MEASUREMENT OF FAST NEUTRON FLUENCE BY SEMICONDUCTOR DETECTOR Russian patent published in 2015 - IPC G01T3/08 

FIELD: physics.

SUBSTANCE: this method comprises plotting of semiconductor detector current-voltage curve before and after irradiation. This detector represents a planar silicon detector of high-resistance single-crystal n- or p-conductance silicon with p-n junction and initial resistivity ρ > 1 kOhm×cm. Irradiation with fast neutron unknown fluence and determination of fast neutron unknown fluence via increment of detector volumetric thermal generation (dark) reverse current are effected owing to formation therein of radiation effects caused by fast neutrons. Fast neutron fluence is defined by the formula: $$Ф=\frac{\Delta I}{{\alpha }_I\times V},$$ where: Φ (cm^-2) is equivalent fluence with energy of 1 MeV, ΔI = (I₁-I₀) (A) is measured increment of detector volumetric thermal generation (dark) reverse current, I₀ is detector current before radiation at full depletion voltage reduced to temperature +20°C, I₁ is detector current after radiation at full depletion voltage reduced to temperature +20°C, α_I = (5±0.5)×10^-17 (A/cm) is current constant of silicon radiation damages for fast neutrons with energy of 1 MeV at +20°C without allowance for self-annealing, V = d×S (cm³) is detector volume ay full depletion voltage, d is detector depth (to be measured) (cm), S is detector active area (cm²) (p-n junction area known from detector topology).

EFFECT: expanded measurement range (10⁸-10¹⁶ cm^-2) at unknown spectrum, no calibration of detector.