An electroluminescence emission detector to search for positron double-beta decays of /sup 124/Xe and of /sup 78/Kr

An emission detector, self-triggered with scintillation, is proposed to search for positron double-beta decays of /sup 124/Xe and of /sup 78/Kr. Ionisation clusters are extracted from liquid phase and measured with matrix of photodetectors as electroluminescent flashes of the gas phase. In case of 2/spl beta//sup +/ decay, a useful event will contain 5 ionisation clusters, cross-laying in the same plane. In case of K/spl beta//sup +/ decay, a useful event will contain 3 clusters, laying in the same line. Proposed detector with 0.4 m/sup 3/ working volume will be able to check the theoretical prediction for T/sub 1/2/ of 2/spl beta//sup +/2/spl nu/ and K/spl beta//sup +/2/spl nu/ decays of /sup 124/Xe isotope in over-ground experiment and of 2/spl beta//sup -/0/spl nu/, 2/spl beta//sup -/2/spl nu/ decays of /sup 134/Xe, /sup 136/Xe isotopes in underground experiment with natural mixture of Xe isotopes. Seeking for 2/spl beta//sup +/0/spl nu/, 2/spl beta//sup +/2/spl nu/, K/spl beta//sup +/0/spl nu/ and K/spl beta//sup +/2/spl nu/ decays of /sup 78/Kr in over-ground experiment with natural mixture of isotopes is also possible with additional NaI(Tl) triggering system surrounding the emission detector. High pressure Xe gas-filled model of the emission detector with working volume of 40 cm diameter and 4 cm depth is built and tested with multi-clusters events generated by absorbing /spl gamma/-radiation.