Measurement of the radiation environment of the ATLAS cavern in 2017–2018 with ATLAS-GaAsPix detectors

A network of ten GaAs:Cr semiconductor Timepix detectors with GaAs:Cr sensors was installed in the ATLAS cavern at CERN's LHC during the shutdown periods 2015–2016 and 2016–2017 in the framework of a cooperation between ATLAS and the Medipix2 Collaboration. The purpose was to augment the existing system of measuring and characterising the radiation environment in the ATLAS cavern that is based on ATLAS-TPX devices with pixelated silicon sensors. The detectors were in continuous operation during 13 TeV proton-proton collisions in 2017–2018. Data were recorded during proton-proton bunch crossings, and during times without bunch crossings (LHC physics runs) as well as between the physics runs. The overall level of particle radiation as well as the ratio between neutral and charged particles were measured. The detectors recorded all interactions of charge particles, neutrons and photons in GaAs sensors, in which the signal was higher than 6.5 keV in individual pixels. This made it possible to register clusters (tracks) of individual radiation particles interacting in the detectors sensors. During LHC beam-beam collisions, these were all particles represented in the radiation field. In the periods without beam-beam collisions, these were photons and electrons resulting from radioactivity induced during previous collisions in GaAs detectors and in surrounding construction materials, namely by neutrons

ЭКСТРАПОЛЯЦИОННЫЕ ОЦЕНКИ ФИЗИКО-ХИМИЧЕСКИХ ХАРАКТЕРИСТИК НИХОНИЯ, ТЕННЕССИНА И ОГАНЕСОНА

Метод сравнительного расчета, основанный на корреляции одних свойств с другими в группе элементов-аналогов и неоднократно применявшийся для определения свойств астата, можно использовать для оценки некоторых физико-химических свойств теннессина, оганесона и нихония. В группах этих элементов наблюдается прямолинейная зависимость одних их свойств от других свойств

Atmospheric Neutrino Spectra: A Statistical Analysis of Calculations in Comparison with Experiment

A statistical analysis is performed to compare calculated spectra of atmospheric neutrinos and measuring data obtained in the Frejus, AMANDA-II, IceCube, ANTARES, and Super-Kamiokande experiments. Atmospheric neutrino spectra are calculated with a certain computational scheme for set of models of hadron–nuclear interaction also used in the EAS simulation. Standard criterion χ$^{2}$ is used to compare the calculated energy spectra and the experimental values. The analysis allows one to estimate the statistical significance level of various models according to their agreement with measurements of different experiments

Detecting Gamma Rays with Energies Greater than 3–4 ТeV from the Crab Nebula and Blazar Markarian 421 by Imaging Atmospheric Cherenkov Telescopes in the TAIGA Experiment

The TAIGA hybrid gamma-ray observatory is currently being developed in the Tunka Valley, 50 km from Lake Baikal, to study gamma radiation and charged cosmic ray fluxes in the 10$^{13}$–10$^{18}$ eV range. The first results are presented for detecting gamma rays from the Crab Nebula in 44 h of observation, and from the blazar Markarian 421 in 62 h of observation with a significance of around 5–6 σ by one of the TAIGA IACT telescopes

The 6^{6}H states studied in the d(8He,α)d(^8\text{He},\alpha) reaction and evidence of extremely correlated character of the 5^{5}H ground state

The extremely neutron-rich system $^{6}$H was studied in the direct $^2\text{H}(^8\text{He},{^4\text{He}})^{6}$H transfer reaction with a 26 $A$MeV secondary $^{8}$He beam. The measured missing mass spectrum shows a resonant state in $^{6}$H at $6.8(3)$ MeV relative to the $^3$H+$3n$ threshold. There is also some evidence of a resonant state at $4.5(3)$ MeV which is a realistic candidate for the $^{6}$H ground state (g.s.). The population cross section of the presumably $p$-wave states in the energy range from 4 to 8 MeV is $d\sigma/d\Omega_{\text{c.m.}} \sim 190$$\mu$b/sr in the angular range $5^{\circ}<\theta_{\text{c.m.}}<16^{\circ}$. The obtained missing mass spectrum is free of the $^{6}$H events below 3.5 MeV ($d\sigma/d\Omega_{\text{c.m.}} \lesssim 3$$\mu$b/sr in the angular range $5^{\circ}<\theta_{\text{c.m.}}<20^{\circ}$), which indicates that the value of 4.5 MeV is the lower limit of the possible $^{6}$H g.s. location. The obtained results confirm that the decay mechanism of the $^{7}$H g.s. (located at 2.2 MeV above the $^{3}$H+$4n$ threshold) is the ``true'' (or simultaneous) $4n$ emission. The resonance energy profiles and the momentum distributions of the sequential $^{6}$H \,\rightarrow \, ^5H(g.s.)+n\, \rightarrow \, ^3H+$3n$ decay fragments were analyzed by the theoretically-updated direct four-body-decay and sequential-emission mechanisms. The measured momentum distributions of the $^{3}$H fragments in the $^{6}$H rest frame indicate a very strong ``dineutron-type'' correlations in the $^{5}$H ground state decay