5) The uncertainty( k=2) of relative measurement is smaller than 5%, and the detection lower limit obtained from the fluctuation of background current is 0.5 Bq.

• 5)不确定度分析表明相对测氡的扩展不确定度(k=2)小于5%25，由本底涨落得出探测下限为0.；5 Bq；