The laser Isotope separation (LIS) methods for the enrichment of 48Ca

Neutrino-less double beta decay measurement is a powerful tool to test the Majorana nature of neutrinos. Among the potential double beta decay nuclei, 48Ca has the largest Q value (4.3 MeV), we can expect the least background measurement. On the other hand, a smallness of natural abundance of 48Ca (~0.2%) requires an enrichment to increase the sensitivity to reach interesting regions (Inverted Hierarchy and Normal Hierarchy). We have been studying the laser isotope separation (LIS) methods for the enrichment of 48Ca, where a narrow band diode laser is used to excite the specific isotope in the calcium vapor beam. For the separation, two methods (deflection and ionization) are employed. In the deflection method, the 48Ca atoms are deflected by momentum transfers from laser photons by multiple absorption and emission. In the ionization method, an additional dye laser is used to ionize the excited 48Ca. In this paper, we will report the current status and future prospects of two methods of LIS for the enrichment of 48Ca.