1 X 10 (< Sup > 4 < / Sup > ~ 10 < Sup > 10 < / Sup >) Bq Gamma Source Activity Measurement Technology Research

Many activities such as the physical experiments often need to use the (1×104～3.7X1010)Bq within small volume of the radioactive sealed gamma source, for a variety of data measurement and monitoring. Therefore, you need fast measurement of these small seals the gamma source activity, ensuring accurate, reliable scientific research workload measurement is of great significance.This thesis literature review on the basis of the comparison of several gamma source activity measurement system and measurement method of measurement range, measurement uncertainty of measurement results of the object’s State and finally picked a4πγ-type ionization chamber detector in the gamma source activity measuring devices for gamma source activity measurements. Article describes a ray and a matter of principle and working principle of ionization chamber measurements of gamma source activity, and by weak current measurement techniques, research and study on traceability of system performance, established within the (1×104～3.7×1010)Bq of radioactive gamma source measurement technology of small seal, main results are as follows(1) The measurement technique of weak current is studied. First study on the effect of weak-current measurement error during source elements, notably the connection is correct, electrometer input grid and input offset voltage load current, and impedance characteristics of measuring systems, cable installation in the resulting leakage current, such as friction, generated by the piezoelectric effect current. Protect the second measurement. Final environmental study on the effect of weak-current measurement conditions. Measurement technology of weak current research suggests that if the proper connection, protection and measurement technology and the environment and the Elimination of other possible error sources of interference, the actual measuring process, activity measurements of lower will raise the level of an order of magnitude.(2) The4πγ well-type ionization chamber measurements systems is established, the performance of the system to be a technical validation. Radiation shielding design processing system, radiation shielding system in addition to protect personnel from radiation at the same time, reducing system background levels of measurement. Design and processing of three-dimension adjustable device, position measurement applied to the source geometry, in the process of reducing the source activity measurements due to the geometric effect of measurement uncertainty associated with it. Design absorption processing source box, applied to the source absorption effect, get source geometry effect absorption curve. System of measurement range lx104Bq～3.7x1010Bq, measurement uncertainty of3%. System measurement repeatability was1.1%, stability of0.6%.(3) The small volume sealed radioactive gamma source of uncertainty of measurement procedures is developed, carried out a study on traceability. In accordance with relevant State regulations and technical documents prepared uncertainty evaluation of measurement procedures, have an impact on measurement results of components for each evaluation, evaluation results objectively true. In order to verify the measurement results of the system proper, reliable, conducted a study on traceability, and upper level units of measurement than on measuring, of the uncertainty of measurement results in consistent within the allowed range.