A double-helix neutron detector using micron-size 10B powder

A double-helix electrode configuration is combined with a 10B powder coating technique to build large-area (9 in × 36 in) neutron detectors. The neutron detection efficiency for each of the four prototypes is comparable to a single 2-bar 3He drift tube of the same length (36 in). One unit has been operational continuously for 18 months and the change of efficiency is less than 1%. An analytic model for pulse heigh spectra is described and the predicted mean film thickness agrees with the experiment to within 30%. Further detector optimization is possible through film texture, power size, moderator box and gas. The estimated production cost per unit is less than 3k US $ and the technology is thus suitable for deployment in large numbers