121 research outputs found
Terahertz Radiation of a Low-inductance Discharge in Vacuum with Laser-plasma Initiation
The results of the study of terahertz radiation, which is generated by the plasma of a low-inductance discharge with micropinchs, are presented in this paper. The discharge was initiated by focused radiation from a pulsed Nd:YAG laser (pulse duration is 10 ns, pulse energy is 0.8 J). The energy that was stored in the capacitor of the discharge system was ∼ 40 J. The principal role of micropinch for the generation of THz radiation was proposed. The oscillogram of the diode current was obtained to visualize the presence of micropinch plasma. The power of the THz source was calculated and an experimental study of the spectrum of this source was carried out
Novel Scintillation Material - ZnO Transparent Ceramics
ZnO-based scintillation ceramics for application in HENPA LENPA analyzers
have been investigated. The following ceramic samples have been prepared:
undoped ones (ZnO), an excess of zinc in stoichiometry (ZnO:Zn), doped with
gallium (ZnO:Ga) and lithium (ZnO:Li). Optical transmission, x-ray excited
emission, scintillation decay and pulse height spectra were measured and
analyzed. Ceramics have reasonable transparency in visible range (up to 60% for
0.4 mm thickness) and energy resolution (14.9% at 662 keV Cs137 gamma
excitation). Undoped ZnO shows slow (1.6 {\mu}s) luminescence with maximum at
2.37 eV and light yield about 57% of CsI:Tl. ZnO:Ga ceramics show relatively
low light yield with ultra fast decay time (1 ns). Lithium doped ceramics
ZnO:Li have better decay time than undoped ZnO with fair light yield. ZnO:Li
ceramics show good characteristics under alpha-particle excitation and can be
applied for the neutral particle analyzers.Comment: 4 pages, 8 figures, research covered in this paper was presented at
SCINT2011 conference as a poster, submitted for publication at IEEE Trans.
Nucl. Sc
Thermodynamic characteristics of the classical n-vector magnetic model in three dimensions
The method of calculating the free energy and thermodynamic characteristics
of the classical n-vector three-dimensional (3D) magnetic model at the
microscopic level without any adjustable parameters is proposed. Mathematical
description is perfomed using the collective variables (CV) method in the
framework of the model approximation. The exponentially decreasing
function of the distance between the particles situated at the N sites of a
simple cubic lattice is used as the interaction potential. Explicit and
rigorous analytical expressions for entropy,internal energy, specific heat near
the phase transition point as functions of the temperature are obtained. The
dependence of the amplitudes of the thermodynamic characteristics of the system
for and on the microscopic parameters of the interaction
potential are studied for the cases and . The obtained
results provide the basis for accurate analysis of the critical behaviour in
three dimensions including the nonuniversal characteristics of the system.Comment: 25 pages, 5 figure
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