Relativistic runaway electron breakdown and Terrestrial Gamma ray Flashes: GEANT4 simulation

Numerical simulation of a relativistic runaway electron breakdown in the upper atmosphere is performed using GEANT4 simulation toolkit. General features of a relativistic runaway electron avalanche are reconstructed and properties of radiations accompanying breakdown are obtained. It is demonstrated dependance of the high energy branch of photon spectra with respect to an altitude and shown what at the reasonable parameters hard photons have spectral index close to the observed value.Comment: 17 pages, 9 figure

Study of Scintillator Strip with Wavelength Shifting Fiber and Silicon Photomultiplier

The performance of the $200\times2.5\times1$ cm$^3$ plastic scintillator strip with wavelength shifting fiber read-out by two novel photodetectors called Silicon PhotoMultipliers (SiPMs) is discussed. The advantages of SiPM relative to the traditional multichannel photomultiplier are shown. Light yield and light attenuation measurements are presented. This technique can be used in muon or calorimeter systems.Comment: 9 pages, 5 figure

Test beam studies of the TRD prototype filled with different gas mixtures based on Xe, Kr, and Ar

Towards the end of LHC Run1, gas leaks were observed in some parts of the Transition Radiation Tracker (TRT) of ATLAS. Due to these leaks, primary Xenon based gas mixture was replaced with Argon based mixture in various parts. Test-beam studies with a dedicated Transition Radiation Detector (TRD) prototype were carried out in 2015 in order to understand transition radiation performance with mixtures based on Argon and Krypton. We present and discuss the results of these test-beam studies with different active gas compositions.Comment: 5 pages,12 figures, The 2nd International Conference on Particle Physics and Astrophysics (ICPPA-2016); Acknowledgments section correcte

Some results of test beam studies of Transition Radiation Detector prototypes at CERN

Operating conditions and challenging demands of present and future accelerator experiments result in new requirements on detector systems. There are many ongoing activities aimed to develop new technologies and to improve the properties of detectors based on existing technologies. Our work is dedicated to development of Transition Radiation Detectors (TRD) suitable for different applications. In this paper results obtained in beam tests at SPS accelerator at CERN with the TRD prototype based on straw technology are presented. TRD performance was studied as a function of thickness of the transition radiation radiator and working gas mixture pressure

Meson vacuum phenomenology in a three-flavor linear sigma model with (axial-)vector mesons

We study scalar, pseudoscalar, vector, and axial-vector mesons with non-strange and strange quantum numbers in the framework of a linear sigma model with global chiral $U(N_f)_L \times U(N_f)_R$ symmetry. We perform a global fit of meson masses, decay widths, as well as decay amplitudes. The quality of the fit is, for a hadronic model that does not consider isospin-breaking effects, surprisingly good. We also investigate the question whether the scalar $\bar{q}q$ states lie below or above 1 GeV and find the scalar states above 1 GeV to be preferred as $\bar{q}q$ states. Additionally, we also describe the axial-vector resonances as $\bar{q}q$ states.Comment: 29 pages, 4 figures, 3 tables. v2 is the updated version after referee remarks (dilaton field discussed, a new figure added

Soil weathering dynamics and erosion in a dry oceanic area of the southern hemisphere (Otago, New Zealand)

Landscape evolution is driven by tectonics, climate and surface denudation. In New Zealand, tectonics and steep climatic gradients cause a dynamic landscape with intense chemical weathering, rapid soil formation, and high soil losses. In this study, soil, and elemental redistribution along two adjacent hillslopes in East Otago, New Zealand, having different landscape settings (ridge versus valley) are compared to identify soil weathering and erosion dynamics. Fallout radionuclides ($^{239+240}$Pu) show that over the last ~ 60 years, average soil erosion rates in the valley (~ 260 [t km$^{−2}$ year$^{−1}$]) are low compared to the ridge (~ 990 [t km$^{−2}$ year$^{−1}$]). The ridge yields up to 26% lower soil weathering intensity than the topographical-protected valley. The lowest soil weathering intensity is found at both hilltop positions, where tors (residual rocks) are present and partially disintegrate. The soil weathering intensity increases with distance from tors, suggesting that tors rejuvenate the chemical weathering signature at the hilltop positions with fresh material. The inversed and decreasing weathering degree with all soil depth indicates that the fresh mineral contribution must be higher at the soil surface than at the bedrock weathering front. Higher erosion rates at the exposed ridge may be partially attributed to wind, consistent with rock abrasion of tors, and low local river sediment yields (56 [t km$^{−2}$ year$^{−1}$]). Thus, the East Otago spatial patterns of soil chemistry and erosion are governed by tor degradation and topographic exposure

Reaction-diffusion equations with spatially distributed hysteresis

The paper deals with reaction-diffusion equations involving a hysteretic discontinuity in the source term, which is defined at each spatial point. In particular, such problems describe chemical reactions and biological processes in which diffusive and nondiffusive substances interact according to hysteresis law. We find sufficient conditions that guarantee the existence and uniqueness of solutions as well as their continuous dependence on initial data.Comment: 30 pages, 14 figure

Совершенствование транспортного обслуживания в городе Брянске

The object of the study of the article is the passenger transport network of the city of Bryansk. The task of improving transport services for the population is solved in the context of modernising vehicle fleet, transport infrastructure and in-depth implementation of digital technologies. The analytical method allowed to assess the state of the transport system of the city of Bryansk. The assessment touched upon several interrelated areas that provide a high quality of transport services. The data were obtained by studying open Internet resources, including the website of the administration of the city of Bryansk, and through field observations.Work on updating the fleet of route vehicles is carried out within the framework of the «Concept for development of public transport in the city of Bryansk for the period 2015–2025», which over the past four years has led to a significant renewal of the bus fleet of medium and large capacity and to the decrease in the share of buses of small capacity. The road network has also been significantly upgraded.The routes of urban passenger transport have been analysed from the point of view of the degree of duplication. Guidelines for improving the routes of the transport network are proposed.Объектом исследования статьи является пассажирская транспортная сеть города Брянска. Совершенствование транспортного обслуживания населения решается в разрезе модернизации средств транспорта, транспортной инфраструктуры и углубленного внедрения цифровых технологий. На основе аналитического метода проведена оценка состояния транспортного комплекса города Брянска, включающая в себя несколько взаимосвязанных направлений, обеспечивающих высокое качество транспортного обслуживания. Данные получены путём исследования открытых интернет-ресурсов, в том числе интернет-сайта администрации г. Брянска, натурных наблюдений.Работы по обновлению парка маршрутных транспортных средств производятся в рамках «Концепции развития транспорта общего пользования города Брянска на период 2015–2025 годы», что привело за последние четыре года к существенному обновлению автобусного парка средней и большой вместимости и снижению доли автобусов малой вместимости. Также существенно модернизирована дорожная сеть.Проанализированы с точки зрения степени дублирования маршруты городского пассажирского транспорта. Предложены направления совершенствования маршрутов транспортной сети