Description
Sponsored by School of Physics, University of the Witwatersrand
The lack of information on how biological systems respond to low-dose and low dose-rate radiation makes it difficult to accurately assess the corresponding health risks. This is of critical importance to space radiation, which remains a serious concern for long-term manned space exploration. Therefore, a growing number of particle accelerator facilities implement ground-based analogues to...
Abstract
Several properties of nuclear structure for even- even 124-130Barium nuclei have been explored with Interacting Boson Model. This work studies the systematic reduced transition probabilities B(E2) ↓ of Ba isotopes with even neutrons from N=68 to 74. The values of parameters have been determined with the formation of cubic terms by Casimir invariant operators and...
In this research, we tested a new idea to measure proton-distribution radii ($r_{\rm{p}}$) by heavy-ion secondary beam experiments. It is important for understanding the structures of nuclei to know the proton- and the neutron-distribution radii independently. From this point of view, we tried to develop a new method to deduce proton-distribution radii ($r_{\rm{p}}$) very efficiently using...
The advent of high-efficiency $\gamma$ ray spectrometers with multiple types of detectors, digital signal processing-based data acquisition system, and the realistic possibility of taking a stride in the hitherto unknown territory of nuclear landscape are driving the low- and medium-energy nuclear physics into the path of exciting exploration. With this in consideration, a novel facility,...
In nuclear reactions induced by low-energy charged particles, atomic electrons can participate in the process by screening the nuclear charge and so, effectively reduce the repulsive Coulomb barrier. Consequently, the measured cross section is enhanced by an effect called electron screening. In numerous experiments, different research groups [1-4] obtained extremely high values of electron...
Nuclei around doubly magic $^{208}$Pb have long served as a testing ground for the validity of the shell model. While the high-spin states of these nuclei have been studied extensively, data on electromagnetic transition rates between the low-spin states are scarce. Members of the $N = 125$ isotone chain – including $^{209}$Po, $^{211}$Rn and $^{213}$Ra – exhibit a ground state with...
The development of deformation in proton deficient N = 28 isotones is analyzed by employing relativistic Hartree-Bogoliubov (RHB) model based on recently introduced energy density functional DD-PCX. The calculations are performed by imposing constraints on axial and triaxial mass quadrupole moments. The regions of low-level density in neutron and proton single-particle states, around the Fermi...
Measurement of lifetime of nuclear excited states and extraction of electromagnetic transition strengths from that provides direct insight into nuclear structure. Gamma ray coincidence spectroscopy with new-age fast scintillator detectors, such as, LaBr$_{3}$(Ce) and CeBr$_{3}$ serves as a useful tool for lifetime measurements in sub-nanosecond ranges. Although the energy...
The study of exotic nuclei is presently a challenge for nuclear physics. Indeed, exotic nuclei properties are useful to investigate nuclear structure models, features of the nuclear force and nuclear reactions important for nuclear astrophysics. These investigations can be helpful also to add a further constraint to the knowledge of the Equation of State of nuclear matter. Within this...
17F is a well-known proton halo nucleus (Sp = 0.6 MeV) that can be described as a 16O core nucleus plus a weakly bounded proton. The 17F breakup mechanism can be induced by electromagnetic and nuclear interactions. Previous experiments of 17F breakup on 58Ni and 208Pb nuclei show a strong interference of Coulomb and nuclear breakup processes. New experimental data of 17F breakup on a 4He...
In recent years, the search for neutrinoless double beta ($0\nu\beta\beta$) decay has attracted much interest among physicists due to the extraordinary consequences that could derive from its observation. The NUMEN project aims to provide experimental information on the nuclear matrix elements involved in the expression of $0\nu\beta\beta$ decay half-life by measuring the cross section of...
Glioblastoma (GB) remains the most fatal brain tumor with a median survival of approximately 14 months and less than 10% of patients living longer than 5 years from diagnosis. GB tumors are characterized by a high infiltration rate and treatment resistance. At recurrence, there is no consensus on the standard of care as no therapeutic options thus far could demonstrate a substantial survival...
The enhancement of halo neutron removal cross sections in neutron halo nuclei is well known and is one of the evidences for the neutron halo structure. We have measured neutron removal cross sections for several exotic light nuclei to reveal their characteristic neutron-halo-like structures.(M.Fukuda et al, Phys. Lett. B 268, (1991), 339-344)
The difference in the nuclear structure between...
The Indian National Gamma Array (INGA), which moves between the three major accelerator centres in India, was recently setup at VECC, Kolkata. Moreover, a complementary horizontal array of clover detector, VENUS (VECC Nuclear Spectroscopy) array was also setup. Several experiments have been performed to study the medium and high spin states in nuclei with these two array using light ion...
With the advent of new facilities for radioactive ion beams mainly rich in neutrons, SPES @ LNL, FRAISE @ LNS and FAIR @ GSI to give some examples, the detection of neutrons and charged particles in Heavy radioactive Ion collisions with both high angular and energy resolutions became a mandatory request. As a consequence, the construction of new multi-detection systems suitable for...
The resonance structure in 11C is important to understand 7Be(α,γ)11C reaction in the pp-chain of Sun and for the 10B(p,α)7Be reaction as the contamination of the candidate of aneutronic fusion reaction 11B(p,2α) 4 He. Above the proton threshold, there are discrepancies in the excitation energies and lack of spin-assignment for the resonances in 11C nucleus. For this, an elastic scattering...
Studies of the "heavy" island of inversion near the N=40 isotones between Ca and Ni have, to date, focused on determining the degree of collectivity in even-even nuclei using properties of 2+ transitions. While collective rotational structures are understood to be present, limited results are available to characterize these structures. In this work, we report on the results from an experiment...
Chirality is a subject of general interest in natural science. Nuclear chirality was first predicted in 1997 [1], and up to now more than 60 candidate chiral doublet bands in around 50 nuclei have been reported [2]. Based on the covariant density functional theory, a phenomenon named multiple chiral doublets (MχD), i.e., more than one pair of chiral doublet bands in one single nucleus, was...
Atomic nuclei are unique quantum-body systems where the spontaneous symmetry breaking phenomena enrich a variety of shapes and structures. In recent years, the nuclei lying in the vicinity of the mid-shell region have attracted considerable attention as it exhibits a class of remarkable phenomena such as shape coexistence, shape evolution, octupole correlations, chirality, etc. The...
The tungsten isotopes exist in a region of deformed nuclei with soft, triaxial shapes that evolve into oblate deformation as the proton, Z, and (or) neutron, N, numbers increase, before reaching sphericity at $Z = 82$ [1]. The heaviest stable W ($Z = 74$) isotope is at $A=186$. Its low-lying structure has been investigated in the past using Coulomb excitation [2] and $\beta$ decay [3];...
The atomic nucleus is a fundamental and unique laboratory of nature for investigating the relationships among the fundamental symmetries. Exploring the relations between these symmetries is one of the major objectives of present-day researches. The nucleon-nucleon interactions inside the nucleus play a crucial role in the occurrence of various exotic phenomena like shape coexistence,...
A recent ab-initio calculation of the monopole transition form factor of $^4$He (Phys. Rev. Lett. 110, 042503 (2013)) pointed to a strong dependence on the different realistic potentials used. The inconsistencies met between the recent ab-initio form factor calculation and the existing data from $^4$He(e,e‘)$^4$He* call for further investigation. In order to shed some light on this challenging...
The yrast spectra and electromagnetic properties of even-even medium mass tellurium isotopes are studied by employing projected shell model. From the analysis of projected shell model wave functions, the structure of yrast states is predicted. The low-lying yrast states up to spin 4+ are predicted to arise from zero-quasiparticle (qp) bands whereas the yrast 6+ states arise from 2-qp proton...
In this work, the principal results of data analysis of the reactions 78Kr +40 Ca and 86Kr +48Ca at laboratory energy of 10 AMeV, will be presented.
The experiment has been carried out at INFN-Laboratori Nazionali del Sud, with the 4π multidetector CHIMERA, which is used for the first time in this low energy regime, thanks to the implementation of its identification capabilities (pulse shape...
Single nucleon transfer reactions are considered among the best resources for probing single particle configurations in the populated many-body nuclear states. Besides a valuable spectroscopic tool, transfer reactions offer also an insight of the reaction dynamics. An example is the study of the degree of competition between sequential nucleon transfer and charge exchange reactions, the latter...
The interacting boson model-1 has been used to calculate the reduced electric transition probability B(E2) ↓ of even-even 122-130Te (Tellurium) isotopes with even neutrons from N = 70 to 78. The three-three boson interactions are also formed in the Hamiltonian from Casimir invariant operators. The parameters of best fit to measure the data is used from the experimental value of B (E2; 21+ →...
The aim of the study was to design a radon chamber for the calibration of radon monitors at the Centre for Applied Radiation Science and Technology. There are radon monitors in South Africa, however, there are no known calibration facilities in the country. Therefore, there is a need to design radon chambers. The radon chamber was designed with a Perspex material of thickness 6mm and of volume...
Observations of Ultra Metal Poor stars such as HD 221170 [1] show that the abundances of elements heavier than silver can be reliably predicted by models of nucleosynthesis. However, elements between iron and silver have much higher observed abundances than predicted by models which only consider the ‘normal’ r- and s- processes. A potential solution for these underestimates is an extension of...
Although logic would suggest the contrary, it seems that cancer incidence is not related to body size (number of cells) and species life span (number of cell divisions). Large, long-living mammals, such as elephants, have no increased risk of developing cancer compared to smaller mammals with fewer cells and shorter lifespans. This lack of correlation between body size, life span and cancer...
