Activity measurement of ~(85)Kr diluted by a large volume balloon technique

摘要

The National Metrology Institute of Japan (NMIJ) participated in the CCRI(II) Key-comparison of ~(85)Kr activity measurement. The absolute internal gas-counting method was used, with a set of proportional counters of different length. The original ~(85)Kr gas was diluted by a factor of 2 X 10~(5) in order to achieve the suitable activity concentration for the proportional counters. A new dilution method was introduced, based on a large-volume balloon and gravimetric determination of the dilution volume with small uncertainties.