arXiv subjects

I. Kovalev

Publications and source records attributed to I. Kovalev.

11 recordsLinked to original sources

arXiv2026

Production of Λ hyperons in 4.0A GeV and 4.5A GeV carbon-nucleus interactions at the Nuclotron

The BM@N experiment (Baryonic Matter at the Nuclotron) is the first fixed-target experiment at the JINR NICA accelerator complex. In this work, data on the interactions of a carbon-ion beam with kinetic energies of 4.0A~GeV and 4.5A~GeV with C, Al, Cu, and Pb targets are used to measure transverse momentum spectra and rapidity distributions of $Λ$ hyperon yields. The results are compared with the predictions of DCM-SMM, UrQMD, and PHSD transport models and with the $Λ$ yield measurements in other experiments at similar collision energies.

hep-ex↗

arXiv2025

Production of protons, deuterons and tritons in argon-nucleus interactions at 3.2 AGeV

Results of the BM@N experiment at the Nuclotron/NICA complex on the production of protons, deuterons and tritons in interactions of an argon beam of 3.2 AGeV with fixed targets of C, Al, Cu, Sn and Pb are presented. Transverse mass spectra, rapidity distributions and multiplicities of protons, deuterons and tritons are measured. The results are treated within a coalescence approach and compared with predictions of theoretical models and with other measurements

hep-ex↗

arXiv2024

The BM@N spectrometer at the NICA accelerator complex

BM@N (Baryonic Matter at Nuclotron) is the first experiment operating and taking data at the Nuclotron/NICA ion-accelerating complex.The aim of the BM@N experiment is to study interactions of relativistic heavy-ion beams with fixed targets. We present a technical description of the BM@N spectrometer including all its subsystems.

hep-ex↗

arXiv2023

Production of $π^+$ and $K^+$ mesons in argon-nucleus interactions at 3.2 AGeV

First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on π+ and K+ meson production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 AGeV. Transverse momentum distributions, rapidity spectra and multiplicities of $π^+$ and $K^+$ mesons are measured. The results are compared with predictions of theoretical models and with other measurements at lower energies.

hep-ex↗

arXiv2020

Ergodicity Bounds for the Markovian Queue With Time-Varying Transition Intensities, Batch Arrivals and One Queue Skipping Policy

In this paper we revisit the Markovian queueing system with a single server, infinite capacity queue and the special queue skipping policy. Customers arrive in batches, but are served one by one according to any conservative discipline. The size of the arriving batch becomes known upon its arrival and at any time instant the total number of customers in the system is also known. According to the adopted queue skipping policy if a batch, which size is greater than the current system size, arrives to the system, all current customers in the system are removed from it and the new batch is placed in the queue. Otherwise the new batch is lost. The distribution of the total number of customers in the system is under consideration under assumption that the arrival intensity $λ(t)$ and/or the service intensity $μ(t)$ are non-random functions of time. We provide the method for the computation of the upper bounds for the rate of convergence of system size to the limiting regime, whenever it exists, for any bounded $λ(t)$ and $μ(t)$ (not necessarily periodic) and any distribution of the batch size. For periodic intensities $λ(t)$ and/or $μ(t)$ and light-tailed distribution of the batch size it is shown how the obtained bounds can be used to numerically compute the limiting distribution of the queue size with the given error. Illustrating numerical examples are provided.

math.PR↗

arXiv2019

A possibility of interpretation of the cosmic ray kneenear 10 TV as a contribution of a single close source

This article presents a description of a cosmic rays diffusive propagationmodel of a close point-like flash lamp like source and an approximation ofexperimentally observed spectral irregularity with this model. We show thatthis spectral irregularity can be explained using the presented model andprovide the most probable characteristics of such a source as well as severalobserved and identified sources which can be candidates for this role.

astro-ph.HE↗

arXiv2018

Cosmic ray Nickel nuclei spectrum by the NUCLEON experiment

The NUCLEON experiment is designed to measure chemical composition of cosmic rays with charges from Z=1 to 30 in an energy region from 5*10^11 to 10^15 eV. In this article the data analysis algorithm and spectra of Ni and Fe nuclei, measured in the NUCLEON experiment, are presented.

astro-ph.HE↗

arXiv2018

NUCLEON-2 Mission for the investigation of heavy cosmic rays nuclei

The NUCLEON-2 experiment is aimed at the investigation of isotope and charge composition of ions from carbon up to trans-uranium elements in the energy range over about a hundred MeV/N. The concept design of the NUCLEON-2 satellite cosmic ray experiment is presented. The performed simulation and preliminary prototype beam test confirms the isotope resolution algorithms and techniques.

astro-ph.IM↗

arXiv2018

Secondary cosmic rays in the NUCLEON space experiment

The NUCLEON space observatory is a direct cosmic ray spectrometer designed to study cosmic ray nuclei with $Z=1-30$ at energies $10^{12}-10^{15}$ eV. It was launched as an additional payload onboard the Russian Resource-P No. 2 satellite. In this work B/C, N/O and subFe/Fe ratios are presented. The experiment has worked for half of its expected time, so the data have preliminary status, but they already give clear indications of several astrophysical phenomena, which are briefly discussed in this paper.

astro-ph.HE↗

arXiv2018

First results of the cosmic ray NUCLEON experiment

The NUCLEON experiment was designed to study the chemical composition and energy spectra of galactic cosmic ray nuclei from protons to zinc at energies of $\sim10^{11}$--$10^{15}$\,eV per particle. The research was carried out with the NUCLEON scientific equipment installed on the Russian satellite "Resurs-P" No.\,2 as an additional payload. This article presents the results for the measured nuclei spectra related to the first approximately 250 days of the scientific data collection during 2015 and 2016. The all-particle spectrum and the spectra of p, He, C, O, Ne, Mg, Si and Fe are presented. Some interesting ratios of the spectra are also presented and discussed. The experiment is now in its beginning stage and the data still have a preliminary character, but they already give numerous indications of the existence of various non-canonical phenomena in the physics of cosmic rays, which are expressed in the violation of a simple universal power law of the energy spectra. These features of the the data are briefly discussed.

astro-ph.HE↗

arXiv2018

A new universal cosmic-ray knee near the magnetic rigidity 10 TV with the NUCLEON space observatory

Data from the NUCLEON space observatory give a strong indication of the existence of a new universal cosmic ray "knee", which is observed in all groups of nuclei, including heavy nuclei, near a magnetic rigidity of about 10\,TV. Universality means the same position of the knee in the magnetic rigidity scale for all groups of nuclei. The knee is observed by both methods of measurement of particles energy implemented in the NUCLEON observatory---the calorimetric method and the kinematic method KLEM. This new cosmic ray "knee" is probably connected with the limit of acceleration of cosmic rays by some generic or nearby source of cosmic rays.

astro-ph.HE↗