Neutrino mass study using 100Mo double beta decay with spectroscopic detector MOON

我们已经为下一代双β衰变实验开发了探测器月球-1的原型。探测器安装在大阪大学核物理研究中心Ohto地下实验室。月球一号由六层塑料闪烁板(53厘米见方)和100Mo箔组成，闪烁板交织在一起。闪光是由60个围绕着平板的光电倍增器收集的。2003年：试验测量2004年：月球一号探测器的设计和研制2005年：安装在地下实验室并开始测量。2006年：继续测量。月球一号在秋季被卸载。2007年：THST测量。建立了低本底环境下的定标方法。能量分辨率使用背景伽马射线的康普顿散射进行评估。能量分辨率是探测器无中微子双β衰变灵敏度的关键。这是休息月球-1号探测器最重要的点之一。在双β衰变的Q值时，得到的分辨率为7%(半高宽)。对于这么大(53厘米见方)的塑料闪烁板来说，这是相当好的分辨率。研究了研制下一代双β衰变探测器的背景。

We have developed prototype detector MOON-1 for the next generation double beta decay experiment. The detector is installed at Ohto underground laboratory, Research Center for Nuclear Physics, Osaka University. MOON-1 is six layers of plastic scintillator plates (53cm square) and 100Mo foils interleaved by the scintillator plates. Scintillation light is collected by 60 photo multipliers surrounding the plates. The developments and the measurements were proceeded as the followings.2003: Test measurements2004: Design and development of the MOON-1 detector2005: Install in the underground laboratory and start the measurements.2006: Continue the measurements. MOON-1 was uninstalled in the autumn.2007: Thst measurements.Calibration method in the low background environment is developed. Energy resolution is evaluated using Compton scattering of background gamma rays. Energy resolution is a key in the detector sensitivity for neutrino-less double beta decay. It is one of the most important points to rest MOON-1 detector. The resolution obtained is 7%(FWHM) at the Q value of the double beta decay. It is quite good resolution for such large (53cm square) plastic scintillator plates. The background is studied for developing the next generation double beta decay detectors.