ABSTRACT: To measure the flux of atmospheric neutrons and study the neutron contribution to the background of the main detector of the PoGOLite (Polarized Gamma-ray Observer) balloon-borne experiment, a thermal-neutron detector with a phoswich system of LiCaAlF<sub>6</sub> (Eu) and BGO crystal scintillators is developed. The performance to separate thermal-neutron events from those of gamma-rays and charged particles is validated with <sup>252</sup>Cf on ground. The detector is attached to the PoGOLite instrument and is launched in 2011 from the Esrange facility in the North of Sweden. Although the emission wavelength of the LiCaAlF<sub>6</sub> (Ce) is ~ 300 nm and overlaps with the absorption wavelength of the BGO, the phoswich capability of the LiCaAlF<sub>6</sub> (Ce) with the BGO is also confirmed with installing a waveform shifter.
Nuclear Science Symposium Conference Record (NSS/MIC), 2010 IEEE; 12/2010