Abstract
The high neutron detection efficiency, good gamma-ray discrimination and non-toxicity of (3)He made of proportional counters filled with this gas the obvious choice for neutron detection, particularly in radiation portal monitors (RPM), used to control the illicit transport of nuclear material, of which neutron detectors are key components. (3)He is very rare and during the last decade this gas has become increasingly difficult to acquire. With the exception of BF(3), which is toxic, no other gas can be used for neutron detection in proportional counters. We present an alternative where the (3)He atoms are replaced by nanoparticles made of another neutron sensitive material, (10)B. The particles are dispersed in a gaseous volume, forming an aerosol with neutron sensitive properties. A proportional counter filled with such aerosol was exposed to a thermal neutron beam and the recorded response indicates that the neutrons have interacted with the particles in the aerosol. This original technique, which transforms a standard proportional gas mixture into a neutron sensitive aerosol, is a breakthrough in the field of radiation detection and has the potential to become an alternative to the use of (3)He in proportional counters.