arXiv subjects

V. V. Alekseenko

Publications and source records attributed to V. V. Alekseenko.

9 recordsLinked to original sources

arXiv2016

Detection of thermal neutrons with the PRISMA-YBJ array in Extensive Air Showers selected by the ARGO-YBJ experiment

We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and $^{6}$LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector.

astro-ph.IM↗

arXiv2016

Barometric pumping effect for radon-due neutron flux in underground laboratories

It is known that neutron background is a big problem for low-background experiments in underground Laboratories. Our global net of en-detectors sensitive to thermal neutrons includes the detectors running both on the surface and at different depths underground. We present here results obtained with the en-detector of 0.75 m^2 which is running more than 3 years in underground room at a depth of 25 m of water equivalent in Skobeltsyn Institute of Nuclear Physics, Moscow. Spontaneous increases in thermal neutron flux up to a factor of 3 were observed in delayed anti-correlation with barometric pressure. The phenomenon can be explained by a radon barometric pumping effect resulting in similar effect in neutron flux produced in (alpha,n)-reactions by alpha-decays of radon and its daughters in surrounding rock

physics.geo-ph↗

arXiv2015

Characteristics of a thermal neutrons scintillation detector with the [ZnS(Ag)+$^6$LiF] at different conditions of measurements

A construction of a thermal neutron testing detector with a thin [ZnS(Ag)+$^6$LiF] scintillator is described. Results of an investigation of sources of the detector pulse origin and the pulse features in a ground and underground conditions are presented. Measurements of the scintillator own background, registration efficiency and a neutron flux at different objects of the BNO INR RAS were performed. The results are compared with the ones measured by the $^3$He proportional counter.

physics.ins-det↗

arXiv2015

Results of measurements of an environment neutron background at BNO INR RAS objects with the helium proportional counter

A method of measurements of the environmental neutron background at the Baksan Neutrino Observatory of the INR RAS are described. Measurements were done by using of a proportional counter filled with mixture of Ar(2 at)+$^3$He(4 at). The results obtained at the surface and the underground laboratory of the BNO INR RAS are presented. It is shown that a neutron background in the underground laboratory at the 4900 m w.e. depth is decreased by $\sim 260$ times without any special shield in a comparison with the Earth surface. A neutron flux density in the 5-1323.5~cm air height region is constant within the determination error and equal to $(7.1\pm0.1_{\rm{stat}}\pm0.3_{\rm{syst}})\times10^{-3}$ s$^{-1}\cdot$cm$^{-2}$.

physics.ins-det↗

arXiv2015

The study of the thermal neutron flux in the deep underground laboratory DULB-4900

We report on the study of thermal neutron flux using monitors based on mixture of ZnS(Ag) and LiF enriched with a lithium-6 isotope at the deep underground laboratory DULB-4900 at the Baksan Neutrino Observatory. An annual modulation of thermal neutron flux in DULB-4900 is observed. Experimental evidences were obtained of correlation between the long-term thermal neutron flux variations and the absolute humidity of the air in laboratory. The amplitude of the modulation exceed 5\% of total neutron flux.

nucl-ex↗

arXiv2012

Thermal neutron flux produced by EAS at various altitudes

The results of Monte-Carlo simulations of Extensive Air Shower are presented to show the difference of hadronic component content at various altitudes with the aim to choose an optimal altitude for the PRISMA-like experiment. CORSIKA program for EAS simulations with QGSJET and GHEISHA models was used to calculate the number of hadrons reaching the observational level inside a ring of 50 m radius around the EAS axis. Then the number of neutrons produced by the hadronic component was calculated using an empirical relationship between the two components. We have tested the results with the ProtoPRISMA array at sea level, and recorded neutrons are close to the simulation results.

astro-ph.HE↗

arXiv2011

The East-West method: an exposure-independent method to search for large scale anisotropies of cosmic rays

The measurement of large scale anisotropies in cosmic ray arrival directions at energies above 10^13 eV is performed through the detection of Extensive Air Showers produced by cosmic ray interactions in the atmosphere. The observed anisotropies are small, so accurate measurements require small statistical uncertainties, i.e. large datasets. These can be obtained by employing ground detector arrays with large extensions (from 10^4 to 10^9 m^2) and long operation time (up to 20 years). The control of such arrays is challenging and spurious variations in the counting rate due to instrumental effects (e.g. data taking interruptions or changes in the acceptance) and atmospheric effects (e.g. air temperature and pressure effects on EAS development) are usually present. These modulations must be corrected very precisely before performing standard anisotropy analyses, i.e. harmonic analysis of the counting rate versus local sidereal time. In this paper we discuss an alternative method to measure large scale anisotropies, the "East-West method", originally proposed by Nagashima in 1989. It is a differential method, as it is based on the analysis of the difference of the counting rates in the East and West directions. Besides explaining the principle, we present here its mathematical derivation, showing that the method is largely independent of experimental effects, that is, it does not require corrections for acceptance and/or for atmospheric effects. We explain the use of the method to derive the amplitude and phase of the anisotropy and we demonstrate its power under different conditions of detector operation.

astro-ph.IM↗

arXiv2009

10-100 TeV cosmic ray anisotropy measured at Baksan EAS "Carpet" array

Preliminary results of one year anisotropy measurement in the energy range 10^{13} -10^{14} eV as a function of energy are presented. The results are compared for two methods of data analysis: the standard one with meteo correction approach in use and another one so-called "East minus West" method. Amplitudes and phases of anisotropy for three median energies E = 25 TeV, E = 75 TeV and E = 120 TeV are reported. Brief consideration of amplitude-phase dependence of anisotropy on energy is expounded.

astro-ph.GA↗

arXiv2009

Evolution of the cosmic ray anisotropy above 10^{14} eV

The amplitude and phase of the cosmic ray anisotropy are well established experimentally between 10^{11} eV and 10^{14} eV. The study of their evolution into the energy region 10^{14}-10^{16} eV can provide a significant tool for the understanding of the steepening ("knee") of the primary spectrum. In this letter we extend the EAS-TOP measurement performed at E_0 around 10^{14} eV, to higher energies by using the full data set (8 years of data taking). Results derived at about 10^{14} and 4x10^{14} eV are compared and discussed. Hints of increasing amplitude and change of phase above 10^{14} eV are reported. The significance of the observation for the understanding of cosmic ray propagation is discussed.

astro-ph.HE↗