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 space-based GAMMA-400 gamma-ray telescope will measure the fluxes of gamma rays in the energy range from ∼20 MeV to several TeV and cosmic-ray electrons and positrons in the energy range from ...several GeV to several TeV to investigate the origin of gamma-ray sources, sources and propagation of the Galactic cosmic rays and signatures of dark matter. The instrument consists of an anticoincidence system, a converter-tracker (thickness one radiation length, 1
X
0
), a time-of-flight system, an imaging calorimeter (2
X
0
) with tracker, a top shower scintillator detector, an electromagnetic calorimeter from CsI(Tl) crystals (16
X
0
) with four lateral scintillation detectors and a bottom shower scintillator detector. In this paper, the capability of the GAMMA-400 gamma-ray telescope for electron and positron measurements is analyzed. The bulk of cosmic rays are protons, whereas the contribution of the leptonic component to the total flux is ∼10
−3
at high energy. The special methods for Monte Carlo simulations are proposed to distinguish electrons and positrons from proton background in the GAMMA-400 gamma-ray telescope. The contribution to the proton rejection from each detector system of the instrument is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of up to ∼1 × 10
4
.
In 2008, the PAMELA magnetic spectrometer has discovered unpredicted abundance of the ratio of the galactic positron flux to the total positron and electron flux at high energies. It does not agree ...with the cosmic-ray fluxes calculated using the GALPROP code. This abundance was called the "PAMELA anomalous effect" and one of the explanations of this effect was the appearance of the additional electron and positron flux due to annihilation or decay of the dark matter particles. Later the precision PAMELA results were confirmed by the Fermi-LAT gamma-ray telescope and the AMS-02 magnetic spectrometer. Currently, the new GAMMA-400 project is being developed. The one of its main goals is to search for signatures of dark matter particles, which produce gamma rays. The GAMMA-400 gamma-ray telescope will have unprecedented angular and energy resolutions. PAMELA and GAMMA-400 are the instruments with the best characteristics for their time, which will improve our understanding of the nature of dark matter. At present, the problem of the nature of dark matter still remains the main challenge in high-energy astrophysics.
The characteristics of the prototype of the scintillation detecting segment of time-of-flight and anticoincidence systems of being developed space-based GAMMA-400 gamma-ray telescope is studied. The ...amplitude resolution, time resolution and charged particle detection efficiency of the prototype with silicon photomultipliers readout obtained using
250 MeV positron beam of synchrotron C-25P ‘‘PAKHRA’’ of P.N. Lebedev Physical Institute are presented. The comparison of applying both ‘‘standard’’ and ‘‘fast’’ outputs of silicon photomultipliers type ON Semiconductor MICROFC-60035-SMT used in the prototype is featured.
The potential of the planned GAMMA-400 gamma-ray telescope for detecting subhalos of mass between 10
6
M
⊙
and 10
9
M
⊙
in the Milky Way Galaxy that consist of annihilating dark matter in the form of ...weakly interacting massive particles (WIMPs) is studied. The inner structure of dark matter subhalos and their distribution in the Milky Way Galaxy are obtained on the basis of respective theoretical models. Our present analysis shows that the expected gamma-ray flux from subhalos depends strongly on the WIMP mass and on the subhalo concentration, but that it depends less strongly on the subhalo mass. Optimistically, a flux of 10 to 100 ph per year in the energy range above 100 MeV can be expected from the closest and most massive subhalos, which can therefore be thought to be detectable sources for GAMMA-400. Because of the smallness of fluxes, however, only via a joint analysis of future GAMMA-400 data and data from other telescopes would it become possible to resolve the inner structure of the subhalos. Also, the recent subhalo candidates 3FGL J2212.5+0703 and J1924.8–1034 are considered within our model. Our conclusion is that these sources hardly belong to the subhalo population.
Cosmophysical Research with GAMMA-400 Topchiev, N. P.; Galper, A. M.; Arkhangelskaja, I. V. ...
Physics of atomic nuclei,
08/2023, Volume:
86, Issue:
4
Journal Article
Peer reviewed
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.
GAMMA-400 Project Galper, A. M.; Topchiev, N. P.; Yurkin, Yu. T.
Astronomy reports,
12/2018, Volume:
62, Issue:
12
Journal Article
Peer reviewed
Extraterrestrial gamma-ray astronomy is now a source of a new knowledge in the fields of astrophysics, cosmic-ray physics, and the nature of dark matter. The next absolutely necessary step in the ...development of extraterrestrial high-energy gamma-ray astronomy is the improvement of the physical and technical characteristics of gamma-ray telescopes, especially their angular and energy resolutions. Such a new generation telescope will be GAMMA-400, currently under development. Together with an X-ray telescope, it will perform precise and detailed observations in the energy range of ~20 MeV to ~10 000 GeV and 3–30 keV the Galactic plane, especially, toward the Galactic Center, Fermi Bubbles, Crab, Cygnus, etc. The GAMMA-400 will operate in the highly elliptic orbit continuously for a long time with the unprecedented angular (~0.01◦ at
E
γ
= 100 GeV) and energy (~1% at
E
γ
= 100 GeV) resolutions, exceeding the Fermi-LAT as well as ground-based gamma-ray telescopes by a factor of 5–10. GAMMA-400 will permit resolving gamma rays from annihilation or decay of dark matter particles, identifyingmany discrete sources (many of which are variable), clarifying the structure of extended sources, specifying the data on the diffuse emission, as well as measuring electron + positron fluxes and specifying electron + positron spectrum in the energy range from 1 GeV to 10 000 GeV.
The space-based gamma-ray telescope must effectively separate photons from charged particles of instrumental background and cosmic rays. It requires that the anticoincidence system of the telescope ...must have high detection efficiency, large dynamic range and good enough energy and time resolution for charged particles. The main results obtained using 246 MeV secondary positron beam of synchrotron S-25R “PAKHRA” of Lebedev Physical Institute with prototype of system of anticoincidence detectors of space-based gamma-ray telescope GAMMA-400 are presented. The amplitude resolution, time resolution and charged particles detection efficiency are adduced. All measurements were performed using “fast” output of silicon photomultipliers of prototype scintillation detectors sensors. Fractal dimensions of temporal profiles registered during measurements using positron beam and atmospheric muons are discussed.
The future GAMMA-400 γ-ray telescope will provide fundamentally new data on discrete sources and spectra of γ-ray emissions and electrons + positrons due to its unique angular and energy resolutions ...in the wide energy range from 20 MeV up to several TeV. The γ-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), the scintillation detectors of the calorimeter (S3 and S4) and lateral anticoincidence detectors of the calorimeter (LD). To extend the GAMMA-400 capabilities to measure γ-ray bursts, Monte-Carlo simulations were performed for lateral aperture of the one of the versions of GAMMA-400. Second-level trigger based on signals from CC2, LD, S3, and S4 allows us to detect γ-ray bursts in the energy range of ~10-300 MeV with high effective area about 1 m2.
The GAMMA-400 gamma-ray telescope is planned for the launch at the end of this decade on the Navigator service platform designed by Lavochkin Association on an elliptical orbit with following initial ...parameters: an apogee ~300000, a perigee ~500 km, a rotation period ~7 days and inclination of 51.4°. The apparatus is expected to operate more than 5 years, reaching an unprecedented sensitivity for the search of dark matter signatures and the study of the unresolved and so far unidentified gamma-ray sources. An electronics system, which consists of 14 front-end multichannel electronics modules and the main processing unit with a total power consumption of about 400 W (74W for main processing unit), has been developed for providing fast trigger and veto for the data taking to the experiment. The communication between front-end modules, main processing unit and scientific data acquisition system of the gamma-ray telescope is performed via high-speed SPACEWIRE network. To assure the long-term reliability in space environment, a series of critical issues such as the radiation hardness, thermal design, components and board level quality control, warm and cold redundancy are taken into consideration. The main design concepts for the system, measurements setups together with some test results are presented.
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