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In this study, T1Br detectors were irradiated with 25MeV protons accelerated by an AVF cyclotron. Isothermal annealing was performed to restore the performance of the detectors. In order to characterize the radiation damage and thermal annealing effects on the T1Br detectors, we measured current-voltage (I-V) characteristics, mobility-lifetime ([Mu][Tau]) products and spectrometric responses. The I-V and [Mu][Tau] measurements suggest that electron traps have been induced by 25MeV protons in the T1Br crystals. X- and [Gamma]-ray energy spectra were measured for two different electronic conditions: the electric signals induced mainly by electron carriers traversing the crystal were used for one case and the signal induced by hole carriers were used in the other case. After irradiation of 25MeV protons, the 241Am X- and [Gamma]-ray spectra obtained in the former showed significantly degraded energy resolution. No degradation of energy resolution, however, was observed in the latter case. Noticeable improvements of the degraded detector performance have been observed after the thermal annealing.

We have been studying a radiation detector which uses lead iodide crystal. The growth of Pb[I.sub.2] crystal used the two methods. One is the zone melting method and the other is the vapor phase epitaxy method. The performance of the detector fabricated from a crystal grown by the former method showed better characteristics than the detector fabricated from the crystal grown by the latter. Results of XPS and PL measurements, suggest that the behavior of the iodine atoms in the crystal influenced and controlled the performance of the detector.

Radiation detectors have been fabricated from lead iodide (Pb[I.sub.2]) crystals grown by two methods: zone melting and Bridgman methods. In response characteristics of the detector fabricated from crystals grown by the zone melting method, a photopeak for [Gamma]-rays from an 241Am source (59.5 keV) has been clearly observed with applied detector bias of 500 V at room temperature. The hole drift mobility is estimated to be about 5.5 [cm.sup.2]/Vs from measurement of pulse rise time for 5.48 MeV [Alpha]-rays from 241Am. By comparing the detector bias versus saturated peak position of the Pb[I.sub.2] detector with that of the CdTe detector, the average energy for producing electron-hole pairs is estimated to be about 8.4 eV for the Pb[I.sub.2] crystal. A radiation detector fabricated from Ph[I.sub.2] crystals grown by the Bridgman method, however, exhibited no response for [Gamma]-rays.

An improved method is proposed for the production of single crystals of lead iodide ([PbI.sub.2]). For the work reported here a modified Bridgman method is used. Bulk-type nuclear radiation detectors have been fabricated by use of crystals grown by this method. The characteristics of the detectors, particularly the response for 5.48 MeV [Alpha]-particles from 241Am source, have been measured and compared with characteristics of other detectors fabricated with crystals grown by the ordinary Bridgman method. An [Alpha]-peak has been clearly observed in the pulse-height spectrum. On the other hand, no peak has been observed in the detectors made from crystals grown by the ordinary Bridgman method. From the relations of peak position versus applied bias voltage, the average energy to produce electron-hole pairs and the [Mu][Tau] product of holes are estimated to be about 30 eV and [10.sup.-7] [cm.sup.2]/V, respectively.

We have developed a new method of growing CdTe crystals doped with chlorine by using a radio frequency (RF)-travelling heater method (THM) which can provide excellent uniformity of Cl atoms in crystal. We discuss the relationship between response characteristics of |Gamma~-ray detector and crystal properties studied by Photoluminescence (PL) measurements. In the RF-THM crystal sample, the emission intensity ratios between the line of 1.5932 eV and 1.5905 eV due to bound exciton relating to chlorine are nearly constant for all parts of the one ingot. From this result, it is suggested that the Cl atoms are uniformly distributed through the whole of the crystal. Using crystals grown by this method, a large number of high quality radiation detectors which exhibit the same characteristics can be produced from one CdTe ingot.

The luminescence properties of divalent ytterbium in alpha-SiAlON at room temperature are reported. The luminescence of Yb(super 2+) in alpha-SiAlON is characterized by the shift of the absorption from UV to the visible spectral region and an intense green emission band centered at 549 nm.

The radiation detector was fabricated from the T1Br crystals grown by TMZ (travelling molten zone) method and the FWHM and transit time of electrons and holes were measured as a function of temperature. The T1Br radiation detector shows the best response characteristics at about 313 K (3.19[K.sup.-1]) in cases where holes mainly contributed to the output pulses. However, in the temperatures higher than 300 K (3.33 [K.sup.-1]), the FWHM for [sup.241]Am [Alpha]-particles (5.48 MeV) becomes worse. An activation energy of about 0.90eV has been deduced from the resistivity measurement.