Coherent Type-B e + e- Pair Production by Photons in a Crystal

An overview of theoretical and experimental studies of the coherent type-B e ⁺ e-pair production by photons in aligned crystals performed at Nuclear Physics Institute at Tomsk Polytechnic University is given.     

Parametric x-ray radiation generated by 5.7-MeV electrons in a pyrolytic-graphite crystal

Parametric x-ray radiation is observed in a mosaic pyrolytic-graphite crystal irradiated with a 5.7-MeV electron beam. The first-order (002) reflection of parametric x-ray radiation is detected in Bragg geometry. In the measured spectra, there is a peak at about 8 keV. The detector used is arranged at an angle of Θ_D=2Θ_B=27° with respect to the electron beam, where Θ_B is the Bragg angle. The target thickness is 0.3 mm. The spectra of parametric x-ray radiation are measured at various angles of target orientation with respect to the axis of the incident-electron beam.     

Parametric x-ray radiation from 500-MeV electrons in a tungsten single crystal with a surface mosaicity less than 1.5′

The yield of parametric x-ray radiation from a tungsten single crystal irradiated with a E=500 MeV electron beam from the Tomsk Sirius synchrotron was studied experimentally in Bragg geometry. The tungsten sample was 1.7 mm thick and had a surface mosaicity less than 1.5′; it was oriented in such a way that the (111) face was at the Bragg angle of θ _B=45° with respect to the electron-beam direction. The x-ray photons were detected at the angle of 2θ _B=90° with respect to the electron beam. The angular distributions of parametric x rays are compared with those calculatedwith allowance for actual experimental conditions.     

Photoelectric Effect on a Hydrogen Atom in an Extremely Strong Magnetic Field

Russian Physics Journal - The photoelectric effect on a hydrogen atom located in an extremely strong magnetic field is considered. The dependence of the cross section on the angle between the...     

Schwinger scattering of fast neutrons in crystals

The coherent effects emerging during fast neutron passage through oriented crystals have been investigated. It has been demonstrated that the cross section of coherent Schwinger neutron scattering in a crystal has maxima at specific entry angles and neutron energies. The effect of energy divergence and angular dispersion in a neutron beam on the coherent peak value has been examined.     

Orientation effects for passage of a relativistic positronium atom through crystals

We examine the passage of a relativistic positronium atom through a crystal for a small entrance angle with respect to the crystallographic axes. We show that the probability for an elastic interaction of the positronium atom with the crystal has orientation dependence. The probability of breakup of a positronium atom in a crystal is significantly greater than in an amorphous target.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 78–82, March, 1989.The author wishes to express his gratitude to S. A. Vorob'ev for his interest in the work and to Yu. L. Pivovarov, L. L. Nemenov, and M. I. Podgoretskii for useful discussions.     

Coherent bremsstrahlung of relativistic electrons in antiferromagnets

The coherent bremssstrahlung (CB) of relativistic electrons in antiferromagnetic crystals is studied theoretically. It is shown that the internal magnetic field of an antiferromagnet has a negligible effect on CB. The complete CB spectrum is calculated for hematite, -Fe₂O₃.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 57–61, February, 1988.