近年来,随着对稀土卤化物闪烁晶体研究的不断深入,该类材料的许多优异性能被不断发现,尤其是备受关注的中子/伽马射线双探测性能.化学组成为A2 LiRX6:Ce(A、R、X分别代表+1价金属元素、稀土元素、卤族元素)的掺铈锂基钾冰晶石型闪烁晶体和化学组成为LiM2 X5:Eu(M、X分别代表+2价金属元素、卤族元素)的掺铕锂基碱土卤化物,因可同时探测中子和伽马射线,且大都具有较高的光输出、较优异的能量分辨率等特性,被认为是非常实用且具有潜力的双探测材料.目前,掺铈锂基钾冰晶石型闪烁晶体中最具代表性的Cs2 LiYCl6:Ce(CLYC)已被广泛研究并产品化,而有望替代CLYC等钾冰晶石型晶体的掺铕锂基碱土卤化物研究报道甚少.本文主要对上述两类双模式探测用材料的研究进展进行简要综述,以期对相关领域的研究学者有所启发.

本文使用垂直坩埚下降法制备了40 mm×40 mm×350 mm的BaF2:5％Y(摩尔分数)晶体,并对晶体样品进行了掺杂含量、闪烁性能、光学性能和辐照损伤的研究.距离籽晶端0～300 mm范围内的Y3+掺杂浓度(摩尔分数)为5.1％ ±0.9％.晶体样品的平均光输出为2100 ph/MeV,在662 keV处的最优能量分辨率为10.1％.经60 Co放射源辐照累积剂量1 Mrad后,样品在波长220 nm处的透过率由辐照前的87.3％下降至83.5％,在波长300 nm处的透过率由91.8％下降至89.9％.BaF2:Y晶体的抗辐照性能差于BaF2晶体,经过累积剂量辐照后,BaF2:Y晶体对波长300 nm光的吸收明显增强.

Due to its ultrafast cross-luminescence, the BaF 2 crystals with a subnanosecond decay time are promising for high-reputation radiation detection. However, there is a slow scintillation component with a decay time of about 600 ns in the crystal, which induces a pile-up effect. The Y doping in the crystal was confirmed to be effective in slow component suppression. In this investigation, the fast/total (F/T) light yield (LY) ratios and fast component LY of BaF 2 :Y crystals with various Y concentrations were investigated by the fast sampling technique. It was demonstrated that Y doping not only suppresses the slow component but also weakens the fast component. A good negative correlation was observed between the F/T LY ratios and fast component LY of BaF 2 :Y crystals, indicating that it was impossible to obtain the BaF 2 :Y crystal with a high F/T LY ratio and a high fast component LY at the same time. The influence of wrapping materials on the F/T LY ratio was also investigated. The result illustrates that both the undoped and Y-doped BaF 2 crystals without wrapping materials show the best F/T LY ratio, indicating that the tradeoff between LY and F/T LY ratio is needed in the applications.

10％ Ce3+-doped lanthanum chloride (LaCl3:Ce) crystals with low-radioactive background have been prepared using raw materials with low content of U-series isotopes. The radioactive background was estimated to be about 0.713 counts·s–1·cm–3 resulted from the natural U-series radioactive isotopes in the prepared LaCl3:Ce crystal. The energy resolution (FWHM) of the LaCl3:Ce crystal was 3.3％ for 662 keVγ-rays. Moreover, the peak-to-valley ratio, relative light output and peak count rate of the LaCl3:Ce crystal were approximately 2.61 times, 87.88％ and 1.96 times of that of NaI:Tl crystal with the same size of ?25 mm× 50 mm, respectively. The effects of crystal size on the scintillation properties of the prepared LaCl3:Ce crystal were discussed.

Cs2 LiYCl6:Ce(CLYC)晶体是一种具有n/γ双探测能力的新型闪烁晶体.采用坩埚垂直下降法生长出富6 Li的CLYC晶体毛坯,经加工、封装得到?50 mm×50 mm的CLYC闪烁晶体封装件,其对137 Cs 662 keVγ射线的能量分辨率为4.22％;测量252Cf中子源的脉冲波形甄别(PSD)品质因子(FOM)为3.45.凭借其优异的性能,CLYC闪烁晶体有望在中子探测领域替代3 He正比计数管,并可作为n/γ双探测的优选材料,应用于中子辐射探测器、放射性同位素识别仪、个人辐射剂量仪,以及其他中子、伽马射线的探测.

A few of halide inorganic scintillation crystals have been applied as radiation detection materials and are playing important roles in nuclear medicine, high energy physics, security inspection, petroleum logging and so on, but most of them are on the way of research and development. In this paper, a series of novel halide scintillation crystals, LaBr3(Ce), LaCl3(Ce), SrI2(Eu), Cs2LiYCl6(Ce) and NaI(Tl) were studied using low energy 241Am radioactive source. The effect of reflective film thickness on low-energy ray transmittance and light output of encapsulated scintillators was investigated, Teflon thickness of 0.48 mm as reflective film is best choice to obtain higher light collection and better radiation transmittance. Among all these crystals, LaBr3(Ce) crystal has excellent energy resolution above 25keV gamma ray radiation, 9.3% at 26.34 keV, 8.4% at 59.54 keV and2.6% at 661.66 keV. Only NaI (Tl) crystal works fine below 25 keV X-rays radiation, with energy resolution of 17.68% at 13.9 keV, 14.16% at 17.8 keV and 13.42% at 20.8 keV.

In this paper, the relative light output, energy resolution and count rate of encapsulated LaBr3 (Ce) crystals were tested under the temperature from 25 °C to 175 °C using 137Cs γ radioactive source. The variation of high temperature scintillation performance of LaBr3 and NaI(Tl) crystal packages was measured and analyzed. The results show that the decline of light output of LaBr3(Ce) scintillation crystal is about 80% of that of NaI(Tl) at 175 °C. The energy resolution of LaBr3(Ce) at high temperature 175 °C is approximately 8%, which is better than the 9.9% energy resolution of NaI(Tl) scintillation crystals at room temperature 25 °C. The count rate of LaBr3(Ce) is about 5-6 times more than that of the NaI(Tl) crystal.

The scintillator detector plays an important role in the detection of ray energy and arrival time.Aiming at the new domestic cerium bromide(CeBr3)scintillator crys-tal,the experimental system for testing its key performance was established.A fast-coincident timing resolution measurement device was established,and it's found that the timing resolution of the new scintillator detector is 142 ps.And the results show that the decay time of the cerium bromide crystal is 16.8 ns and the rise time is 0.18 ns.The relative light output measurement device was established and tested to obtain the relative light output to NaI(Tl),and the relative light output of the cerium bromide crystal scintillator detector is 161% for 661.66 keV energy ray.At the same time,the energy response of the detector was measured,and the energy resolution is 4.7% for 661.66 keV energy ray.The performance of the novel scintillator crystals made in China was compared with that of aboard cerium bromide crystal and other kinds of scintillator crystals,such as barium fluoride,lanthanum bromide and sodium iodide,and its appli-cation prospect was discussed.