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Proceedings Paper

Development of a portable thermal neutron detector based on a boron rich heterodiode
Author(s): R. Tomov; R. Venn; A. Owens; A. Peacock
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Paper Abstract

Results are presented on the development of a portable detector suitable for detection of individual thermal neutrons. The device is based on direct absorption of neutrons in an absorber film containing 10B. The resultant charge arising from the capture products is detected by a p-n junction partly formed from this absorber and internal to the device. When a small bias voltage is applied (typically a few volts) a current pulse is observed due to the movement of this charge in the electric field of the p-n junction. For each detected neutron the charge pulse height, rise time and time of detection are recorded. Device performance, in terms of efficiency and spectral response, is explored as a function of neutron absorber thickness, geometry and overall diode electrical characteristics and validated against neutron source measurements at the UK National Physical Laboratory (NPL). The diodes have a natural background suppression capability through traditional pulse height and pulse rise time discrimination. The manufacturing process permits fabrication of arrays of diodes, with typical areas of ~15 mm2, thus increasing the collecting area and the signal to noise ratio, albeit with increased readout complexity. The associated multi-channel readout electronics is standard, however, and commonly used in existing X-ray sensors. Simple portable sensors based on these heterodiodes are expected to have applications in the detection of nuclear materials in a variety of security related situations.

Paper Details

Date Published: 3 October 2008
PDF: 9 pages
Proc. SPIE 7119, Optics and Photonics for Counterterrorism and Crime Fighting IV, 71190H (3 October 2008); doi: 10.1117/12.800668
Show Author Affiliations
R. Tomov, Cambridge Microfab Ltd. (United Kingdom)
R. Venn, Cambridge Microfab Ltd. (United Kingdom)
A. Owens, ESA/ESTEC (Netherlands)
A. Peacock, ESA/ESTEC (Netherlands)

Published in SPIE Proceedings Vol. 7119:
Optics and Photonics for Counterterrorism and Crime Fighting IV
Gari Owen, Editor(s)

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