The Dcba Experiment for Neutrinoless Double Beta Decay

A magnetic tracking detector called DCBA (Drift Chamber Beta-ray Analyzer) is proposed for double beta decay experiments. The DCBA project is divided into two stages: DCBA-I and -II. DCBA-I will be able to measure the half life of the two-neutrino double beta decay of 150Nd, though natural Nd is used as the decay source material. DCBA-II will make it possible to investigate the effective mass of the Majorana neutrino down to 0.5-0.1 eV, since it is expected to have the ability to measure the half-life limit up to 4 × 1024yr using enriched 150Nd. A fundamental strategy of the DCBA project and some details of DCBA-I are described.