Quest for double beta decay of 160Gd and Ce isotopes

The 2 beta decay study of Gd-160 has been performed in the Solotvina Underground Laboratory with the help of Gd2SiO5:Ce crystal scintillator (volume 95 cm(3)). The background of the detector in the vicinity of the Q(beta beta) energy of Gd-160 was reduced to 1.0 cpd/(keV kg). The new improved half-life Emits have been established for 0 upsilon2 beta decay of Gd-160 to the ground (0(+)) and first excited (2(+)) levels of Dy-160: T-1/2(0 upsilon) greater than or equal to 2.3(1.3) X 10(21) yr at 68%(90%) C.L. The T-1/2 bounds have been also set for 2 upsilon, O upsilon (X) and O upsilon (XX) modes of Gd-160 decay, as well as for different 20 decay processes in Ce-136, Ce-138 and Ce-142. (C) 2001 Elsevier Science B.V. All rights reserved.