The origin and nature of extreme energy cosmic rays (EECRs), which have energies above the
5
⋅
10
19
eV
—the Greisen-Zatsepin-Kuzmin (GZK) energy limit, is one of the most interesting and complicated ...problems in modern cosmic-ray physics. Existing ground-based detectors have helped to obtain remarkable results in studying cosmic rays before and after the GZK limit, but have also produced some contradictions in our understanding of cosmic ray mass composition. Moreover, each of these detectors covers only a part of the celestial sphere, which poses problems for studying the arrival directions of EECRs and identifying their sources. As a new generation of EECR space detectors, TUS (Tracking Ultraviolet Set-up), KLYPVE and JEM-EUSO, are intended to study the most energetic cosmic-ray particles, providing larger, uniform exposures of the entire celestial sphere. The TUS detector, launched on board the Lomonosov satellite on April 28, 2016 from Vostochny Cosmodrome in Russia, is the first of these. It employs a single-mirror optical system and a photomultiplier tube matrix as a photo-detector and will test the fluorescent method of measuring EECRs from space. Utilizing the Earth’s atmosphere as a huge calorimeter, it is expected to detect EECRs with energies above
10
20
eV
.
It will also be able to register slower atmospheric transient events: atmospheric fluorescence in electrical discharges of various types including precipitating electrons escaping the magnetosphere and from the radiation of meteors passing through the atmosphere. We describe the design of the TUS detector and present results of different ground-based tests and simulations.
•Preliminary irradiation accelerates poly(L-lactide) hydrolysis.•Irradiated poly(L-lactide) crystallizes at higher rate during hydrolysis.•Radiation treatment may eliminate induction period during ...polymer degradation.
The present study aimed to examine the effect of gamma-irradiation on subsequent hydrolytic degradation of poly(L-lactide) (PLLA) and polymer crystallization behavior during this process. Absorbed doses were 29 and 75 kGy, unirradiated sample was also studied. Hydrolysis was performed at 60 °C for up to 50 days. Radiation treatment of PLLA accelerates hydrolysis process. It affects polymer mass loss, molecular weight distribution, change of hydrolysis media pH, and values of the hydrolytic degradation rate constant. Preliminary irradiation makes it possible to eliminate the induction period of PLLA mass loss during hydrolysis. However, a decrease of polymer molecular weight during irradiation leads to an increase of PLLA crystallization rate upon hydrolysis. It was found that α crystals can be formed during hydrolytic degradation. Parameters of PLLA unit cell were calculated. When polymer degree of crystallinity becomes high enough its hydrolytic degradation slows down. Thus, faster crystallization of irradiated PLLA reduces the acceleration effect of radiation treatment on polymer hydrolysis.
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Analysis of Anomalous Events in TUS Data Lavrova, M. V.; Blinov, A. V.; Grinyuk, A. A. ...
Physics of atomic nuclei,
08/2023, Letnik:
86, Številka:
4
Journal Article
Recenzirano
The main goal of the TUS experiment was to search for and study extremely high-energy cosmic rays with energies
EeV. The TUS detector registered a number of unusual events, the origin of which is ...unclear. The analysis of not similar to EAS and unique anomalous events is the subject of the study presented in this paper.
The TAIGA experiment (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) combines heterogeneous arrays of imaging and non-imaging Cherenkov light detectors for registration of ...extensive air showers. Monte Carlo simulation of the whole detector response was carried out and is described in this article.
The multiplicities of light (anti)nuclei were measured recently by the ALICE collaboration in Pb+Pb collisions at the center-of-mass collision energy sNN=2.76TeV. Surprisingly, the hadron resonance ...gas model is able to perfectly describe their multiplicities under various assumptions. For instance, one can consider the (anti)nuclei with a vanishing hard-core radius (as the point-like particles) or with the hard-core radius of proton, but the fit quality is the same for these assumptions. In this paper we assume the hard-core radius of nuclei consisting of A baryons or antibaryons to follow the simple law R(A)=Rb(A)13, where Rb is the hard-core radius of nucleon. To implement such a relation into the hadron resonance gas model we employ the induced surface tension concept and analyze the hadronic and (anti)nuclei multiplicities measured by the ALICE collaboration. The hadron resonance gas model with the induced surface tension allows us to verify different scenarios of chemical freeze-out of (anti)nuclei. It is shown that the most successful description of hadrons can be achieved at the chemical freeze-out temperature Th = 150 MeV, while the one for all (anti)nuclei is TA = 168.5 MeV. Possible explanations of this high temperature of (anti)nuclei chemical freeze-out are discussed.
We review the recent approach to model the hadronic and nuclear matter equations of state using the induced surface tension concept, which allows one to go far beyond the usual Van der Waals ...approximation. Since the obtained equations of state, classical and quantum, are among the most successful ones in describing the properties of low density phases of strongly interacting matter, they set strong restrictions on the possible value of the hard-core radius of nucleons, which is widely used in phenomenological equations of state. We summarize the latest results obtained within this novel approach and perform a new detailed analysis of the hard-core radius of nucleons, which follows from hadronic and nuclear matter properties. Such an analysis allows us to find the most trustworthy range of its values: the hard-core radius of nucleons is 0.3–0.36 fm. A comparison with the phenomenology of neutron stars implies that the hard-core radius of nucleons has to be temperature and density dependent. Such a finding is supported when the eigenvolume of composite particles like hadrons originates from their fermionic substructure due to the Pauli blocking effect.
We present physical motivations and advantages of the new gamma-observatory TAIGA (Tunka Advanced Instrument for cosmic ray physics and gamma-ray astronomy). TAIGA will be located in the Tunka ...valley, 50km to the west of Lake Baikal, at the same place as the integrating air Cherenkov detector for cosmic rays Tunka-133. The TAIGA array is a complex, hybrid detector for ground-based gamma-ray astronomy for energies from a few TeV to several PeV as well as for cosmic ray studies from 100TeV to several EeV. The array will consist of a wide angle Cherenkov array – TAIGA-HiSCORE with 5km2 area, a net of 16 IACT telescopes (with FOV of about 9.72°×9.72°) as well as muon and other detectors. We present the current status of the array construction.
The TUS experiment is aimed to study the energy spectrum and arrival direction of Ultra High Energy Cosmic Rays at
E
∼ 100 EeV from the space orbit by measuring the fluorescence radiation of the ...Extensive Atmospheric Shower in the atmosphere. It is the first orbital telescope aimed for such measurements and is taking data since April 28, 2016. During the first turns of operation ∼20% PMTs were broken due to the HV tuning system failure. For the same reason, the properties of the remaining PMTs are changed. Relative calibration of PMT gains in flight was done and presented based on analyzing TUS background data itself. A reconstruction of EAS arrival directions is done using the relative calibration coefficients.
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