Research of modifications of a beam and signals parameterd in technological linacs

The power current pulse linacs of electrons are used in the Science Research Complex "Accelerator" at NSC KIPT for irrradiation of materials and some products. The irrradiation sessions usually last tens of hours. Some results of the linac parameters for this period are given in the present paper

Exciton-induced lattice defect formation

The lattice defect formation in solid Ne induced by electronic excitation was studied using the selective vacuum ultraviolet spectroscopy method. The samples were excited with synchrotron radiation in the range of excitonic absorption n = 2Г(3/2). The dose dependence of the intensity distribution in the band of atomic type self-trapped exciton luminescence was analyzed. A direct evidence of the formation and accumulation of point lattice defects in solid Ne via the excitonic mechanism was obtained for the first time. The model of the permanent lattice defect formation is discussed

Formation of uniform electron beams on large-area targets

The report describes the results of calculations and experimental studies of the system for scanning the beam on outside targets of electron accelerators by magnetic quadrupole lenses.Представлені результати розрахунків та експериментальних досліджень системи розгортки пучка на вихідних мішенях прискорювачів електронів магнітними квадрупольними лінзами.Представлены результаты расчета и экспериментальных исследований системы развертки пучка на выходных мишенях ускорителей электронов магнитными квадрупольными линзами

Exciton self-trapping into diatomic and triatomic molecular complexes in xenon cryocrystals

The recent study of molecular trapped centers in Xe cryocrystals was extended on triatomic self-trapped excitons. Time- and spectrally-resolved molecular luminescence was measured in the temperature range 5–60 K. The processes of intrinsic exciton self-rapping into diatomic and triatomic molecular complexes and extrinsic exciton trapping at lattice imperfections were separated by selective photoexcitation of Xe cryocrystals by synchrotron radiation. The temperature dependencies of triplet lifetimes of molecular exciton subbands were measured for the first time

Monitoring of the electron beam position in industrial linacs

Recently the technological linear electron accelerators with the energy up to 10 and 25 MeV and the pulse current up to 1A have been developed and put into operation in the "Accelerator" R&D Production Establishment of the National Science Center, Kharkov Institute of Physics and Technology [1]. The zone of the technological object irradiation by the accelerated electrons is created by the magnetic scanning system. Wide-aperture (50x200 and 50x300 mm) magneto-induction position monitors have been designed to control the electron beam position. Signals from the monitor are used in the accelerator control system

Stimulated by laser light exoelectron emission from solid Ar pre-irradiated by an electron beam

Spatially separated stable charge centers, self-trapped holes and trapped electrons, were generated in Ar cryocrystals by a low-energy electron beam. A combination of the cathodoluminescence (CL) and photon- stimulated exoelectron emission (PSEE) methods was used to monitor center formation and selected relaxation channel – exoelectron emission. It was found that photon-promoted electron current decreased exponentially under irradiation with the laser operating in the visible range. Influence of the laser parameters (power and wavelength) on the characteristic lifetime of exoelectron emission is discussed. Effective bleaching of the low-temperature peaks of thermally stimulated exoelectron emission by the laser light in a visible range was observed

Thermally stimulated exoelectron emission from solid Xe

Thermally-stimulated emission of exoelectrons and photons from solid Xe pre-irradiated by low-energy electrons were studied. A high sensitivity of thermally-stimulated luminescence (TSL) and thermally-stimulated exoelectron emission (TSEE) to sample prehistory was demonstrated. It was shown that electron traps in unannealed samples are characterized by a much broader distribution of trap levels in comparison with annealed samples and their concentration exceeds in number that in annealed samples. Both phenomena, TSL and TSEE, were found to be triggered by release of electrons from the same kind of traps. The data obtained suggest a competition between two relaxation channels: charge recombination and electron transport terminated by TSL and TSEE. It was found that TSEE predominates at low temperatures while at higher temperatures TSL prevails. An additional relaxation channel, a photon-stimulated exoelectron emission from pre-irradiated solid Xe, was revealed

Oxygen-driven relaxation processes in pre-irradiated Ar cryocrystals

Relaxation processes in oxygen-containing Ar cryocrystals pre-irradiated by low-energy electrons are studied with the focus on the role of diffusion controlled atom-atom recombination reaction of oxygen in the relaxation cascades. The results of correlated in real time measurements of thermally stimulated phenomena are presented. The experiments have been performed using activation spectroscopy methods — thermally stimulated exoelectron emission and spectrally resolved thermally stimulated luminescence. Solid evidence of the radiative mechanism of electron detrapping triggering the relaxation cascades is obtained

Linac failure diagnostics

The data processing subroutine from 60 discrete detectors is developed for the operating control system [1] of the technological linac. It uses a dialogue regime of work. This subroutine allows us to find a basic cause of linac failures in certain circuit, as well as the site of fault. Recommendations for repair are also given