Test of Proportional Counter System with Effective Detective Area Larger than 1000 cm²

In order to determine the emission rate of the large-area source whose active area is up to 1 000 cm², and to expend current standard ability of 2πα, 2πβ emission rate, a suit of large-area 2π multi-wire proportional counter system was established. The test about the characteristics of the whole system was carried out using both point source with active diameter of 8 mm and large-area source with active size of 10 cm×15 cm in this paper. The results show that the effective detective area is about 1 400 cm² with homogeneity of counts of better than ±0.4%. The high-voltage plateau of ²⁴¹Am source is about 1 400 V with a slope of 0.27%/100 V and variation coefficient of 0.87%, while the high-voltage plateau of ⁹⁰Sr-⁹⁰Y source is about 300 V with a slope of 0.75%/100 V and variation coefficient of 0.80%. The repeatability of 10 measurements is better than 0.4%. Short term stability within 8 h is better than 0.3%, while long term stability within one year is better than 0.8%.