Estimations of electron-positron pair production at high-intensity laser interaction with high-Z targets

Electron-positron pairs' generation occuring in the interaction of $10^{18}$-$10^{20}$~W/cm$^2$ laser radiation with high-Z targets are examined. Computational results are presented for the pair production and the positron yield from the target with allowance for the contribution of pair production processes due to electrons and bremsstrahlung photons. Monte-Carlo simulations using the PRIZMA code confirm the estimates obtained. The possible positron yield from high-Z targets irradiated by picosecond lasers of power $10^2$-$10^3$~TW is estimated to be $10^9$-$10^{11}$

EXPERIMENTAL SUBSTANTIATION OF APPLICATION GEL IMPLANT «SFERO®GEL» AND FILM IMPLANT «ELASTOPOB»® AT A TRAUMA OF PERIPHERAL NERVOUS SYSTEM IN EXPERIMENT

The purpose of the present work was the experimental substantiation of application of new biodegraded materials: gel implant «Sfero®Gel» and a film membrane of «ElastoPOB»® a domestic production, in surgery of defeats of peripheral nerves. Experimental researches carried out on females of nonlinear rats, is powerful 200–250 gramme. In experience 10 animals are used, 20 operative interventions on sciatic nerves are executed. Morphological studying of the received material in 101 days after operation was carried out. At application of a membrane «ElastoPOB»® it was defined delimitin of peripheral nerves from surrounding tissue. A film membrane of «ElastoPOB»® is perspective to apply at traumas of a nervous fabric for the purpose of formation of a friable hem in a damage zone. On the basis of the received experimental data it is possible to make the conclusion about possibility and expediency of application of biodegraded materials in surgical treatment of defeats of peripheral nervous system

Formation of 24Mg* in the Splitting of 28Si Nuclei by 1-GeV Protons

The 28Si(p, p' gamma)24Mg reaction has been studied at the ITEP accelerator by the hadron-gamma coincidence method for a proton energy of 1 GeV. Two reaction products are detected: a 1368.6-keV gamma-ray photon accompanying the transition of the 24Mg* nucleus from the first excited state to the ground state and a proton p' whose momentum is measured in a magnetic spectrometer. The measured distribution in the energy lost by the proton in interaction is attributed to five processes: the direct knockout of a nuclear alpha cluster, the knockout of four nucleons with a total charge number of 2, the formation of the DeltaSi isobaric nucleus, the formation of the Delta isobar in the interaction of the incident proton with a nuclear nucleon, and the production of a pi meson, which is at rest in the nuclear reference frame. The last process likely corresponds to the reaction of the formation of a deeply bound pion state in the 28P nucleus. Such states were previously observed only on heavy nuclei. The cross sections for the listed processes have been estimated.Comment: 14 pages, 3 figures submitted to JETP Letter

Microscopics of meson degrees of freedom in nucleons and mesons in nuclei - what can be seen in the process of quasielastic knockout of mesons by high-energy electrons

Developed earlier concept of quasielastic knock out of pions from nucleons by high-energy electrons is propounded as a tool for checking microscopical model ($^3P_0$ - fluctuation) for decay of N to different channels $\pi+B$ and Preparata model of nucleus structure.Comment: 6 pages, 5 figures, Talk given at 16 Baldin Symposium in June 200

Examination of the astrophysical S-factors of the radiative proton capture on 2H, 6Li, 7Li, 12C and 13C

Astrophysical S-factors of radiative capture reactions on light nuclei have been calculated in a two-cluster potential model, taking into account the separation of orbital states by the use of Young schemes. The local two-body potentials describing the interaction of the clusters were determined by fitting scattering data and properties of bound states. The many-body character of the problem is approximatively accounted for by Pauli forbidden states. An important feature of the approach is the consideration of the dependence of the interaction potential between the clusters on the orbital Young schemes, which determine the permutation symmetry of the nucleon system. Proton capture on 2H, 6Li, 7Li, 12C, and 13C was analyzed in this approach. Experimental data at low energies were described reasonably well when the phase shifts for cluster-cluster scattering, extracted from precise data, were used. This shows that decreasing the experimental error on differential elastic scattering cross sections of light nuclei at astrophysical energies is very important also to allow a more accurate phase shift analysis. A future increase in precision will allow more definite conclusions regarding the reaction mechanisms and astrophysical conditions of thermonuclear reactions.Comment: 40p., 9 fig., 83 ref. arXiv admin note: substantial text overlap with arXiv:1005.1794, arXiv:1112.1760, arXiv:1005.198

In memoriam two distinguished participants of the Bregenz Symmetries in Science Symposia: Marcos Moshinsky and Yurii Fedorovich Smirnov

Some particular facets of the numerous works by Marcos Moshinsky and Yurii Fedorovich Smirnov are presented in these notes. The accent is put on some of the common interests of Yurii and Marcos in physics, theoretical chemistry, and mathematical physics. These notes also contain some more personal memories of Yurii Smirnov.Comment: Submitted for publication in Journal of Physics: Conference Serie

Influence of the re-scattering process on polarization observables in reaction gamma + d --> p + p + pi- in Delta - resonance region

Influence of the effects of the pion-nucleon and nucleon-nucleon re-scattering on the polarization observables of the reaction gamma + d = p + p + pi- in Delta - isobar region is investigated. Pion-nucleon and nucleon-nucleon re-scattering are studied in the diagrammatic approach. Relativistic-invariant forms of the pion photoproduction and pion-nucleon scattering operators are used. The unitarization procedure in K-matrix approach is applied for the resonance partial amplitudes. It is shown a considerable influence of the re-scattering effects on the polarization observables of this reaction in the Delta - resonance region for the large momenta of the final protons.Comment: 16 pages, 5 Postscript figure

Astrophysical S-factor for the radiative capture reaction 13C(p,g)14N

The phase shift analysis, done on the basis of the known measurements of the differential cross-sections of the p13C elastic scattering at the energy range 250-750 keV, shows that it is enough to take into account only 3S1 wave in the considered energy region. The potential for the triplet 3S1 state in p13C system at the resonance energy 0.55 MeV corresponding to quantum numbers JpT = 1-1 as well as the potential for the 3P1 bound state of 14N were constructed on the basis of the obtained scattering phase shifts. The possibility to describe the experimental data of the astrophysical S-factor of the p13C radiative capture at the energies 0.03-0.8 MeV was considered within the potential cluster model with the forbidden states. It was shown that we properly succeed in explanation of the energy behavior of the astrophysical S-factor for the p13C radiative capture at the resonance energy range 0.55 MeV (laboratory system).Comment: 8 p., 2 fi