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
Pakarinen J
(2009)
Evidence for prolate structure in light Pb isotopes from in-beam ? -ray spectroscopy of Pb 185
in Physical Review C
Andreyev A
(2009)
a decay of At 194
in Physical Review C
Grahn T
(2009)
Evolution of collectivity in Hg 180 and Hg 182
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
Andreyev A
(2009)
a decay of Pb 180 , 181
in Physical Review C
Sandzelius M
(2009)
? -ray spectroscopy of Ta 163
in Physical Review C
Andreyev A
(2009)
Identification and decay of the 0.48 ms 13 / 2 + isomer in Hg 181
in Physical Review C
Gómez Hornillos M
(2009)
?-ray spectroscopy approaching the limits of existence of atomic nuclei: A study of the excited states of Pt 168 and Pt 169
in Physical Review C
Grahn T
(2009)
Collectivity of Po 196 at low spin
in Physical Review C
Herzberg R
(2009)
Structure of rotational bands in 253No
in The European Physical Journal A
Andreyev A
(2009)
Decay of the 9 / 2 - isomer in Tl 181 and mass determination of low-lying states in Tl 181 , Au 177 , and Ir 173
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
Bianco L
(2010)
Discovery of 157W and 161Os
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
Andreyev AN
(2010)
New type of asymmetric fission in proton-rich nuclei.
in Physical review letters
Thomson J
(2010)
Competing quasiparticle configurations in W 163
in Physical Review C
Scheck M
(2010)
Lifetimes of odd-spin yrast states in Hg 182
in Physical Review C
Darby IG
(2010)
Orbital dependent nucleonic pairing in the lightest known isotopes of tin.
in Physical review letters
Cocolios T
(2010)
Structure of 191 Pb from a- and ß-decay spectroscopy
in Journal of Physics G: Nuclear and Particle Physics
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
Darby I
(2011)
Decay of the high-spin isomer in 160Re: Changing single-particle structure beyond the proton drip line
in Physics Letters B
Ghazi Moradi F
(2011)
High-spin study of 162 Ta
in Physical Review C
Elseviers J
(2011)
Shape coexistence in 180 Hg studied through the ß decay of 180 Tl
in Physical Review C
Cocolios TE
(2011)
Early onset of ground state deformation in neutron deficient polonium isotopes.
in Physical review letters
Lagergren K
(2011)
? -soft shapes and quasiparticle excitations in 73 161 Ta 88
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
Darby I
(2011)
Precision measurements of proton emission from the ground states of Ta 156 and Re 160
in Physical Review C
Watkins H
(2011)
Lifetime measurements probing triple shape coexistence in 175 Au
in Physical Review C
Scheck M
(2011)
Combined in-beam electron and ? -ray spectroscopy of Hg 184 , 186
in Physical Review C
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
Liu Z
(2011)
Structure of the proton emitter 117La studied by proton and ?-ray spectroscopy
in Physics Letters B
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
Cartegni L
(2012)
Experimental study of the decays of 112 Cs and 111 Xe
in Physical Review C
Venhart M
(2012)
Determination of a-decay branching ratios for 178, 179Hg
in The European Physical Journal A
O'Donnell D
(2012)
First observation of excited states of 173 Hg
in Physical Review C
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
Paul E
(2012)
Four-quasiparticle high-K band in 130Ce
in The European Physical Journal A
Andreyev A
(2013)
ß -delayed fission of 192 , 194 At
in Physical Review C
Procter M
(2013)
Proton emission from an oblate nucleus 151Lu
in Physics Letters B
Grahn T
(2013)
Transition probability studies in 175 Au
in Journal of Physics: Conference Series
Lane J
(2013)
ß -delayed fission of 186 , 188 Bi isotopes
in Physical Review C
Kalaninová Z
(2013)
a decay of the very neutron-deficient isotopes 197 - 199 Fr
in Physical Review C
Liberati V
(2013)
ß -delayed fission and a decay of 178 Tl
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
Andreyev A
(2013)
a -decay spectroscopy of the chain 179 Tl g ? 175 Au g ? 171 Ir g ? 167 Re m
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
Elseviers J
(2013)
ß -delayed fission of 180 Tl
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 |