籽晶保护条件下铈掺杂溴化镧晶体生长及其性能

Growth of Ce^(3+)-Doped LaBr_(3) with Protected-Seed and Its Scintillation Properties

为定向生长出铈掺杂溴化镧(LaBr_(3):Ce)晶体,改进了坩埚下降法,并在籽晶接种过程引进冷却气体的保护装置。生长出的LaBr_(3):Ce晶体在^(137)Cs放射源辐照下,其能量分辨率为3.08%,衰减时间为20.1 ns。采用多通道DRS4采集系统,以XP20D0型光电倍增管耦合Ф20 mm×5 mm溴化镧器件作为开始道探测器,H8500型光电倍增管耦合LaBr_(3):Ce阵列作为被测停止道探测器,放射源为22 Na(511 keV)。制备了6×6的LaBr_(3):Ce阵列,单根晶体条的尺寸为2 mm×2 mm×15 mm。利用数字化波形分析法,获得阵列的清晰二维散点图和一维位置谱,阵列x和y方向的位置分辨率分别为1.01 mm和0.89 mm。制备出的LaBr_(3):Ce晶体具有优异的能量分辨率和位置分辨率,可以应用于PET等医学成像技术领域。

Ce 3+-doped LaBr_(3)crystals were grown by a modified Bridgman technique with selective-seed,which was protected under cool gas.LaBr_(3):Ce scintillator has an FWHM energy resolution of 3.08%and a decay time of 20.1 ns underγ-ray excitation of^(137)Cs radioactive source.A 6×6 array of LaBr_(3)scintillator pixels was developed with a pixel size of 2 mm×2 mm×15 mm.A muti-channels DRS4 board system was used to process signals from a pair of detectors with XP20D0 PMT coupled with aФ20 mm×5 mm LaBr_(3):Ce scintillator as START Channel,and H8500 PMT coupled with a LaBr_(3):Ce scintillators array as tested STOP Channel,which were placed apart from a 22 Na source for 511 keVγ-ray.The results based on analysis of digital waveform methods show that the DRS4 system has clear black scattered points on two-dimensional crystal scatter image.While the one-dimensional position images show that the position resolutions are 1.01 mm and 0.89 mm,in x and y directions respectively.The excellent energy resolution and position resolution properties of LaBr_(3):Ce samples,indicate that it can be used in the nuclear image technique such as PET data acquisition system.