Development of a low-alpha-emitting µ-PIC for NEWAGE direction-sensitive dark-matter search

NEWAGE is a direction-sensitive dark-matter-search experiment that uses a micro-patterned gaseous detector, or µ-PIC, as the readout. The main background sources are α-rays from radioactive contaminantsin the µ-PIC. We have therefore developed a low-alpha-emitting µ-PICs and measured its performances. We measured the surface α-ray emission rate of the µ-PIC in the Kamioka mine using a surface α-ray counter based on a micro TPC.