From Event: SPIE Optical Engineering + Applications, 2017
The National Ignition Facility (NIF) is one of the highest fluence neutron sources provided by the nuclear fusion of deuterium and tritium nuclei. One of the resultant products is 14.1 MeV neutrons which provide key information to the conditions in which they were formed. The degree of polar and azimuthal symmetry of the neutron flux is a key metric for the performance of the capsule, thus a spatially-resolved measurement of the neutron distribution is critical. Implementing a suite of 48 lanthanum bromide detectors with zirconium activation samples around the target chamber has been developed to measure the neutron distribution. The system provides near real-time time estimates of the neutron fluence distribution. It is designed to operate over six orders of magnitude of neutron yield, providing overall yield estimates precise to 2%. The system is designed to operate continuously through the NIF shot cycles, accommodating high data rates. We will describe the nuclear counting system, data acquisition and archiving, analysis, and yield distribution results for some NIF high yield shots. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-CONF-736439
Jaben R. Root, Donald R. Jedlovec, Ellen R. Edwards, Charles B. Yeamans, Tony Golod, Jose Hernandez, Phil Adams, and Gordon Brunton, "Development of the real-time neutron activation diagnostic system for NIF," Proc. SPIE 10390, Target Diagnostics Physics and Engineering for Inertial Confinement Fusion VI, 103900J (Presented at SPIE Optical Engineering + Applications: August 09, 2017; Published: 26 September 2017); https://doi.org/10.1117/12.2274343.
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