This set is used for determining the resolving time of GM Counters. It consists of three half discs, two of which contain 5 μCi of Tl-204 plus a third half disc with no activity. The count-rate of each half disc plus the blank (to maintain constant geometry) is measured and then both active half discs are combined for a measurement with high count-rate. The counting loss may now be calculated by adding the rates from each half disc and comparing the result to the count-rate with both halves combined.
![GM Resolving Time Set, 3003911 [U41510], Radioactive Sources](/imagelibrary/U41510/U41510_01_GM-Resolving-Time-Set.jpg)
![GM Resolving Time Set, 3003911 [U41510], Radioactive Sources](/thumblibrary/U41510/U41510_01_1200_1200_GM-Resolving-Time-Set.jpg)
