arXiv subjects

A. A. Golubev

Publications and source records attributed to A. A. Golubev.

13 recordsLinked to original sources

arXiv2022

Conceptual design of the Spin Physics Detector

The Spin Physics Detector, a universal facility for studying the nucleon spin structure and other spin-related phenomena with polarized proton and deuteron beams, is proposed to be placed in one of the two interaction points of the NICA collider that is under construction at the Joint Institute for Nuclear Research (Dubna, Russia). At the heart of the project there is huge experience with polarized beams at JINR. The main objective of the proposed experiment is the comprehensive study of the unpolarized and polarized gluon content of the nucleon. Spin measurements at the Spin Physics Detector at the NICA collider have bright perspectives to make a unique contribution and challenge our understanding of the spin structure of the nucleon. In this document the Conceptual Design of the Spin Physics Detector is presented.

hep-ex↗

arXiv2020

Significant Contribution of Projectile Excited States to the Stopping of Slow Helium Ions in Hydrogen Plasma

The energy deposition and the atomic processes, such as the electron-capture, ionization, excitation and radiative-decays for slow heavy ions in plasma remains an unsolved fundamental problem. Here we investigate, both experimentally and theoretically, the stopping of 100 keV=u helium ions in a well-defined hydrogen plasma. Our precise measurements show a much higher energy loss than the predictions of the semi-classical approaches with the commonly used effective charge. By solving the Time Dependent Rate Equation (TDRE) with all the main projectile states and for all relevant atomic processes, our calculations are in remarkable agreement with the experimental data. We also demonstrated that, acting as a bridge for electron-capture and ionization, the projectile excited states and their radiative decays can remarkably influence the equilibrium charge states and consequently lead to a substantial increasing of the stopping of ions in plasma.

physics.plasm-ph↗

arXiv2019

Dynamics of supernova bounce in laboratory

We draw attention to recent high explosive (HE) experiments which provide compression of macroscopic amount of matter to high, even record, values of pressure in comparison with other HE experiments. The observed bounce after the compression corresponds to processes in core-collapse supernova explosions after neutrino trapping. Conditions provided in the experiments resemble those in core-collapse supernovae, permitting their use for laboratory astrophysics. A unique feature of the experiments is compression at low entropy. The values of specific entropy are close to those obtained in numerical simulations during the process of collapse in supernova explosions, and much lower than those obtained at laser ignition facilities, another type of high-compression experiment. Both in supernovae and HE experiments the bounce occurs at low entropy, so the HE experiments provide a new platform to realize some supernova collapse effects in laboratory, especially to study hydrodynamics of collapsing flows and the bounce. Due to the good resolution of diagnostics in the compression of macroscopic amounts of material with essential effects of nonideal plasma in EOS, and observed development of 3D instabilities, these experiments may serve as a useful benchmark for astrophysical hydrodynamic codes.

physics.plasm-ph↗

arXiv2017

Monte-Carlo Geant4 numerical simulation of experiments at 247-MeV proton microscope

A radiographic setup for an investigation of fast dynamic processes with areal density of targets up to 5 g/cm$^2$ is under development on the basis of high-current proton linear accelerator at the Institute for Nuclear Research (Troitsk, Russia). A virtual model of the proton microscope developed in a software toolkit Geant4 is presented in the article. Full-scale Monte-Carlo numerical simulation of static radiographic experiments at energy of a proton beam 247 MeV was performed. The results of simulation of proton radiography experiments with static model of shock-compressed xenon are presented. The results of visualization of copper and polymethyl methacrylate step wedges static targets also described.

physics.plasm-ph↗

arXiv2017

First measeurements in search for keV-sterile neutrino in tritium beta-decay by Troitsk nu-mass experiment

We present the first measurements of tritium beta-decay spectrum in the electron energy range 16-18.6 keV. The goal is to find distortions which may correspond to the presence of a heavy sterile neutrinos. A possible contribution of this kind would manifest itself as a kink in the spectrum with a similar shape but with end point shifted by the value of a heavy neutrino mass. We set a new upper limits to the neutrino mixing matrix element U^2_{e4} which improve existing limits by a factor from 2 to 5 in the mass range 0.1-2 keV.

hep-ex↗

arXiv2016

Electron scattering on hydrogen and deuterium molecules at 14-25 keV by the "Troitsk nu-mass" experiment

We've performed precise measurements of electron scattering on molecular hydrogen and deuterium by using the "Troitsk nu-mass" setup. Electrons were generated by the electron gun with an energy line width better than 0.3 eV. The electron energies were 14, 17, 18.7, 19 and 25 keV. The windowless gaseous tritium source (WGTS) was filled by hydrogen isotopes and served as a target. The total column density was adjusted to form a length of 0.35--0.7 of the electron mean free path. The integral spectrum of scattered electrons was measured by the electrostatic spectrometer with a magnetic adiabatic collimation and relative energy resolution 8.3 10^{-5}. As a result, the shapes of molecular excitation and ionization spectra were extracted for both isotopes. We did not find any difference between hydrogen and deuterium targets. The relative energy dependence was extracted too.

physics.ins-det↗

arXiv2016

Commissioning of the PRIOR proton microscope

Recently a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR) has been designed, constructed and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5-4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 um spatial and 10 ns temporal resolutions of the proton microscope have been demostrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This paper describes the PRIOR setup as well as the results of the first static and dynamic proton radiography experiments performed at GSI.

physics.ins-det↗

arXiv2015

The current status of "Troitsk nu-mass" experiment in search for sterile neutrino

We propose a new experiment to search for a sterile neutrino in a few keV mass range at the "Troitsk nu-mass" facility. The expected signature corresponds to a kink in the electron energy spectrum in tritium beta-decay. The new goal compared to our previous experiment will be precision spectrum measurements well below end point. The experimental installation consists of a windowless gaseous tritium source and a high resolution electromagnetic spectrometer. We estimate that the current bounds on the sterile neutrino mixing parameter can be improved by an order of magnitude in the mass range under 5 keV without major upgrade of the existing equipment. Upgrades of calibration, data acquisition and high voltage systems will allow to improve the bounds by another order of magnitude.

physics.ins-det↗

arXiv2015

Current progress in laser cooling of antihydrogen

We discuss laser cooling methods of (anti)hydrogen and its importance for current and future experiments. The exploration of antimatter presents a great interest for $CERN$ and $GSI$ experiments aimed at check of quantum mechanics laws, fundamental symmetries of nature and gravity and investigations in atomic and nuclear physics. The spectral transition $1S\rightarrow 2P$ in $\bar{H} (H)$ atom is the most suitable for laser cooling due to a small lifetime of $2P$ state and insignificant ionization losses. However the pulsed and continuous laser sources at Lyman-$α$ wavelength do not possess enough power for fast and efficient cooling. The small power of laser sources at $λ=121.6\ \nm$ is poor technical problem associated with a complexity of generation scheme of such radiation, which arises due to absence of nonlinear $BBO$ crystals at this wavelength. The advances in this area will completely destine the future progress of the experiments aimed at study of antimatter.

physics.atom-ph↗

arXiv2014

A search for an additional neutrino mass eigenstate in 2 to 100 eV region from "Troitsk nu-mass" data - detailed analysis

In this paper we present the details of our previously published results for a search for an additional neutrino mass state in $β$-electron spectrum from the Troitsk nu-mass experiment. Here we present steps of the analysis, show a set of likelihood functions obtained for each additional heavy mass value. We demonstrate how systematic errors were estimated. We also compare our results with those published recently for a similar analysis for Mainz data and try to explain why there is a factor of 2-3 difference in the sensitivity for an additional heavy mass.

hep-ex↗

arXiv2012

An upper limit on additional neutrino mass eigenstate in 2 to 100 eV region from "Troitsk nu-mass" data

We performed a search for any sign of an additional neutrino mass state in beta-electron spectrum based on data reanalysis of direct electron antineutrino mass measurements in Tritium beta-decay in the Troitsk nu-mass experiment. The existing data set allows us to search for such a state in the mass range up to 100 eV. The lowest value at a 95% C.L. upper limit for the contribution of a heavy eigenstate into electron neutrino is around or less than 1% for masses above 20 eV.

hep-ex↗

arXiv2011

An upper limit on electron antineutrino mass from Troitsk experiment

An electron antineutrino mass has been measured in tritium beta-decay in the "Troitsk nu-mass" experiment. The setup consists of a windowless gaseous tritium source and an electrostatic electron spectrometer. The whole data set acquired from 1994 to 2004 was reanalysed. A thorough selection of data with the reliable experimental conditions has been performed. We checked every known systematic effect and got the following experimental estimate for neutrino mass squared m_{nu}^{2}=-0.67+/- 2.53 {eV}^{2}. This gives an experimental upper sensitivity limit of m_{nu}<2.2 eV and upper limit estimates m_{nu}<2.12 eV, 95% C.L. for Bayesian statistics and m_{nu}<2.05 eV, 95% C.L. for the Feldman and Cousins approach.

hep-ex↗

arXiv2003

Nuclide Production Cross Sections for 59Co and nat-Cu Irradiated with 0.2 and 2.6 GeV Protons and 0.2 GeV/Nucleon Carbon Ions

Results of experimental cross sections for residual nuclide production in interactions of 200 MeV/A 12C ions and 0.2 and 2.6 GeV protons with nat-Cu, 59Co, and 27Al targets are presented. The residual products are measured at ITEP (Moscow) by gamma-spectrometry with a detector of 1.8 keV resolution in the 1332 keV 60Co gamma-line. The measured data are compared with predictions by the LANL (Los Alamos) code LAQGSM+GEM2 and JINR (Dubna) code CASCADE.

nucl-ex↗