Abstract：The molybdenum target X-rays machine is used as the radiation source. A free air cylindrical chamber is designed for detecting photon.Four standard radiation qualities are established as per international standards file , the half-value layers, the second half value layer and homogeneous coefficients of each quality are measured by using curve fitting method, and standardize the quality of radiation energy can be calculated. Compared with that of BIPM, the HVL （half-value layer） deviation is around 1%.
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2018, Vol. 39 
