On a set of permanent magnet beta-ray spectrometers

The advantages of the use of a set of at least three permanent magnet beta-ray spectrometers, each spectrometer designed for a certain energy interval, are emphasized. It is found that a design which gives good homogeneity for strong magnetic fields might fail to do so for weak ones. A simplified construction of high resolution spectrometers is given. Reproductions of conversion line spectra of ThB + C + C″ and of Hg^{195, 195m, 197, 197m} illustrate the efficiency of the spectrometers. The suitability of a high resolution permanent magnet beta-ray spectrometer for use also in the low energy region (about 6–15 keV) is demonstrated by a record of more than 50 L-Auger lines in the electron spectrum of ThB + C + C″.