Double Beta Decay: Historical Review of 75 Years of Research

Main achievements during 75 years of research on double beta decay have been reviewed. The existing experimental data have been presented and the capabilities of the next-generation detectors have been demonstrated.Comment: 25 pages, typos adde

Das Problem der Objektivierung unscharfer Eigenschaften in einem realen quantenmechanischen Messprozess

SIGLETIB Hannover: DR 5895 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Spannungsintensitaetsfaktoren fuer Risse in Kerben - FE-Analysen und Naeherungsformeln

In the frame of linear-elastic fracture mechanics approximation formulas for stress intensity factors K have been derived for surface-, edge- and through-cracks in notched plates under tension load as a function of crack depth, crack length, plate thickness, depth, height and radius of notches, notch factor and angle along the crack contour. The compiled approximation formulas were verified by FE analyses. K factors were calculated for 200 notch crack problems by means of 2D and 3D elastic finite element calculations covering a representive parameter field of different kinds and configurations of cracks. For the FE calculations the commercially available program ABAQUS was used. (WEN)Available from TIB Hannover: RO 1533(1996,1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Critical dimensions of water-tamped slabs and spheres of active material

The magnitude and distribution of the fission rate per unit area produced by three energy groups of moderated neutrons reflected from a water tamper into one side of an infinite slab of active material is calculated approximately in section II. This rate is directly proportional to the current density of fast neutrons from the active material incident on the water tamper. The critical slab thickness is obtained in section III by solving an inhomogeneous transport integral equation for the fast-neutron current density into the tamper. Extensive use is made of the formulae derived in The Mathematical Development of the End-Point Method by Frankel and Goldberg. In section IV slight alterations in the theory outlined in sections II and III were made so that one could approximately compute the critical radius of a water-tamper sphere of active material. The derived formulae were applied to calculate the critical dimensions of water-tamped slabs and spheres of solid UF{sub 6} leaving various (25) isotope enrichment fractions

Postdeposition annealing induced transition from hexagonal Pr2O3Pr_2O_3 to cubic PrO2PrO_2 films on Si(111)

Films of hexagonal praseodymium sesquioxide (h-Pr$_2$O$_3$) were deposited on Si(111) by molecular beam epitaxy and thereafter annealed in 1 atm oxygen at different temperatures, ranging from 100 to 700 °C. The films of the samples annealed at 300 °C or more were transformed to PrO2 with B-oriented Fmˉ3m structure, while films annealed at lower temperatures kept the hexagonal structure. The films are composed of PrO2 and PrO2−δ species, which coexist laterally and are tetragonally distorted due to the interaction at the interface between oxide film and Si substrate. Compared to PrO$_2$, PrO$_2$−δ has the same cubic structure but with oxygen vacancies. The oxygen vacancies are partly ordered and increase the vertical lattice constant of the film, whereas the lateral lattice constant is almost identical for both species and on all samples. The latter lattice constant matches the lattice constant of the originally crystallized hexagonal praseodymium sesquioxide. That means that no long range reordering of the praseodymium atoms takes place during the phase transformatio