Absorption Method for Determining the Range of Recoil Atoms

Abstract

THE determination of the recoil ranges of atoms resulting from radioactive disintegrations has hitherto been restricted almost entirely to gases, on account of the extremely short range of recoil atoms in solids; in silver, for example, the range of α-particle recoil atoms is of the order of a few hundred angstroms, whilst that of β-particle recoil atoms is many thousandfold less. It is clear, therefore, that absorption measurements and subsequent range determination in solids are possible only if the thickness of the absorbing layer can be varied by amounts corresponding to a small number of molecular layers. It occurred to us that the built-up molecular films prepared by the method of Blodgett and Langmuir¹ might serve as adjustable absorption screens of this kind; we have now demonstrated the feasibility of this idea and have obtained preliminary quantitative results.