Determining the role of non-axial deformation on proton decays; DPUNS - A Differential Plunger for Unbound Nuclear States.

Lead Research Organisation: University of Manchester
Department Name: Physics and Astronomy

Abstract

This grant will further our understanding of one of the fundamental limits of nuclear stability. As more and more protons are added to a nucleus there comes a point at which the nucleus can no longer hold on to the last proton. This point is called the proton drip line. The last proton will usually be re-emitted in a very short time, on the scale of milliseconds or microseconds, after it has been absorbed. Nevertheless, excited states which decay by gamma-ray emission, on a picosecond time scale, can still exist in proton-unbound nuclei. In this grant we will characterise these excited states by building a new detector, DPUNS, which will uniquely allow the measurement of their lifetimes. This in turn permits, for the first time, the determination of the shapes of proton-unbound nuclei. Since the proton emission half-life depends sensitively on the shape of the nucleus, a consistent understanding of proton decay is our objective. This proposal contains a collaborative aspect with some of the world's experts in proton decays. Together, we will perform new calculations with unique new data to examine the role of asymmetric nuclear shapes on the proton emission rates and thereby, learn about the binding of the nuclear force. This is a challenging proposal which has the potential to bring about a step change in our ability to investigate nuclear structure beyond the proton drip line.

Publications

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Procter M (2012) Electromagnetic transition strengths in 52 109 Te in Physical Review C

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Procter M (2011) High- K four-quasiparticle states in Gd 138 in Physical Review C

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Procter M (2013) Proton emission from an oblate nucleus 151Lu in Physics Letters B

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O'Donnell D (2009) Spectroscopy of the neutron-deficient nucleus Os 167 91 in Physical Review C

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Nyman M (2015) First observation of superdeformed states in 191Bi in The European Physical Journal A

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Nara Singh B (2018) Level structure above the 17 + isomeric state in Tm 83 69 152 in Physical Review C

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Müller-Gatermann C (2018) Low-lying electromagnetic transition strengths in Pt 180 in Physical Review C

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Mason P (2010) Spectroscopy of Ho 144 using recoil-isomer tagging in Physical Review C

 
Description In this award, a new differential plunger device was built which enable the lifetime of nuclear states in exotic nuclei to be determined for the first time. This information was used to guid nuclear theory and gain a better understanding of how proton are emitted from exotic nuclei at the limits of nuclear existence.
Exploitation Route The new device is being used in collaboration by other international users to further their research at the moment in Finland.
Sectors Education

Electronics

 
Description STFC Industrial CASE Studentship Panel (Dave Cullen)
Geographic Reach National 
Policy Influence Type Membership of a guideline committee
URL https://stfc.ukri.org/funding/studentships/industrial-case-studentships/
 
Description Nuclear physics consolidated grant 2014
Amount £1,300,000 (GBP)
Funding ID ST/L005794/1 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 07/2014 
End 09/2018
 
Title A new charge plunger device to measure the lifetimes of excited nuclear states with transitions dominated by internal conversion 
Description The DPUNS plunger device has been adapted to allow for a different method of measuring nuclear lifetimes that does not rely on the detection of gamma rays. Instead, the charge state distribution of excited nuclei is detected as a function of plunger distance. This allows for the measurement of nuclear lifetimes that depopulate through transitions that have a low rate of gamma ray emission, such as a in super-heavy nuclei and low energy transitions, that would not have been possible with the standard DPUNS plunger approach. This work is currently being prepared for publication. 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact The application of the charge plunger technique to DPUNS will allow for lifetime measurements to be made in super-heavy nuclei that were not previously accessible. There are a lack of experimental lifetime measurements for excited states in super-heavy nuclei, while there are several motivations for obtaining them. The application of this method with the adapted DPUNS plunger will allow for shell-gaps and deformation in super-heavy nuclei to be determined. 
URL http://www.doi.org/10.1016/j.nima.2020.164454
 
Title DPUNS - A new differential plunger device was constructed to measure the lifetime of exotic nuclear states. 
Description DPUNS - A new differential plunger device was constructed to measure the lifetime of exotic nuclear states. This device enable the lifetime of nuclear states to be measured in exotic nuclei beyond the drip line for the first time. The device enable a new simultaneous theoretical approach to determining proton-emission and gamma-emission rates in nuclei. The plunger device was commissioned in Finland and is now used by a series of international groups to further their research. 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact The plunger device was commissioned in Finland and is now used by a series of international groups to measure liefeimte in nuclei beyond what was originally thought o be possible. A series of papers have been published in high-impact journals, Physical Review Letters, Physics Letters B and Physical Review C. 
 
Title TPEN- A new triple-foil differential plunger device was constructed to measure the lifetime of exotic nuclear states. 
Description TPEN- A new Triple Foil differential plunger device was constructed to measure the lifetime of exotic nuclear states. This device enable the lifetime of nuclear states to be measured in exotic nuclei and was able to reduce the beam time required by a factor of 4 over previous plunger devices. The plunger device was commissioned in Finland and is now used by a series of international groups to further their research. 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? Yes  
Impact Research papers have been produced based on this device. 
 
Title Several large database of nuclear gamma-ray spectroscopy for lifetime analysis of particular isotopes. 
Description These databases consist of collections of gamma-ray coincidence data for transitions between nuclear energy levels in a series of isotopes produced in heavy-ion fusion-evaporation reactions with large arrays of germanium detectors. The data are primarily constructed for analysing nuclear state lifetimes. 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? No  
Impact Mainly publications and invited talks. 
 
Description IFIN-HH, Romania 
Organisation Horia Hulubei National Institute of Physics and Nuclear Engineering
Country Romania 
Sector Public 
PI Contribution Our collaboration performed lifetime measurements of excited states in the triaxial nucleus 163Ta using the DPUNS device.
Collaborator Contribution P. Petkov at IFIN-HH performed particle-triaxial rotor model calculations in order to describe the experimental lifetimes of 163Ta in a theoretical framework. The partners have also provided our collaboration with the codes themselves, which have since been developed by our collaboration.
Impact Experimental lifetimes in 163Ta have been successfully described by the particle-triaxial rotor model. The contributions from this collaboration are being prepared for publication.
Start Year 2019
 
Description Univeristy of Jyvaskyla 
Organisation University of Jyvaskyla
Department Department of Physics
Country Finland 
Sector Academic/University 
PI Contribution Brought the differential plunger to JYFL in order to carry out experiments with this device
Collaborator Contribution Collaboration supportedd this device and paid for some infrastructure.
Impact Many publications and support for additional STFC grant proposals
 
Description University of Cologne 
Organisation University of Cologne
Department Department of Physics
Country Germany 
Sector Academic/University 
PI Contribution Collaboration on experiments involving plungers and differential plunger devices for lifetime measurements.
Collaborator Contribution The partner has provided expertise and knowledge to this collaboration.
Impact Several research papers
Start Year 2008