Enhanced variant designs and characteristics of the microstructured solid-state neutron detector

High-efficiency microstructured semiconductor neutron detectors for direct 3He replacement

“…Semiconductor with a thin-film coating of neutron reactive material deposited on a planar rectifying diode have been investigated for the past few decades as a potential neutron detector technology while maintaining high gamma-ray rejection characteristics [1][2][3]. MSNDs were developed as a means of increasing the relatively low efficiency of the planar thin-film-coated devices (typicallyo4-5% intrinsic) up to their theoretical maximums above 40% intrinsic detection efficiency for single 0.5-mm thick devices [4][5][6][7][8][9][10][11][12][13][14][15][16] while maintaining gamma-ray rejection ratios (GRR) of 10 À 6 or better [12]. The increase in intrinsic neutron detection efficiency stems from the two primary benefits of perforating a semiconductor diode; increased neutron absorption and increased probability of interaction of the charged neutron reaction products in the semiconductor diode.…”

Present status of microstructured semiconductor neutron detectors

“…Wet etching results reported by the authors and their colleagues show significant improvement over dry etch methods with aspect ratios greater than 1:23 [59,61,62]. The method allows for straightforward batch processing at low cost, with etch rates exceeding 1.5 µm per minute in Si.…”

“…(17)) and superior definition in the pulse height spectra [51,53,60,62,63]. As pointed out in the literature, the drawback to the conformal diffusion method is that the electric field inside the semiconductor material forming the microstructures is reduced, thereby, reducing charge carrier velocities [59,62]. Hence, the integration time on the electronics must be increased in order to collect the ioninduced charges [59,62].…”

Semiconductor neutron detectors

“…The two materials that are commonly used as a converter are 10 B and 6 Li, featuring a relative high cross section of 3840 barn and 940 barn, respectively. The Boron reaction with neutron is the following: 10 B + n 94% −→ α(1.47MeV ) + 7 Li(0.84MeV ) + γ(0.48MeV ) 6% −→ α(1.78MeV ) + 7 Li(1.01MeV ) When a thermal neutron is absorbed the most probable reaction will produce 7 Li at 0.84 MeV in its first excited state that rapidly decades to the ground state releasing 480 keV gamma and alpha at 1.47 MeV. The other possibility is the release of 7 Li at the ground state with an energy of 1.01 MeV and an alpha particle at 1.78 MeV, the two different particles being released in opposition directions.…”

“…Moreover, the deposition techniques of converter materials should be optimized to ensure conformal filling of small cavities and good stability. Figure 1 resumes the main geometries proposed using 6 Li based neutron converter by Kansas State University (USA) [7][8][9] [10]. The best efficiency obtained by perforated neutron detector filled by 6 Li was of 29% at 10 V [11].…”