In the framework of its search for new heavy, fast, and radiation-hard scintillators for calorimetry at future colliders, the Crystal Clear Collaboration performed a systematic investigation of the properties and of the scintillation and radiation damage mechanisms of CeF 3 monocrystals. Many samples of various dimensions up to 3 × 3 × 28 cm 3 were produced by industry and characterized in the laboratories by different methods such as optical transmission, light yield and decay time measurements, excitation and emission spectra, gamma and neutron irradiations. The results of these measurements are discussed. The measured light yield is compared with the theoretical expectations. Tests in high-energy electron beams on a crystal matrix were also performed. The suitability of CeF 3 for calorimetry at high-rate machines is confirmed. Production and economic considerations are discussed.

K 29 5 T4 T T9 T8 T7 T6 1 phys. stat. sol. 33, K29 (1969) Subject classification: I 0.2; 22.5.2 Institute of Physics, Academy of the Socialist Republic of Romania, Bucharest Electrolytically Coloured =++-Doped Alkali Halide Crystals

fa) and ~e p a r t~e n t of Physics, University of Bucharestz) (b) The Conversion of Electronic Centres into U and OH-Centres BY V. TOPA (a), A. IOAN (b), B. ILIESCU (a), and G. MITROAICA (a) A quantitative treatment is made of F + U conversion in H, in very pure KCI crystals and the conversion of electronic centres (like Ag-, Cu-, T1-, P b ? J in U centres by the same treatment. This fact gives the possibility to elaborate a method for detecting negative metal ion centres. By thermal treatment in water vapour, electronic centres like Ag-, Cu-, T1-, Phiare transformed mainly into OHions and colloids of heavy metal elements. Ce travail rapporte sur un traitement quantitatif de la conversion F -+ U, en H,, dans de tres purs cristaux KCI et sup la conversion des centres Blectroniques (du type Ag-, Cu-, T1-, Pb:-) en centres U par le meme traitement. Cela donne la possibilitB d'blaborer une mBthode de mettre en Bvidence les centres mBtalliques n6gatifs. Par traitement thermique en vapeurs d'eau des centres Blectroniques du type Ag-, Cu-, TI-, Phisont notamment transform& dans des ions OHet dans des colloids des mBtaux Iourds.

a), V. A. VETROV (a), N. G. ROMANOV (a), and V. TOPA (b) Optically detected magnetic resonance (ODMR) is applied for the first time to the investigation of triplet relaxed excited states (RES) of divalent ns2 ions in alkali halide crystals. Four types of ODMR spectra related to the RES of Ge2+ are found. Spectral and angular dependences of ODMR are studied. ODMR data on the RES of monovalent (Gat) and divalent (Ge2+) ns2 ions are discussed. These results provide the first experimental evidence of the effect of nuclear charge on the wavefunction density distribution for excited states of impurity ions in crystals. OIITIIqeCHII ZeTeKTHpyeMbIfi MarHIITHbIfi pe30HaHC (OfiMP) BnepBbIe IlpHMeHeH nJIH HCCJIe-AOBaHIIH TpIInJIeTHbIX peJIaHCMpOBaHHbIX B036ymAeHHbIX COCTOHHHfi (PBC) L(ByX3apHH-HbIX nSz IIOHOB B WeJIOqHO-raJIOIIL(HbIX KpMCTaJIJIaX. O 6~a p y w e~o YeTbIpe TElIIa CIIeKTpOB OfiMP, OTHOCHWHXCH K PBC HOHOB Ge2+. M3YqeHbI HX CIIeHTpaJIbHbIe H OpHeHTaIUIOH-Hble 3aBEICIIMOCTH. O~CYHER~IOTCH pe3yJIbTaTbI O D M p HCCJIeAOBaHHfi OAH03aPRAHbIX (Ga+) II aByX3apHaHbIX (Ge2+) nSz IIOHOB. BnepBbIe LtJIFi B036YlfCAeHHbIX COCTOHHHfi IIpH-MeCHbIX MOHOB B KpMCTaJIJIaX 3KCnepI' IMeHTaJIbHO AOKa3aHO BJlHFIHHe 3apHAa RApa Ha pacnpenenemie nnoTHocTn BOJIHOBO~Y~ (PYHK4HH. I) 194021 Leningrad, USSR. 2,

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