Physics of Atomic Nuclei最新文献

Results of a search for the masked regularities in the ({}^{214})Po (alpha)-active isotope half-life solar-daily variation parameters in the data collected during 2012–2015 years are presented. It is shown, that an amplitude of a sinusoidal function approximating half-life solar-daily dependence obtained by averaging data during 90 days for each season of the years could reach ({sim}2.9times 10^{-3}) from the average daily value. Similar analysis of the ({}^{213})Po data collected in 2018–2022 years shows that amplitude of the deviation from the average value could reach ({sim}3.8times 10^{-3}). This effect limits an accuracy of the high precision measurements with this or similar short-lived isotopes generating systematic errors if the data were collected during a relatively short time. The new value of the ({}^{213})Po half-life which is (tau(^{213})Po()=(3.6984pm 0.0006)mu)s was obtained on the base of the data collected during 2018–2022 years.

In heavy-ion-induced projectile fragmentation reactions at Fermi energies vast amount of different nuclides far from stability line are born. These neutron or proton-reach isotopes can be used as secondary beams to obtain even more exotic new isotopes or to study nuclear interactions of halo nuclei and their radii and other yet unsolved scientific problems. Radioactive isotopes produced in fragmentation reactions can be used in medical and industrial applications. In this paper we present velocity and isotope distributions of fragments from Na to Ca obtained in the collision of ({}^{40})Ar beam of 36.5 (A) MeV on ({}^{9})Be target on COMBAS mass-spectrometer at FLNR, JINR. We compare the experimental results with the calculations fulfilled in combined transport-statistical model and show good agreement between them.

The Bayesian estimates of the value of the residual neutron–proton interaction energy (Delta_{np}) using the Markov chain Monte Carlo method and Tikhonov regularization. These estimates are used for calculation of the nuclear mass table for (A>20). The accuracy of the obtained predictions is evaluated by comparison with experimental data from AME2020 and other theoretical nuclear mass models.

Astronomical observations strongly incompatible with the canonical cosmological model are reviewed. In particular too early formation of galaxies, as discovered by HST and JWST, is discussed in detail. Other data revealing highly dense population of the very young universe with plethora of other different types of objects are presented. It is demonstrated that similar or maybe even more pronounced problems can be seen also in the present day universe. It is argued that all of the above mentioned problems can be nicely fixed by assumption that the universe is filled with primordial black holes in wide mass interval from a fraction of the solar mass up to supermassive BH. The mechanism of PBH formation presented in 1993 is described. The predicted by this mechanism log-normal mass spectrum of such PBH is shown to agree very well with the data. Finally possible rich population of our Galaxy by antimatter is discussed and new ways of its identification are presented.

This article presents the slice method for estimating the background induced by misidentification of a jet as a photon. The approach is based on a likelihood fit of the signal and background distributions to the data. The main advantage of the considered method is the increase in the estimation accuracy by several times compared to the two-dimensional sideband method due to taking into account the shape of distributions and the dependence of the estimate on the photon isolation.

An overview is provided for a new class of states, which we have named as the size isomers. Such states are weakly bound and have an exotic structure (cluster states, halo/‘‘skin’’). The development of methods for measuring the radii of nuclei in their short-lived excited states led to the discovery of new classes of states. The size of a nucleus defined by the radius of its nucleon (proton and neutron) density distribution and the proton charge distribution is one of the most fundamental and important nuclear characteristics. Nuclear radius determines the basic properties of nuclei and is a consequence of the fundamental features of the strong interaction. Up to now two groups of the size isomers were identified: the excited states with halos (({}^{9})Be, ({}^{11})Be, ({}^{13})C, ({}^{13})N) and some specific alpha-cluster states (({}^{11})B, ({}^{12})C, ({}^{13})C). All the observed states are dilute, however, some indication to possible existence of more compact than the ground states was obtained as well (in ({}^{13})C). The phenomenon of size isomerism occurred to be not a rare one especially if we take into account rotational bands based on some of such states. The structure of size isomers is related with some new features, e.g., rotating halos, halos in continuum, different types of quasimolecular configurations. Some rudimentary signs of alpha-particle condensation (a ‘‘ghost’’ of condensate) were observed in the Hoyle state of ({}^{12})C, however, we cannot speak about confirmation of this ambitious theory. Analogs to the Hoyle state, expected in ({}^{11})B, ({}^{13})C, ({}^{16})O, ({}^{20})Ne near the (alpha)-emission thresholds, are considered.

The physical motivations and performance of the TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) project are presented. The TAIGA observatory addresses ground-based gamma-ray astronomy at energies from a few TeV to several PeV, as well as cosmic ray physics from 100 TeV to several EeV and astroparticle physics. The pilot TAIGA-1 complex locates in the Tunka valley, (sim 50) km West from the southern tip of the lake Baikal. It includes integrated air Cherenkov TAIGA-HiSCORE array with 120 wide-angle optical stations distributed over on area 1.1 square kilometer about and three 4-m class Imaging Atmospheric Cherenkov Telescopes of the TAIGA-IACT array. The latter array has a shape of triangle with side lengths of about 300, 400 and 500 m. The integral sensitivity of the 1-km({}^{2}) TAIGA-1 detector is about (2.5times 10^{-13}) TeV cm({}^{-2}) s({}^{-1}) for detection of (Egeq 100) TeV gamma-rays in 300 hours of source observations. The combination of the wide-angle Cherenkov array and IACTs could offer a cost effective-way to build a large (up to 10 km({}^{2})) array for very high energy gamma-ray astronomy. The reconstruction of a given EAS energy, incoming direction, and the core position, based on the TAIGA-HiSCORE data, allows one to increase the distance between the relatively expensive IACTs up to 600–800 m. These, together with the surface and underground electron/Muon detectors, will be used for selection of gamma-ray-induced EAS. Present status of the project, together with the current array description, the first experimental results and plans for the future are reported.

A further development of the expanded microscopic version of the IBM is presented by considering two-quasiparticle phonons with multipolarity up to (J^{pi}=14^{+}). The developed theoretical scheme is applied to describe the properties of the yrast-band states in ({}^{248})Cm up to spin 34({}^{+}). This heavy transactinide nucleus is the only nucleus in this mass region where the values of (B(E2)) up to spin (I^{pi}=28^{+}) are measured. That is why it is considered foremost, because this information allows testing the presented theoretical scheme based on a larger volume of experimental data. The region of transactinide nuclei differs from lighter ones by the absence of the effect of the back bending in the moment of inertia dependence on the square of the rotation frequency up to the spin (I^{pi}=34^{+}). This article is intended in particular to find out the reason for this effect. Peculiar properties of the rotational bands in heavy and superheavy nuclei are discussed.

The famous 7.65-MeV 0({}^{+}_{2}) Hoyle state of ({}^{12})C is always attracting plenty attention. This state has dilute 3(alpha) configuration and plays important role in nucleosynthesis. Question is if there are states analog to the Hoyle state in other 4(N) nuclei. It is possible that (alpha)-cluster 0({}^{+}_{2}) state in ({}^{20})Ne can be considered as an analog of the 7.65-MeV 0({}^{+}_{2}) Hoyle state of ({}^{12})C.