Search for double beta decay of 136Ce and 138Ce with HPGe gamma detector

Search for double β decay of 136Ce and 138Ce was realized with 732 g of deeply purified cerium oxide sample measured over 1900 h with the help of an ultra-low background HPGe γ detector with a volume of 465 cm3 at the STELLA facility of the Gran Sasso National Laboratories of the INFN (Italy). New improved half-life limits on double beta processes in the cerium isotopes were set at the level of lim⁡T1/2∼1017–1018 yrlim⁡T1/2∼1017–1018 yr; many of them are even two orders of magnitude larger than the best previous results.