Two-neutrino double beta decay of <sup>100</sup>Mo with ELEGANTS-IV
T Watanabe; H Ejiri; K Okada; N Kamikubota; H Sano; T Shima; J Tanaka; K Fushimi; H Kinoshita; Y Nagai; T Shibata; T Watanabe; Dept. of Phys., Osaka Univ., Japan; H Ejiri; Dept. of Phys., Osaka Univ., Japan; K Okada; Dept. of Phys., Osaka Univ., Japan; N Kamikubota; Dept. of Phys., Osaka Univ., Japan; H Sano; Dept. of Phys., Osaka Univ., Japan; T Shima; Dept. of Phys., Osaka Univ., Japan; J Tanaka; Dept. of Phys., Osaka Univ., Japan; K Fushimi; Dept. of Phys., Osaka Univ., Japan; H Kinoshita; Dept. of Phys., Osaka Univ., Japan; Y Nagai; Dept. of Phys., Osaka Univ., Japan; T Shibata; Dept. of Phys., Osaka Univ., Japan
Журнал:
Journal of Physics G: Nuclear and Particle Physics
Дата:
1991-12-01
Аннотация:
The normal double beta decay with two neutrinos (2 nu beta beta ) has been studied for <sup>100</sup>Mo in order to study experimentally the 2 nu beta beta nuclear matrix element (M<sub>2 nu </sub>). 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. <sup>nat</sup>Mo and 94% enriched <sup>100</sup>Mo 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)*10<sup>18</sup> years at the 68(90)% confidence level. The present experiment suggests a finite 2 nu half-life of the order of 10<sup>19</sup> years. However, it is necessary to estimate the contribution from contamination in the <sup>100</sup>Mo disks by a Monte Carlo calculation.
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