title: Absolute calibration method for laser megajoule neutron yield measurement by activation diagnostics.
abstract: The laser megajoule (LMJ) and the National Ignition Facility (NIF) plan to demonstrate thermonuclear ignition using inertial confinement fusion (ICF). The neutron yield is one of the most important parameters to characterize ICF experiment performance. For decades, the activation diagnostic was chosen as a reference at ICF facilities and is now planned to be the first nuclear diagnostic on LMJ, measuring both 2.45 MeV and 14.1 MeV neutron yields. Challenges for the activation diagnostic development are absolute calibration, accuracy, range requirement, and harsh environment. At this time, copper and zirconium material are identified for 14.1 MeV neutron yield measurement and indium material for 2.45 MeV neutrons. A series of calibrations were performed at Commissariat à l'Energie Atomique (CEA) on a Van de Graff facility to determine activation diagnostics efficiencies and to compare them with results from calculations. The CEA copper activation diagnostic was tested on the OMEGA facility during DT implosion. Experiments showed that CEA and Laboratory for Laser Energetics (LLE) diagnostics agree to better than 1% on the neutron yield measurement, with an independent calibration for each system. Also, experimental sensitivities are in good agreement with simulations and allow us to scale activation diagnostics for the LMJ measurement range.
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France. olivier.landoas@cea.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Landoas
authors.forename: Vladimir Yu
authors.initials: VY
authors.lastname: Glebov
authors.forename: Bertrand
authors.initials: B
authors.lastname: Rossé
authors.forename: Michelle
authors.initials: M
authors.lastname: Briat
authors.forename: Laurent
authors.initials: L
authors.lastname: Disdier
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Sangster
authors.forename: Tim
authors.initials: T
authors.lastname: Duffy
authors.forename: Jean Gabriel
authors.initials: JG
authors.lastname: Marmouget
authors.forename: Cyril
authors.initials: C
authors.lastname: Varignon
authors.forename: Xavier
authors.initials: X
authors.lastname: Ledoux
authors.forename: Tony
authors.initials: T
authors.lastname: Caillaud
authors.forename: Isabelle
authors.initials: I
authors.lastname: Thfoin
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Bourgade