A neutron detector comprises a gas-filled dielectric shell, preferably a glass balloon, having opposite electrodes. An electric field is established whereby ionizing particles may be detected via ionization and current flow in the gas, using a pulse height analyzer or other conventional means. The dielectric shell preferably has low gas permeability and a bulk resistivity in the range of 10.sup.8 to 10.sup.17 .OMEGA.-m, and is preferably in the millimeter to centimeter size range. Multiple balloons may be arranged in parallel or may be individually addressable by the detector electronics.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
 The United States Government has rights in this invention pursuant to contract No. DE-AC05-00OR22725 between the United States Department of Energy and UT-Battelle, LLC. and Agreement No. HSHQPA-05-9-00047 awarded by the U.S. Department of Homeland Security to Material Innovations, Inc.