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.
Display omitted
TUS (Tracking Ultraviolet Set-up) is the world's first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on 28th April 2016 as a part of the scientific payload of ...the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above ∼100 EeV in the Earth atmosphere from space. During its operation for 1.5 years, TUS registered almost 80,000 events with a few of them satisfying conditions anticipated for extensive air showers (EASs) initiated by UHECRs. Here we discuss an event registered on 3rd October 2016. The event was measured in perfect observation conditions as an ultraviolet track in the nocturnal atmosphere of the Earth, with the kinematics and the light curve similar to those expected from an EAS. A reconstruction of parameters of a primary particle gave the zenith angle around 44ˆ but an extreme energy not compatible with the cosmic ray energy spectrum obtained with ground-based experiments. We discuss in details all conditions of registering the event, explain the reconstruction procedure and its limitations and comment on possible sources of the signal, both of anthropogenic and astrophysical origin. We believe this detection represents a significant milestone in the space-based observation of UHECRs because it proves the capability of an orbital telescope to detect light signals with the apparent motion and light shape similar to what are expected from EASs. This is important for the on-going development of the future missions KLYPVE-EUSO and POEMMA, aimed for studying UHECRs from space.
Using the variational principle, we show that the condition of spatial collapse in a Bose gas is not determined by the value of the scattering length of the interaction potential between particles ...contrary to the result following from the Gross–Pitaevskii equation, where the collapse should take place at a negative scattering length.
We study the role of the nonperturbative input to the transverse momentum dependent (TMD) gluon density in hard processes at the LHC. We derive the input TMD gluon distribution at a low scale ...(ProQuest: Formulae and/or non-USASCII text omitted) from a fit of inclusive hadron spectra measured at low transverse momenta in pp collisions at the LHC and demonstrate that the best description of these spectra for larger hadron transverse momenta can be achieved by matching the derived TMD gluon distribution with the exact solution of the Balitsky-Fadin-Kuraev-Lipatov equation obtained at low x and small gluon transverse momenta outside the saturation region. Then, we extend the input TMD gluon density to higher mu super(2) numerically using the Catani-Ciafoloni-Fiorani-Marchesini gluon evolution equation. Special attention is paid to phenomenological applications of the obtained TMD gluon density to some LHC processes, which are sensitive to the gluon content of a proton.
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.
PDF
