5,473 research outputs found
The first light of Mini-MegaTORTORA wide-field monitoring system
Here we describe the first light of the novel 9-channel wide-field optical
monitoring system with sub-second temporal resolution, Mini-MegaTORTORA, which
is being tested now at Special Astrophysical Observatory on Russian Caucasus.
The system is able to observe the sky simultaneously in either wide (~900
square degrees) or narrow (~100 square degrees) fields of view, either in clear
light or with any combination of color (Johnson B, V or R) polarimetric filters
installed, with exposure times ranging from 100 ms to 100 s. The primary goal
of the system is the detection of rapid -- with sub-second characteristic
time-scales -- optical transients, but it may be also used for studying the
variability of the sky objects on longer time scales.Comment: 9 pages, 9 figures, based on the talk presented on "Modern stellar
astronomy-2014" (Rostov-on-Don
Optical Camera with high temporal resolution to search for transients in the wide field
The wide field optical camera with high temporal resolution for the
continuous monitoring of the sky in order to catch the initial stages of GRBs
is described.Comment: 4 pages, 4 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
Study of thermoelastoplastic contact deformation of production tooling mixed structures
A calculation technique based on the unified methodological approach is proposed for the analysis of thermoelastoplastic contact deformation of mixed structures. The proposed numerical technique involves the finite element method. The problem of stress-strain state evaluation for one class of mixed shrouded half-hot extrusion dies is considered. Recommendations on production tooling design are give
Measurement of the ionization yield of nuclear recoils in liquid argon at 80 and 233 keV
The energy calibration of nuclear recoil detectors is of primary importance
to rare-event experiments such as those of direct dark matter search and
coherent neutrino-nucleus scattering. In particular, such a calibration is
performed by measuring the ionization yield of nuclear recoils in liquid Ar and
Xe detection media, using neutron elastic scattering off nuclei. In the present
work, the ionization yield for nuclear recoils in liquid Ar has for the first
time been measured in the higher energy range, at 80 and 233 keV, using a
two-phase Cryogenic Avalanche Detector (CRAD) and DD neutron generator. The
ionization yield in liquid Ar at an electric field of 2.3 kV/cm amounted to
7.8+/-1.1 and 9.7+/-1.3 e-/keV at 80 and 233 keV respectively. The Jaffe model
for nuclear recoil-induced ionization, in contrast to that Thomas-Imel, can
probably consistently describe the energy dependence of the ionization yield.Comment: 6 pages, 6 figures. Fig. 6 changed. Submitted to EP
On the low-temperature performances of THGEM and THGEM/G-APD multipliers in gaseous and two-phase Xe
The performances of THGEM multipliers in two-phase Xe avalanche mode are
presented for the first time. Additional results on THGEM operation in gaseous
Xe at cryogenic temperatures are provided. Stable operation of a double-THGEM
multiplier was demonstrated in two-phase Xe with gains reaching 600. These are
compared to existing data, summarized here for two-phase Ar, Kr and Xe
avalanche detectors incorporating GEM and THGEM multipliers. The optical
readout of THGEMs with Geiger-mode Avalanche Photodiodes (G-APDs) has been
investigated in gaseous Xe at cryogenic temperature; avalanche scintillations
were recorded in the Near Infrared (NIR) at wavelengths of up to 950 nm. At
avalanche charge gain of 350, the double-THGEM/G-APD multiplier yielded 0.07
photoelectrons per initial ionization electron, corresponding to an avalanche
scintillation yield of 0.7 NIR photons per avalanche electron over 4pi. The
results are compared with those of two-phase Ar avalanche detectors. The
advantages, limitations and possible applications are discussed.Comment: 22 pages, 14 figures. Revised Figs. 10,11 and Table 1. To be
published in JINS
Cool spots on the surface of the active giant PZ Mon
Based on the multiband (BVRIJHKL) photometric observations of the active red
giant PZ Mon performed for the first time in the winter season of 2017-2018, we
have determined the main characteristics of the spotted stellar surface in a
parametric three-spot model. The unspotted surface temperature is Teff=4730 K,
the temperature of the cool spots is Tspot=3500 K, their relative area is about
41%, and the temperature of the warm spots is Twarm=4500 K with a maximum
relative area up to 20%. The distribution of spots over the stellar surface has
been modeled. The warm spots have been found to be distributed at various
longitudes in the hemisphere on the side of the secondary component and are
most likely a result of its influence.Comment: 5 pages, 7 figure
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