AN ELECTROLUMINESCENCE EMISSION DETECTOR TO SEARCH FOR DOUBLE-BETA POSITRON DECAYS OF XE-124 AND OF KR-78

An emission detector, self-triggered with scintillation, is proposed t o search for double-beta positron decays of Xe-124 and of Kr-78. Ioniz ation clusters are extracted from the liquid xenon or krypton and meas ured with a matrix of photodetectors as electroluminescent flashes of the equilibrium gas phase. In the case of 2 beta(+) decay, a useful ev ent consists of 5 ionization clusters, which cross-lie in the same pla ne. In the case of K beta(+) decay, a useful event consists of 3 clust ers along the same line. Detector with 0.4 m(3) working volume will be able to check the theoretical prediction for T-1/2 of 2 beta(+)2v and K beta(+)2 nu decays of Xe-124 isotope in the over-ground experiment and of 2 beta(-)0 nu, 2 beta(-)2 nu decays of Xe-134, Xe-136 isotopes in the underground experiment with a natural mixture of Xe isotopes. S eeking for 2 beta(+)0 nu, 2 beta(+)2 nu, K beta(+)0 nu and K beta(+)2 nu decays of Kr-78 in the over-ground experiment with a natural mixtur e of isotopes is also possible with an additional NaI(TI) triggering s ystem surrounding the emission defector. A high pressure Xe gas-filled model of the emission detector with a 40 cm diameter and 4 cm depth w as built and tested with multi-cluster events generated by incident ga mma-rays.