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General Information:
Address: No.18,Bei San Huan
Dong Lu,Chaoyang
Dist,Beijing,P.R.China, 100013
ws@nim.ac.cn
Tel:+86-10-64525678
Description:
It is very important to disseminate ambient dose equivalent and personal dose equivalent to user to control the occupational exposure.The dissemination of the secondary standard is performed via calibration of gamma-ray measuring instruments using gamma-ray irradiator sources. The main gamma-ray exposure unit contains three 137Cs and two 60Co sources of different activity. These calibration facilities provide a range of air-kerma rates that help to serve a large number of users: three 137Cs sources provide air-kerma rates from 50μGy/h to 170 mGy/h; two 60Co sources provide air-kerma rates from 60μGy/h to 4 mGy/h, respectively. In addition, an 241Am source with optional collimator is housed on the outer face of the exposure unit, producing an air kerma rate of about 0.4 mGy h-1.
Measurement conditions of protection-level field at the NIM
Humidity range / % |
50±20 |
Temperature/℃ |
20±1 |
Pressure/kPa |
99 to 102 |
Position of the centre of the standard chamber |
From 80cm to 600cm |
Measurement of charge |
Keithley electrometer or standard dosimeter |
The motivation of this project is to establish facilities and national rules to resolve the traceability. This project was supported by fund from government and finished in 2012.