Next stage of search for 2K(2$\hat{I}½$)-capture of ${}^{78}$Kr

Abstract

A technique to search for 2K-capture of ${}^{78}$Kr with large low-background proportional counter filled with an enriched in ${}^{78}$Kr up to 99.8% sample of Krypton at a pressure of 4.51 is described in this paper. The results of first measurements are presented. Analysis of data collected during 159 hours yielded new limit to the half-life of ${}^{78}$Kr with regard to 2K-capture (T${}_{1/2}\ge 6\cdot 10^{21}$ yr (90% C.L.)). Sensitivity of the facility to the process for one year of measurement was evaluated to be $\text{S}=1.0\cdot 10^{22}$ yr (90% C.L.).

4 pages, 5 figures; talk at the NANP'05 Conference; submitted to Phys. At. Nucl