https://doi.org/10.1051/epjconf/20135913015
Measuring neutron yield and ρR anisotropies with activation foils at the National Ignition Facility
1 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
2 University of New Mexico, Albuquerque, NM 87131, USA
3 Sandia National Laboratory, Albuquerque, NM 87185, USA
a e-mail: bleuel1@llnl.gov
Published online: 15 November 2013
Neutron yields at the National Ignition Facility (NIF) are measured with a suite of diagnostics, including activation of ∼20–200 g samples of materials undergoing a variety of energy-dependent neutron reactions. Indium samples were mounted on the end of a Diagnostic Instrument Manipulator (DIM), 25–50 cm from the implosion, to measure 2.45 MeV D-D fusion neutron yield. The 336.2 keV gamma rays from the 4.5 hour isomer of 115mIn produced by (n,n′) reactions are counted in high-purity germanium detectors. For capsules producing D-T fusion reactions, zirconium and copper are activated via (n,2n) reactions at various locations around the target chamber and bay, measuring the 14 MeV neutron yield to accuracies on order of 7%. By mounting zirconium samples on ports at nine locations around the NIF chamber, anisotropies in the primary neutron emission due to fuel areal density asymmetries can be measured to a relative precision of 3%.
© Owned by the authors, published by EDP Sciences, 2013
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
