LXXX. Proportional counters in a magnetic field: an investigation of the isomerism of Br80and a measurement of the fluorescence yield of Krypton

Summary The proportional counter technique for measuring the energy of soft electrons has been extended to include higher energy radiations by placing the counter in a strong magnetic field. Suitable X-ray calibration sources consisting of long lived K-capture bodies which give lines at energies up to 50 keV. have been developed. In an application of the technique to a study of the isomerism of Br80, the conversion coefficient of the 37 keV. gamma ray was found to be 1·2, which is close to the calculated value for an electric dipole transition. In a second application, the fluorescence yield of the K shell of Krypton was measured. The value obtained was 0·67.