Physics of Atomic Nuclei最新文献

The study of the momentum spectra of charged particles allows one to obtain information about the thermodynamic characteristics of system arising from the collision of heavy ions. This research can improve our understanding of their interactions and dynamics in various physical processes. The aim of this work is to study the momentum spectra of pions, kaons, and protons in Ar (+) Ar and ({p}+{p}) at energy (sqrt{s_{NN}}=11) and 27 GeV, respectively, using the UrQMD (Ultrarelativistic Quantum Molecular Dynamics) model for the SPD experiment at NICA. The spectra are presented as a function of transverse momentum. The extracted kinetic temperature for the protons, pions and kaons was obtained using hydrodynamic Blast-Wave parametrization based on Boltzmann statistics. Physics implications will be discussed.

Charged-particle correlations in terms of charge balance functions (CBF) are studied within HYDJET++ model for nucleus–nucleus interactions at the energies of the Beam Energy Scan (BES) program at RHIC and NICA collider. It is shown that taking into account event-by-event conservation of the electric net-charge of produced particles together with finite values of isospin, strangeness, and baryon chemical potentials in the model, allows one to reproduce STAR/RHIC data on CBF pseudorapidity widths in Au (+) Au collisions at center-of-mass energy per nucleon pair (sqrt{s_{NN}}=7.7) and (11.5) GeV. Based on the model results at RHIC energies, a prediction for CBF pseudorapidity widths for Bi (+) Bi collisions at planned NICA energy of (sqrt{s_{NN}}=9.2) GeV is made.

The Multi-Purpose Detector (MPD) is one of the key experiments of the Nuclotron-based Ion Collider Facility (NICA), which is nearing completion at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The MPD will operate in both fixed-target and collider modes, with an energy range of (sqrt{s_{NN}}=2.4) to (3.5) GeV and 4 to 11 GeV, respectively. The primary goal of the MPD experiment is to investigate the phase diagram of Quantum Chromodynamics (QCD) matter, with a specific emphasis on the domain of high baryon density and intermediate temperature, where a first-order phase transition is anticipated to occur. The paper presents an overview of the current status of the MPD commissioning and physics program.

The process of neutrino interaction with ({}^{128})Te and ({}^{130})Te nuclei is studied with allowance for the effect of charge-exchange resonances. The cross sections (sigma)((E_{nu})) for solar-neutrino capture by the isotopes ({}^{128})Te and ({}^{130})Te are calculated. Both experimental data obtained for the strength functions (S(E)) in (({}^{3})He, (t)) charge-exchange reactions and the functions (S(E)) calculated within the microscopic theory of finite Fermi systems are used. The effect of the resonance structure of (S(E)) on the calculated cross sections for solar-neutrino capture is studied, and the contribution of each high-lying resonance to the capture cross section (sigma)((E_{nu})) is analyzed. The contributions of all components of the solar-neutrino spectrum are calculated. The contribution of background solar neutrinos to the double-beta decay of ({}^{130})Te nuclei is estimated.

Based on corrected experimental data, this study presents and discusses the temperature characteristics of carbon spectator fragments produced in carbon–carbon collisions at a primary momentum of 4.2 GeV/c per nucleon. We also investigated the multiplicities associated with spectator protons, deuterons, and tritons in inelastic nucleus–nucleus interactions. Our findings reveal that the temperature absorbed by the spectator fragments depends on their mass. We also observed a liquid-gas phase transition in singly and multiply charged projectile fragments.

The primary purpose of the ALICE experiment at the Large Hadron Collider is to study the properties of nuclear matter at extremely high temperatures and energy density produced by relativistic nucleus–nucleus collisions. During the Long Shutdown 2 (2019–2022), new detectors were incorporated into the ALICE setup, including the Fast Interaction Trigger (FIT). The FIT detector system consists of three sub-detectors based on different technologies: FDD, FT0 and FV0. In addition to online functionality, the FIT data are used offline for multiplicity, centrality, collision time, event-plane determination, vertex position, and veto for selection of diffractive and ultra-peripheral heavy-ion collisions. The mentioned above global observables are essential for event characterization and the study of nuclear matter properties. This material presents a preliminary overview of FIT’s performance in the extraction of global observables from pp and Pb–Pb collisions during the LHC Run 3.

Using the activation technique without chemical separation, cross sections for the production of 119 fission products—from ({}^{72})Zn to ({}^{151})Pm—belonging to 32 different chemical elements (Zn, Ga, Ge, As, Br, Se, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm) were measured under independent irradiation of two metallic ({}^{232})Th foils with 20.9 MeV protons. The irradiations were carried out at the NS-20M facility, based on the I-2 linear proton accelerator, and lasted 1 hour and 1 minute. The proton flux was determined using monitor reactions ({}^{textrm{nat}})Cu((p,x))({}^{62})Zn and ({}^{textrm{nat}})Cu((p,x))({}^{63})Zn. The obtained results, together with data from other authors available in the EXFOR database and our previously measured data (also included in EXFOR) for proton energies of 100, 200, 800, 1200, and 1600 MeV, are presented in the form of excitation functions and mass yield curves. The ({}^{232})Th fission product cross sections were modeled using the PHITS-3.31 code with the INCL4.6/GEM, JAM/GEM, and Bertini/GEM models for 42 proton energies in the range from 0.01 to 3 GeV. Cumulative cross sections for fission products in the mass range (72<A<151) were computed using custom software based on the independent cross sections obtained from PHITS-3.31 output. For selected proton energies (20.9, 100, 200, 800, 1200, and 1600 MeV), a comparison between calculated and experimental results was performed using standard statistical criteria ((bar{F}), (Deltabar{F}) and (langle Frangle)), allowing evaluation of the predictive performance of each model implemented in PHITS-3.31. In addition, the GEF2023/2.1 code was used to analyze the mass yields of ({}^{232})Th fission products.

In this overview, the recent results on direct-photon production and correlations in Pb–Pb collisions at (sqrt{s_{NN}}=5.02) TeV obtained by the ALICE collaboration are presented. The invariant yields of direct photons have been measured in a wide range of transverse momentum ((p_{T})) from 0.4 to 16 GeV/(c) in different centrality classes from central to peripheral collisions. Obtained spectra are consistent with perturbative Quantum Chromodynamics (pQCD) calculations and hydrodynamic predictions. Promising measurements of direct-photon correlations have been performed, resulting in estimation of the correlation radii of the emitting source in central and semicentral collisions. In addition, two-photon correlations are used to extend the (p_{T})-dependent invariant yields of direct photons down to 250 MeV/(c).

Direct photons produced in electromagnetic processes in heavy-ion collisions do not interact with other particles in the collision zone. Analysis of direct photon anisotropic flow provides additional information about the conditions at the production time and the development of collective flow. Direct photon flow is extracted based on flow and spectra of inclusive photons and of neutral pions, the main source of decay photons. Moreover, the measurement of the neutral pion spectra and flow is interesting by itself as it allows to constrain properties of hot and dense nuclear matter thanks to the robust particle identification and wide coverage in transverse momentum. We present the performance of measurement of anisotropic flow for inclusive photons and neutral pions with the MPD experiment.

We study the energy spectrum of three-particle systems (He-(p)-(mu)), (He-(d)-(mu)), (Li-(p)-(mu)) and (Li-(d)-(mu)) on the basis of variational approach with exponential and Gaussian basis. Using the Complex Coordinate Rotation (CCR) method we calculate energies of resonant states of listed molecules.