P. Kramer

The beta-decay of 233Pa

Synopsis Further measurements on the electron spectrum of 233Pa have been performed. 14 gamma transitions were determined from the observed conversion lines. A very weak indication was found of an electron line at 360 keV which might be the K-conversion line of a 475.6 keV transition. The Fermi-Kurie analysis led to three partial beta-spectra with endpoints of 568 ± 5, 257 ± 5 and 145 ± 10 keV and intensities of 5%, 58% and 37% respectively. These results agree with the decay scheme proposed by B r o d i e. e− and β− coincidences were also performed.

The decay of 90Nb

Synopsis Measurements have been performed on the radiations of 90Nb with a double focusing spectrometer and with a scintillation spectrometer. The positon spectrum consists of three partial spectra with maximum energies of 1.500, 0.865 and 0.55 MeV. Seven γ-transitions have been deduced from the conversion electrons and the γ-scintillation spectrometer measurements. Together with the results of β-e−-coincidence measurements a probable decay scheme has been constructed.

Beta-gamma coincidence spectrum of the UX-complex

Synopsis From coincidence measurements, made in a magnetic coincidence spectrometer, the maximum energies of the partial beta-spectra of UX 1 and UX 2 were found to be about 100 keV ( UX 1 ), 600 keV and 1500 keV ( UX 2 ), while furthermore some conversion lines due to gamma-gamma cascades have been obtained. Possible decay schemes are discussed.

On the K/β+ ratio in the decay of 58Co

Abstract Using an internal source in a 4π proportional counter, the K/β+ ratio in the decay of 58Co was determined to be 4.83 ± 0.1.

Measurements on electron capture branching ratios in the decay of the nuclides 54Mn, 65Zn 57Co

The fraction K capture of a nuclide decaying by electron capture to an excited state can be determined by measuring coincideness between gamma quanta de-exciting this level and X-radiation and/or Auger electrons following the K capture process. By using a double proportional counter with an internal source we could detect X-quanta and Auger electrons with nearly 100% efficiency. This was the main cause of a great accuracy in the measurement of the K capture fractions, Pk, in the decay of 65Zn and 54Mn, resulting in values of the fraction K capture resp. 87.5 ± 0.6% and 90.2 ± 0.6%. With summation measurements in the proportional counter we could determine the Pk of 57Co as 87 ± 4%.

Measurements on the K fluorescence yield of Cr, Mn, Cu and Ga

With a double proportional flow counter absolute counting of both K x rays and K Auger electrons can be achieved in the energy region 5 to 12 kev, using argon-methane as filling gas at pressures up to 20 atm. Absolute counting of Auger electrons is only achieved if the counter was filled with helium gas. By comparing the two counting rates accurate values for the K fluorescence yield ( omega /sub K/) of some elements can be obtained by measuring isotopes decaying by electron capture. The results are: omega /sub K/(Cr) = 0.222 plus or minus 0.003; omega / sub K/ (Mn) = 0.273 plus or minus 0.003; omega /sub K/(Ga) = 0.457 plus or minus 0.004; and omega /sub K/(Cu) = 0.400 plus or minus 0.004. (auth)

The beta-decay of 230Pa

Summary The beta-decay of 230Pa was investigated with a magnetic beta-ray and a scintillation spectrometer. This led to 9 gamma-transitions from which two possible schemes of 230Th could be constructed. A positon spectrum and a negaton spectrum with maximum energies of 0.4 MeV and 0.405 ± 0.02 MeV were also observed. These results, however, are not so certain because of possible contaminations of fission products.