Nuclear Pairing Research Articles

Simulation of heavy ion collision using a time-dependent density functional theory including nuclear superfluidity

We carried out a simulation of heavy ion collision using a time-dependent density functional theory. We call it the canonical-basis time-dependent Hartree-Fock-Bogoliubov theory (Cb-TDHFB) which can describe nuclear dynamics in three-dimensional coordinate space, treating nuclear pairing correlation. We simulate 20O+20O collision using the Cb-TDHFB with a contact-type pairing functional, and show the behavior of gap energy which is decreasing and vibrating while colliding.

Role of neutrons and protons in entropy, spin cut off parameters, and moments of inertia

The nuclear level densities, spin cut off parameters, and entropies have been extracted in ${}^{116\ensuremath{-}119}$Sn and ${}^{162,163}$Dy nuclei using superconducting theory, which includes nuclear pairing interaction. The results agree well with the recent data obtained from experimental level densities by the Oslo group for these nuclei. Also, the entropy excess ratio proposed by Razavi et al. [R. Razavi, A.N. Behkami, S. Mohammadi, and M. Gholami, Phys. Rev. C 86, 047303 (2012)] for a proton and neutron as a function of nuclear temperature have been evaluated and are compared with the spin cut off excess ratio. The role of the neutron (proton) system is well determined by the entropy excess ratio as well as the spin cut off excess ratio. The moment of inertia for even-odd and even-even nuclei are also compared. The moment of inertia carried by a single hole is smaller than the single particle moment of inertia.

Detailedβ-transition rates for URCA nuclear pairs in 8–10 solar-mass stars

We calculate $\ensuremath{\beta}$-transition rates for URCA nuclear pairs using the $sd$-shell-model framework of Wildenthal [B. H. Widenthal, Prog. Part. Nucl. Phys. 11, 5 (1984)] with the modified Hamiltonian. We consider many $\ensuremath{\beta}$ transitions including excited states necessary for electron capture and $\ensuremath{\beta}$ decay with high Fermi energy of electrons at high electron density $\ensuremath{\rho}{Y}_{e}$ and temperature $T$ relevant for the massive star and super-asymptotic-giant-branch star evolution. We provide $\ensuremath{\beta}$-transition rates for URCA nuclear pairs ($A=23$, 25, and 27) in the range of density 8.0 $l{\mathrm{log}}_{10}\ensuremath{\rho}{Y}_{e}l$ 9.2 in steps of 0.02 (${Y}_{e}$ is the electron mole number and $\ensuremath{\rho}$ is the nucleon density in units of g cm${}^{\ensuremath{-}3}$) and temperature 8.0 $l{\mathrm{log}}_{10}Tl$ 9.2 in steps of 0.05 ($T$ is the temperature in units of K). This fine mesh is able to provide clearly the URCA density at ${\mathrm{log}}_{10}\ensuremath{\rho}{Y}_{e}=8.92$ for $A=23$ and at ${\mathrm{log}}_{10}\ensuremath{\rho}{Y}_{e}=8.81$ for $A=25$, while the URCA density is not clear for $A=27$. For the evolution of 8--10${M}_{\ensuremath{\bigodot}}$ stars, the use of the fine mesh is found to increase the cooling effect and affects the final fate of these stars.

The role of three-nucleon forces and many-body processes in nuclear pairing

We present microscopic valence-shell calculations of pairing gaps in the calcium isotopes, focusing on the role of three-nucleon (3N) forces and many-body processes. In most cases, we find a reduction in pairing strength when the leading chiral 3N forces are included, compared to results with low-momentum two-nucleon (NN) interactions only. This is in agreement with a recent energy density functional study. At the NN level, calculations that include particle–particle and hole–hole ladder contributions lead to smaller pairing gaps compared with experiment. When particle–hole contributions as well as the normal-ordered one- and two-body parts of 3N forces are consistently included to third order, we find reasonable agreement with experimental three-point mass differences. This highlights the important role of 3N forces and many-body processes for pairing in nuclei. Finally, we relate pairing gaps to the evolution of nuclear structure in neutron-rich calcium isotopes and study the predictions for the 2+ excitation energies, in particular for 54Ca.

Isospin nonconservation insd-shell nuclei

The question of isospin-symmetry breaking in nuclei of the $sd$ shell is addressed. We propose a new global parametrization of the isospin-nonconserving shell-model Hamiltonian which accurately describes experimentally known isobaric mass splittings. The isospin-symmetry violating part of the Hamiltonian consists of the Coulomb interaction and effective charge-dependent forces of nuclear origin. Particular attention has been paid to the effect of the short-range correlations. The behavior of $b$ and $c$ coefficients of the isobaric-mass-multiplet equation (IMME) is explored in detail. In particular, a high-precision numerical description of the staggering effect is proposed and contribution of the charge-dependent forces to the nuclear pairing is discussed. The Hamiltonian is applied to the study of the IMME beyond a quadratic form in the $A=32$ quintet, as well as to calculation of nuclear structure corrections to superallowed ${0}^{+}\ensuremath{\rightarrow}{0}^{+}$ Fermi $\ensuremath{\beta}$ decay and to amplitudes of Fermi transitions to nonanalog states in $sd$-shell nuclei.

Advanced model for the prediction of the neutron-rich fission product yields

The consistent models for the description of the independent fission product formation cross sections in the spontaneous fission and in the neutron and proton induced fission at the energies up to 100MeV is developed. This model is a combination of new version of the two-component exciton model and a time-dependent statistical model for fusion-fission process with inclusion of dynamical effects for accurate calculations of nucleon composition and excitation energy of the fissioning nucleus at the scission point. For each member of the compound nucleus ensemble at the scission point, the primary fission fragment characteristics: kinetic and excitation energies and their yields are calculated using the scission-point fission model with inclusion of the nuclear shell and pairing effects, and multimodal approach. The charge distribution of the primary fragment isobaric chains was considered as a result of the frozen quantal fluctuations of the isovector nuclear matter density at the scission point with the finite neck radius. Model parameters were obtained from the comparison of the predicted independent product fission yields with the experimental results and with the neutron-rich fission product data measured with a Penning trap at the Accelerator Laboratory of the University of Jyvaskyla (JYFLTRAP).

Diamond-based single-molecule magnetic resonance spectroscopy

The detection of a nuclear spin in an individual molecule represents a key challenge in physics and biology whose solution has been pursued for many years. The small magnetic moment of a single nucleus and the unavoidable environmental noise present the key obstacles for its realization. In this paper, we demonstrate theoretically that a single nitrogen-vacancy center in diamond can be used to construct a nano-scale single-molecule spectrometer that is capable of detecting the position and spin state of a single nucleus and can determine the distance and alignment of a nuclear or electron spin pair. The proposed device would find applications in single-molecule spectroscopy in chemistry and biology, for example in determining the protein structure or in monitoring macromolecular motions, and can thus provide a tool to help unravel the microscopic mechanisms underlying bio-molecular function.

The Generalized Model for the Description of Prompt Neutrons in the Low-energy Fission

Abstract The generalized model for the description of neutron emission from the spontaneous and neutron-induced fission in the energy interval up to 20 MeV is developed. For accurate calculations of nucleon composition and excitation energy of the fissioning nucleus at the scission point, the time-dependent statistical model including the pre-equilibrium neutron emission and nuclear friction effects is used. For each member of the compound nucleus ensemble at the scission point, the primary fission-fragment characteristics such as kinetic and excitation energies and yields are calculated using the scission-point fission model with nuclear shell and pairing effects, and based on the multimodal approach. The charge distribution for the primary fragment isobaric chains is considered as a result of the frozen quantal fluctuations of the isovector nuclear matter density at the finite scission neck radius. The post-scission neutron spectra are calculated as the result of the equilibrium emission from the fully accelerated fission fragments with calculated kinetic energies. The pre- scission neutron multiplicity and spectra for multi-chance fission are also calculated. The neutron and γ-ray emission during the saddle-to-scission time is also included in the consideration. This mechanism may partially explain the long standing problem of the so-called isotropic component of prompt fission neutrons.

Genetic variation and differentiation in Juniperus excelsa M. Bieb. populations in Turkey

Genetic variation within and among six populations of Juniperus excelsa M. Bieb., in a common garden in Lakes District of Turkey, was analyzed using four nuclear microsatellite primer pairs originally developed for J. communis. A total of five loci were observed as Jc037 amplified two distinct size ranges. The number of alleles observed for the species varied from 2 to 13, with an average of 4.5 alleles per locus. The mean expected heterozygosity (He) of populations was 0.584, after correction for null alleles. The mean FIS value (−0.014) was close to zero showing no significant deviation from Hardy–Weinberg equilibrium. A low level of genetic differentiation was observed among populations (FST = 0.028; p < 0.001) and Nei’s genetic distance ranged from 0.014 to 0.120 between population pairs. Furthermore, there was no significant correlation between genetic distances on the one hand and geographic distances and trait differentiation on the other hand. However, the eastern populations Beysehir and Sorgun showed very similar genotypic structures and were differentiated from all other populations. A continuous monitoring of phenotypic traits and the association between nucleotide variation in functional genes and adaptive traits such as drought and frost tolerance of J. excelsa populations in common gardens will be useful to design effective conservation strategies in the future.

Search for resonant enhancement of neutrinoless double-electron capture by high-precision Penning-trap mass spectrometry

The search for neutrinoless double-electron capture can be a good alternative to the neutrinoless double-beta-decay experiments in shedding light on such aspects of neutrino physics as the neutrino type, non-conservation of the total lepton charge and magnitude of the effective Majorana neutrino mass. The probability of neutrinoless double-electron capture can be resonantly enhanced by some orders of magnitude. Although the phenomenon of the resonant enhancement was predicted some decades ago, the search for resonantly enhanced neutrinoless double-electron-capture transitions was hampered by a lack of precise experimental values of the atomic mass differences of the transition initial and final states. Only recent progress in high-precision Penning-trap mass spectrometry has finally provided suitable means for a determination of atomic masses with a sufficient precision and thus given rise to the experimental campaign for a search for resonantly enhanced transitions. In this article, after an introduction to the theory of neutrinoless double-electron capture and the Penning-trap technique, a review is given on the results of systematic very precise direct Penning-trap measurements of the atomic mass differences of the nuclides which can undergo double-electron capture. The mass differences of 14 nuclear pairs have already been determined with a typical uncertainty of tens to a few hundreds of eV. Partial or even full resonant enhancement of the neutrinoless double-electron-capture probability has been discovered for 152Gd and 156Dy. In 156Dy a multiple resonance phenomenon has been revealed. For some transitions the half-lives have been estimated (152Gd, 164Er, 180W, 156Dy).

Nuclear pairing from chiral pion-nucleon dynamics: Applications to finite nuclei

The 1S0 pairing gap in isospin-symmetric nuclear matter and finite nuclei is investigated using the chiral nucleon-nucleon potential at the N3LO order in the two-body sector, and the N2LO order in the three-body sector. To include realistic nuclear forces in RHB (Relativistic Hartree Bolgoliubov) calculations we rely on a separable form of the pairing interaction adjusted to the bare nuclear force. The separable pairing force is applied to the analysis of pairing properties for several isotopic and isotonic chains of spherical nuclei.

Microscopic study of nuclear level densities and thermodynamical properties in 170,171,172Yb

The nuclear level density and entropy were extracted for 170,171,172Yb isotopes within microscopic theory, which includes nuclear pairing interaction. The calculations were based on the modified harmonic oscillator according the Nilsson potential for deformed nuclei. From the level densities, thermodynamical quantities such as temperature and entropy have been deduced. The entropies of the neutron hole and particle are estimated from the entropy difference between the odd-mass and even–even nuclei. The critical temperature of the pair-breaking process is found to be Tc ∼ 0.4–0.5 MeV. The results were compared with experimental data obtained by the Oslo group.

Monte Carlo eikonal scattering

Monte Carlo evaluation is used to calculate heavy-ion elastic scattering including the center-of-mass correction and the Coulomb interaction.Angular distributions are presented for a number of nuclear pairs over a wide energy range using nucleon-nucleon scattering parameters taken from phase-shift analyses and densities from independent sources. A technique for the efficient expansion of the Glauber amplitude in partial waves is developed.

Calculation of double mass differences for near-magic nuclei on the basis of a semimicroscopic model

Double mass differences between nuclei having a magic number of protons (neutrons) and their neighbors differing by one or two protons (neutrons) have been calculated on the basis of a semimicroscopic model that has been proposed recently for the problem of nuclear pairing. A dominant term of the effective nucleonnucleon interaction has been calculated on the basis of the realistic Argonne nucleon-nucleon potential v18. It has been supplemented with a moderately small phenomenological term that contains one universal parameter common to protons and neutrons. Double mass differences have been calculated for proton neighbors of the lead-isotope chain (Z = 82) and for neutron neighbors of N = 82 isotones. Corrections to the model that are caused by the contribution of low-lying surface vibrations (phonons) have been estimated.

Comparative Family Law, Korean Family Law and the Missing Definitions of Family

This article uses comparative law to analyze the concept of ‘family’. In particular, the research focuses on how is defined when a group assembles outside of a nuclear marital family. The article discovers that ‘family’ is rarely defined outside of the concept of marriage in modern legal codes. That family is rarely defined per se requires additional legal scrutiny in the context of providing for non-traditional nuclear families.A definition of family can be developed from the material found in law. Eight characteristics and identifying behaviors of families can be found in the analysis of law. These eight concepts are used to rebuild a potential definition of that does not require the act of marriage.This article proposes that law should include a parallel definition for families that do not meet current marital definitions of family. This article does not advocate changing current marriage codes; it merely suggests adding room for non-nuclear families in law. These other, non-nuclear families deserve legal support and recognition. It is time for law to recognize that all families need legal protection and legal affirmation as families.The reason to focus on outside of the concept of marriage is that many family-type groups today fulfill the role of life without legal recognition. These families serve broader societal goals of raising children, of providing for the elderly, and of sharing the burdens and responsibilities of life in a small group setting. Family law should extend the legal notion of to include a wider array of options for non-nuclear families. These types of families are all ‘normal’ families in some sense of the idea of family, but they may simply lack two central ingredients: marriage and a nuclear spousal pair. These types of families should have as much legal right to formally exist as families based in nuclear marriage and sexually-based procreation. Specifically, there should be a legal entity called a 'family' that serves a small group of individuals living in some form of interdependency under a common roof. The basic argument is to provide a parallel option for these types of alternative families alongside the traditional marriage-based option.

Development of nuclear microsatellite markers for the fonio, Digitaria exilis (Poaceae), an understudied West African cereal

We developed nuclear microsatellite primers to explore the genetic diversity, population genetic structure, and evolutionary history of the fonio (Digitaria exilis), an understudied cereal cultivated in West Africa. We used a microsatellite-enriched library approach to isolate and characterize 38 nuclear primer pairs (31 di-, five tri-, and two tetranucleotide repeats), of which 21 were polymorphic and exhibited a clear pattern in 36 accessions from West Africa. The number of alleles per locus ranged from two to 22, with a mean of 4.71, and expected heterozygosity ranged from 0.03 to 0.93. The developed set of 21 polymorphic SSR markers will provide tools for population and evolutionary genetics studies of the cultivated fonio.

K. Kamienska-Trela (Ed.): Nuclear Magnetic Resonance. Volume 40. Specialist Periodical Reports of the Royal Society of Chemistry

This volume is a compilation and summary of the nuclear magnetic resonance (NMR) spectroscopy literature from June 2009 to May 2010 and is the latest in a long line of similar volumes, the first being published in 1972. Selected aspects of NMR spectroscopy are chosen for each volume, because it would indeed be impossible to cover the whole of the NMR literature for even one year in a single volume. In this edition, the first chapter lists NMR books and reviews for the period in question, these alone providing 635 references. The next two chapters describe research into theoretical and physical aspects of nuclear shielding (the property giving rise to the chemical shift) including full tensor calculations and isotope shifts, followed by applications of nuclear shielding, covering comprehensively all of the various nuclides that give rise to NMR spectra. Similarly the next two chapters cover theoretical aspects of spin–spin couplings (by this is meant only the indirect or J-coupling, although there is a short section on residual dipolar couplings as seen in oriented samples), again covering a wide range of nuclear pairs and also anisotropy in the J tensor, followed by applications of spin–spin couplings for many pairs of nuclides, listing interactions over one, two, three and more bonds, plus through-space effects and couplings across hydrogen bonds. One section lists new pulse methods for obtaining J-coupling values. Next comes an excellent critical review chapter on nuclear spin relaxation in liquids and gases covering theory, experimental methods and selected applications. This is followed by a chapter on solid state NMR spectroscopy, describing new experimental methods, determination of NMR parameters for both spin one-half and quadrupolar nuclei, and applications ranging over organic and inorganic systems, amino acids, peptides and proteins, biomedical and pharmaceutical systems, coals, polymers, glasses, porous solids and surfaces. There are also subsequent chapters on applications of NMR spectroscopy to proteins and nucleic acids, carbohydrates, lipids and membranes, synthetic macromolecules, liquid crystals and micellar solutions and finally NMR in living systems, including new methodologies. The fields chosen are all very active, ranging over physical, organic, analytical and biological chemistry, with much research being undertaken across the world. The coverage of the literature has resulted in thousands of citations just in these selected fields, with several chapters providing over 400 references. Whilst the book provides a comprehensive compilation of the literature over the designated 12-month period (with one chapter covering 24 months from June 2008), in general there is not a great deal of critical review of the papers cited and of course by the time the book is published even the latest references are Bibliography

The first quadrupole excitations in spherical nuclei and nuclear pairing

Excitation energies and transition probabilities of the first 2+ excitations in even lead, tin and nickel isotopes are calculated within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. A reasonable agreement with available experimental data is obtained. The effect of the density dependence of the effective pairing interaction is analyzed in detail by comparing results obtained with volume and surface pairing. The effect is found to be noticeable, especially for the 2+ energies which are systematically higher at 200-300 keV for the volume paring as compared with the surface pairing case, the latter being in a better agreement with the data.

Perspectives on Entangled Nuclear Particle Pairs Generation and Manipulation in Quantum Communication and Cryptography Systems

Entanglement between two quantum elements is a phenomenon which presents a broad application spectrum, being used largely in quantum cryptography schemes and in physical characterisation of the universe. Commonly known entangled states have been obtained with photons and electrons, but other quantum elements such as quarks, leptons, and neutrinos have shown their informational potential. In this paper, we present the perspective of exploiting the phenomenon of entanglement that appears in nuclear particle interactions as a resource for quantum key distribution protocols.

Nuclear Inheritance and Genetic Exchange without Meiosis in the Binucleate ParasiteGiardia intestinalis

The protozoan parasite Giardia intestinalis (also known as Giardia lamblia) is a major waterborne pathogen. During its life cycle, Giardia alternates between the actively growing trophozoite, which has two diploid nuclei with low levels of allelic heterozygosity, and the infectious cyst, which has four nuclei and a tough outer wall. Although the formation of the cyst wall has been studied extensively, we still lack basic knowledge about many fundamental aspects of the cyst, including the sources of the four nuclei and their distribution during the transformation from cyst into trophozoite. In this study, we tracked the identities of the nuclei in the trophozoite and cyst using integrated nuclear markers and immunofluorescence staining. We demonstrate that the cyst is formed from a single trophozoite by a mitotic division without cytokinesis and not by the fusion of two trophozoites. During excystation, the cell completes cytokinesis to form two daughter trophozoites. The non-identical nuclear pairs derived from the parent trophozoite remain associated in the cyst and are distributed to daughter cells during excystation as pairs. Thus, nuclear sorting (such that each daughter cell receives a pair of identical nuclei) does not appear to be a mechanism by which Giardia reduces heterozygosity between its nuclei. Rather, we show that the cyst nuclei exchange chromosomal genetic material, perhaps as a way to reduce heterozygosity in the absence of meiosis and sex, which have not been described in Giardia. These results shed light on fundamental aspects of the Giardia life cycle and have implications for our understanding of the population genetics and cell biology of this binucleate parasite.