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
Andel B
(2016)
Short-lived isomers in Po 192 and Po 194
in Physical Review C
Andel B
(2017)
Detailed a -decay study of Tl 180
in Physical Review C
Andreyev A
(2014)
a decay of Au 176
in Physical Review C
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
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
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
Andreyev A
(2009)
Identification and decay of the 0.48 ms 13 / 2 + isomer in Hg 181
in Physical Review C
Andreyev A
(2009)
a decay of At 194
in Physical Review C
Andreyev A
(2013)
ß -delayed fission of 192 , 194 At
in Physical Review C
Andreyev A
(2009)
a decay of Pb 180 , 181
in Physical Review C
Andreyev AN
(2013)
Signatures of the Z = 82 shell closure in a-decay process.
in Physical review letters
Andreyev AN
(2010)
New type of asymmetric fission in proton-rich nuclei.
in Physical review letters
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
Bianco L
(2010)
Discovery of 157W and 161Os
in Physics Letters B
Bree N
(2014)
Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation.
in Physical review letters
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
Carroll R
(2016)
Multiparticle configurations of excited states in Lu 155
in Physical Review C
Carroll R
(2016)
Excited states in the proton-unbound nuclide Ta 158
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
Carroll RJ
(2014)
Blurring the boundaries: decays of multiparticle isomers at the proton drip line.
in Physical review letters
Cartegni L
(2012)
Experimental study of the decays of 112 Cs and 111 Xe
in Physical Review C
Cocolios T
(2010)
Structure of 191 Pb from a- and ß-decay spectroscopy
in Journal of Physics G: Nuclear and Particle Physics
Cocolios TE
(2011)
Early onset of ground state deformation in neutron deficient polonium isotopes.
in Physical review letters
Cubiss J
(2018)
Change in structure between the I = 1/2 states in 181Tl and 177,179Au
in Physics Letters B
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 | £2,176,557 (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 | 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 | GREAT |
Organisation | University of Jyvaskyla |
Country | Finland |
Sector | Academic/University |
PI Contribution | Led design and construction of GREAT. Spokesperson for many experiments. |
Collaborator Contribution | Contributions to design & constraction of GREAT. Experimental collaborators. |
Impact | Many publications. |
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 |