Linear accelerator x-ray sources with high duty cycle

Journal Article · Fri Apr 19 00:00:00 EDT 2013 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4802418· OSTI ID:22117033

Condron, Cathie; Brown, Craig; Gozani, Tsahi; Langeveld, Willem G. J. ^[1]; Hernandez, Michael ^[2]

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1. Rapiscan Laboratories, Inc., 520 Almanor Ave. Sunnyvale, CA 94085 (United States)
2. XScell corp., 2134 Old Middlefield Way, Mountain View, CA 94043 (United States)

X-ray cargo inspection systems typically use a several-MV pulsed linear accelerator (linac) to produce a bremsstrahlung spectrum of x rays by bombarding a target with electrons. The x rays traverse the cargo and are detected by a detector array. Spectroscopy of the detected x rays is very desirable: if one can determine the spectrum of the transmitted x rays, one can determine the Z of the material they traversed. Even in relatively low-dose modes of operation, thousands of x rays arrive at each detector element during each pulse, unless the x rays are heavily absorbed or scattered by the cargo. For portal or fixed-site systems, dose rates, and therefore x-ray count rates, are even higher. Because of the high x-ray count rate, spectroscopy is impractical in conventional cargo inspection systems, except in certain special cases. For a mobile system, typical pulse durations are a few microseconds, and the number of pulses is on the order of 100 per second, leading to a duty factor of about 0.04%. Clearly, a linear accelerator x-ray source with much higher duty factor would be useful, since then the same number of x rays could be spread out over time, reducing the x-ray count rate. In this paper, we explore the possibility of designing a linear accelerator system, using more or less Conventional Off the Shelf (COTS) components, capable of duty cycles of 1% or greater. A survey was conducted of available linac RF source options and, given the possibilities, calculations were performed for suitable beam centerline designs. Keeping in mind that the size and cost of the accelerator system should be practical for use in a mobile cargo inspection system, only a few options are shown to be reasonably feasible, both requiring the use of klystrons instead of the magnetrons used in conventional systems. An S-Band design appears clearly possible, and there is also a promising X-Band design.

• OSTI ID: 22117033
• Journal Information: AIP Conference Proceedings, Vol. 1525, Issue 1; Conference: 22. international conference on application of accelerators in research and industry, Ft. Worth, TX (United States), 5-10 Aug 2012; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BEAM PRODUCTION
BREMSSTRAHLUNG
CARGO
COUNTING RATES
DESIGN
DOSE RATES
ELECTRONS
EMISSION SPECTRA
INSPECTION
KLYSTRONS
LINEAR ACCELERATORS
MAGNETRONS
OPERATION
PHOTON BEAMS
RF SYSTEMS
X RADIATION
X-RAY SOURCES
X-RAY SPECTROSCOPY