Decay of A⁴¹

The beta and gamma radiations from 110-min A⁴¹ were investigated with a 180 and a lens-type magnetic beta spectrometers and a NaI(Tl) scintillation spectrometer. Two beta groups are observed with end points of 2. 48+0. 04 Mev and 1.199&0.008 Mev with relative intensities of 0. 88% and 99. 1% respectively. The beta spectrum of the upper energy group exhibits an o. shape in agreement with shell model predictions for the spins of the involved levels. The log f&t of this transition is 8. 50. The gamms, -ray energy is 1. 290+0.005 Mev. This results in a mass difference of 2.489%0. 010 Mev between the ground states of A⁴¹ and K⁴¹. A procedure is described for determining the background contribution in the region of the very weak, high-energy group due to the scattering of beta and gamma radiation.