International Conference on Mathematics, Computational Methods & Reactor Physics (M&C 2009) Saratoga Springs, New York, May 3-7, 2009, on CD-ROM, American Nuclear Society, LaGrange Park, IL (2009) OPTIMIZATION OF A NOVEL SOLID-STATE SELF POWERED NEUTRON DETECTOR Justin Dingley a , Yaron Danon a , Nicholas LiCausi b , Jian-Qiang Lu b and Ishwara B. Bhat b a Department of Mechanical, Aerospace and Nuclear Engineering, b Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute 110 8 th St Troy, NY 12180 dinglj@rpi.edu ABSTRACT Analytical and Monte Carlo calculations were performed to optimize a novel self-powered solid-state neutron detector. New manufacturing techniques, allowing for micron and sub-micron structures, along with the ability to efficiently collect the electron-hole pairs created in the detector, have resulted in improved theoretical thermal neutron detection efficiencies. Four differing configurations were examined, including a parallel-trench design, a pillar-type design, and two etched hole-type designs (square and hexagonal). First order analytical calculations provided initial parameter values for Monte Carlo simulations. Simulation results show the following maximum efficiencies: 40 percent efficiency for the pillar-type device, 43 percent for the parallel trench, 47 percent for the square hole device, and 48 percent for the hexagonal hole design. Key Words: neutron, detection, optimization, solid-state 1. INTRODUCTION Solid-state devices have been investigated for neutron detection numerous times over the years [1-6]. Although the specific configurations have changed, such as using several thin reactive films for thermal neutron detection, the inclusion of a hydrogenous material to detect fast neutrons via recoiled protons, or a combination of these two, all of these designs have suffered from extremely low (3-5%) detection efficiencies. Attempts to improve efficiency, including the utilization of a sandwich configuration, via-holes, and parallel trench designs, have met with limited success [7]. New manufacturing techniques [8] have enabled the creation of micron and sub-micron structures in silicon, with continuous, fully depleted solar-cell type p-n junctions throughout these structures. This results in increased electron-hole pair collection, allowing for the fabrication of higher efficiency detectors then were previously possible. To take full advantage of these advances, such a detector requires identification of parameters affecting efficiency and the optimization of these parameters. In this work it was decided to focus on the detection of thermal neutrons. As neutrons themselves would not interact appreciably with the silicon, a conversion material is required; absorption of the low energy neutrons produces charged particles, which can subsequently be detected. 10 B was chosen as the conversion material due to an extremely high thermal absorption cross section (3980 barns). Four basic designs were chosen for optimization: a parallel-trench design, in which trenches are etched into the silicon and filled with a neutron converter, a pillar type design, where most of the silicon has been etched away leaving pillars that are then surrounded by the converter, and square or hexagonal holes that have been etched and filled with converter. First order analytical calculations provided initial parameters for the Monte Carlo