•The GAMMA-400 gamma-ray telescope performance for lateral aperture.•Detection of GRB from the lateral aperture in the energy range from ∼ 10 to ∼ 100 MeV.•The problem of connection between high- and ...low-energy gamma-ray emissions of GRBs.
The currently developing space-based gamma-ray telescope GAMMA-400 will measure the gamma-ray and electron + positron fluxes using the main top-down aperture in the energy range from ∼ 20 MeV to several TeV in a highly elliptic orbit (without shading the telescope by the Earth and outside the radiation belts) continuously for a long time. The instrument will provide fundamentally new data on discrete gamma-ray sources, gamma-ray bursts (GRBs), sources and propagation of Galactic cosmic rays and signatures of dark matter due to its unique angular and energy resolutions in the wide energy range. The gamma-ray telescope consists of the anticoincidence system (AC), the converter-tracker (C), the time-of-flight system (S1 and S2), the position-sensitive and electromagnetic calorimeters (CC1 and CC2), scintillation detectors (S3 and S4) located above and behind the CC2 calorimeter and lateral detectors (LD) located around the CC2 calorimeter.
In this paper, the capabilities of the GAMMA-400 gamma-ray telescope to measure fluxes of GRBs from lateral directions of CC2 are analyzed using Monte-Carlo simulations. The analysis is based on off-line second-level trigger construction using signals from S3, CC2, S4 and LD detectors. For checking the numerical algorithm the data from space-based GBM and LAT instruments of the Fermi experiment are used, namely, three long bursts: GRB 080916C, GRB 090902B, GRB 090926A and one short burst GRB 090510A. The obtained results allow us to conclude that from lateral directions the GAMMA-400 space-based gamma-ray telescope will reliably measure the spectra of bright GRBs in the energy range from ∼ 10 to ∼ 100 MeV with the on-axis effective area of about 0.13 m2 for each of the four sides of CC2 and total field of view of about 6 sr.
The space observatory GAMMA-400 is processed currently in accordance with the Federal Space Program of the Russian Federation for 2016–2025. The observatory includes a gamma-ray telescope for ...experimental studies of gamma rays in the energy range from ~20 MeV to ~1 TeV with high angular and energy resolution, as well as for research of electrons + positrons at energies above 100 GeV in both the main (top-down), and lateral apertures. At present time, there are experimental indications concerning the possibility of existing of spectrum break in electrons + positrons intensities about TeV energies. This point stimulates several speculations to explain such phenomena. In this paper we examined capabilities of GAMMA-400 telescope to explore this problem. The methods for electron detection in the energy range from 100 GeV up to 10 TeV from the lateral aperture of a gamma-ray telescope are presented. Also, the results of calculation for proton rejection factor and for electron acceptance are revealed.
A simplified method for taking into account the magnetization branch when using a T-shaped equivalent circuit of a two-winding transformer for the analysis of a resonant dc voltage converter (DCVC) ...at the time interval of its linearity is proposed. The method allows us to replace the exact description of the DCVC in the interval of its linearity with two differential equations of the first order, which greatly simplifies the calculations. Calculations of the processes in the linearity interval of the DCVC using exact and simplified equations showed almost perfect matching of the results. The equation for determining the initial value of the state vector of the DCVC at the interval of its linearity in the steady-state mode is solved. Formulas for calculating the external (load) characteristics of the DCVC are given. The calculated external characteristics with the parameters of a mass-produced DCVC practically coincide with the experimental ones obtained using the Simulink model.
Cosmophysical Research with GAMMA-400 Topchiev, N. P.; Galper, A. M.; Arkhangelskaja, I. V. ...
Physics of atomic nuclei,
08/2023, Letnik:
86, Številka:
4
Journal Article
Recenzirano
The GAMMA-400 gamma-ray telescope is the successor of Soviet and Russian gamma-ray telescopes. GAMMA-400 is being developed for cosmophysical research in accordance with the Russian Federal Space ...Program 2016–2025. The GAMMA-400 experiment will be implemented aboard the Russian astrophysical space observatory in a highly elliptic orbit during 7 years to provide new data on gamma-ray emission mainly from the Galactic plane, Galactic Center, the Sun and cosmic-ray electron
positron fluxes. The main mode of observations will be the continuous point-source mode with the duration of up to
100 days. The GAMMA-400 gamma-ray telescope will study high-energy gamma-ray emission up to several TeV and cosmic-ray electrons
positrons up to 20 TeV. GAMMA-400 will have the never-achieved angular resolution, the high-energy and time resolutions, as well as very good separation efficiency of gamma rays from cosmic-ray background and of electrons
positrons from protons. The distinctive features of GAMMA-400 are the excellent angular resolution of
at
GeV that exceeds resolutions of the space-based and ground-based gamma-ray telescopes by a factor of 5–10, as well as high-energy resolution of
at
GeV. GAMMA-400 studies can discover gamma-ray emission from annihilation or decay of dark matter particles, identify many unassociated discrete sources, explore the structure of extended sources, search for gamma-ray bursts and solar gamma-ray flares, improve the data on cosmic-ray electron
positron spectra for energies of >50 GeV.
For a linear equivalent circuit of a dc–dc converter of
LLC
type, a generalized vector-matrix equation is obtained for individual intervals of circuit linearity. When solving the third-order ...vector-matrix differential equation for an
LC
circuit based on the method of dividing processes into fast (in the
LC
circuit) and slow (in the converter output circuit) ones, the output voltage of the converter is assumed to be constant over the circuit half-cycle operation. This voltage is calculated by averaging over the average value of the converter output current obtained in the previous half-cycle. The processes in the dc–dc converter are calculated using the fitting method, in which the value of the
LC
circuit state vector at the end of the circuit linearity interval is used as its initial value in the next linearity interval. This method includes a standard algorithm for calculating the process over a half-cycle. A half-cycle can consist of several intervals of linearity. The start and end moments of these intervals are determined, as well as the voltage values on the output diagonal of the inverter bridge and on the secondary winding of the output transformer. The integral of the converter output current is calculated. The comparison of the calculated results with the results of simulation in the MATLAB/Simulink environment at the start confirms the correctness of the proposed method for calculating transients.
This paper presents a conceptual design of the compact SC230 superconducting cyclotron that accelerates a beam of protons to 230 MeV and is intended for proton therapy and biomedical research. SC230 ...is an isochronous four-sector cyclotron based on a shell-type magnet with a magnetic field in the center of 1.7 T. Superconducting coils will be enclosed in a cryostat; all other parts of the cyclotron are warm. Acceleration is carried out at the fourth harmonic mode of the accelerating high-frequency (HF) system consisting of four resonators located in the cyclotron valleys. The accelerator employs an internal Penning-type hot cathode source. Extraction is carried out using an electrostatic deflector located in the gap between the sectors and two passive magnetic channels.
The future space-based GAMMA-400
-ray telescope will operate onboard the Russian astrophysical observatory in a highly elliptic orbit during 7 years. Observing
-ray sources from Galactic plane,
-ray ...bursts,
-ray diffuse emission,
rays from the Sun, and
rays from dark matter particles will be performed uninterruptedly for a long time (
100 days) in point-source mode in contrast to scanning mode for Fermi-LAT and other space- and ground-based instruments. GAMMA-400 will measure
rays in the energy range from
20 MeV to several TeV units, have the unprecedented angular (
at
GeV) and energy (
at
GeV) resolutions better than for Fermi-LAT, as well as ground-based
-ray facilities, by a factor of 5–10, and perfectly separate
rays from cosmic-ray background.
The contamination of the recirculated powder, namely, the material retained after the selective laser sintering of VZh159 and EP648 alloys, is studied as a function of the geometry of a part. The ...contamination of the recirculated powder is shown to depend mainly on the complex geometry of the part with a long perimeter of its contours and supporting elements rather than on the area of the section to be sintered. The main source of the contamination of the recirculated powder is represented by ejected particles, i.e., secondary granules, which form during a local microexplosion in the focal laser spot on a powder layer. The laws of ejection formation during synthesis are determined as functions of the type of part element to be synthesized.
A new domestic procedure is described for the installation of “Atlant” anchor piles. Characteristic features and advantages over other procedures are presented.
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