Ein doppelfokussierendes Betaspektrometer für Konversionselektronen aus (n, γ)-Prozessen Das Konversionselektronenspektrum von Dy 165—Ho 165

For the Garching research reactor at Munich, a BETA spectrometer was built in order to measure the conversion electrons from (n, gamma ) processes. The preparation was near the reactor core. The electrons emerge through an evacuated tube in the reactor shield and are passed into the BETA spectrometer. This is a surface spectrometer which deflects the electrons about 90 deg through a partially homogeneous, partially inhomogeneous magnetic sector field with double focusing. With a preparation surface of 10 x 30 mm/sup 2/, a space angle of 10/sup -5/ sterad/4 pi , a transmission of 3 x 10/sup -6/, and a luminosity of 3 x 10/sup -5/ cm/sup 2/, a half-value width of 0.11% was obtained for the lines in the pulse fraction. Electrons between 35 kev and 10 Mev could be measured. The entire installation was first constructed outside the reactor in order to test and adjust it. The spectrometer was calibrated with a known conversion line of Cs/sup 135/-Ba/sup 137/ and Au/sup 198/-Hg/sup 198/. Then the conversion ratios of Cs/sup 135/-Ba/sup 13 and Au/sup 198/-Hg/sup 198/ were determined. With the spectrometer constructed outside the reactor the conversion spectrum of Dy/sup 165/-Ho/sup 165/ was measured. Three lines with themore » following conversion ratios were found: gamma /sub 1/ at 92.00 plus or minus 0.15 kev, K: L/sub 1/: L/sub 2/: L/sub 3/:M:N = (6.6 plus or minus 0.7):1.0:(0.103 plus or minus 0.006):. (0.048 plus or minus 0.004):(0.19 plus or minus 0.01):(0.059 plus or minus 0.005); gamma /sub 2/ at 27.8 plus or00.2 kev, K:L =4.3 plus or minus 0.6; gamma /sub 3/ at 362.6 plus or minus 0.25 kev, K:L = 7.9 plus or minus 0.8. (tr-auth)« less