Gamma Ray Measurements at OMEGA with the Newest Gas Cherenkov Detector "GCD-3"

• Published in: Journal of physics. Conference series 2016-05, Vol.717 (1), p.12109
• Main Authors: McEvoy, A M, Herrmann, H W, Kim, Y, Zylstra, A B, Young, C S, Fatherley, V E, Lopez, F E, Oertel, J A, Sedillo, T J, Archuleta, T N, Aragonez, R J, Malone, R M, Horsfield, C J, Rubery, M, Gales, S, Leatherland, A, Stoeffl, W, Johnson, M Gatu, Shmayda, W T, Batha, S H
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Cerenkov counters; Gamma rays; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; Physics; Precursors; Pressure vessels; Sensors; Shielding
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/717/1/012109

Initial results from the newest Gas Cherenkov Detector (GCD-3) are reported demonstrating improved performance over previous GCD iterations. Increased shielding and lengthening of the Cherenkov photon optical path have resulted in a diminished precursor signal with increased temporal separation between the precursor and the primary DT Cherenkov signal. Design changes resulted in a measured GCD-3 sensitivity comparable to GCD-1 at identical 100 psia CO2 operation. All metal gasket seals and pressure vessel certification to 400 psia operation allow for a GCD-3 lower Cherenkov threshold of 1.8 MeV using the fluorinated gas C2F6 as compared to the 6.3 MeV lower limit of GCD-1 and GCD-2. Calibration data will be used to benchmark GEANT4 and ACCEPT detector models. The GCD-3 acts as a prototype for the Super GCD being fielded at the National Ignition Facility (NIF) as part of the National Diagnostics Plan and will be installed at NIF in early 2016.