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
Andreyev A
(2013)
ß -delayed fission of 192 , 194 At
in Physical Review C
Lane J
(2013)
ß -delayed fission of 186 , 188 Bi isotopes
in Physical Review C
Elseviers J
(2013)
ß -delayed fission of 180 Tl
in Physical Review C
Liberati V
(2013)
ß -delayed fission and a decay of 178 Tl
in Physical Review C
Grahn T
(2013)
Transition probability studies in 175 Au
in Journal of Physics: Conference Series
Pakarinen J
(2014)
The SAGE spectrometer
in The European Physical Journal A
Andreyev A
(2010)
The new isotope 179 Pb and a-decay properties of 179 Tl m
in Journal of Physics G: Nuclear and Particle Physics
Liu Z
(2011)
Structure of the proton emitter 117La studied by proton and ?-ray spectroscopy
in Physics Letters B
Herzberg R
(2009)
Structure of rotational bands in 253No
in The European Physical Journal A
Cocolios T
(2010)
Structure of 191 Pb from a- and ß-decay spectroscopy
in Journal of Physics G: Nuclear and Particle Physics
O'Donnell D
(2009)
Spectroscopy of the neutron-deficient nucleus Os 167 91
in Physical Review C
Mason P
(2014)
Spectroscopy of Hf 161 from low to high spin
in Physical Review C
Joss D
(2017)
Spectroscopy at the two-proton drip line: Excited states in 158W
in Physics Letters B
Wang F
(2017)
Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151Lu
in Physics Letters B
Stolze S
(2021)
Single-particle and collective excitations in the transitional nucleus 166 Os
in Journal of Physics G: Nuclear and Particle Physics
Andreyev AN
(2013)
Signatures of the Z = 82 shell closure in a-decay process.
in Physical review letters
Andel B
(2016)
Short-lived isomers in Po 192 and Po 194
in Physical Review C
Bree N
(2014)
Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation.
in Physical review letters
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
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
Elseviers J
(2011)
Shape coexistence in 180 Hg studied through the ß decay of 180 Tl
in Physical Review C
Zheng K
(2021)
Rich band structure and multiple long-lived isomers in the odd-odd Cs 118 nucleus
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
Lv B
(2022)
Refined description of the positive-parity bands and the extent of octupole correlations in Ba 120
in Physical Review C
Saygi B
(2017)
Reduced transition probabilities along the yrast line in W 166
in Physical Review C
Li H
(2015)
Recoil-decay tagging spectroscopy of 74 162 W 88
in Physical Review C
Peura P
(2014)
Quasiparticle alignments and a -decay fine structure of 175 Pt
in Physical Review C
Procter M
(2013)
Proton emission from an oblate nucleus 151Lu
in Physics Letters B
Page R
(2016)
Proton emission - new results and future prospects
in EPJ Web of Conferences
Darby I
(2011)
Precision measurements of proton emission from the ground states of Ta 156 and Re 160
in Physical Review C
Darby IG
(2010)
Orbital dependent nucleonic pairing in the lightest known isotopes of tin.
in Physical review letters
Zhang W
(2022)
Observation of the proton emitter $${}_{\,57}^{116}$$La59
in Communications Physics
Andreyev AN
(2010)
New type of asymmetric fission in proton-rich nuclei.
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
Zheng K
(2021)
Neutron excitations in Ba 119
in Physical Review C
Auranen K
(2022)
Nanosecond-Scale Proton Emission from Strongly Oblate-Deformed ^{149}Lu.
in Physical review letters
Carroll R
(2016)
Multiparticle configurations of excited states in Lu 155
in Physical Review C
Drummond M
(2013)
Low-lying excited states in the neutron-deficient isotopes 163 Os and 165 Os
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
Scheck M
(2010)
Lifetimes of odd-spin yrast states in Hg 182
in Physical Review C
Watkins H
(2011)
Lifetime measurements probing triple shape coexistence in 175 Au
in Physical Review C
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
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
Li H
(2016)
Lifetime measurements in Re 166 : Collective versus magnetic rotation
in Physical Review C
Scholey C
(2010)
Isomeric and ground-state properties of 78 171 Pt , 76 167 Os , and 74 163 W
in Physical Review C
Mistry A
(2017)
In-beam study of 253No using the SAGE spectrometer
in The European Physical Journal A
Page R
(2011)
In-beam conversion-electron spectroscopy of 180 Hg
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
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 | 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 |