Φ300mm碘化铯晶体发光非均匀性与生长界面的关系

Non-uniformity of Luminescence of Φ300 mm CsⅠ(Tl) Scintillation Crystals and Its Growth Interface

报道了迄今为止国内首次生长出的最大直径(300 mm)碘化铯CsⅠ(Tl)闪烁晶体,并采用X射线和137Cs所发射的-射线为激发源分别测试了该晶体不同部位的发光强度,分析了这些部位的铊离子浓度,并对发光强度与铊离子浓度及其空间关系进行了讨论,认为该晶体在水平面上的发光不均匀性反映出生长界面具有凸向上的特征,进而提出调节温度场对改善均匀性具有重要作用。

CsⅠ( Tl) single crystal with diameter of 300 mm is reported for the first time in domestic region.The crystal was grown with modified vertical Bridgman method under vacuum condition. It's light outputs at different area were measured with multichannel energy spectra excited by-ray from137 Cs and X-ray excited luminescence spectrometer respectively. Meanwhile,the concentration of activator,Tl was also analyzed by means of ICP-Mass and the dependence of light output on Tl concentration was discussed. It was found that the non-uniformity of light output among the growth transection has closed relationship to the distribution of Tl ions,and the non uniform distribution of Tl ions results from the convex shape of the solid-liquid interface.Therefore,it was proposed that adjusting the thermal field of the furnace to get a flat growth interface is an effective way to obtain large size CsⅠ( Tl) crystal with high uniform light output.