Improving thermal-neutron detection efficiency of silicon neutron detectors using the combined layers of ~(10)B_4C on ~6LiF

摘要

We tested a layered structure of (B4C)-B-10 on (LiF)-Li-6 ((B4C)-B-10/(LiF)-Li-6) neutron converter for use with silicon neutron detectors. The combined layers effectively improve the efficiency of thermal-neutron detection over that of traditional single-layer converters. Silicon neutron detectors were constructed from a 2 cm x 2 cm silicon planar detector and coupled with removable neutron converters made from layers of (B4C)-B-10, (LiF)-Li-6, or (B4C)-B-10/(LiF)-Li-6 deposited on ceramics. The responses of these devices were tested with an Am-241-Li neutron source and the accompanying background gamma rays. The capability of the devices to discriminate neutron events from background gamma rays was tested by varying the bias voltages of the detectors when irradiated with an Am-241-Li neutron source and with Cs-137 or Co-60 gamma sources. The silicon neutron detector using the (B4C)-B-10/(LiF)-Li-6 converter of 1.2-mu m-thick (B4C)-B-10 and 21.1-mu m-thick (LiF)-Li-6 achieved the expected thermal-neutron detection efficiency of 5.6%. The compact size, simple construction, and low bias voltage of these devices make them promising for neutron detector applications like neutron dosimeters and beam monitors.