Boris M. Kuzhevskij

Development of the solar flare plasma density investigation method based on the 2.2 MeV gamma-line time profile analysis

Abstract We propose the method of studying the flare plasma density in different layers of the solar atmosphere, in particular, in the deep layers, which are inaccessible for optical observations. The method is based on the analysis of the time profile of 2.223 MeV gamma-rays, produced by neutron captures by hydrogen. We present the model calculations of the 2.223 MeV gamma-ray production time profiles and depth distribution densities at initial neutron energies 0.1–100 MeV. Both monoenergetic neutrons and power low spectra neutrons are considered at 5 solar plasma density altitude models. The dependence of the resultant curves on the initial neutron energy spectrum and on the altitude profile of the solar atmospheric and subphotospheric density is analysed. Applicability of the method to experimental data is discussed.

Measurements of neutron fluxes with energies from thermal to several MeV in near-Earth space: SINP results.

Neutron measurement results obtained at SINP MSU since 1970 are presented. These measurements were made using techniques based on neutron moderation and subsequent detection in a Li6I(Eu) crystal or a He3 coronal counter. The measurements were mainly carried out in orbits with inclination of 52 degrees and altitudes of 200-450 km. The spatial and angular distributions of the measured neutron fluxes were studied. The albedo neutron flux was estimated according to the count rate difference for opposite detector orientations towards Earth and away from it. This flux is comparable to the local neutron flux outside the Brazil anomaly region, where local neutrons dominate. Neutron fluxes, generated by solar protons, were detected during a solar flare on June 6, 1991 for the first time. Their spectrum was estimated as a power law with alpha>2.

VARIATIONS IN THE NEUTRON INTENSITY NEAR THE EARTH'S SURFACE MODULATE THE FUNCTIONAL STATE OF THE BLOOD

83 † Studies using cell cultures in periods of solar proton events accompanied by an increase in neutron count rate near the Earth’s surface [1–3] and during background variations in the neutron component of the secondary radiation of cosmic rays (CRs) [4] demonstrated that the neutron component may have strong biological effects. Experimental measurements of the neutron energy spectrum near the Earth’s surface [5] have shown that thermal and slow neutrons account for about 70% of all neutrons [6, 7]. Apparently, these neutrons originate from two sources [8]: first, neutron reproduction in Earth’s atmosphere as a result of the interaction of high-energy cosmic particles with the nuclei of atmospheric elements; second, radioactive gases producing α particles with energies higher than several MeV that may generate thermal neutrons upon the interaction with the elements of the Earth’s crust and atmosphere [7]. We assessed the possible biological effects of neutron fluxes in the low-energy range recorded in the directions to and from the Earth on the functional state of the blood estimated using the vesicle formation reaction (VFR). Experimental. The functional state of the blood was studied by analyzing VFR in samples of whole blood taken from healthy volunteers and patients of the outpatient clinic of the Russian Academy of Sciences in Pushchino, Moscow oblast (31 subjects) between October 11 and 25, 1996. By the term VFR is meant the following phenomenon: if whole blood is diluted with an electrolyte solution, light zones (vesicles) are formed

Correlation between the synthetic activity of lymphocytes and the intensity of neutron radiation near the Earth surface

The synthetic activity of lymphocytes from rat and ground squirrel was assessed for correlation with the rate of neutron radiation about the Earth surface. In the periods 1999–2002 for rats and 2002–2003 for ground squirrels, significant positive correlation was obtained with the neutron flux incident on Earth and the overall “terrestrial neutron field” but not with the neutron efflux from Earth. No correlation was observed in 2005–2006 when the solar activity and the variation in neutron count were minimal. It is concluded that low-energy neutrons may be bioeffective in periods of substantial variation in flux intensity.