L. Frevert

K-Einfang der Silberisotope Ag110 und Ag108

K-electron capture of Ag110 has been observed for the first time using scintillation spectrometers in anticoincidence technique. The ratio of electron capture toβ−-decay was determined to (0.3±0.06)%.K-electron capture of Ag108 has been remeasured with better accuracy, yielding a relative frequency of (1.73±0.12)% for the capture transition to the ground state of Pd108.

Zum Zerfall von Tc96g und Tc96m

Theγ spectra of Tc96g (103 h) and Tc96m (51.5 min) have been investigated using Ge(Li) detectors. In the decay of Tc96mγ transitions of 480, 720, 779, 851, 1094, 1201 and 1499 keV have been identified. These results are only compatible with spin and parity 7+ and 4+ for Tc96g and Tc96m respectively,γ-γ coincidence measurements yielded a revised level scheme of Mo96.

Die Störung der Resonanzstreuung von γ-Strahlung einer Kr79-Quelle an Br79 durch gaskinetische Stöße in der Quelle

Abstractγ-quanta emitted by gaseous Kr79-sources were scattered resonantly from Br79-nuclei. By increasing the density in the source the effective cross section for resonance scattering was influenced due to gaskinetic collisions of the recoiling Br79-nuclei with atoms before emission of theγ-quantum. The cross section for gaskinetic collisions was determined to beσst=(12.0±1.8) 10−16 cm2 in agreement with the theoretical value obtained from a hard sphere model. This technique, similar to the usual “Doppler shift technique”, yields, if combined with the measurement of the absolute cross section for resonance scattering, spin and lifetime of the levels at 398 and 606 keV. The resonance scattering from the 834 keV level shows an unexpected behaviour in complete contradiction to the hard sphere model, indicating that the velocity of the recoiling nuclei is increased in a dense source atmosphere.

Verzweigungsverhältnisse undβ+-Maximalenergie beim Zerfall von Ag108

The branching ratios of Ag108 have been remeasured with scintillation spectrometers. There is evidence for a weak 177 keV-β−-branch going to the 1473 keV level of Cd108, followed by aγ-γ-cascade of (841+632)keV. Spin and parity 2+ of this level are supported by logft=4.7 of theβ−-branch. Theβ+-spectrum has been measured for the first time yielding an end point energy of (880±25)keV, in agreement with the value derived from theK/β+ratio.The branching ratios of Ag108 were remeasured with scintillation spectrometers. There is evidence for a weak 177 kev β - branch going to the 1473 kev level of Cd108, followed by a γ - γ cascade of (841 + 632) kev. Spin and parity 2+ of this level are supported by log ft = 4.7 of the β branch. The β + spectrum was measured for the first time yielding an end point energy of (880 plus or minus 25) kev, in agreement with the value derived from the K/ β + ratio.

Branching ratios and maximim β+ energy in the decay of Ag108

The branching ratios of Ag108 have been remeasured with scintillation spectrometers. There is evidence for a weak 177 keV-β−-branch going to the 1473 keV level of Cd108, followed by aγ-γ-cascade of (841+632)keV. Spin and parity 2+ of this level are supported by logft=4.7 of theβ−-branch. Theβ+-spectrum has been measured for the first time yielding an end point energy of (880±25)keV, in agreement with the value derived from theK/β+ratio.The branching ratios of Ag108 were remeasured with scintillation spectrometers. There is evidence for a weak 177 kev β - branch going to the 1473 kev level of Cd108, followed by a γ - γ cascade of (841 + 632) kev. Spin and parity 2+ of this level are supported by log ft = 4.7 of the β branch. The β + spectrum was measured for the first time yielding an end point energy of (880 plus or minus 25) kev, in agreement with the value derived from the K/ β + ratio.

K-Einfang beim Rh104 (42,8 sec)

The ratio of electron capture toβ−-decay for Rh104 was determined to (4.5±1)·10−3 for the first time using scintillation spectrometers in anticoincidence technique.