2010

Viktorov V. A., Mende N. P., Podlaskin A. B., Popov P. A., Sakharov V. A.  Identification of aerodynamic characteristics with discontinuities of the first kind from trajectory data for a free - flying object   //   Technical Physics. The Russian Journal of Applied Physics. 2010. Т. 55. № 6. С. 795 - 798.

Russian Federal Nuclear Center ( VNIIEF ), Sarov, Russia

A method is proposed for identifying the aerodynamic characteristics of a model the flow about which varies considerably in the course of motion. In this method, the trajectory of the model is split into sections with different types of the flow and then similar data from these sections are collected into groups and processed. The aerodynamic characteristics are identified by the method of successive approximation using a differential correction algorithm. The accuracy of the results is analyzed.

Tsvetkov V. M., Pikulev A. A., Sosnin E. A., Avdeev S. M., Tarasenko V. F.  Dynamic pressure jump in barrier - discharge excilamps   //   Technical Physics. The Russian Journal of Applied Physics. 2010. Т. 55. № 6. С. 807 - 811.

Russian Federal Nuclear Center ( VNIIEF ), Sarov, Russia

Data for the pressure jump are used to study thermodynamic processes in barrier-discharge excilamps under the conditions of a diffuse (uniform) discharge and microdischarges. It is shown that a linear relationship between the pressure jump and excilamp radiation intensity can help to control the radiation power.

Tren'kin A. A.  Fractal spatial structure of lightning discharge and its relation to the structures of high - voltage discharges of other types   //   Technical Physics Letters. 2010. Т. 36. № 4. С. 299 - 301.

Russian Federal Nuclear Center ( VNIIEF ), Sarov, Russia

The fractal dimension of a lightning discharge is determined. It is established that, with respect to the fractal dimension and, hence, the character of spatial structure organization, the lighting discharge is analogous to high - voltage discharges of other types, including streamer corona, surface, nanosecond diffuse, spark, and streamer - free discharges. This analogy leads to a conclusion concerning the generality of physical mechanisms involved in the self - organization of various high - voltage discharges.

Pikulev A. A., Tsvetkov V. M.  Photodecomposition of hexachlorobiphenyl by radiation of a KrCl  ( 222 nm )  barrier - discharge excilamp   //   Technical Physics Letters. 2010. Т. 36. № 1. С. 43 - 46.

Russian Federal Nuclear Center ( VNIIEF ), Sarov, Russia

The process of dechlorination of  2,2′; 4,4′; 5,5′ - hexachlorobiphenyl ( PCB 153  ) under the action of  UV  radiation of a  KrCl*  ( 222 nm  )  barrier - discharge excilamp has been studied. The photolysis was performed in  PCB 153 solutions in hexane with concentrations of  10  μg/ml ( sample 1 )  and 1 μg/ml ( sample 2 )  and in a  PCB 153  film on a silica plate  ( sample 3 ). The degree of  PCB 153  decomposition was determined using the optical transmission spectra measured in a 185 – 350  nm  wavelength range. An analysis of these spectra showed that chlorine atoms in ortho 2,2′ - positions are detached first. At a UV radiation intensity of  3  mW/cm²  on the sample surface, the residual  PCB 153  content in samples 1 – 3  was below 2%  ( 60 - min exposure  ),  below  3%  ( 25 - min exposure  ), and below 20% ( 60 - min exposure  ), respectively.

Kudasov Yu. B., Maslov D. A., Korshunov A. S., Pavlov V. N.   Magnetic phase diagram of frustrated spin - chain compounds   //   Bulletin of the Russian Academy of Sciences: Physics. 2010. Т. 74. № 1. С. 6 - 8.

Russian Federal Nuclear Center ( VNIIEF ), Sarov, Russia

The magnetic ordering in frustrated triangular lattices of Ising chains is discussed. It is shown that the differences in the low - temperature  CsCoCl₃,  Ca₃Co₂O₆,  and  Sr₅Rh₄O₁₂   phases are related to the interaction between the next – to - nearest pairs of chains, which partially lifts the degeneracy of the ground state of the  2D  antiferromagnet Ising model. In zero magnetic field and at low temperature, a stripe structure arises in the new compound   Sr₅Rh₄O₁₂.

Jensen B. J.^a, Cherne F. J.^a, Cooley J. C.^a, Zhernokletov M. V.^b, Kovalev A. E.^b   Shock melting of cerium   //   Physical Review B: Condensed Matter and Materials Physics. 2010. Т. 81. № 21. С. 214109.

^a Los Alamos National Laboratory, Los Alamos, New Mexico, USA
^b Russian Federal Nuclear Center ( VNIIEF ), Sarov, Nizhnii Novgorod Region, Russia

Shock - wave experiments were performed to examine the melt transition for cerium. Despite past work which points to a higher - pressure transition, the large volume collapse associated with the low - pressure  γ - α   phase transition is expected to result in a low - pressure melt transition. Multiple experimental configurations including front - surface impact and transmission experiments using velocimetry were used to obtain Hugoniot data and sound - speed data for impact stresses up to approximately  18 GPa.  Sound - speed data exhibit a structured release consisting of a longitudinal wave followed by a slower plastic wave. The difference between these two wave speeds is observed to decrease with increasing impact stress until a single shock wave is observed indicating the onset of the melt transition which was estimated to be  GPa  10,24  ±  0,34.  Additional data show that the sound speed is in agreement with liquid data at approximately  18 GPa  likely indicating the completion of the melt transition. Further results and implications are discussed.

Frank A.a, Harres K.^a, Hoffmann D. H. H.^a, Knobloch - Maas R.^a, Nürnberg F.^a, Pelka A.^a, Schaumann G.^a, Schökel A.^a, Schollmeier M.^a, Schumacher D.^a, Schütrumpf J.^a, Roth M.^a, Blažević A.^b, Heßling T.^b, Grande P. L.^c, Kuznetsov P. G.^d, Vatulin V. V.^d, Vinokurov O. A.^d, Schiwietz G.^e   Energy loss of argon in a laser - generated carbon plasma   //   Physical Review E - Statistical, Nonlinear, and Soft Matter Physics. 2010. Т. 81. № 2. С. 026401.

^a Institut für Kernphysik, Technische Universität Darmstadt, Germany
^b GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
^c Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves, Porto Alegre, RS, Brazil
^d Russian Federal Nuclear Center ( VNIIEF ), Sarov, Nizhnii Novgorod Region, Russia
^e Helmholtz - Zentrum Berlin für Materialien und Energie, Glienicker Strasse 100, Berlin, Germany

The experimental data presented in this paper address the energy loss determination for argon at  4 MeV/u   projectile energy in laser - generated carbon plasma covering a huge parameter range in density and temperature. Furthermore, a consistent theoretical description of the projectile charge state evolution via a Monte Carlo code is combined with an improved version of the CasP code that allows us to calculate the contributions to the stopping power of bound and free electrons for each projectile charge state. This approach gets rid of any effective charge description of the stopping power. Comparison of experimental data and theoretical results allows us to judge the influence of different plasma parameters.

Aleksandrov D.^a, Alme J.^b, Basmanov V.^c, Batyunya B.^d , Blau D.^a, Bogolyubsky M.^e, Budilov V.^d, Budnikov D.^c, Buskenes J. I.^k, Cai X.^f, Chuman F.^g, Deloff A.^h, Demanov V.^c, Djuvsland O.^b, Dobrowolski T.^h, Faltys M.ⁱ,  Fehlker D.^b,  Fil’chagin S.^c, Hiei A.^g, Hille P. T.^j, Horaguchi T.^g, Huang M.^b, Il’kaev R.^c, Ilkiv I.^h, Ippolitov M.^a, Iwasaki T.^g, Kazantsev A.^a, Karadzhev K.^a, Kharlov Y.^e, Kucheryaev Y.^a, Kurashvili P.^h, Kuryakin A.^c, Larsen D. T.^b, Lindal S.^j, Liu L.^b, Lovhoiden G.^j, Ma K.^f, Mamonov A.^c, Manko V.^a, Mao Y.^f, Mares J.ⁱ, Maruyama Y.^g, Müller H.^k, Mizoguchi K.^g, Nazarenko S.^c, Nazarov G.^c, Nikolaev S.^a, Nikulin S.^a, Nomokonov P.^d, Nystrand J.^b, Pavlinov A.^e, Peresunko D.^a, Petrov V.^e, Polak K.ⁱ, Polichtchouk B.^e, Potcheptsov T.^d, Punin V.^c, Qvigstad H.^b, Redlich K.^h, Roehrich D.^b, Sadovsky S.^e, Senko V.^e, Shigaki K.^g, Sibiryak I.^a, Siemiarczuk T.^h, Skaali B.^j, Skjerdal K.^b, Shabratova K.^d, Soloviev A.^e, Stolpovsky P.^e, Sugitate T.^g, Sukhorukov M.^c, Torii H.^g, Tveter T.^j, Ullaland K.^b, Wikne J.^j, Vikhlyantsev O.^c, Vinogradov A.^a, Vinogradov Y.^c, Vodopyanov A.^d, Wan R.^f, Wang Y.^f, Wilk G.^h,  Wang D.^f, Xu C.^f, Yin Z.^f, Yanovsky V.^c, Yuan X.^f, Zaporozhets S.^d, Zenin A.^e, Zhang X.^f, Zhou D.^f   Solving a deconvolution problem in photon spectrometry   //  Nuclear Instruments and Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2010. Т. 620. № 2 - 3. С. 526 - 533.

^a Russian Research Centre Kurchatov Institute, Moscow, Russia
^b Department of Physics and Technology, University of Bergen, Bergen, Norway
^c Russian Federal Nuclear Center ( VNIIEF ), Sarov, Nizhnii Novgorod Region, Russia
^d Joint Institute for Nuclear Research ( JINR ), Dubna, Russia
^e Institute for High Energy Physics, Russian Federation State Research Centre ( IHEP ), Protvino, Russia
^f Hua - Zhong Normal University, Wuhan, China
^g Hiroshima University, Higashi - Hiroshima, Japan
^h Soltan Institute for Nuclear Studies, Warsaw, Poland
ⁱ The Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
^j Department of Physics, University of Oslo, Oslo, Norway
^k European Ogranization for Nuclear Research ( CERN ), Geneva, Switzerland

We solve numerically a deconvolution problem to extract the undisturbed spectrum from the measured distribution contaminated by the finite resolution of the measuring device. A problem of this kind emerges when one wants to infer the momentum distribution of the neutral pions by detecting the π⁰ decay photons using the photon spectrometer of the  ALICE LHC  experiment at  CERN  [ 1 ]. The underlying integral equation connecting the sought for pion spectrum and the measured gamma spectrum has been discretized and subsequently reduced to a system of linear algebraic equations. The latter system, however, is known to be ill - posed and must be regularized to obtain a stable solution. This task has been accomplished here by means of the Tikhonov regularization scheme combined with the  L - curve  method. The resulting pion spectrum is in an excellent quantitative agreement with the pion spectrum obtained from a Monte Carlo simulation.