Efficiency of Boric acid coated semiconductor neutron detector - A GEANT4 simulation study

In the present studies, GEANT4 simulation based on Monte Carlo technique has been performed to optimize the thickness of boric acid (H
₃
BO
₃
) as a converter material in a semiconductor neutron detector, to achieve maximum detection efficiency for thermal energy neutrons. The construction of the detector is in planar configuration with boric acid as an over layer on top of Si surface, which acts as the detecting medium. Simulation was also carried out for different enrichment of
¹⁰
B content in boric acid. The results showed that a maximum detection efficiency of 0.73% was obtained for converter layer thickness of 5 μm with 100% enrichment of
¹⁰
B. The histograms depicting the energy deposited in Si by the generated charge particles upon neutron interaction with boron, revealed two distinct and discernable peaks corresponding to 0.839 MeV for
⁷
Li ion and 1.47 MeV for α ion, only for thicknesses less than 100 nm. An experimental attempt has also been made to coat the boric acid as converter material on silicon PIN diode and preliminary neutron sensitivity measurements carried out using nuclear electronics is also reported.