ELECTRON SPECTRA IN THE DECAY OF THALLIUM-204

The continuous beta spectrum and the K Auger-line spectrum in the decay of 204Tl were investigated using a high-resolution, iron-free, [Formula: see text] double-focusing spectrometer. Instrumental distortion of the beta spectrum was shown to be very small and a linear Fermi–Kurie plot was obtained using the generalized unique first forbidden shape factor bq2 + λ2p2, with b = 1.161 ± 0.005. The end-point energy was determined to be (763.24 ± 0.31) keV. Measured values for the energies and relative intensities of the K Auger lines were in broad agreement both with theory and with previous experimental work. The K fluorescence yield was estimated to be 0.97 ± 0.017.