Paper
26 September 2013 Compact low-noise preamplifier for noise spectroscopy with biased photodiodes in cargo inspection systems
Bob Benetti, Willem G. J. Langeveld
Author Affiliations +
Abstract
Noise Spectroscopy, a.k.a. Z-determination by Statistical Count-rate ANalysis (Z-SCAN), is a statistical technique to determine a quantity called the “noise figure” from digitized waveforms of pulses of transmitted x-rays in cargo inspection systems. Depending only on quantities related to the x-ray energies, it measures a characteristic of the transmitted x-ray spectrum, which depends on the atomic number, Z, of the material penetrated. The noise figure can thus be used for material separation. In an 80-detector prototype, scintillators are used with large-area photodiodes biased at 80V and digitized using 50-MSPS 12-bit ADC boards. We present an ultra-compact low-noise preamplifier design, with one high-gain and one low-gain channel per detector for improved dynamic range. To achieve adequate detection sensitivity and spatial resolution each dual-gain preamplifier channel must fit within a 12.7 mm wide circuit board footprint and maintain adequate noise immunity to conducted and radiated interference from adjacent channels. The novel design included iterative SPICE analysis of transient response, dynamic range, frequency response, and noise analysis to optimize the selection and configuration of amplifiers and filter response. We discuss low-noise active and passive components and low-noise techniques for circuit board layout that are essential to achieving the design goals, and how the completed circuit board performed in comparison to the predicted responses.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bob Benetti and Willem G. J. Langeveld "Compact low-noise preamplifier for noise spectroscopy with biased photodiodes in cargo inspection systems", Proc. SPIE 8852, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XV, 88520G (26 September 2013); https://doi.org/10.1117/12.2027651
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CITATIONS
Cited by 3 scholarly publications.
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KEYWORDS
Amplifiers

Capacitors

Photodiodes

Electromagnetic coupling

Digital filtering

Interference (communication)

Sensors

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