Showing papers by "Ken-Ichi Fushimi published in 1991"
TL;DR: In this paper, a finite half-life of T 2v 1 2 =(1.15 + 0.30 − 0.20 )×10 19 yr (68% CL ) for 2νββ decay and the most stringent lower limit of T 0v 1/2 > 4.7 × 10 21 yr ( 68% CL ), for the 0v ββ decay were obtained.
102 citations
TL;DR: In this paper, a finite half-life of T12/2 nu = 1.15-0.30*1019 y (68% CL) for the two neutrino beta beta decay of 100Mo and the most stringent lower limit of T 12/0 nu > 4.1*1023 y by searching for the gamma decay was obtained.
Abstract: Double beta ( beta beta ) decays of 100Mo and charge nonconserving excitations of 127I were studied by means of ELEGANTS V. A finite half-life of T12/2 nu =1.15-0.20+0.30*1019 y (68% CL) for the two neutrino beta beta decay of 100Mo and the most stringent lower limit of T12/0 nu >4.7*1021 y (68% CL) on the half-life for the neutrinoless beta beta decay of 100Mo were obtained. Lower limits on the mean life of the charge nonconserving (CNC) processes 127I+eK to 127I*+ nu leading to the first excited states of 127I were obtained as tau >1.1*1023 y by searching for the gamma decay.
19 citations
TL;DR: In this paper, a low background spectrometer, ELEGANTS-IV, consisting of eleven Si(Li) beta-detectors and surrounding 4 pi -NaI(Tl) gamma detectors, has been used for the present experiment.
Abstract: The normal double beta decay with two neutrinos (2 nu beta beta ) has been studied for 100Mo in order to study experimentally the 2 nu beta beta nuclear matrix element (M2 nu ). A low background spectrometer, ELEGANTS-IV, which consists of eleven Si(Li) beta -detectors and surrounding 4 pi -NaI(Tl) gamma -detectors, has been used for the present experiment. natMo and 94% enriched 100Mo source-disks have been measured simultaneously for 8006 hours. A lower limit for the 2 nu half-life was obtained as 7.9(6.2)*1018 years at the 68(90)% confidence level. The present experiment suggests a finite 2 nu half-life of the order of 1019 years. However, it is necessary to estimate the contribution from contamination in the 100Mo disks by a Monte Carlo calculation.
3 citations