Straw-based Portal Monitor

摘要

He-based NDM in current installations. Multiple (up to 95) BCS detectors are distributed in an array, within a high-density polyethylene moderator block. Each BCS detector is 4.43 mm in diameter, 200 cm long, and individually sealed inside an aluminum tube just large enough to contain the thin walled straw. Straws are organized into 5 rows at different depths within the moderator. The response of five production NDM units to a neutron and gamma source are presented, together with environmental testing aimed to simulate operating conditions encountered in typical RPM applications. The mean neutron absolute efficiency measured at 2 m among 4 units was 3.55α0.06 cps/ng for a moderated