广东地区氟化锂热释光探测器长期稳定性实验研究

Experimental study on long term stability of LiF thermoluminescent detector in Guangdong area

目的探讨氟化锂（镁，铜，磷）[LiF（Mg，Cu，P）]热释光探测器的长期稳定性及其在广东地区气候条件下的衰退规律。方法随机抽取1080个分散性相同的LiF（Mg，Cu，P）热释光探测器，分成6组，每组180个。分别以0．5、1．0、3．0、5．3和10．0mSv剂量约定真值辐照第1～5组，第6组为跟随本底。将6组剂量计分别贮存于室温、28℃恒温和5℃恒温。于第1、90、180、270和360天每组分别取出12个平行样本测读，分析热释光探测器储能的长期稳定性变化规律。根据实验结果作曲线拟合，使用曲线回归方程和插值法计算热释光探测器信号衰退的修正值。结果辐照后360d内，3个不同贮存温度之间热释光探测器评定值比较，差异有统计学意义（P〈0．01），贮存温度越高，热释光探测器信号衰退越大；5个不同辐照剂量之间热释光探测器评定值比较，差异有统计学意义（P〈0．01），随着辐照剂量的增加热释光探测器信号衰退呈降低趋势；5个贮存时间点间热释光探测器评定值比较，差异有统计学意义（P〈0．01），热释光探测器信号衰退随着贮存时间的增长而增加。热释光探测器评定值在贮存温度、辐照剂量和贮存时间三者之间有交互效应（P〈0．01）。贮存120d时热释光探测器信号衰减最大值为0．889，说明其在120d贮存周期内稳定性不大于10％，可不修正。结论广东地区职业性外照射个人剂量监测周期最长不超过3个月，剂量计回收后存放于阴凉处，并于30d内完成测读，逾期测读应进行结果的修正。

Objective To discuss the long-term energy stability of LiF （ Mg, Cu, P） thermoluminescent detector and its recession rule under the climate condition in Guangdong area. Methods One thousand and eighty LiF （ Mg, Cu, P） thermoluminescent detectors with the same dispersion were randomly sampled as experimental objects, and divided into 6 groups with 180 detectors in each group. Groups of 1-5 were irradiated by radial with different doses of conventional true value of 0. 5, 1. 0, 3. 0, 5.3 and 10. 0 mSv respectively, the group 6 was used as the background. Six groups of dosimeter were stored at room temperature, constant temperature of 28 ℃ and constant temperature of 5 ℃ respectively, 12 parallel samples were taken out from each group for measure at day 1, 90, 180, 270 and 360 respectively. The change rules of long-term stability of the thermoluminescent detector was analyzed. According to the results of the experiment, signal recession correction value of thermoluminescent detector was counted by interpolation method. Results Within 360 days after irradiation, among 3 kinds of different temperature, the difference of the evaluated value of thermolumineseent detector was statistically significant （ P 〈 0.01 ）, the higher the storage temperature, the greater the thermoluminescent detector signal recession. While compared among 5 different irradiation doses, the difference of evaluated value of thermoluminescent detector was statistically significant （ P 〈0. 01 ）. So were those of the 5 storage time points （ P 〈0. 01 ）. With the increase of irradiation doses, there was a trend of lower thermoluminescent detector signal recession. With the increase of storage time, there was a trend of increase thermolumineseent detector signal recession. There was interaction effect among temperature, irradiation dose, and storage time （ P 〈 0. 01 ）. The maximal signal value of recession of thermoluminescent detector was 0.889 after 120 days of storage, showing that the stability was no more than 10% during the storage period of 120 days, and the correction was not a must. Conclusion In Guangdong area, the monitoring period of occupational individual dosimeter should not be longer than 3 months. When recycling, dosimeters should be stored in cool place. Measure test should be done within 30 days. If measurement is overdue, the results should be amended.