Electron capture in potassium 40

Abstract

TheK-capture of the naturally radioactive isotope potassium 40 has been studied using a special large proportional counter whose cathode made of thin metallized polyester foil was common to a ring of surrounding proportional counting units connected in anticoincidence. As source potassium cyanide has been employed evaporated in vacuum on the cathode and covered by antimony. From the measured spectrum ofK X-radiation of argon the specific activity of potassium due toK-capture has been determined as 2,25±0,25 disintegrations per sec per gram of natural potassium. This result yields for the ratio ofK and (L+Mü ...) electron capture probabilities the value 0,44±0,9.