Low energy electron behavior in double beta decay experiment

(1) NEMO 3合作项目正在Frejus地下实验室（LSM, Laboratoire Souterrain de Modane）寻找无中微子双β衰变，以研究亚ev区域的马约拉纳中微子质量。(2) NEMO 3探测器运行2年后，氡被认为是实验最严重的背景源。我们研制的高灵敏度氡探测器和研制的氡自由制气系统，为NEMO 3号实验的最终目标的实现起到了有效的作用。(3) 2 ν β β β的标准双β衰变数据的统计量已达到10^6个事件的数量级，其量比以往的典型测量值高出3个数量级。现在我们可以非常精确地研究我们的实验和标准理论之间的差异（如果有的话）。通过实验了解低能电子的行为（如高阶轫致或摩尔散射等）对于研究这种差异是非常重要的。紧张的研究正在进行中。(4)在2 ν β β附近，同时进行了^<100>Mo, ^<116>Cd, ^<15>Nd, ^<96>Zr, ^<48>Ca几个原子核的测量。在某些核的分析中，了解电子的低能量行为对消除背景事件是非常重要的，特别是在^<48>Ca中消除^<90>Sr背景源的Mollor散射。

(1) The NEMO 3 Collaboration is looking for neutrinoless double beta decays to investigate Majorana neutrino mass in the sub-eV region at the Frejus underground laboratory (LSM, Laboratoire Souterrain de Modane).(2) After two years running of the NEMO 3 detector, radon was fond to be the most serious origins of background of the experiment. Our contributions of the high sensitive radon detectors, and developing radon free air making system, have been effective to achieve the final goal of the NEMO 3 experiment.(3) Already the statistics of the standard double beta decay of 2 ν β β data is in the order of 10^6 events, and the amount is three order of the magnitude higher than the typical previous measurements. Now we can study very precisely the difference (if we have) between our experiment and standard theories. It is very important to understand low energy electron behavior (for example, higher order bremsstrahlung or Mollor scattering etc.) experimentally for the study of the difference. The intense study is now going on.(4) About 2 ν β β, the measurements of several nuclei, ^<100>Mo, ^<116>Cd, ^<15>Nd, ^<96>Zr, ^<48>Ca are going on at the same time. In the analysis of some nuclei, it have been very important to understand the lower energy behavior of the electron to remove background events, especially in ^<48>Ca to remove Mollor scattering from ^<90>Sr background source.