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1.
Experimental data are obtained on the dynamics of conduction-electron relaxation at the stage preceding the melting of a silicon surface layer. The energy of a quantum of probe radiation is smaller than the band gap, making it possible to obtain information about the electron-phonon relaxation processes for an electron concentration of ~ 1021 cm?3 in the conduction band. 相似文献
2.
V. D. Ashitkov A. S. Barabash S. G. Belogurov G. Carugno S. I. Konovalov I. O. Pilugin G. Puglierin R. R. Saakyan V. N. Stekhanov V. I. Umatov I. A. Vanushin 《Nuclear Physics B - Proceedings Supplements》1999,70(1-3)
First two runs with 138.7 g of 100Mo were done 9202 h and 238 h). Limits on half-lives for 0ν- and 0νχ0-decays of 100Mo were obtained, > 2.3 · 1021 y and 0.8 · 1020 y, respectively at 90% CL. Also the limit on the content of radioactive 42Ar in the natural Ar was obtained, < 5 · 10−21 g/g. Perspectives for the future are discussed. 相似文献
3.
M. B. Agranat S. I. Ashitkov A. V. Kirillin A. V. Kostanovskii V. E. Fortov S. I. Anisimov P. S. Kondratenko 《JETP Letters》1997,66(10):699-703
Observations of microcrystalline graphite subjected to picosecond laser pulses reveal the formation of a liquid phase with
a subsequent transition to a uniform amorphous state of a surface layer upon solidification. This phenomenon is observed on
a definite type of graphite and with the radiation incident on a plane parallel to the sixfold symmetry axis, and only for
certain parameters of the laser pulse. A structural analysis of the amorphous phase is performed by electron microscopy and
Raman scattering spectroscopy. A periodic structure with a period of the order of the wavelength of the heating pulse is formed
in the heating region. The “rulings” of this periodic structure are oriented in the direction of polarization of the heating
pulse. A study of the reflection kinetics of the probe laser pulse showed that the characteristic existence time of the liquid
phase and of the solidification process is ∼10−10 s.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 10, 661–665 (25 November 1997) 相似文献
4.
N. A. Inogamov S. I. Ashitkov V. V. Zhakhovsky V. V. Shepelev V. A. Khokhlov P. S. Komarov M. B. Agranat S. I. Anisimov V. E. Fortov 《Applied Physics A: Materials Science & Processing》2010,101(1):1-5
Ultrashort laser pulse transfers metal into a two-temperature warm dense matter state and triggers a chain of hydrodynamic
and kinetic processes—melting, expansion, stretching, creation of tensile stress and transition into metastable state. We
study the response of aluminum film deposited on a glass substrate to irradiation by a pump laser pulse transmitted through
glass. Several films with thicknesses from 350 to 1200 nm have been investigated. The smallest thickness is of the order of
the heating depth d
T∼100 nm in Al. The d
T-layer and the free rear side of the film are coupled through pressure waves propagating between them. Therefore, the processes
within d
T-layer affects the time dependent displacement Δ
x
rear(t) of the rear surface. We compare simulated and experimental dependencies Δ
x
rear(t) obtained by the pump–probe technique. It allows us to define a thickness of molten Al layer and explore the two-temperature
processes occurring inside the heated layer. 相似文献
5.
S. I. Anisimov N. A. Inogamov Yu. V. Petrov V. A. Khokhlov V. V. Zhakhovskii K. Nishihara M. B. Agranat S. I. Ashitkov P. S. Komarov 《Applied Physics A: Materials Science & Processing》2008,92(4):939-943
The developed model including hydrodynamics with electron heat conduction and electron–ion energy exchange, and cavitation
breakup of stretched metastable liquid aluminum (Al) is compared with our laser experiments. For the first time the measured
and calculated ablation thresholds agree well in both crater depth and fluence. 相似文献
6.
Khokhlov V. A. Zhakhovsky V. V. Inogamov N. A. Ashitkov S. I. Sitnikov D. S. Khishchenko K. V. Petrov Yu. V. Manokhin S. S. Nelasov I. V. Shepelev V. V. Kolobov Yu. R. 《JETP Letters》2022,115(9):523-530
JETP Letters - Laser shock peening with ultrashort laser pulses has been studied by hydrodynamic and atomistic simulations, as well as experimentally. It has been shown that, in contrast to... 相似文献
7.
M.B. Agranat S.I. Ashitkov V.E. Fortov A.V. Kirillin A.V. Kostanovskii S.I. Anisimov P.S. Kondratenko 《Applied Physics A: Materials Science & Processing》1999,69(6):637-640
A new method of crystalline-order detection in highly absorbing anisotropic crystals is worked out and is demonstrated experimentally
on a monocrystal Zn. The method is based on partial transformation of incident p-polarized electromagnetic wave into s-polarizedreflected wave due to optical anisotropy. The method is applicable to anisotropic metals (for example, Zn, Ti, Cd)
and makes it possible to follow changes of crystalline structure in thin (10–100 nm) surface layers. It must be emphasized,
that the method permits the detection of changes of the long-range order, whereas most of the conventional methods provide
information on changes of the short-range order, which need not be changed on melting and amorphization for certain crystals.
Using picosecond laser pump pulse (time duration ≈1 ps) and streak camera “Agat”, surface melting and evaporation of Zn are
studied. By means of measurement of time dependencies of s- and p-components of a reflected probe pulse (time duration ≈500 ps) the dynamics of melting and evaporation of a surface layer
was studied at various flows of energy laser pump pulse. The characteristic time of disappearance of the long-range order
is <3 ps. The crystal structure is restored through 100–300 ps after action of a pump pulse. The theoretical analysis of experimental
results was performed. Estimations, based on the proposed model, are in satisfactory agreement with the experimental results.
Pump-probe experiments with time resolution higher than 3 ps are in progress.
Received: 27 November 1998 / Accepted: 21 April 1999 / Published online: 27 October 1999 相似文献
8.
V. D. Ashitkov A. S. Barabash S. G. Belogurov G. Carugno S. I. Konovalov F. Massera G. Puglierin R. R. Saakyan V. N. Stekhanov V. I. Umatov 《JETP Letters》2001,74(11):529-531
Two-neutrino double beta decay of 100Mo with half-life T 1/2=[7.2±0.9(stat)± 1.8(syst)]×1018 yr was detected using a liquid argon ionization chamber. With a C.L. of 68% (90%), the bounds on neutrinoless decay and decay with majoron emission were found to be 8.4(4.9)×1021 and 4.1(3.2)×1020 yr, respectively. An analysis of all available results provides the average “world” value T 1/2=(8.0±0.7)×1018 yr for the two-neutrino decay of 100Mo, and the corresponding nuclear matrix element is M GT=0.118±0.005. 相似文献
9.
V. D. Ashitkov A. S. Barabash V. Ya. Bradnova L. A. Goncharova O. I. Orurk E. A. Pozharova N. G. Polukhina V. A. Smirnitskii N. I. Starkov Tan Nang So V. I. Yumatov 《Bulletin of the Lebedev Physics Institute》2013,40(12):357-364
The last results on the preparation of the experiment on the search for double neutrinoless decay using emulsion chambers with molybdenum filling are presented. The results of testing emulsions prepared by the OJSC “Slavich Company” are presented. Algorithms for recognizing electron tracks in rectilinear and curvilinear portions are described. 相似文献
10.
N. A. Inogamov V. V. Zhakhovsky S. I. Ashitkov V. A. Khokhlov V. V. Shepelev P. S. Komarov A. V. Ovchinnikov D. S. Sitnikov Yu. V. Petrov M. B. Agranat S. I. Anisimov V. E. Fortov 《等离子体物理论文集》2011,51(4):367-374
We combine theoretical and experimental methods to study the processes induced by fast laser heating of metal foils. These processes reveal themselves through motion of frontal (irradiated) and rear‐side foil boundaries. The irradiated targets are 0.3‐2 micron thick aluminum foils deposited on much thicker (150 microns) glass plate. The instant boundary positions is measured by pump‐probe technique having ∼40‐150 fs time and ∼1 nm spatial resolutions. Ultrashort laser pulse transforms a frontal surface layer with thickness dT into two‐temperature (Te ≫ Ti) warm dense matter state. Its quantitative characteristics including its thickness are defined by poorly known coefficients of electron‐ion energy exchange α and electron heat conductivity κ. Fast laser heating rises pressure in the dT‐layer and therefore produce acoustic waves. Propagation and reflection from the frontal and rear boundaries of these waves causes the displacement Δx (t) of boundary positions. Pressure wave profiles, and hence functions Δx (t), depend on thickness dT. This is why the experimental detection of Δx (t) opens a way to accurate evaluation of the coefficients α and κ (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献