Lithium foil gas-filled neutron detector using microstrip electrodes

Abstract

Microstrip electrodes have been fabricated and combined with one and five suspended 6Li foils positioned within a pressurized, gas-filled chamber to create a suspended foil microstrip neutron detector. This new detector offers a mechanically and electrically robust alternative to multi-wire proportional counters. Incident neutrons are converted into charged-particle reaction products that ionize the backfill gas. Charge carriers produced from the ionization of the backfill gas drift toward their respectively-charged electrodes due to the influence of the electric field formed from the potential difference between the drift electrode and the microstrip electrode anode and cathode strips. Gas multiplication occurs as electrons approach the surface of the microstrip electrode resulting in an increase in signal amplitude. Suspended foil microstrip neutron detectors containing one and five suspended 6Li foils were simulated using MCNP6 and compared to experimental results. The measured count rates from a moderated 26-ng 252Cf source positioned 18 cm from microstrip neutron detectors equipped with one and five suspended 6Li foils were 3.25 ± 0.04 and 10.62 ± 0.14 counts per second, respectively. The intrinsic thermal neutron detection efficiency of each detector was 4.02 ± 0.04% and 14.58 ± 0.11% for one and five suspended 6Li foils, respectively.