Project of detecting Xe-136 daughter nuclei due to double beta decay by resonance ionization spectroscopy

There are three decay modes in the double beta decay of atomic nuclei which is one of rare decay phenomena. The research on double beta decay has been advanced energetically in various places of the world in the last 10 years theoretically and experimentally as the knowledge on neutrinos can be obtained. As for the method of measuring double beta decay, there are the real time measuring method that measures the energy of two electrons or their sum, the geochemical method that quantitatively determines the candidate nuclei of double beta decay and the decay daughter nuclei contained in minerals, the age of which is known, and the method of accumulating and measuring decay daughter nuclei in laboratories. At present, the authors advance the project of measuring the double beta decay of 136Xe in the order of the development of liquid Xe drift ionization chamber, the development of decay daughter nucleus collecting device and resonance ionization mass analyzer using liquid Xe and the identification of decay daughter nuclei within the detector. In this report, the plan and the present status of the second step are described. There are mine isotopes in natural Xe, and 134Xe and 136Xe are the candidates of double beta decay. The utilization of liquid Xe, the cation collector and the collection efficiency, the resonance ionization spectroscopy time of flight mass analyzer, the collection and detection efficiency and the half life and the efficiency of double beta decay are described. (K.I.)