Montreal, Canada/canada240
Previous | Home | NextCase B. This device was used to measure the rate of decay of thorium emanation. The thorium emanation (after being filtered in a manner similar to that above) was passed into the chamber and swept through at a slow rate (0.8 cm/sec). As the gas decayed, its half-life could be determined by measuring the radioactivity at each of the three different detectors. The half-life was thus determined to be about 1 minute (today the Rn-220 isotope is known to have a half-life of 55 seconds). The concept of half-life was developed by Rutherford and Soddy. (The emanation from radium is radon-222, which has a half-life of 3.8 days).
