The large-area multi-wire proportional counting system for 2π alpha and beta emission measurement at the NIM China.

An alpha/beta emission rate counting system which comprises of a large-area windowless multi-wire proportional counter and a digital pulse processing module has been established at the National Institute of Metrology of China, aiming at realizing the absolute measurement of emission rate for alpha and beta sources. Performance of the detector, including high-voltage plateaus and uniformity were measured. Measured emission rates for large-area Am and Sr/Y sources when compared with certificated values showed difference within 1.0%, and good agreements achieved.