This paper is devoted to the study of a degradation of CsI(Tl) crystals’ scintillation characteristics under irradiation with gamma-rays at the uniformly distributed absorbed dose up to 3700rad. The sample set consisted of 25 crystals of 30cm long having a truncated pyramid shape and 30 rectangular crystals of the same length. A large difference in the light output deterioration caused by the radiation was observed for the samples of the same shape. A substantial dependence of the average light output loss from the sample shape is seen as well. On the other hand, the crystals from the same ingot behave very similarly under irradiation.

We examined the effect of the radiation damage on optical and scintillation properties of BGO crystals produced by the low-thermal-gradient Czochralski growth technique. Irradiation tests were performed for γ-ray doses from 1krad to 10Mrad. Optical absorption and light output were measured upon irradiation and self-recovery. Based on the shape of radiation-induced absorption, degradation of transparency and light output upon radiation damage as well as their self-recovery, two distinct types of BGO crystals were established.

In the work presented here the parameters of powerful electron accelerators of continuous action are given and the main systems of the accelerator and a wide set of supplementary devices extending the application range of the accelerator are given and some directions of further development are noted.

Simultaneously with production of industrial accelerators BINP develops new EB technologies. For this purpose the set of equipment based on electron accelerators was installed. The accelerator has an energy range of 0.8-1.5 MeV and a maximum electron beam power of 100 kW. Electron beam is extracted into the atmosphere through the system of diaphragms with output holes about 1 mm in diameter. The operational vacuum in the accelerating tube is provided by a differential pumping system. The extraction device is equipped with additional scanning magnets. It allows the operator to change average beam power density in extra wide region from 10 to 10(7) Wt/cm(2). The focused beam has many applications due to its unique properties. (C) 2000 Elsevier Science Ltd. All rights reserved.

The kinetics of the thermal dehydration of CaSO4 · 2H2O single crystals, which have a layered structure, has been studied in vacuo by means of a quartz crystal microbalance. It has been found that the rate of the reaction interface advance in the crystallographic [010] direction is controlled by diffusion of water molecules through the layer of the solid product, whereas in the [001] direction it is controlled by the chemical step. To explain the experimental results, a topochemical model has been suggested. The kinetic parameters for the [001] direction are: activation energy (E) = (19.8 ± 0.4) kcalmol and frequency factor (v) = (1.5 ± 0.9) · 1014 s−1.