Physics of Atomic Nuclei最新文献

A solution to the relativistic generalization of the four-particle integral Faddeev–Yakubovsky equation is carried out. Only states with zero orbital angular momentum, (S) states, are considered in the calculations. A rank-one separable potential for the nucleon–nucleon interaction is used to solve the two-nucleon Bethe–Salpeter equation. Calculations are carried out taking into account both the ‘‘(3+1)’’ and ‘‘(2+2)’’ subchannels in the equation. The system of integral equations is solved by the iteration method and the binding energy of the helium-4 nucleus is found. The calculated results are compared with experimental data and nonrelativistic calculations.

The research on (K^{ast}(892)) meson production can lead to new discoveries in properties of exotic state of matter called quark–gluon plasma (QGP) in which quarks and gluons are deconfined. Strangeness enhancement is one of the main observables of QGP which can be measured by studying the production of particles containing strange quark(s). (K^{ast}(892)) meson is one of such particles. Production of (K^{ast}(892)) can be described by its invariant (p_{T}) spectra. Comparison of production of (K^{ast}(892)) in heavy and in (p+p) collision systems can be shown by nuclear modification factors. Since QGP isn’t formed in (p+p) collisions at (sqrt{{}^{S}NN}) GeV strangeness enhancement can be observed through the nuclear modification factors. Current report is dedicated to measurements of (K^{ast}(892)) meson’ invariant (p_{T}) spectra and nuclear modification factors as functions of transverse momentum and centrality in Au (+) Au collision system at (sqrt{{}^{S}NN}) GeV.

In non-central heavy-ion collisions emitted particles’ spin can be polarized along the initial global angular momentum due to spin–orbit coupling. Global polarization of hyperons is measured utilizing parity violating weak decay of hyperons and is used to probe the vortical properties of the system. The STAR experiment at RHIC measured the global polarization of (Lambda) hyperons in Au (+) Au collisions at (sqrt{s_{NN}}=3{-}200) GeV, and similar measurements were conducted at the LHC for Pb (+) Pb collisions at (sqrt{s_{NN}}=2.76) and 5.02 TeV. Measurement of multistrange hyperons have been only limited to top RHIC energy. In these proceedings, we will report results of (Xi) global polarization for Au (+) Au collisions at (sqrt{s_{NN}}=14.6), 19.6 and 27 GeV by STAR. The global polarization of (Xi) hyperons exhibits a trend comparable to that of (Lambda) and is consistent with predictions from transport model calculations. This observation reinforces the idea of global nature of hyperon polarization in heavy-ion collisions.

A nonequilibrium hydrodynamic approach to the description of heavy-ion collisions is formulated and the calculated differential cross sections for fragment emission are compared with experimental data of the Institute for Theoretical and Experimental Physics (ITEP, Moscow). In this approach, a description of the experimental data on double-differential cross sections for the emission of ({}^{11})Be and ({}^{12})B nuclei at an angle of (3.5^{circ}) in the reaction (300 MeV/nucleon) ({}^{12}textrm{C}+{}^{9}textrm{Be}to f+X)(ITEP) is obtained. A comparison with other models is made and the dynamics of the fragmentation process are analyzed. Hubble’s law and particle polarization in high-energy heavy-ion collisions are analyzed in the framework of the hydrodynamic approach.

The notable discrepancy between the densities of neutrons and protons impacts numerous features of nuclear matter, raising the nuclear symmetry energy in neutron-rich environments. Determining the symmetry energy’s density dependency thus becomes a significant scientific goal. A model of coherent density fluctuation (CDFM) is used to compute the energy of nuclear symmetry ((S)), the pressure of neutrons ((P_{o})), and the compressibility asymmetry ((Delta K)) in neon isotopes ((A=20{-}34)). The CDFM, a theoretical framework for examining the properties of restricted nuclei, is a helpful alternative for bridging the gap between the nuclear substance characteristics and features of finite nuclei. The connection between the skin thickness of neutrons ((Delta R_{n})) and the density-dependent characteristics of the energy of nuclear symmetry in Ne isotope chains is also examined more comprehensively. The skin thickness of neutrons, the nuclear symmetry energy’s mass dependency, and the significance of neutron–proton asymmetry are all discussed. We found a complicated, nonlinear link between the energy of nuclear symmetry and the thickness of the neutron skin in Ne isotopes that are high in neutrons and have mass numbers between 20 and 34. The detailed research further explores the relationship between the skin thickness of the neutrons and the density-dependent characteristics of the symmetry energy associated with proton–neutron asymmetry. The results showed that the estimated skin thickness of the neutron for these isotopes agreed well with the existing experimental evidence.

A total of 77 experimental values of reaction rates for the ((n,2n)), ((n,p)), ((n,pn)), ((n,alpha)), ((n,gamma)), and ((n,f)) channels were obtained in the neutron spectrum generated by 21.5 MeV protons irradiating a beryllium target. The measurements were carried out using both natural and highly enriched samples of the following elements: ({}^{textrm{nat}})Ni, ({}^{textrm{nat}})Zr, ({}^{textrm{nat}})Nb, ({}^{textrm{nat}})Cd, ({}^{textrm{nat}})Ti, ({}^{textrm{nat}})Co, ({}^{63,65,textrm{nat}})Cu, ({}^{64})Zn, ({}^{textrm{nat}})In, ({}^{textrm{nat}})Al, ({}^{textrm{nat}})Mg, ({}^{textrm{nat}})Fe, ({}^{textrm{nat}})Au and ({}^{textrm{nat}})Th. The experiments were performed using the activation technique without destructive analysis of the irradiated samples. Reaction products were measured via (gamma)-ray spectrometry employing two coaxial high-purity germanium (HP Ge) detectors and one planar detector. The acquired (gamma)-spectra were processed using the GENIE2000 software suite. Independent and/or cumulative reaction rates were calculated using the SIGMA code. In total, 77 reaction products were identified, with half-lives ranging from 9.458 minutes (({}^{27})Mg) to 5.27 years (({}^{60})Co). The resulting dataset was utilized to assess the predictive capabilities of the PHITS-3.31 code coupled with the JENDL-5 nuclear data library, as applied to the modeling of blanket systems in hybrid reactor facilities.

This study presents the production cross sections of({}^{232,230})Pa resulting from proton irradiationof ({}^{232})Th at an energy of 20.9 MeV. In addition, theexcitation functions of ({}^{233})Pa and ({}^{231})Th produced viaproton-induced reactions on ({}^{232})Th in the energy range from0.02 to 1.6 GeV are analyzed, with consideration of the possiblecontribution of secondary neutrons to their formation. Theproduction cross sections for all reaction products were measuredusing direct gamma-ray spectrometry without chemical separation.The obtained experimental data are compared with results reportedby other authors, as well as with calculated excitation functionsgenerated using the PHITS-3.31 code (INCL4.6/GEM, JAM, and Bertinimodels) and the TENDL-2023 nuclear data library.

The cross section for the weak interaction of high-energy electrons with protons is calculated. These calculations are performed on the basis of the Standard Model. It is shown that the cross section for the capture of 1-GeV electrons by protons is about (10^{{-}38}) cm({}^{2}), which is six orders of magnitude larger than, for example, the cross section for reactor-antineutrino capture by protons. Possible experimental applications of the process being considered are discussed.

This article presents the latest results of Higgs invisible decay searches in vector boson fusion production mode obtained in the ATLAS experiment at Large Hadron Collider using (pp) collisions data collected for the Run 2 ((sqrt{s}=13) TeV) with luminosity of 139 fb({}^{-1}). Plans for upcoming ATLAS analysis using partial Run 3 data are also presented.

Measurement of properties of short-lived resonances produced in heavy-ion collisions plays an important role in study of the hot and dense medium produced in such collisions. The study of resonance production in heavy-ion collisions is an important part of the physical program of the MPD experiment at NICA. We present results of feasibility studies for measurement of (varphi)(1020), (rho(770)^{0}) and (K^{*}(892)^{0}) meson production in Bi (+) Bi collisions at (sqrt{s_{NN}}=9.2) GeV using the MPD detector at NICA collider. Results are obtained using full-scale Monte Carlo simulations of heavy-ion collisions and the experimental setup.