X、γ系列标准源的研制

DEVELOPMENT OF X,γSTANDARDIZED SOURCE SERIES

本文主要介绍用于Ｘ、γ谱仪能量及效率刻度的一套系列标准源的研制方法和检验结果。它是发射射线能量范围为５．９－１８３６．１ｋｅＶ的￣（５５）Ｆｅ、￣（１０９）Ｃｄ、￣（２４１）Ａｍ、￣（５７）Ｃｏ、￣（１３３）Ｂａ、￣（１３７）Ｃｓ、￣（５４）Ｍｎ、￣（６０）Ｃｏ、￣（２２）Ｎａ和￣（８８）Ｙ１０种核素标准源。采用的高纯放射性核素标准溶液，杂质的相对强度小于０．１％；由４π（ＬＳ）和４π（ＰＣ）β－γ符合方法确定的放射性浓度均在总不确定度范围（＜２．０％，置信水平为９９．７％）内相符。放射性核素密封于质量厚度为１５ｍｇ／ｃｍ￣２（除￣（５５）Ｆｅ源用７ｍｇ／ｃｍ￣２）的圆形聚脂膜中，活性区直径≤３ｍｍ。对６个￣（５７）Ｃｏ源活度用ＮｐＧｅ谱仪测定检验，偏差在０．５１％－１．０２％之间。经擦试检验表明，未见表面污染和泄漏。

Techniques and testing results Were presented in this paper for the development ofstandardized source series, which were used for energy and(detecting) efficiency calibrationof X,γ spectrometers. The standardized source series consist of ten radionuclides :￣(55)Fe,￣(109)Cd,￣(241)Am,￣(57)Co,￣(133)Ba,￣(137)Cs,￣(%$)Mn,￣(60)Co,￣(22)Na and￣(88)Y, of which the X, γ ray energy is inthe range 5.9-1 836.1 keV, All the radionuclides were purified repeatedly until the relativeintensity of each radioactive impurity was less than 0.1%。 They were used to prepare stan-dardized solution, which were measured for radioactive concentration with both 4π(LS)β-γand 4π(PC)β-γ coincidence methods. The results from both methods , having uncertainty<2.0%at a confidence level of 99.7%, were well consistent. From these standardized solu-tions , point sources( Φ≤3mm) were prepared by being sealed in between two thin circledpolyester films , each of 15 mg/cm￣2(excep for 7 mg/cm￣2 for ￣(55)Fe)in thickness, The ra-dioactivities of six ￣(57)Co sources were measti red with a HpGe spectrometer , and the resultsshowed that the differences between them were within 0. 51%-1. 02%. Wipe tests showedno radioactive contamination or leakage.