航空伽玛能谱测量中基线测量评价方法研究

摘要

Airborne Gamma ray spectrometry survey includes baseline,survey line and repeat line measurement.The baseline is an important link to monitor working status of airborne Gamma ray spectrometry system and to monitor changes of atmospheric radon.There is no specific evaluation method and technical indexes to evaluate the baseline measurement results.Based on the existing historical 648 early baseline data and 648 late baseline data measured,evaluation method and technical indicators were studied.The raw count rate of the "downward" total count window,the "downward" K window,the "down ward" U window,the "downward" Th window,and the "downward" net total count rate,radioelement concentrations of K (potassium),U(uranium) and Th(thorium) were analyzed after live time,background,Compton and height correction were processed.Through the research,the evaluation method of the total window count rate and thorium concentration data are better.To evaluate quality by raw total count rate,the change rate of early baseline measurement and late baseline measurement of raw total counts should be within ±20％;To evaluate quality by corrected result data,the change rate of early baseline meas urement and late baseline measurement of net total counts should be within ± 15％ and Th concentration changes within ± 12 ％,respectively.%航空伽玛能谱测量中包括基线、测线和重复线测量三部分,基线测量是监控航空伽玛能谱测量系统工作状态和监测大气氡变化的重要环节,但如何评价基线测量结果,目前还没有明确评价方法及其技术指标.这里以648个飞行架次的早、晚基线测量数据作为研究对象,分别对原始下测总窗计数率、钾窗计数率、铀窗计数率和钍窗计数率,及经过各项数据修正后的下测总窗净计数率、钾含量、铀含量和钍含量等进行了评价方法及其技术指标地研究.通过研究,采用总窗计数率和钍含量数据的评价方法较好;其技术指标为,采用原始计数率进行评价时,原始下测总窗计数率早晚变化士20％以内;采用经过各项数据修正后的结果进行评价时,下测总窗净计数率及钍含量早晚变化则分别为±15％以内和±12％以内.