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

Abstract

The experiment for the 2${\hat{I}}^2$-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${\hat{I}}^2$(2$\hat{I}½$)- and 2${\hat{I}}^2$(0$\hat{I}½$)-decay. The decay half lifetime limit based on data measured during 8000 h is T${}_{1/2}$$\ge 8.5\cdot 10^{21}$yr for 2$\hat{I}½$-mode and T${}_{1/2}$$\ge 3.1\cdot 10^{23}$yr for 0$\hat{I}½$-mode (90%C.L.).

9 pages, 8 figures; talk at the NANP'05 Conference; submitted to Phys. At. Nucl