Nuclear Transformation by K-Electron Capture

Abstract

THE theoretical expectation that a nucleus which emits positive electrons may, as an alternative mode of transformation, change by capturing a K-electron, was recently demonstrated experimentally by Alvarez1, who was able to detect by means of a counter arrangement the fluorescent X-radiation which follows K-capture. Earlier experiments by Jacobsen2, using an active isotope of scandium in an expansion chamber, had not shown any evidence of such fluorescent radiation. Alvarez's observations were made on titanium which had been bombarded by fast deuterons. Walke3 had previously shown that one of the products of the bombardment is an isotope of vanadium, of mass number 48 and half-life 16 days, which emits positrons and thus transforms to 48Ti. Alvarez concluded from his experiments that 48V also transforms to 48Ti by the capture of a K-electron, the two modes of transformation being about equally probable.