title: Gamma ray imager on the DIII-D tokamak.
abstract: A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1-60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Pace
authors.affiliation: Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Cooper
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: D
authors.initials: D
authors.lastname: Taussig
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: N W
authors.initials: NW
authors.lastname: Eidietis
authors.affiliation: University of California-San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Hollmann
authors.affiliation: State University of New York-Buffalo, 12 Capen Hall, Buffalo, New York 14260-1660, USA.
authors.forename: V
authors.initials: V
authors.lastname: Riso
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Van Zeeland
authors.affiliation: General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
authors.forename: M
authors.initials: M
authors.lastname: Watkins