^(46)Sc示踪沙核探测器的标定及其应用

CALIBRATION OF THE ^(46)Sc SAND TRACER DETECTOR AND IT' S APPLICATION

叙述了放射性示踪沙探测器的标定过程和结果,其特点是在模拟现埸测量条件的前提下,用硝酸钪溶液制成一个^(46)Sc平面源,用钪玻璃沙制成一块含^(46)Sc的平板源和均匀混合沙层源进行试验。利用^(46)Sc制成的平面源,仔细研究了探测器在不同水层厚度复盖条件下,γ射线反散射作用的影响。其标定目的是通过室内模拟研究,测出该探测器的灵敏度因子f_0和水饱和沙对γ射线的线性吸收系数,以便利用计数率平衡法公式计算泥沙运动层厚度。利用^(46)Sc沙制成的平板源和混合沙层源,研究了不同沙层厚度与计数率变化的关系曲线。该关系曲线将作为确定现埸跟踪观测示踪沙回收率的标定曲线。在整理和分析示踪沙扫测资料时,通过计算回收率来评价是否能算出计数率等值线的重心,以便进行输沙率或回淤量的定量计算。

This paper describes the process and result for the calibration of radioactive ^(46)Sc detector in details. The calibration was carried out under the hydrological conditions similar to the field test. The relation between the intensity of the scattered γ-rays and the various water depths was studied by using a ^(46)Sc plane source. The purpose of calibration of the detector with the plane source is to determine both the detector sensitivity factor and the γ-ray absorption coefficient for sand/water mixture in order to calculate the thickness of the mobile water layer by means of the countrate balance method. The rela tion curve between the various thicknesses of the mobile layers and countrates was studied in details by using a slab source and the uniformly mixed layers with ^(46)Sc glass. The curve is used as the calibration curve for determing the recovery of tracking radioactive tracer in situ. The recovery of tracer shows whether the field tracer data can be used to calculate the transport sediment rate or the infill rate of sed iment.