In the efficiency conversion factor of in-situ gamma spectrometer by Beck formula,the parameters of effective front area(EFA)and angular response are indispensable.The experiments to obtain these two parameters of one wide-energy HPGe detector were performed by measuring point source and in-situ object counting system(ISOCS),and the values and trends as a function of the distance were obtained.The results indicated that the values of the parameters at 1 m could be used to calculate the efficiency conversion factor when the distance from the object to the detector was farther than 1m.When the distance was less than 1m,efficiency conversion factor must be calculated in accordance with the true values of these two parameters at different distance,or corrected depending on the distance.%用“Beck”公式计算就地γ谱仪探测效率时,所用参数主要有探测器有效前面积(EFA)和角响应.通过点源实验和ISOCS无源刻度软件计算获得一宽能HPGe探测器的EFA和角响应,并给出了其随探测距离的变化规律.结果表明,当测量对象与探测器间距离大于1 m时,可使用1 m时的刻度参数计算效率转换因子；当距离小于1 m时,应采用实际测量距离下的刻度参数计算或进行距离修正.
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