Modeling the National Ignition Facility neutron imaging system

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3496993· OSTI ID:22055773

Wilson, D C; Grim, G P; Tregillis, I L; Wilke, M D; Morgan, G L; Loomis, E N; Wilde, C H; Oertel, J A; Fatherley, V E; Clark, D D; Schmitt, M J; Merrill, F E; Wang, T.-S. F.; Danly, C R; Batha, S H ^[1]; Patel, M V; Sepke, S M; Hatarik, R; Fittinghoff, D N; Bower, D E ^[2] ; others, and

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1. Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)
2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

Numerical modeling of the neutron imaging system for the National Ignition Facility (NIF), forward from calculated target neutron emission to a camera image, will guide both the reduction of data and the future development of the system. Located 28 m from target chamber center, the system can produce two images at different neutron energies by gating on neutron arrival time. The brighter image, using neutrons near 14 MeV, reflects the size and symmetry of the implosion ''hot spot.'' A second image in scattered neutrons, 10-12 MeV, reflects the size and symmetry of colder, denser fuel, but with only {approx}1%-7% of the neutrons. A misalignment of the pinhole assembly up to {+-}175 {mu}m is covered by a set of 37 subapertures with different pointings. The model includes the variability of the pinhole point spread function across the field of view. Omega experiments provided absolute calibration, scintillator spatial broadening, and the level of residual light in the down-scattered image from the primary neutrons. Application of the model to light decay measurements of EJ399, BC422, BCF99-55, Xylene, DPAC-30, and Liquid A suggests that DPAC-30 and Liquid A would be preferred over the BCF99-55 scintillator chosen for the first NIF system, if they could be fabricated into detectors with sufficient resolution.

• OSTI ID: 22055773
• Journal Information: Review of Scientific Instruments, Vol. 81, Issue 10; Other Information: (c) 2010 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CALIBRATION
CAMERAS
HOT SPOTS
IMAGES
IMPLOSIONS
LIQUIDS
MEV RANGE
NEUTRON DETECTION
NEUTRON EMISSION
NEUTRONS
PLASMA
RESOLUTION
SCINTILLATION COUNTERS
SIMULATION
TARGET CHAMBERS
US NATIONAL IGNITION FACILITY
VISIBLE RADIATION
XYLENES