PRECISION DETERMINATION OF K-SHELL FLUORESCENCE YIELD OF GALLIUM

A large, wall-less multiwire proportional counter containing a gaseous source of 71GeH4 has been used in a precision determination of the K-shell fluorescence yield of gallium. Runs were performed with various pressures (0.3-6 atm) of pure propane and of argon-propane mixtures. Extensive evaluation was made of the detector efficiencies for K-Auger electrons and K X-rays following K-capture events in 71Ge. The value found is ωk = 0.528 ± 0.006. Critical comparison with previous, measurements of ωk for gallium shows that methods involving solid sources of 71Ge are subject to large systematic errors. © 1969.