Characterization of photodetector temporal response for neutron time-of-flight (nToF) diagnostics at the National Ignition Facility

Journal Article · 01 October 2018 · Review of Scientific Instruments

DOI: https://doi.org/10.1063/1.5039390 · OSTI ID:1545518

Gordon, J. M. ^[1]; Schlossberg, D. J.  ^[2]; Eckart, M. J. ^[2]; Datte, P. S. ^[2]; Durand, C. E. ^[2]; Grim, G. P. ^[2]; Hartouni, E. P.  ^[2]; Hatarik, R. ^[2]; Moore, A. S. ^[2]

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1. Univ. of California, Berkeley, CA (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

The temporal response of a microchannel plate photomultiplier tube used in the suite of neutron time of flight (nToF) diagnostics at the National Ignition Facility has been characterized to reduce uncertainty in, and understanding of, shot parameters obtained from nTOF data. A short singular pulse laser, neutral density glass filters, and electrical attenuators were used to gather statistically significant samples of photodetector impulse response functions (IRF) in rapid succession. Individual components have been absolutely calibrated to minimize systematic uncertainties. The zeroth (collected charge), first (transit time), and second central moments (transit time spread) of the IRF were calculated as either the bias voltage or the amount of light incident on the detector was varied. Timing reference was provided by a monitor photodiode viewing a pickoff of the incident laser pulse. The primary sources of uncertainty are jitter in the monitor photodiode and the statistical variation across our measurement period. The spreads in the first moment, with respect to the timing photodiode, and the square root of the second central moment were found to be less than 50 ps and 150 ps, respectively.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); USDOE
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1545518
• Alternate ID(s): OSTI ID: 1477527
• Journal Information: Review of Scientific Instruments, Vol. 89, Issue 10; ISSN 0034-6748
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English