The paper presents a current status of the simulation of the pure CsI crystal calorimeter of the detector of charm-tau factory project in Novosibirsk. The calorimeter employs the scheme with the ...crystals focusing at the beams interaction point to obtain the optimal energy and coordinate resolutions. We present a detailed description of the calorimeter design, optimized using the specially developed parametrized crystal geometry generator. The report also presents the results for the coordinate and energy correction functions calculation. After application of these corrections the estimation of the photon energy and coordinate resolutions for the ideal conditions of negligibly small stochastic, electronic and pileup noises was performed. The π0 reconstruction efficiency and mass resolution depending on it's momentum were also determined.
Study of the radiation hardness of CsI(Tl) scintillation crystals Beylin, D.M.; Korchagin, A.I.; Kuzmin, A.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2005, Letnik:
541, Številka:
3
Journal Article
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This paper is devoted to the study of a degradation of CsI(Tl) crystals’ scintillation characteristics under irradiation with gamma-rays at the uniformly distributed absorbed dose up to 3700
rad. The ...sample set consisted of 25 crystals of 30
cm long having a truncated pyramid shape and 30 rectangular crystals of the same length. A large difference in the light output deterioration caused by the radiation was observed for the samples of the same shape. A substantial dependence of the average light output loss from the sample shape is seen as well. On the other hand, the crystals from the same ingot behave very similarly under irradiation.
Filamentation is a type of magnetohydrodynamic instability that may develop in a current-carrying plasma. It is supposed that filaments, individual current channels, are formed due to thermal ...instabilities. The growth of these instabilities is determined by the behavior of the electrical conductivity of the material depending on its thermodynamic parameters. If the conductivity increases with temperature, as is the case in a plasma, thermal instabilities should give rise to the formation of separate current channels. This paper presents an analysis of the development of thermal instabilities in imploding plasma liners performed in terms of small perturbation theory. The theoretical predictions are compared with the results of experiments conducted on the IMRI-5 facility at a current of amplitude up to 450 kA and rise time about 500 ns.
Abstract
This paper presents the results of experimental and theoretical studies of imploding metal-puff Z-pinches. The experiments were carried out on the MIG high-current pulse generator at a ...current level of about 2 MA and a current rise time of about 100 ns. A plasma gun was used to produce a plasma column with a tailored density profile through which the main electromagnetic pulse of the MIG generator was passed. The experiments have shown that pinches of this type, being compressed, are resistant to dynamic magneto-Rayleigh–Taylor (MRT) instabilities. The experimental results were analyzed using one-dimensional radiation magnetohydrodynamic simulations. It has been shown that in a pinch with a tailored density profile, the formation of a high-temperature plasma at the pinch axis and the generation of x-rays occur at the stagnation stage, i.e. under conditions close to Bennett equilibrium. At this stage, flute-like MRT instabilities develop, causing the pinch to decay.
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The review presents the experiments performed with the KEDR detector at the
collider VEPP-4M in the energy range of
= 1.84–3.88 GeV. The cross section of
annihilation to hadrons was measured at 22 ...points of this range and the search for narrow resonances was conducted below 3.1 GeV. The masses of
and
mesons were measured with a record accuracy better than
; their partial and total widths were determined. Measurements of the tau lepton mass and masses of charged and neutral
mesons were performed with high precision. The measurements of the
parameters are discussed, and attention is drawn to some inconsistency of the procedure employed by the Particle Data Group for determining its parameters.
We report the results of in situ investigation of the structural evolution and crystallization behavior of Ni-based bulk metallic glass. The X-ray diffraction, transmission electron microscopy, ...nanobeam diffraction, differential scanning calorimetry, radial distribution function and scanning tunneling microscopy (STM)/spectroscopy techniques were applied to analyze the structure and electronic properties of Ni63.5Nb36.5 glasses before and after crystallization. According to our STM measurements, the primary crystallization originally starts with the Ni3Nb phase formation as a leading eutectic phase. It was shown that surface crystallization differs drastically from bulk crystallization due to the possible surface reconstruction. The mechanism of Ni63.5Nb36.5 glass alloy two-dimensional crystallization was suggested, which corresponds to the local metastable (3×3)− Ni(111) surface phase formation. The possibility of different surface nanostructures developing by annealment of the originally glassy alloy in an ultrahigh vacuum at a temperature lower than the bulk crystallization temperature was shown. The increase of the mean square surface roughness parameter Rq while transforming from a glassy to a fully crystallized state can be caused by concurrent growth of Ni3Nb and Ni6Nb7 bulk phases. The simple empirical model for the estimation of Ni63.5Nb36.5 cluster size was suggested, and the value obtained (about 8Å) is in good agreement with the corresponding STM measurements (8–10Å).
Current advances in the development of tools of environmental monitoring for anticholinesterase agents are considered. The aim of this analysis was to substantiate the most promising trends in the ...development of an up-to-date biosensor based on cholinesterase inhibition with an optimum sensitivity-analytical-signal formation time relation for the monitoring of atmospheric air for organophosphorus warfare agents and insecticides.
Wire Explosion in Vacuum Oreshkin, Vladimir I.; Baksht, Rina B.
IEEE transactions on plasma science
48, Številka:
5
Journal Article
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This article presents a review of experimental and theoretical studies devoted to the processes that occur during explosions of wires in vacuum when the current densities in the wire are of the order ...of 10 8 A/cm 2 and the current density rise rates are no less than 10 15 A/(cm<inline-formula> <tex-math notation="LaTeX">^{2}\cdot \text {s} </tex-math></inline-formula>). The theoretical background is focused on the transformation of the wire metal into ionized plasma. In particular, the basic physical notions used to describe wire explosions (WEs; state diagram, current action integral, and metal conductivity changes in phase transitions) are given; magnetohydrodynamic equations are described which are used to simulate WEs, and the simulation predictions are discussed together with their reliability. Extensive experimental data on WEs in vacuum are presented which made it possible to describe the corona and core formation and the development of electrothermal instabilities in the core. The data on the energy deposited in a wire exploding in vacuum reported by different authors are compared. In conclusion, problems are discussed that require additional experimental investigations, namely, the role of metastable states in a WE and the mechanism by which the core is shunted.
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