
in Physical Review C
Cubiss J
(2018)
Change in structure between the I = 1/2 states in 181Tl and 177,179Au
in Physics Letters B
Lewis M
(2018)
Decay of a 19 - isomeric state in Lu 156
in Physical Review C
Mistry A
(2017)
In-beam study of 253No using the SAGE spectrometer
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
Saygi B
(2017)
Reduced transition probabilities along the yrast line in W 166
in Physical Review C
Andel B
(2017)
Detailed a -decay study of Tl 180
in Physical Review C
Lica R
(2017)
Identification of the crossing point at N = 21 between normal and intruder configurations
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
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
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
Wang F
(2017)
Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151Lu
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
Joss D
(2017)
Spectroscopy at the two-proton drip line: Excited states in 158W
in Physics Letters B
Carroll R
(2016)
Multiparticle configurations of excited states in Lu 155
in Physical Review C
Joss D
(2016)
Evolution of collective structures in the heavy transitional nuclei above the N = 82 closed shell
in EPJ Web of Conferences
Andel B
(2016)
Short-lived isomers in Po 192 and Po 194
in Physical Review C
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
Li H
(2016)
Lifetime measurements in Re 166 : Collective versus magnetic rotation
in Physical Review C
Carroll R
(2016)
Excited states in the proton-unbound nuclide Ta 158
in Physical Review C
Lund M
(2016)
Beta-delayed proton emission from 20Mg
in The European Physical Journal A
Lica R
(2016)
Fast-timing study of the l -forbidden 1 / 2 + ? 3 / 2 + M 1 transition in Sn 129
in Physical Review C
Grahn T
(2016)
Excited states and reduced transition probabilities in Os 168
in Physical Review C
Joss D
(2016)
Evolving collective structures in the transitional nuclei W 162 and W 164
in Physical Review C
Page R
(2016)
Proton emission - new results and future prospects
in EPJ Web of Conferences
Li H
(2015)
Recoil-decay tagging spectroscopy of 74 162 W 88
in Physical Review C
Wady P
(2015)
High-spin states beyond the proton drip-line: Quasiparticle alignments in 113 Cs
in Physics Letters B
Davis-Merry T
(2015)
Collective excitations in the transitional nuclei Re 163 and Re 165
in Physical Review C
Carroll R
(2015)
Competing Decay Modes of a High-spin Isomer in the Proton-unbound Nucleus $^{158}$Ta
in Acta Physica Polonica B
Li H
(2015)
First identification of rotational band structures in Re 91 75 166
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
Gaffney L
(2014)
Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements in Hg 184 , 186 and two-state mixing calculations
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 | 07/2014 |
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 | 07/2011 |
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 |