arXiv subjects

S. A. Bulychjov

Publications and source records attributed to S. A. Bulychjov.

8 recordsLinked to original sources

arXiv2026

Nuclear Fragmentation at Intermediate Energies in the DCM-QGSM-SMM Model

The development of nucleus-nucleus interaction models is a rapidly developing area of heavy-ion physics. Recently, a new model DCM-QGSM-SMM, developed at JINR and oriented toward use within the NICA project at energies of several GeV/nucleon, became available. However, the mechanisms of nuclear interactions used in this model can potentially operate effectively at lower energies. In this paper, the model predictions are compared with the FRAGM and FIRST/GSI experimental data in the energy range of nucleus-nucleus interactions starting from 300 MeV/nucleon, as well as with the predictions of other models used in this energy range.

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arXiv2022

Status and initial physics performance studies of the MPD experiment at NICA

The Nuclotron-base Ion Collider fAcility (NICA) is under construction at the Joint Institute for Nuclear Research (JINR), with commissioning of the facility expected in late 2022. The Multi-Purpose Detector (MPD) has been designed to operate at NICA and its components are currently in production. The detector is expected to be ready for data taking with the first beams from NICA. This document provides an overview of the landscape of the investigation of the QCD phase diagram in the region of maximum baryonic density, where NICA and MPD will be able to provide significant and unique input. It also provides a detailed description of the MPD set-up, including its various subsystems as well as its support and computing infrastructures. Selected performance studies for particular physics measurements at MPD are presented and discussed in the context of existing data and theoretical expectations.

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arXiv2019

Cross Section for $γn \to π^0 n$ measured at Mainz/A2

The $γn \to π^0 n$ differential cross section evaluated for 27 energy bins span the photon-energy range 290-813 MeV (W = 1.195-1.553 GeV) and the pion c.m. polar production angles, ranging from 18 deg to 162 deg, making use of model-dependent nuclear corrections to extract pi0 production data on the neutron from measurements on the deuteron target. Additionally, the total photoabsorption cross section was measured. The tagged photon beam produced by the 883-MeV electron beam of the Mainz Microtron MAMI was used for the 0-meson production. Our accumulation of 3.6 x 10^6 $γn \to π^0 n$ events allowed a detailed study of the reaction dynamics. Our data are in reasonable agreement with previous A2 measurements and extend them to lower energies. The data are compared to predictions of previous SAID, MAID, and BnGa partial-wave analyses and to the latest SAID fit MA19 that included our data. Selected photon decay amplitudes $N^* \to γn$ at the resonance poles are determined for the first time.

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arXiv2015

Light fragments from (C + Be) interactions at 0.6 GeV/nucleon

Nuclear fragments emitted at 3.5 degrees in 12C fragmentation at 0.6 GeV/nucleon have been measured. The spectra obtained are used for testing the predictions of four ion-ion interaction models: INCL++, BC, LAQGSM03.03 and QMD as well as for the comparison with the analytical parametrization in the framework of thermodynamical picture of fragmentation.

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arXiv2015

Verification of Monte Carlo transport codes against measured small angle p-, d-, and t-emission in carbon fragmentation at 600 MeV/nucleon

Momentum spectra of hydrogen isotopes have been measured at 3.5 deg from C12 fragmentation on a Be target. Momentum spectra cover both the region of fragmentation maximum and the cumulative region. Differential cross sections span five orders of magnitude. The data are compared to predictions of four Monte Carlo codes: QMD, LAQGSM, BC, and INCL++. There are large differences between the data and predictions of some models in the high momentum region. The INCL++ code gives the best and almost perfect description of the data.

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arXiv2013

Quark cluster contribution to cumulative proton emission in fragmentation of carbon ions

In the FRAGM experiment at heavy ion accelerator complex TWAC-ITEP, the proton yields at an angle 3.5$^\circ$ have been measured at fragmentation of carbon ions at $T_0 = $ 0.6, 0.95 and 2.0 GeV/nucleon on beryllium target. The data are presented as invariant proton yields on cumulative variable $x$ in the range 0.9 < $x$ < 2.4. Proton spectra cover six orders of invariant cross section magnitude. They have been analyzed in the framework of quark cluster fragmentation model. Fragmentation functions of quark-gluon string model are used. The probabilities of the existence of multi-quark clusters in carbon nuclei are estimated to be 8--12% for six-quark clusters and 0.2--0.6% for nine-quark clusters.

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arXiv2003

Inclusive pion double charge exchange on Oxygen(16) at 0.6-1.1 GeV

The inclusive pion double charge exchange (DCX) on oxygen nuclei has been measured in the region where additional pion production is kinematically forbidden. The experiment was performed at ITEP PS at incident pi- kinetic energies T_0= 0.59, 0.75 and 1.1 GeV. The integrated forward differential cross section was found to decrease with energy slowly. At 1.1 GeV it exceeds the theoretical prediction within the conventional sequential single charge exchange mechanism with a neutral pion in the intermediate state (Glauber elastic rescattering) by about half an order of magnitude. The sequential mechanism with two pions in the intermediate state (Glauber inelastic rescatterings), which was proposed recently, seems to be able to explain the observed slow energy dependence and allows to predict the DCX cross section for higher energies.

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arXiv1999

Parameters of Fermi-motion from Quasielastic Backward Pion-Proton Scattering on Nuclei

In experiment on the study of the quasielastic pion-proton scattering at large momentum transfer on nuclei the proton Fermi-momentum distributions have been analysed in plane-wave approximation for light nuclei $^6$Li, $^7$Li and $^{12}$C. It was found that, contrary to (e,e') experiments, that the oscillator model gives slightly better description of our data than the Fermi - gas model. But the values of parameters of the distributions obtained in our analysis are considerably smaller, than in (e,e') experiments. It gives evidence that the plane-wave approximation is not sufficient and more complicated theoretical models which take into account the effects of distortion of pion-nucleon amplitude in a nuclear medium are necessary for analysis of our data.

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