No abstract

A resistance-heated furnace with a good control of temperature gradients is used for the Czochralski growth of precipitate and colour free Bi,Ge,O,, (BGO) crystals up to 30 mm in diameter and 80 mm in lcngth from a 45 mm diameter crucible. The quality of the grown crystals is discussed in connection with the growth conditions. Spectrometric tests made on scintillators obtained from BGO crystals are presented. A Monte Carlo program is used in order to compute the full energy peak efficiency of the detector for different energies and geometries. The computed values are compared to the experimental reSUllS.

No abstract

Radiation induced colour centres in CeF3 crystals have been studied by spectroscopic techniques using eight crystals produced with various degrees of purity by different manufacturers in slightly different growing conditions. The crystals were irradiated at liquid nitrogen temperature with electrons of 7 MeV at doses of lo4 to 3. lo6 rad. Absorption spectra ranging between 250 and 750 nm recorded at irradiation temperature are quite different from one producer to another, regarding both the values of absorption coefficient (17 cm-' -5 cm-') and the number and form of the absorption bands.Step-by-step annealing up to room temperature produces new absorption bands. In the range of 200-240 K, three well resolved bands appear as in the case of crystals irradiated at room temperature.