Überk-homogene unendliche Permutationsgruppen

Ohne Zusammenfassung     

The automorphism group of the universa distributive lattice

We describe the normal subgroup lattice of the automorphism groups of the countable universal homogeneous distributive lattice and of the countable atomless generalized Boolean lattice. Also, we show that subgroups of these automorphism groups of index less than lie between the pointwise and the setwise stabilizer of a finite set. Received March 8, 1999; accepted in final form September 16, 1999.     

New bands and spin-parity assignments in 111Ru

The ¹¹¹Ru nucleus, populated in the spontaneous fission of ²⁴⁸Cm has been studied by means of prompt gamma spectroscopy using the EUROGAM2 array. Spin and parity assignments, based on angular correlations, linear polarization, and conversion coefficient measurements differ from those available in the literature. New bands are reported, which incorporate transitions seen previously but not placed in the scheme of ¹¹¹Ru or placed incorrectly. The bands are interpreted as neutron excitations into subshells originating predominantly from the h _11/2, g _7/2 and s _1/2 spherical orbitals. The s _1/2 band, strongly mixed with the d _3/2, d _5/2 and g _7/2 configurations, is observed for the first time in this region.PACS: 23.20.Lv transitions and level energies - 21.60.Cs Shell model - 25.85.Ca Spontaneous fission - 27.60. + j      

Zur Gamma- und Röntgenstrahlung von Holmium-164

The photon spectrum in the decay of¹⁶⁴Ho was investigated using a high resolution solid state detector separating theK-X-rays of Dy, Ho and Er. The two γ-rays depopulating the 3⁺ and 2⁺ levels in¹⁶⁴Ho were found to have energies of 56.6 and 37.3 keV. The 91.4 keV radiation of Er from our sample seems to have a non resolved high energy component with about 2.5% intensity. It may be due to the cross-over transition 3⁺→1⁺ or a sum line. The half-life of the isomeric state of¹⁶⁴Ho was found to be 36.7 ± 1 min. The total transition rates between different levels were calculated from the measured photon intensities. The fraction 0.27 found in the branching of thee ^?-capture feeding the 2⁺-state of Dy has nearly the same value as the analog branching in the β^?-decay. Combining the measured complex ground state decay curve and the transition intensities of the isomeric and of the ground state the ground state half-live can be deduced and was found to be (28.1 ± 1.0) min. The corresponding ratio of the ground state and the isomeric state production rates is 2.8₄:1. A ratio of 0.04 was found for the cross section of¹⁶⁵Ho (γ, 3n),¹⁶²Ho and¹⁶⁵Ho (γ,n)¹⁶⁴Ho for a 90 MeV bremsspectrum.