Investigation of ββ decay in 150Nd and 148Nd to the excited states of daughter nuclei

Double beta decay of Nd-150 and Nd-148 to the excited states of daughter nuclei have been studied using a 400 cm(3) low-background HPGe detector and an external source consisting of 3046 g of natural Nd2O3 powder. The half-life for the two-neutrino double beta deca of Nd-150 to the excited 0(1)(+) state in Sm-150 is measured to be T-1/2 = [1.33(-0.23)(+0.36)(stat)(-0.13)(+0.27)(syst)] x 10(20) yr. For other (0 nu + 2 nu) transitions to the 2(1)(+),2(2)(+),2(3)(+), and 0(2)(+) levels in Sm-150, limits are obtained at the level of similar to(2-8) x 10(20) yr. In the case of Nd-148 only limits for the (0 nu + 2 nu) transitions to the 2(1)(+), 0(1)(+), and 2(2)(+) excited states in Sm-148 were obtained and are at the level of similar to(4-8) x 10(20) yr.