The OLIMPIYA project investigates tracks of galactic cosmic rays (GCR) in olivine crystals from two meteorites-pallasites of different exposure ages. Extended statistics (up to 21 743 processed ...tracks) enabled to reveal a difference between the charge spectra of heaviest nuclei registered in these pallasites versus those from detectors mounted on near-Earth orbit satellites, as well as a difference between the GCR spectra registered in the meteorites themselves. Comparison of the
-element abundances in these spectra points that GCR fluxes from at least two rare cosmic nucleosynthesis events with enhanced production of these elements reached the Solar System during the exposition age of the older meteorite. Correlations of the experimental results with parameters of supernovae, asymptotic giant branches stars and neutron star mergers (NSM) are also discussed.
We report on the results of model calculations for estimating the fragmentation effect in the registration of heavy and superheavy nuclei of galactic cosmic rays in olivine crystals from pallasite at ...the Marjalahti and Eagle Station. The measurement of fluxes and spectra of heavy and superheavy nuclei in cosmic rays is a sensitive method for studying the composition and possible sources of cosmic rays, the processes occurring in the sources themselves and in the interstellar medium, and forms the basis for constructing models of cosmic ray confinement in the Galaxy. The database obtained in the OLIMPIYA experiment, which includes characteristics of 21743 tracks, is the largest database for charges
Z
> 55 at present. The estimates of fragmentation of nuclei in pallasites, which have been obtained based on model calculations, show that the effect of this process on the resulting charge spectrum is insignificant.
For the first time the emission of neutron bursts in the process of high-voltage discharge in air was observed. Experiments were carried out at an average electric field strength of ∼1 MV·m(-1) and ...discharge current of ∼10 kA. Two independent methods (CR-39 track detectors and plastic scintillation detectors) registered neutrons within the range from thermal energies up to energies above 10 MeV and with an average flux density of ≳10(6) cm(-2) per shot inside the discharge zone. Neutron generation occurs at the initial phase of the discharge and correlates with x-ray generation. The data obtained allow us to assume that during the discharge fast neutrons are mainly produced.
Geant4 Simulation of the p+11B → 3α Reaction Bagulya, A. V.; Grichine, V. M.; Zavestovskaya, I. N. ...
Bulletin of the Lebedev Physics Institute,
2023/4, Letnik:
50, Številka:
4
Journal Article
Recenzirano
In order to increase the absorbed dose around the Bragg peak region, it is proposed to use the p+
11
B → 3α reaction for proton therapy. This reaction is not implemented in the Geant4 software ...package. A simplified model of this reaction is proposed which will allow its full-scale simulation. The model is fully compatible with the Geant4 software package and can be integrated with it. The model predictions and background events from other processes are discussed.
At the ion accelerator HELIS at LPI, the neutron yield is investigated in DD reactions within a strongly textured polycrystalline deuterium-saturated CVD diamond under irradiation by a deuterium ion ...beam with the energy of less than 30keV. The measurements of the neutron flux in the beam direction are performed using a multichannel detector based on 3He counters, in dependence on the target angle, β, with respect to the beam axis. A significant anisotropy in the neutron yield is observed. At β=0° the yield is higher by a factor of 3 as compared to that at β=±45°. The possible reasons for the anisotropy, including ion channeling, are discussed.
This work was performed within the OLYMPIA experiment on the study of tracks of heavy and superheavy cosmic ray nuclei in olivine crystals from Marjalahti and Eagle Station pallasites. Depth ...distributions of the track formation rate for heavy cosmic ray nuclei in olivine crystals from pallasites of different pre-atmospheric sizes were obtained. The dependences obtained were used to analyze the data on the track density in olivine crystals from the Marjalahti pallasite. In three crystals, the track distribution with a high density gradient was detected, which indicates a complicated radiation history of the meteorite.
Cosmic ray muonography is a novel technique for imaging of the internal structures of large natural and industrial objects. It exploits the capability of high energy muons from cosmic rays to ...penetrate large thicknesses of large subjects to be studied, in order to obtain a density map. It uses muon flux attenuation and absorption in materials of investigated objects. Nuclear emulsions are tracking detectors well suited to be employed in muonography for investigations of inner structure of large objects up to kilometers size, since emulsions have firstly an excellent angular resolution, they are compact and robust, do not require power supply. The muonography methods are applied to study one of UNESCO world heritage objects, the unusual building in the Naryn-Kala citadel hidden underground. The use of nuclear emulsions as probing radiation detectors provides for a uniquely high resolution capacity of recording instrumentation combined with the potential of modern image analysis methods giving 3D reconstruction of the internal structures of the investigated object.
Results of nuclear physics research made using track detectors are briefly reviewed. Advantages and prospects of the track detection technique in particle physics, neutrino physics, astrophysics and ...other fields are discussed on the example of the results of the search for direct origination of tau neutrino in a muon neutrino beam within the framework of the international experiment OPERA (Oscillation Project with Emulsion-tRacking Apparatus) and works on search for superheavy nuclei in nature on base of their tracks in meteoritic olivine crystals. The spectra of superheavy elements in galactic cosmic rays are presented. Prospects of using the track detection technique in fundamental and applied research are reported.
The software tools developed for the validation and verification of the standard electromagnetic physics package of Geant4 are described. The validation is being performed versus experimental data ...and in regression to a previous version of Geant4. Examples of validation results are presented.
The results of the search for tracks of heavy and superheavy nuclei of galactic cosmic rays in the charge range
Z
= 26 − 129, identified in olivine crystals from Maryalahti and Eagle Station ...meteorites are presented. The database including characteristics of 21743 tracks, obtained in the OLIMPIA experiment, is currently the largest one within the charge range under study. It includes three tracks of superheavy nuclei with charge 119
−6
+10
and a minimum lifetime estimated as several tens of years, which can be considered as a direct experimental validation of the existence of natural superheavy nuclei from the “stability island”.
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