Background reduction by position reconstruction for CANDLES III

CANDLES is the project to search for double beta decay of 48Ca. We use CaF2 crystals as 48Ca sources and scintillation detectors. They are immersed in liquid scintillator. Signals that fire liquid scintillator are backgrounds. Their rejection is achieved by employing pulse shape difference of signals from the CaF2 scintillator and liquid scintillator. In addition to that position resolution helps further to reduce backgrounds. We employed the least squares method to give position of each crystal. We will report the background reduction with a help of position information.