The purpose of this work is to describe, in light of shell model calculations using the PSDPF interaction, the particular states with J = 0 in sd shell nuclei. These states are difficult to observe. ...It is well known that the ground state in even-even nuclei has J.sup.pi = 0.sup.+ and therefore we are interested in describing their first excited 0.sup.+.sub.2 states. We have also studied the first and second excited 0.sup.- states in all sd nuclei. The experimental and theoretical excitation energies of these states were confronted. This study allowed us to make predictions of the existence of 0.sup.+.sub.2 and (or) 0.sup.-.sub.1 and/or 2 states in nuclei, which do not possess these states, or to have an idea of their excitation energies for possible experiments in the future.
The review considers the peculiarities of symmetry breaking and symmetry transformations and the related physical effects in finite quantum systems. Some types of symmetry in finite systems can be ...broken only asymptotically. However, with a sufficiently large number of particles, crossover transitions become sharp, so that symmetry breaking happens similarly to that in macroscopic systems. This concerns, in particular, global gauge symmetry breaking, related to Bose–Einstein condensation and superconductivity, or isotropy breaking, related to the generation of quantum vortices, and the stratification in multicomponent mixtures. A special type of symmetry transformation, characteristic only for finite systems, is the change of shape symmetry. These phenomena are illustrated by the examples of several typical mesoscopic systems, such as trapped atoms, quantum dots, atomic nuclei, and metallic grains. The specific features of the review are: (i) the emphasis on the peculiarities of the symmetry breaking in finite mesoscopic systems; (ii) the analysis of common properties of physically different finite quantum systems; (iii) the manifestations of symmetry breaking in the spectra of collective excitations in finite quantum systems. The analysis of these features allows for the better understanding of the intimate relation between the type of symmetry and other physical properties of quantum systems. This also makes it possible to predict new effects by employing the analogies between finite quantum systems of different physical nature.
Pear-shaped atomic nuclei Butler, P. A.
Proceedings of the Royal Society. A, Mathematical, physical, and engineering sciences,
07/2020, Letnik:
476, Številka:
2239
Journal Article
Recenzirano
Odprti dostop
This review presents the current status of experimental evidence for the occurrence of reflection-asymmetric or ‘pear’ shapes in atomic nuclei, which arises from the presence of strong octupole ...correlations in the nucleon–nucleon interactions. The behaviour of energy levels and electric octupole transition moments is reviewed, with particular emphasis on recent measurements. The relevance of nuclear pear shapes to measurements of fundamental interactions is also discussed.
The masses of the recently reported by LHCb two pentaquark charmonium states
P
c
*
(4380) and
P
c
*
(4450) which are supposed to have the configuration
(
u
u
d
c
c
¯
)
have been estimated in the ...framework of the quasiparticle model of diquarks considering
u
d
u
c
c
¯
configuration. The masses are reproduced very well which indicates that the description of diquark as quasiparticle is very useful for describing multiquark state and to understand the dynamics of it.
Supplementing the experimental data of excited states of nuclei with those of the canonical assemble, we determine the temperature-dependent specific heat formula, with finite system corrections, in ...the mass range of 22<A<206. Phase transition structures in shapes of peaks in the specific heat diagram have been identified as distinct pairing processes and are used in comparison to the pairing energy correction term (Gilbert and Cameron, 1965). Through mass dependent pairing gap equations the addition of the proton–neutron pairing procedure and finally the distinction of the pairing tendency, of each nuclei, was made possible.
Relativistic quantum mechanics predicts that when the charge of a superheavy atomic nucleus surpasses a certain threshold, the resulting strong Coulomb field causes an unusual atomic collapse state; ...this state exhibits an electron wave function component that falls toward the nucleus, as well as a positron component that escapes to infinity. In graphene, where charge carriers behave as massless relativistic particles, it has been predicted that highly charged impurities should exhibit resonances corresponding to these atomic collapse states. We have observed the formation of such resonances around artificial nuclei (clusters of charged calcium dimers) fabricated on gated graphene devices via atomic manipulation with a scanning tunneling microscope. The energy and spatial dependence of the atomic collapse state measured with scanning tunneling miaoscopy revealed unexpected behavior when occupied by electrons.
Describing the fundamental theory of particle physics and its applications, this book provides a detailed account of the Standard Model, focusing on techniques that can produce information about real ...observed phenomena. It begins with a pedagogic account of the Standard Model, introducing essential techniques such as effective field theory and path integral methods. It then focuses on the use of the Standard Model in the calculation of physical properties of particles. Rigorous methods are emphasized, but other useful models are also described. The second edition has been updated to include theoretical and experimental advances, such as the discovery of the Higgs boson, our understanding of neutrinos, and the major advances in CP violation and electroweak physics. This book is valuable to graduate students and researchers in particle physics, nuclear physics and related fields. This edition, first published in 2014, has been reissued as an Open Access publication on Cambridge Core.
Magnetostatics, the mathematical theory that describes the forces and fields resulting from the steady flow of electrical currents, has a long history. By capturing the basic concepts, and building ...towards the computation of magnetic fields, this book is a self-contained discussion of the major subjects in magnetostatics. Overviews of Maxwell's equations, the Poisson equation, and boundary value problems pave the way for dealing with fields from transverse, axial and periodic magnetic arrangements and assemblies of permanent magnets. Examples from accelerator and beam physics give up-to-date context to the theory. Both complex contour integration and numerical techniques for calculating magnetic fields are discussed in detail with plentiful examples. Theoretical and practical information on carefully selected topics make this a one-stop reference for magnet designers, as well as for physics and electrical engineering undergraduate students. This title, first published in 2016, has been reissued as an Open Access publication.
Nuclear magic numbers correspond to fully occupied energy shells of protons or neutrons inside atomic nuclei. Doubly magic nuclei, with magic numbers for both protons and neutrons, are spherical and ...extremely rare across the nuclear landscape. Although the sequence of magic numbers is well established for stable nuclei, experimental evidence has revealed modifications for nuclei with a large asymmetry between proton and neutron numbers. Here we provide a spectroscopic study of the doubly magic nucleus .sup.78Ni, which contains fourteen neutrons more than the heaviest stable nickel isotope. We provide direct evidence of its doubly magic nature, which is also predicted by ab initio calculations based on chiral effective-field theory interactions and the quasi-particle random-phase approximation. Our results also indicate the breakdown of the neutron magic number 50 and proton magic number 28 beyond this stronghold, caused by a competing deformed structure. State-of-the-art phenomenological shell-model calculations reproduce this shape coexistence, predicting a rapid transition from spherical to deformed ground states, with .sup.78Ni as the turning point.
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