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.