arXiv subjects

A. A. Kuznetsov

Publications and source records attributed to A. A. Kuznetsov.

26 records · Page 2Linked to original sources

arXiv2011

Diagnostics of electron beam properties from the simultaneous hard X-ray and microwave emission in the 10 March 2001 flare

Simultaneous simulation of HXR and MW emission with the same populations of electrons is still a great challenge for interpretation of observations in real events. In this paper we apply the FP kinetic model of precipitation of electron beam with energy range from 12 keV to 1.2 MeV to the interpretation of X-ray and microwave emissions observed in the flare of 10 March 2001. Methods. The theoretical HXR and MW emissions were calculated by using the distribution functions of electron beams found by solving time-dependent Fokker-Planck approach in a converging magnetic field (Zharkova at al., 2010; Kuznetsov and Zharkova, 2010) for anisotropic scattering of beam electrons on the ambient particles in Coloumb collisions and Ohmic losses. The simultaneous observed HXR photon spectra and frequency distribution of MW emission and polarization were fit by those simulated from FP models which include the effects of electric field induced by beam electrons and precipitation into a converging magnetic loop. Magnetic field strengths in the footpoints on the photosphere were updated with newly calibrated SOHO/MDI data. The observed HXR energy spectrum above 10 keV is shown to be a double power law which was fit precisely by the photon HXR spectrum simulated for the model including the self-induced electric field but without magnetic convergence. The MW emission simulated for different models of electron precipitation revealed a better fit to the observed distribution at higher frequencies for the models combining collisions and electric field effects with a moderate magnetic field convergence of 2. The MW simulations were able to reproduce closely the main features of the MW emission observed at higher frequencies.

astro-ph.SR↗

arXiv2005

Search for Signal on Percolation Cluster Formation in Nucleus-Nucleus Collisions at Relativistic Energies

The appearance of the strongly interacting matter mixed phase (MP)has been suggested to consider to understand qualitatively the regime change existence in the behavior of some centrality depending characteristics of events. The MP has been predicted by QCD for the temperatures around the critical temperature Tc and could be formed as a result of nucleon percolation in the density nuclear matter. Our main goal is to get a new experimental confirmation of the percolation cluster formation as an accompanying effect of the MP formation. To reach the goal, the experimental data on Kr+Em - reaction at 0.95 GeV/nuc and Au+Em - reaction at 10.6 GeV/nucl. with a number of target fragments N_h > 8, have been analyzed. The behavior of the distributions of the target and the projectile fragments has been studied. The experimental data have been compared of the data coming from the cascade-evaporation model. We can conclude that: -- the centrality of the collision could be defined as a number of the target g-fragments in Kr+Em reactions at energies 0.95 A GeV/nucl and as a number of projectile F-fragments with Z>=1 in Au + Em reactions at energies 10.6 A GeV/nucl; -- the formation of the percolation cluster sufficiently influences the characteristics of nuclear fragments; -- there are points of the regime changes in the behavior of some characteristics of $s$-particles as a function of centrality which could be qualitatively understood as a result of the big percolation cluster formation.

hep-ex↗

arXiv2005

Random Matrix Theory and Analysis of Nucleus-Nucleus Collision at High Energies

We propose a novel method for analysis of experimental data obtained at relativistic nucleus-nucleus collisions. The method, based on the ideas of Random Matrix Theory, is applied to detect systematic errors that occur at measurements of momentum distributions of emitted particles. The unfolded momentum distribution is well described by the Gaussian orthogonal ensemble of random matrices, when the uncertainty in the momentum distribution is maximal. The method is free from unwanted background contributions.

hep-ex↗

arXiv2001

Transition to the region of central collisions

The experimental results on the behaviour of the characteristics of secondary particles depending on the disintegration degree of nuclei are used to determine the region of central collisions. It was therefore possible that : - the correlation between the prosesses of total disintegration of nuclei and the central collisions of nuclei had been shown; - the existence of the regime change points in the behaviour of the considered characteristics of secondary particles depending on the disintegration degree of nuclei had been observed in the other earlier experiments as well. The number of all protons in 12CC-interactions at the momentum of 4.2 A GeV/c obtained from the 2-m propane bubble chamber exposed at the Dubna machine is considered as a disintegration degree of nuclei. The experimental results demonstrate that there are cases corresponding to the critical phenomena among the events with the central collisions of nuclei. For 12CC-interaction the behaviour of the number of the events, depending on Q also depends on the number of fragments and has a two-steps form. This result could be explained by the existence of nuclear clusters. The experimental results on the relation between the number of events, the angular distributions of protons and full number of protons are presented for 12CC-interactions at the momentum of 4.2 A GeV/c. The influence of nuclear fragmentation process on the results is also considered. The obtained results confirm the assumption that there exist the critical phenomena among the central collisions and it is necessary to use a percolation approach for the full description of the central collisions.

hep-ex↗

arXiv2000

Investigation of an angular distribution of protons in peripheral and central nucleus-nucleus collisions at the momentum of 4.2 A GeV/c

The experimental results on the relation between the number of events, the angular distributions of protons and full number of protons are presented for ${}^{12}CC$-interactions at the momentum of 4.2 A GeV/c. The influence of nuclear fragmentation process on the results is also considered. The obtai- ned results confirm the assumption that there exist the critical phenomena among the central collisions and it is necessary to use a percolation approa- ch for the full description of the central collisions.

hep-ex↗

arXiv1999

Centrality of collisions and total disintegration of nuclei

The interrelation of the processes of total disintegration of nuclei with the processes, characterized by the "centrality" of collisions and a minimum flow of energy of secondary particles emitted at a zero angle in pC, dC, 4HeC and 12CC interactions, is investigated at 4.2 A GeV/c . The events with total disintegration of nuclei are characterized by a high degree "centrality" of collisions and similar to the events having a minimum flow of energy of particles emitted at a zero angle.

hep-ex↗

arXiv1998

Inverses of slopes of invariant inclusive spectra of emitted protons and pi minus mesons in 4HeC and 12CC interactions with the total disintegration of nuclei

The ideas that extreme states of nuclear matter arise in events with total dis- integration of nuclei (TDN) and as these states arise, the properties of events qualitatively change with the number of protons emitted from the nucleus Q,star- ting from its certain boundary numbe Q*,are used in this paper for the experi- mentally search for extreme states of nuclear matter. For realization of these ideas, the invariant inclusive spectra of protons and pi minus mesons as a func- tion of their kinetic energies T in the lab. system for 4HeC and 12CC interacti- ons at the momentum 4.2 A GeV/c with different values of Q are used. The spect- ra are fitted by the exponential expressions and the Q-dependencies of the in- verses of slopes Ti are studied. It is found that these spectra have two compo- nents and contain the regime change points .In the TDN region the values of Ti for pi minus mesons begin to increase with increasing the number of protons. We consider this increasing to be a signal from the extreme states of nuclear mat- ter. The value of the "temperature" of these states is about 0.140 GeV.

hep-ex↗

arXiv1997

Single - particle correlations in events with the total disintegration of nuclei

New experimental data on the behaviour of the single-particle two-dimensional correlation functions R versus Q (Q is the number of nucleons emitted from nuc- lei) and Ap (Ap is the mass of projectile nuclei) are presented in this paper. The interactions of protons, d, 4He and 12C nuclei with carbon nuclei (at a momentum of 4.2 A GeV/c) are considered.The values of R are obtained separately for pi minus mesons and protons.In so doing,the values of R are normalized so that -1=<R=<1.The value of R=0 corresponds to the case of the absence of corre- lations.It has been found that the Q- and Ap-dependence of R takes place only for weak correlations (R< 0.3).In the main (90 %),these correlations are con- nected with the variable pt and have a nonlinear character, that is the regi- ons with different characters of the Q-dependence of R are separated: there is a change of regimes in the Q-dependences of R.The correlations weaken with increasing Ap, and the variable R gets the least values of all the considered ones in 12CC interactions.Simultaneously with weakening the correlations in the region of large Q, the character of the Q-dependence of R changes.

hep-ex↗