New Limit for the Half-Life of 2K(2neutrino)-Capture Decay Mode of 78Kr

Features of data accumulated at 1817 hours in the experimental search for 2K(2 \nu)-capture decay mode of Kr-78 are discussed. The new limit for this decay half-life is found to be T_{1/2} > 2.3 *10^{20} yr. (90% C.L.).Comment: 7 pages, 4 figures, submitted to Phys. of Atom. Nuc

Results of a search for 2β\beta-decay of 136^{136}Xe with high-pressure copper proportional counters in Baksan Neutrino Observatory

The experiment for the 2$\beta$-decay of $^{136}$Xe search with two high-pressure copper proportional counters has been held in Baksan neutrino observatory. The search for the process is based on comparison of spectra measured with natural and enriched xenon. No evidence has been found for 2$\beta$(2$\nu$)- and 2$\beta$(0$\nu$)-decay. The decay half lifetime limit based on data measured during 8000 h is T$_{1/2}$$\geq8.5\cdot10^{21}$yr for 2$\nu$-mode and T$_{1/2}$$\geq3.1\cdot10^{23}$yr for 0$\nu$-mode (90%C.L.).Comment: 9 pages, 8 figures; talk at the NANP'05 Conference; submitted to Phys. At. Nuc

Influence of carbon and nitrogen on electronic structure and hyperfine interactions in fcc iron-based alloys

Carbon and nitrogen austenites, modeled by Fe8N and Fe8C superstructures are studied by full-potential LAPW method. Structure parameters, electronic and magnetic properties as well as hyperfine interaction parameters are obtained. Calculations prove that Fe-C austenite can be successfully modeled by ordered Fe8C superstructure. The results show that chemical Fe-C bond in Fe8C has higher covalent part than in Fe8N. Detailed analysis of electric field gradient formation for both systems is performed. The calculation of electric field gradient allow us to carry out a good interpretation of Moessbauer spectra for Fe-C and Fe-N systems.Comment: 8 pages, 3 figures, IOP-style LaTeX, submitted to J. Phys. Condens. Matte

Working characteristics of the New Low-Background Laboratory (DULB-4900, Baksan Neutrino Observatory)

A concise technical characteristic of a new low-background laboratory DULB-4900 of the BNO INR RAS is presented. The technique and the results of background measurements in the Hall, ordinary box and low-background box are presented. Rn-222 contamination in the laboratory air has been measured by direct detection of gamma-radiation of its daughter Bi-214 distributed over the volume of the low-background box. The results of the data analysis are presented.Comment: 5 pages, 6 figure