|
|
|
| Establishment and Performance Testing of Measurement System for 4πγ Ionization Chamber Radioactivity Standard |
| LIU Jia-cheng1,WU Yong-le1,LIANG Jun-cheng2,YUAN Zhi-lun1,CHEN Jing2,YANG Yuan-di2 |
1. Nuclear and Radiation Safety Center of Ministry of Environment Protection, Beijing 100082, China;
2. National Institute of Metrology, Beijing 100013, China |
|
|
|
|
Abstract A measuring system based on Townsend induction balance method for 4πγ ionization chamber radioactivity standard is developed. The measuring system consists of high voltage source, voltage measurement, compensation circuit and control software. During Townsend balance process, the leakage currents and offset current are small in comparison with the current to be measured. The leakage and background current obtained with the measuring system is less than 3×10-14A. Measurements are performed to check the repeatability, stability, linearity and angle response of the system. The testing result shows that the measuring system meets the requirement of 4πγ ionization chamber radioactivity standard.
|
|
|
|
|
|
［1］Rytz A. The international reference system for activity measurements of γ-ray emitting nuclides［J］. Int Appl Radiat Isot, 1983, 34(8):1047-1056.
［2］马国华．4pγ高压电离室活度测量国家标准［J］.现代计量测试, 2002, （3）:12-16.
［3］柳加成.汤姆逊平衡法应用于4πγ电离室活度计量标准的研究［J］. 计量技术,2010, （2）: 28-30.
［4］Weiss H M. 4pγ ionization chamber measurements ［J］.Nuclear Instruments and Methods, 1973, 112(1):291-297.
［5］Schrader H.Measurement of small currents using a modified Townsend method with fast programmable A/D and D/A converters.［J］.Nucl Instr and Meth A, 1992, 312(1-2):34-38.
［6］Hino Y,Kawada Y, Nazaroh. An improved leakage current compensation technique for a 4pγ ionization chamber system.［J］.Nuclear Instruments and Methods in Physics Research A, 1996, 369(2-3): 392-396.
［7］Brancaccio F,Dias M S,Koskinas M F. Automatic system for ionization chamber current measurements.［J］. Applied Radiation and Isotopes,2004, 61(6):1339-1342. |
|
|
|
2013, Vol. 34 
