V. N. Zabaev

Experimental investigation of spectral characteristics of coherent bremsstrahlung and channeling radiation for high-energy electrons

Abstract The transformation of the spectral distributions of gamma-radiation for channeled electrons with the energy Eo = 870 MeV in diamond crystal of 0.35 mm thickness was experimentally investigated. The present results distinctly show the ranges of orientation angles of the crystal target at which the effect of coherent bremsstrahlung or the channeling radiation is mainly displayed. The procedure of the crystal orientation and the experimental technique are described.

Detection of parametric X-ray radiation from moderately relativistic protons in crystals

The spectral maxima of parametric x-ray radiation that are emitted by moderately relativistic protons interacting with various crystals have been detected. The spectral positions of these maxima depend on the crystal orientation angle and they are consistent with the theoretical values. The measurements were carried out with silicon and graphite crystals on the 5-GeV proton beam extracted from the Nuclotron at the Laboratory of High Energies, JINR.

Deflection of a γ-radiation beam produced by 900 MeV channeled electrons in a bent crystal

Abstract The angular distributions of photons produced by 900 MeV electrons channeled along the 〈111〉 axis of a silicon crystal were measured. A broadening of the angular distributions was observed in a bent crystal with radius R = 76 cm, which was caused most probably by the deflection of the channeled electron beam.

Effect of channeling on γ-radiation spectra of 870 MeV electrons in diamond crystal

Abstract The spectral distribution of coherent bremsstrahlung and of channeling γ-radiation was measured for 870 MeV electrons in a 〈110〉 diamond crystal of 0.35 mm thickness. The results clearly show the conditions under which the effect of channeling or the coherent bremsstrahlung are mainly displayed.

Suppression of hard gamma-radiation yield in transmission of ultrarelativistic electrons along crystallographic axes or planes

Abstract Decrease of the hard part of the gamma-radiation spectra for 900 MeV electrons transmitted along the crystallographic axes of silicon and diamond, tungsten, diamond and (100) planes of tungsten crystals, has been observed experimentally. Collimation of the measured gamma-radiation beam was θc = 0.6 mrad ≈ 1/γ.

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 ΘD=2ΘB=27° with respect to the electron beam, where ΘB 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.

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.

Generation of X-ray beams by photons and relativistic electrons on crystals under the Bragg condition

The parametric x-ray (PXR) photon yield from single-crystal tungsten was studied in the Bragg geometry in an experiment on the SIRIUS synchrotron in Tomsk using an e-beam with the energy E=500 MeV. The tungsten crystal thickness was 1.7 mm and the surface mosaicity - not more than 1.5. The crystal was aligned as [111] with the Bragg angle /spl theta//sub B/=45/spl deg/ to the e-beam direction. The photons were detected at 2/spl theta//sub B/=90/spl deg/ with respect to the e-beam. The angular PXR distributions were compared with the calculations including the real experimental conditions. The experimental setup for measurement diffraction of bremstrahlung of electrons in the silicon crystal is described. The arrangement is based on the microtrone MT-22, with electron beam energy 13 MeV and 22 MeV.

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 θB=45° with respect to the electron-beam direction. The x-ray photons were detected at the angle of 2θB=90° with respect to the electron beam. The angular distributions of parametric x rays are compared with those calculatedwith allowance for actual experimental conditions.

Generation of photoneutrons by means of a channeled electron beam

Abstract Data from measurements of photoneutron yield produced in H21O, H22O, H2, Be, Bi targets under irradiation by a γ-ray beam are presented. The γ-rays were generated from channeled electrons transmitted through 0.35 mm thick 〈110〉 diamond target. The strong orientation dependence of the photoneutron production on the tilting angle of the diamond radiator relative to the electron beam is observed.