Theβ-ray Spectra ofRubidium86,Strontium89, Ekatantalum, and Protactinium

Abstract

The theory of the action of a recently developed $\beta$-ray spectrograph is discussed briefly and an account is given of several improvements. In particular a baffle system of greater resolving power and a G-M counting system of greater stability are described in detail. The $\beta$-ray spectra of ${\mathrm{rubidium}}^{86}$, ${\mathrm{strontium}}^{89}$, ekatantalum, and protactinium were measured. The use of thin collodion for the backing of sources and windows of counter permitted accurate measurements down to 50 kev. The upper energy end points were found to be: ${\mathrm{rubidium}}^{86}$—1.60±.03 Mev; ${\mathrm{strontium}}^{89}$—1.32±0.03 Mev; ekatantalum—230 kev. The Fermi and K-U plots of ${\mathrm{Rb}}^{86}$ and ${\mathrm{Sr}}^{89}$ are given.