The Growth And Some Properties Of Ce:YAP Scintiallation Single Crystal

The research works have verified that Ce:YAP is a excellent scintillator. It has good mechanical process properties, stable chemical character and good detecting properties. All these characters make it a promising scintillator in high-energy physics, nuclear physics, nuclear medicine, astronomic physics and nuclear protection.In this paper, the growth of Ce:YAP single crystal by middle RF heating is introduced. The motives of the experiment are two: one is to improve the quality of the crystal, to decrease the macroscopic defects and the other, to improve the light yield of the crystal. When the appropriate thermal field designed and the proper growth parameters suited to the thermal field given, several Ce: YAP single crystals roughs were grown. The as-grown crystals are transparent with no color, the surfaces are smooth and the ridges of the crystals are obvious. The crystals have integrity as well as good optical quality and stress-homogeneous. The macroscopic defects are observed and analysesed. Then the measure and analysesed result of the concentration of the elements are given, as well as those of the material pliase. The optical spectra and detection properties are investigated, too.The key factor that induces the crystal cracks is the thermal stress releasing when the crystals cooling down after growth. The macroscopic defects such as twins, small-cracking, scattering particles, growth layer and cores are examined; they are related with the temperature difference between gas and melt: the twins and small-cracking come out when the difference is large, the bubbles and scattering particles come out when that is small. By studying the luminescence mechanism and the optical spectra, the two reasons for the diminish of light yield are given: the absorption of the fluorescence by the point defects when that produced and the scatter of the fluorescence by the macroscopic defects when that transmitting. In Ce:YAPscintillators, the available approach to improve the light yield is to diminish the self-absorption of the point defects.The light yield of the as-grown crystal is 1 865phe/MeV , , the decay time of fast component is 23ns and that of slow component is 99ns, the proportion of fast component and slow component is 88% and 12% respectively. The decay time of the crystal grown in our lab reaches advanced international level. It is first time to report the Ce:YAP scintillator in China.