University of the West of Scotland Nuclear Physics Group Consolidated Grant
Lead Research Organisation:
University of the West of Scotland
Department Name: School of Science
Abstract
It is almost exactly 100 years since Ernest Rutherford's pioneering experiments which demonstrated the existence of the atomic nucleus. In the century that has followed, landmark developments, such as the inception of the nuclear shell model in the 1940s, the construction of heavy-ion accelerators in the 1960s, and major advances in nuclear-detector techniques, have firmly established nuclear physics as an international activity at the forefront of scientific research. In the past few decades, the quest to understand the properties of exotic nuclei ever further from the valley of stability has led to considerable experimental progress. The programme of research described in this Consolidated Grant application covers research into the structure and properties of atomic nuclei that lie far from stability. One of the main aims of our research programme is to achieve a better understanding of the structure and behaviour of exotic nuclei on both the neutron-rich and proton-rich sides of the valley of stability. Recent experimental observations, supported by theoretical calculations, have begun to suggest that the structure of neutron-rich nuclei may be different from those near stability. For example, the well known sequence of magic numbers, corresponding to energy gaps in nuclear shell structure, is now thought to change in nuclei with an extreme excess of neutrons. The evidence for such a change is already convincing around neutron number N=20, and similar effects are expected for the other shell gaps at N=28, 50, and 82. We will study the evolution of shell gaps in neutron-rich nuclei using both gamma-ray and charged-particle spectroscopy techniques. Above mass number A~100, electrostatic repulsion causes stable nuclei to have more neutrons than protons. Proton-rich nuclei just above the doubly-magic Sn100 nucleus are those with near equal numbers of neutrons and protons. These nuclei are known to decay by exotic decay modes such as proton emission. Spectroscopic study of the properties of these decays can give invaluable information about the properties of the nucleus in its ground state and in the first few excited states. Our research programme will include studies of proton-rich nuclei around A~110 by investigating their particle decays and by gamma-ray spectroscopy. Another aspect of our research programme will be devoted to studying fission of the nucleus. Fission is a collective mode of decay most commonly associated with heavy nuclei in the uranium region, but in our research we will study the beta-delayed fission of exotic nuclei in the lead region that lie very far from stability (by ~20-25 neutrons) and which have only recently become experimentally accessible with the development of radioactive beams. A study of the properties of beta-delayed fission, such as the mass distributions of the fission fragments, will give important information about nuclear structure and shell effects at low excitation energy. In a related part of our research programme, we will use radioactive At beams to study other nuclear-structure effects such as shape coexistence. Our research programme has several themes which will use different methodologies. Primarily, our experiments will be carried out using state-of-the-art apparatus at large international facilities. Gamma-ray spectroscopy offers one of the best methods of studying the structure of exotic nuclei, and here we will exploit the new AGATA gamma-ray tracking spectrometer at Legnaro National Laboratory, GSI and GANIL. Another part of our research will make use of the Jurogam gamma-ray spectrometer with the RITU recoil separator at Jyväskylä in Finland. Our programme to study beta-delayed fission will make use of beams of radioactive isotopes from the ISOLDE facility at CERN and at the JAEA laboratory in Japan. Furthermore, we will exploit the development of new radioactive beams of astatine at ISOLDE.
Publications
Wady P
(2015)
High-spin states beyond the proton drip-line: Quasiparticle alignments in 113 Cs
in Physics Letters B
Vogt A
(2016)
High-spin structure of Xe 134
in Physical Review C
Vogt A
(2017)
Isomers and high-spin structures in the N = 81 isotones Xe 135 and Ba 137
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
Urban W
(2012)
Isomeric levels in 92 Rb and the structure of neutron-rich 92 , 94 Rb isotopes
in Physical Review C
Tandel S
(2016)
Configurations and decay hindrances of high- K states in Hf 180
in Physical Review C
Szwec S
(2016)
Rearrangement of valence neutrons in the neutrinoless double- ß decay of Xe 136
in Physical Review C
Szilner S
(2013)
Structure of chlorine isotopes populated by heavy ion transfer reactions
in Physical Review C
Steppenbeck D
(2012)
Magnetic rotation and quasicollective structures in 58 Fe: Influence of the ? g 9 / 2 orbital
in Physical Review C
Smith J
(2012)
? -ray spectroscopy of neutron-deficient 123 Ce
in Physical Review C
Saygi B
(2017)
Reduced transition probabilities along the yrast line in W 166
in Physical Review C
Sahin E
(2012)
Structure of the As, Ge, Ga nuclei
in Nuclear Physics A
Procter M
(2012)
Electromagnetic transition strengths in 52 109 Te
in Physical Review C
Parr E
(2016)
Identification of the J p = 1 - state in Ra 218 populated via a decay of Th 222
in Physical Review C
Parr E
(2019)
a -decay spectroscopy of the N = 130 isotones Ra 218 and Th 220 : Mitigation of a -particle energy summing with implanted nuclei
in Physical Review C
Orlandi R
(2015)
Single-neutron orbits near 78 Ni: Spectroscopy of the N = 49 isotope 79 Zn
in Physics Letters B
Nishio K
(2015)
Excitation energy dependence of fragment-mass distributions from fission of 180,190 Hg formed in fusion reactions of 36 Ar + 144,154 Sm
in Physics Letters B
Mason P
(2013)
Half-life of the yrast 2 + state in 188 W: Evolution of deformation and collectivity in neutron-rich tungsten isotopes
in Physical Review C
Mach H
(2016)
On the enhanced E1 transitions in the K = 3/2 parity doublet band in 223Ra
in The European Physical Journal A
Kurpeta J
(2012)
Low-spin structure of 85 Se and the ß n branching of 85 As
in Physical Review C
Kurpeta J
(2014)
Neutron configurations in Pd 113
in Physical Review C
Hodge D
(2016)
Deformation of the proton emitter Cs 113 from electromagnetic transition and proton-emission rates
in Physical Review C
Gaffney L
(2015)
Collectivity in the light radon nuclei measured directly via Coulomb excitation
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
Czerwinski M
(2013)
Yrast excitations in the neutron-rich N = 52 isotones
in Physical Review C
Chapman R
(2016)
First in-beam ? -ray study of the level structure of neutron-rich S 39
in Physical Review C
Chapman R
(2016)
Particle-core coupling in S 37
in Physical Review C
Chapman R
(2015)
Spectroscopy of neutron-rich P 34 , 35 , 36 , 37 , 38 populated in binary grazing reactions
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
Capponi L
(2020)
Delayed or absent p ( h 11 / 2 ) 2 alignment in Xe 111
in Physical Review C
Bucher B
(2016)
Direct Evidence of Octupole Deformation in Neutron-Rich ^{144}Ba.
in Physical review letters
Bree N
(2014)
Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation.
in Physical review letters
Alharbi T
(2012)
Electromagnetic Transition Rate Measurements in the N =80 Isotone, 138 Ce
in Journal of Physics: Conference Series
Alharbi T
(2013)
Electromagnetic transition rates in the N = 80 nucleus 58 138 Ce
in Physical Review C
Description | One of the main aims of our research programme is to achieve a better understanding of the structure and behaviour of exotic nuclei on both the neutron-rich and proton-rich sides of the valley of stability. Recent experimental observations, supported by theoretical calculations, have begun to suggest that the structure of neutron-rich nuclei may be different from those near stability. For example, the well known sequence of magic numbers, corresponding to energy gaps in nuclear shell structure, is now thought to change in nuclei with an extreme excess of neutrons. The evidence for such a change is already convincing around neutron number N=20, and similar effects are expected for the other shell gaps at N=28, 50, and 82. We will study the evolution of shell gaps in neutron-rich nuclei using both gamma-ray and charged-particle spectroscopy techniques. Above mass number A~100, electrostatic repulsion causes stable nuclei to have more neutrons than protons. Proton-rich nuclei just above the doubly-magic Sn100 nucleus are those with near equal numbers of neutrons and protons. These nuclei are known to decay by exotic decay modes such as proton emission. Spectroscopic study of the properties of these decays can give invaluable information about the properties of the nucleus in its ground state and in the first few excited states. Our research programme will include studies of proton-rich nuclei around A~110 by investigating their particle decays and by gamma-ray spectroscopy. Primarily, our experiments are carried out using state-of-the-art apparatus at large international facilities. Gamma-ray spectroscopy offers one of the best methods of studying the structure of exotic nuclei, and here we have exploited a variety of different experimental set-ups at different laboratories. |
Exploitation Route | This research uses state-of-the-art methods in experimental nuclear physics which involve precise techniques of radiation detection and measurement. The techniques used could be of use in various areas of industry and society such as nuclear medical imaging, environmental monitoring and nuclear forensics. |
Sectors | Education,Energy,Environment,Healthcare,Security and Diplomacy |