0 30 10 07 v 1 1 4 Ja n 20 03 A Search for various Double Beta Decay Modes of Cd , Te and Zn Isotopes

Various double beta decay modes of Cd, Zn and Te isotopes are explored with the help of CdTe and CdZnTe semiconductor detectors. The data set is splitted in an energy range below 1MeV having a statistics of 134.5 g·d and one above 1MeV resulting in 532 g·d. No signals were observed in all channels under investigation. New improved limits for the neutrinoless double beta decay of Zn of T1/2 > 1.3·10 yrs (90%CL), the longest standing limit of all double beta isotopes, and 0νβEC of Te of T1/2 > 2.2 · 10 yrs (90%CL) are given. For the first time a limit on the half-life of the 2νECEC of Te of T1/2 > 9.4 · 10 yrs (90%CL) is obtained. In addition, limits on 2νECEC for ground state transitions of Cd, Cd and Zn are improved. The obtained results even under rough background conditions show the reliability of CdTe semiconductor detectors for rare nuclear decay searches.