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Research Projects

Current

The ongoing projects and recently funded are given below

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Plunger and Charge Plunger

  2018 - now

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We have a few ongoing projects to measure lifetimes of excited states in exotic nuclei using the standard plunger (based on the detection of gamma rays) and charge plunger (based on the detection of ionic charge states) techniques.  

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In 2019, we revived and established the charge plunger technique using a plunger device at the MARA separator, opening up the gateway to study a variety of phenomena in nuclei, including the stability of superheavy nuclei and emergence of exotic shapes and symmetries in nuclei through a campaign of lifetime measurements.    

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We are on the way to further develop the applicability of the technique with a new experiment in June 2022

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For further information, see..  

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http://ebulletin.uws.ac.uk/2019/08/new-method-to-measure-the-lifetimes-of-the-heaviest-atomic-nuclei-study-led-by-uws-academic/.  

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https://research-portal.uws.ac.uk/en/publications/lifetime-measurements-of-yrast-states-in-sup178suppt-using-the-ch 

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https://research-portal.uws.ac.uk/en/publications/a-charge-plunger-device-to-measure-the-lifetimes-of-excited-nucle

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Two PhD studentships are available

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Funding status: Available to self-funded students

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A NEW TECHNIQUE TO STUDY SHAPES OF SHORT-LIVED NUCLEI

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Project Description: The nature of nuclear force gives nuclei in different parts of the nuclear chart different shapes. The most prevalent are rugby ball shapes while spherical shapes are found in some nuclei. Although rare, nuclei are found in pancake type and reflection-asymmetric pear shapes. Some nuclei also take spinning top like shapes. Experimental studies of shapes in short-lived nuclei constitute a major area of current nuclear-research and have been a major focus of the proposals, especially at laboratories such as CERN. The underlying reason for the intense interest is the following. An atomic nucleus is a quantum-mechanical system and the emergence of a shape is a direct consequence of the interaction between nucleons. Therefore, studies of shapes and shape dynamics in nuclei give information about nuclear force that is yet to be fully understood. At CERN we have recently proposed experiments based on a new method to study shapes of radioactive nuclei. This method allows nuclei to interact through two of the four fundamental forces of nature, namely, Coulomb and nuclear forces. The nuclei absorb energy due to these time-varying forces and find themselves in excited states. After the excitation, they emit radiation by rearranging nucleons to come back to their ground states. This radiation is an information carrier of shape of a nucleus. Such data has been obtained from a recent experiment that will be analysed during this project. Further data will also be obtained from CERN and elsewhere. During the project, an analysis of the data from CERN, design work for experiments at other laboratories, participation in the experiments and an analysis of new data from future experiments will be carried out. It is preferable to have some prior knowledge of basic nuclear physics, C++ and Linux operating systems.

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STUDY OF NUCLEI WITH SIMILAR PROTON AND NEUTRON NUMBERS

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Project Description: A nucleus has protons and neutrons as constituents that experience nuclear force among them. It is an approximation that the nuclear force between two protons is the same as that between two neutrons or a proton and neutron. In reality, this may not be the case because proton carries a positive charge while neutron has no charge. In fact, it is an open problem how the interactions between proton-proton, neutron-neutron and proton-neutrons change across the nuclear chart. How these three interactions evolve for nuclei with same protons and neutron number as the mass is changed is particularly interesting. Firstly, such nuclei, known as self-conjugate nuclei are very good laboratories to study the proton-neutron interaction because the probability to find protons and neutrons close by is very high. This interaction may also be responsible to alter the shapes of nuclei as they absorb energy or as the number of nucleons is changed. The properties of these nuclei are also important to understand composition of our bodies from start dust as these nuclei are in the pathways of astrophysical processes that occur in in our universe. Furthermore, the nuclei have the special Fermi super allowed beta decay that allows precision tests of the standard model of particle physics. During this project development of a detector for the study of these nuclei will be carried out. The objectives include, but not limited to, designing the detector, participating in test experiments, analysing data from these experiment and incorporating it in the experiments of self-conjugate nuclei to address the aforementioned physics. Some knowledge of radiation detection, hands-on experience working with detectors, experience with C++ programming and Linux systems is desirable.

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Research: Research

Current

The ongoing projects recently funded are given below

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Nuclear Astrophysics 

February  2022

For details on the Project with CMAM/CSIC see 

https://s34-uws.web.cern.ch/default.htm

 

Predictions of the standard big bang nucleosynthesis model disagree with the observations of the abundance of lithium-7 (7Li) by a factor of three.  Solving this open problem is of high priority in nuclear astrophysics and requires an accurate 3He(alpha, gamma)7Be reaction rate as input for the calculations.

 

The sun produces neutrinos via this reaction, therefore, the rate is required to predict the solar-neutrino flux and compare it with the observations to study physics beyond the standard model of particle physics.

 

We are developing a new γ-ray detection setup to measure the reaction rate using the accelerator at CMAM, Madrid with high accuracy to help solve the cosmological lithium-7 problem. 

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This project is in collaboration with Prof. O. Tengbald, CSIC, Madrid and supported by the RSE SALTIRE INTERNATIONAL COLLABORATION AWARDS 

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A PhD studentship is available

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Funding status: Available to self-funded students

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MEASUREMENT OF THE HE-3(ALPHA, GAMMA)BE-7 REACTION RATE

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Project Description: Big bang nucleosynthesis occurred at very high temperatures (~1000000000K or 109K), producing light elements like helium and lithium through the fusion of hydrogen. Predictions of the standard big bang nucleosynthesis model disagree with the observations of abundance of mass-7 isotope of lithium (7Li) by nearly a factor three. This is an open problem in nuclear astrophysics. Solving this lithium puzzle is currently of high priority that requires accurate knowledge of the 3He(alpha,gamma)7Be reaction rate. Hydrogen is turned into helium in our sun at temperatures ~6000K. Several other fusion reactions follow, producing energy that is required to maintain life here on earth. The reactions also produce neutrinos that reach us here on earth, which are detected to study physics beyond the standard model of particle physics. The 3He(alpha,gamma)7Be reaction rate is also required to calculate the number of neutrinos that can be detected on earth using the standard solar model and compare it with the observations. Measurements of the 3He(alpha,gamma)7B reaction rate will be performed by directly counting 7Be fusion products using mass separators or through gamma-ray detection. For these measurements, the facilities in Vancouver, Canada, and Madrid, Spain would be used. The data from these experiments will help us solving the 7Li puzzle, testing the nuclear reaction theories, the standard big bang nucleosynthesis model, the standard solar model and the standard model of particle physics.

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A sketch of the prompt-gamma ray setup to be used at the CMAM facility in Madrid is shown below.

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Coupling among quadrupole, octupole and hexadecapole
degrees of freedom in nuclei

December, 2021

The nucleus is a quantum mechanical system where the strong, electromagnetic and weak forces are in action and nucleons occupy orbitals forming structured shells.  Nuclei with filled shells, so-called “closed shells” take spherical shapes, while non-spherical “deformed” shapes are known for open-shell nuclei. The most common deformed shapes observed for nuclei across the Segre chart are "rugby ball" or prolate and "disc" or oblate shapes that are characterised by a non-zero quadrupole deformation (|beta2|>0). Some nuclei take "spinning top" shapes with hexadecapole deformations (|beta4|>0). Both beta2 and beta4 deformations give rise to axially symmetric reflection-symmetry shapes, while octupole deformations (|beta3|>0) break reflection symmetry leading to axially asymmetric “pear” shapes for nuclei. It is an open problem – how deformations and properties of nuclei transpire near open shells as a result of competition among quadrupole, octupole, and hexadecapole degrees of freedom. In addition, the matter-antimatter asymmetry puzzle may have a solution in “pear-shaped” nuclei that are good candidates for searching electron dipole moment.  In general, all three quadrupole, octupole, and hexadecapole deformations may be present in a deformed nucleus. The magnitudes of these deformations may also change with the excitation energy within the nucleus. This complexity is rooted in the effective interaction between nucleons, which is composed of couplings between quadrupole and octupole, and/or octupole and hexadecapole correlations.

 

This project is funded by the Royal Society International Exchanges.  The work will be carried out in collaboration with Prof. Luis Robledo, Universidad Autonoma de Madrid, Madrid to study nuclei with such complicated shapes to provide an insight into the aforementioned couplings for the first time by invoking beta3 and beta4 that are usually not considered.

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July, 2021

Development of a segmented
LaBr3(Ce)-detector module to improve
nuclear data collection 

Compton events give rise to low-energy Compton background, severely degrading the resolving power (RP) of a gamma-ray spectrometer. This effect can be partly eliminated either by suppressing these events or by applying addback methods to them (Compton addback, CA).  This project is in collaboration with University of York aims to improve RP by exploiting CA for sufficiently segmented novel LaBr3(Ce) scintillators with relatively good intrinsic resolution and efficiency.  The enhanced resolving power and identification of gamma rays of the new detector modules will directly impact a wide variety of areas in industrial and academic nuclear data research. For example, both the energy and timing performances of the UK-FATIMA array of LaBr3(Ce) detectors, that are strongly affected by Compton background, can be improved.

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A PhD studentship is available

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Project summary:  UK Nuclear Data Network (UKNDN) funded a grant started in 2021  to develop a detector to improve nuclear data for the energy, security, and health industries and contribute to techniques used for fundamental nuclear research.   This development will help answer key questions in nuclear astrophysics such as the longstanding 7Li puzzle. Research in this area has been funded by an RSE grant to start in 2022.  The student will have the opportunity to work on experiments, data analysis and simulations for the detector development, tests using materials from assays and nuclear astrophysics experiments. 
 

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