Properties Of Isotopes Research Articles

On the Possibility of Delayed Fission of Nuclei in the Region of Superheavy Transuranium Elements

Delayed fission of atomic nuclei was discovered in 1966. It is observed primarily in odd–odd nuclei for which the energy released in beta decay (K capture) is commensurate with the fission barrier in the nucleus formed after this process. Delayed fission was found in four nuclide regions: neutrondeficient isotopes in the Pb region, neutron-deficient isotopes in the Ac and Pa regions, and neutrondeficient and neutron-rich isotopes of transuranium elements. In the wake of investigations into the properties of isotopes of superheavy transuranium elements, numerous calculations were performed in order to determine the masses of new nuclei and to predict their decay properties. Explored and predicted properties of superheavy-element nuclides, where, for some odd–odd nuclei of transuranium elements, the K-capture energy is commensurate with the fission barriers in the corresponding daughter nuclei formed after K capture, are analyzed. Estimates of the delayed-fission probability are presented for some isotopes of elements whose charge number Z ranges from 103 to 107.

The Examination of the Halo Nucleus Properties of 6-11Li Isotopes According to the Shell Model

The Examination of the Halo Nucleus Properties of 6-11Li Isotopes According to the Shell Model

Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

Octupole deformation and the relevant spectroscopic properties of neutron-rich odd-mass barium isotopes are investigated in a theoretical framework based on nuclear density functional theory and the particle-core coupling scheme. The interacting-boson Hamiltonian that describes the octupole-deformed even-even core nucleus, as well as the single-particle energies and occupation probabilities of an unpaired nucleon, are completely determined by microscopic axially-symmetric $(\beta_{2},\beta_{3})$-deformation constrained self-consistent mean-field calculations for a specific choice of the energy density functional and pairing interaction. A boson-fermion interaction that involves both quadrupole and octupole degrees of freedom is introduced, and their strength parameters are determined to reproduce selected spectroscopic data for the odd-mass nuclei. The model reproduces recent experimental results both for the even-even and odd-mass Ba isotopes. In particular, for $^{145,147}$Ba our results indicate, in agreement with recent data, that octupole deformation does not determine the structure of the lowest states in the vicinity of the ground state, and only becomes relevant at higher excitation energies.

The thermal dependence of carbon stable isotope incorporation and trophic discrimination in the domestic cricket, Acheta domesticus

Stable isotopes are valuable tools in physiological and ecological research, as they can be used to estimate diet, habitat use, and resource allocation. However, in most cases a priori knowledge of two key properties of stable isotopes is required, namely their rate of incorporation into the body (incorporation rate) and the change of isotope values between consumers and resources that arises during incorporation of the isotopes into the consumer’s tissues (trophic discrimination). Previous studies have quantified these properties across species and tissue types, but little is known about how they vary with temperature, a key driver of many biological rates and times. Here, we explored for the first time how temperature affects both carbon incorporation rate and trophic discrimination via growth rates, using the domestic cricket, Acheta domesticus. We raised crickets at 16 °C, 21 °C, and 26 °C and showed that temperature increased carbon isotope incorporation rate, which was driven by both an increased growth rate and catabolism at higher temperatures. Trophic discrimination of carbon isotopes decreased at higher temperatures, which we attributed to either lower activation energies needed to synthesize non-essential amino acids at higher temperatures or the increased utilization of available resources of consumers at higher temperatures. Our results demonstrate that temperature is a key driver of both carbon isotope incorporation rate and trophic discrimination, via mechanisms that likely persist across all ectotherms. Experiments to determine incorporation rates and trophic discrimination factors in ectotherms must include temperature as a major factor, and natural variation in temperature might have significant effects on these isotopic properties that then can affect inferences made from isotope values.

Principles of Radiometric Dating

Even after more than 100 years of the initial discovery of isotopes, we are yet to fully utilize their potential in science and technology. The unique properties of isotopes of elements covering the entire periodic table have wide-ranging applications. The modern earth and planetary sciences owe a lot to such exploits for understanding of the fundamental aspects of evolution of the solar system and planetary interiors. Isotopes have remained the most advanced tools in determining the timescales of various events that shaped the solar system and understanding the nature of processes that occur in it. Isotopes are either stable or radioactive. Stable isotopes are powerful tracers of geochemical processes, whereas radioactive isotopes and their products (radiogenic isotopes) are the basis of geochronology or radiometric dating.

Ground-state Nuclear Properties of Neutron-rich Copper Isotopes and Lepton Capture Rates in Stellar Matter

Ground-state Nuclear Properties of Neutron-rich Copper Isotopes and Lepton Capture Rates in Stellar Matter

Nuclear structure with radioactive muonic atoms

Muonic atoms have been used to extract the most accurate nuclear charge radii based on the detection of X-rays from the muonic cascades. Most stable and a few unstable isotopes have been investigated with muonic atom spectroscopy techniques. A new research project recently started at the Paul Scherrer Institut aims to extend the highresolution muonic atom spectroscopy for the precise determination of nuclear charge radii and other nuclear structure properties of radioactive isotopes. The challenge to combine the high-energy muon beam with small quantity of stopping mass is being addressed by developing the concept of stopping the muon in a high-density, a high-pressure hydrogen cell and subsequent transfer of the muon to the element of interest. Status and perspectives of the project will be presented.

Systematic shell-model study on spectroscopic properties from light to heavy nuclei

A systematic shell-model study is performed to study the spectroscopic properties from light to heavy nuclei, such as binding energies, energy levels, electromagnetic properties, and β decays. The importance of cross-shell excitation is shown in the spectroscopic properties of neutron-rich boron, carbon, nitrogen, and oxygen isotopes. A special case is presented for low-lying structure of 14C. The weakly bound effect of proton 1s1/2 orbit is necessary for the description of the mirror energy difference in the nuclei around A=20. Some possible isomers are predicted in the nuclei in the southeast region of 132Sn based on a newly suggested Hamiltonian. A preliminary study on the nuclei around 208Pb are given to show the ability of the shell model in the heavy nuclei.

A systematic study of band structure and electromagnetic properties of neutron rich odd mass Eu isotopes in the projected shell model framework

The positive and negative parity rotational band structure of the neutron rich odd mass Eu isotopes with neutron numbers ranging from 90 to 96 are investigated up to the high angular momentum. In the theoretical analysis of energy spectra, transition energies and electromagnetic transition probabilities we employ the projected shell model. The calculations successfully describe the formation of the ground and excited band structures from the single particle and multi quasiparticle configurations. Calculated excitation energy spectra, transition energies, exact quantum mechanically calculated B(E2) and B(M1) transition probabilities are compared with experimental data wherever available and a reasonably good agreement is obtained with the observed data. The change in deformation in the ground state band with the increase in angular momentum and the increase in neutron number has also been established.

Spontaneous fission properties of superheavy elements

Spontaneous fission properties of transuranium isotopes are reviewed. Specific emphasis was laid on brief historical overviews of theoretical descriptions and experimental determination of basic properties as spontaneous fission half-lives, fission barriers, or total kinetic energy release in fission. Experimental spontaneous fission half-lives are compared with the results of recent theoretical predictions. Hindrance factors for spontaneous fission of odd-mass nuclei are discussed in context with the configuration (spin, parity) of the fissioning states and the change in energy of single particle levels at deformation. Kinetic energy release and mass distributions are discussed in the context of different fission modes, as symmetric and asymmetric or fission from elongated or compact shapes of the nascent fission fragments. An overview of recent fission barrier calculations of superheavy elements on the basis of macroscopic-microscopic models or self-consistent calculations is given, and the results are compared for selected examples.

Shell Model Description of the $${}^\mathbf{32,34,36}$$ 32 , 34 , 36 S Isotopes

The energy spectra and electromagnetic properties of Sulfur isotopes have been carried out using the PSDPF interaction. A detailed comparison, experiment versus theory, is presented for these isotopes with A = 32 (N = Z), 34 (N = Z + 2) and 36 (N = Z + 4) for normal 0\( {\hbar {\omega }} \) (positive parity) and intruder 1\( {\hbar {\omega }}\) (negative parity) states up to excitation energies of several MeV. Electric E2 and E3 transition strengths are also calculated and compared to available data.

β -decay properties of neutron-rich rare-earth isotopes

In this paper, beta-decay properties of even-even neutron-rich isotopes in the rare-earth mass region are studied within a microscopic theoretical approach based on a proton-neutron quasiparticle random-phase approximation. The underlying mean field is constructed selfconsistently from a deformed Hartree-Fock calculation with Skyrme interactions and pairing correlations to which particle-hole and particle-particle residual interactions are added. Nuclei in this mass region participate in the astrophysical rapid neutron capture process and are directly involved in the generation of the rare-earth peak in the isotopic abundance pattern centered at A=160. The energy distributions of the Gamow-Teller strength as well as the beta-decay half-lives and the beta-delayed neutron-emission probabilities are discussed and compared with the available experimental information and with calculations based on different approaches.

The oxygen isotopes

The properties of the oxygen isotopes provide diverse examples of progress made in experiments and theory. This chain of isotopes has been studied from beyond the proton drip line in [Formula: see text]O to beyond the neutron drip line in [Formula: see text]O. This short survey starts with the microscopic G matrix approach for [Formula: see text]O of Kuo and Brown in the 1960’s and shows how theory has evolved. The nuclear structure around the doubly-magic nucleus [Formula: see text]O is particularly simple in terms of the nuclear shell model. The nuclear structure around the doubly-magic nucleus [Formula: see text]O exhibits the coexistence of single-particle and collective structure.

Measurement of the heaviestβ-delayed 2-neutron emitter:136Sb

The β-delayed neutron emission probability, Pn , of very exotic nuclei is crucial for the understanding of nuclear structure properties of many isotopes and astrophysical processes such as the rapid neutron capture process (r -process). In addition β-delayed neutrons are important in a nuclear power reactor operated in a prompt sub-critical, delayed critical condition, as they contribute to the decay heat inducing fission reactions after a shut down. The study of neutron-rich isotopes and the measurement of β-delayed one-neutron emitters (β1n) is possible thanks to the Rare Isotope Beam (RIB) facilities, where radioactive beams allow the production of exotic nuclei of interest, which can be studied and analyzed using specific detection systems. This contribution reports two recent measurements of β-delayed neutron emitters which allowed the determination of half-lives and the neutron branching ratio of isotopes in the mass region above A = 200 and N > 126, and a second experiment which confirmed 136 Sb as the heaviest double neutron emitter (β2n) measured so far.

Use of molybdenum as a structural material of fuel elements for improving the safety of nuclear reactors

Main purpose of the study is justifying the use of molybdenum as a structural material of fuel elements for improving the safety of nuclear reactors. Particularity of used molybdenum is that its isotopic composition corresponds to molybdenum, which is obtained as the tailing during operation of the separation cascade for producing a material for medical diagnostics of cancer.When performing the study the neutron-physical properties of isotopes of natural molybdenum (nuclear data library JENDL-4.0) and thermal properties of metallic molybdenum were used. The following results were obtained:1. A method for reducing the thermal constant of fuel elements for light water and fast reactors by using dispersion fuel in cylindrical fuel rods containing, for example, granules of metallic U-Mo-alloy into Mo-matrix was proposed.2. The necessity of molybdenum enrichment by weakly absorbing isotopes was shown.3. Total use of isotopic molybdenum will be more than 50%.A method for reducing the thermal constant of the fuel elements, allowing us to increase the safety of light water and fast nuclear reactors by using dispersion fuel in cylindrical fuel rods containing, for example, granules of metallic U-Mo-alloy into Mo-matrix with enrichment by weakly absorbing isotopes of molybdenum is proposed.

Ground State Properties of Isotopes within the Relativistic Mean Field Model**Supported by the National Natural Science Foundation of China under Grant Nos. 11675066, 11475050, 11265013, and the CAS Knowledge Innovation under Grant No. KJCX2-EW-N02

The ground state properties of isotopes with neutron numbers are calculated by the relativistic mean field (RMF) theory with effective interactions NL-Z2. In order to make a comprehensive understanding of the possible proton magic number , we also perform the calculations in the vicinity of , such as and 130 isotopic chains. The calculated results show there exist evident magicity for proton number and relatively weak magicity for proton number .

Shell-model configuration-interaction description of quadrupole collectivity in Te isotopes

Systematic calculations on the spectroscopy and transition properties of even-even Te isotopes are carried out by using the large-scale shell-model configuration-interaction approach with a realistic interaction. These nuclei are of particular interest since their yrast spectra show a vibrational-like equally spaced pattern whereas the few known $E2$ transitions show rotational-like behavior. This cannot be explained by available collective models. My calculations reproduce well the equally spaced spectra of those isotopes as well as the constant behavior for the $B(E2)$ values of $^{114}\mathrm{Te}$. The calculated $B(E2)$ values of neutron-deficient and heavier Te isotopes show contrasting different behaviors along the yrast line. The $B(E2)$ of light isotopes can exhibit a nearly constant behavior up to high spins. It is shown that this is related to the enhanced neutron-proton correlation when approaching $N=50$.

Estimation of thermodynamic properties of hydrogen isotopes and modeling of hydrogen isotope systems using Aspen Plus simulator

Abstract Physical properties of hydrogen isotopes, hydrogen (H2), hydrogen-deuterium (HD), hydrogen-tritium (HT), deuterium (D2), deuterium-tritium (DT), and tritium (T2) were estimated through vapor pressure prediction, and validated by steady-state simulation of ITER isotope separation system (ISS). Peng–Robinson (PR) equation of state with Twu alpha function was selected for modelling which showed favorable prediction from the experimental vapor pressures of each hydrogen isotopes. The steady-state simulation of ITER ISS using Aspen Plus consists of four distillation columns and seven equilibrium reactors with four purified products: D2, T2, HD, and DT. Converged solution from simulation produced potential scenario for actual ITER ISS process.

Thermal properties of the Tin odd isotopes 117,119,121Sn

We propose to study the thermal properties of the odd isotopes of Tin: [Formula: see text]Sn. To this end, one used two methods to evaluate the properties of these elements. The first theoretical consideration uses a simple prescription to perform the calculation of these properties based on those of even–even neighboring isotopes, assuming the quasi-particle entropy extensivity. The even–even elements are treated as part of the Modified Lipkin–Nogami (MLN) method that allows to take into account the quantal and statistical fluctuations. The second theoretical approach consists of the generalization of the MLN formalism in the case of odd systems, by using the blocking technique. Then, this approach is applied to evaluate the thermal properties of the considered elements. The obtained results by both theoretical approaches are compared to the experimental data. The latter are deduced from the experimental level density within the canonical ensemble. It appears that the assumption of quasi-particle entropy extensivity at low excitation energy allows a simple and an effective treatment of thermal properties of odd nuclei. Indeed, this approach allows to give a good reproduction of experimental data in the particular in the region where the pairing transition occurs.

Hartree–Fock–Bogoliubov calculation of ground state properties of even–even and odd Mo and Ru isotopes

In a previous work (El Bassem and Oulne (2015) [20]), hereafter referred to as paper I, we have investigated the ground-state properties of Nd, Ce and Sm isotopes within Hartree–Fock–Bogoliubov method with SLy5 Skyrme force in which the pairing strength has been generalized with a new proposed formula. However, that formula is more appropriate for the region of Nd. In this work, we have studied the ground-state properties of both even–even and odd Mo and Ru isotopes. For this, we have used Hartree–Fock–Bogoliubov method with SLy4 Skyrme force, and a new formula of the pairing strength which is more accurate for this region of nuclei. The results have been compared with available experimental data, the results of Hartree–Fock–Bogoliubov calculations based on the D1S Gogny effective nucleon–nucleon interaction and predictions of some nuclear models such as Finite Range Droplet Model (FRDM) and Relativistic Mean Field (RMF) theory.