Absolute calibration method for laser megajoule neutron yield measurement by activation diagnostics.

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.

[1]  C. Kapetanakos,et al.  Diagnostics for intense pulsed ion beams , 1977 .

[2]  J. M. Adams,et al.  A versatile pulse shape discriminator for charged particle separation and its application to fast neutron time-of-flight spectroscopy , 1978 .

[3]  H. J. Brede,et al.  The Braunschweig accelerator facility for fast neutron research: 1: Building design and accelerators , 1980 .

[4]  G. Cooper,et al.  Absolute calibration of a total yield indium activation detector for DD and DT neutrons , 1992 .

[5]  F. Bronson,et al.  Mathematical calibration of Ge detectors, and the instruments that use them , 1997 .

[6]  Samuel A. Letzring,et al.  Initial performance results of the OMEGA laser system , 1997 .

[7]  J. Lindl,et al.  Inertial Confinement Fusion: The Quest for Ignition and Energy Gain Using Indirect Drive , 1998 .

[8]  B. Young,et al.  VALIDATION OF IN SITU OBJECT COUNTING SYSTEM (ISOCS) MATHEMATICAL EFFICIENCY CALIBRATION SOFTWARE , 1999 .

[9]  Guy Schurtz,et al.  Evolution of the target design for the MJ laser , 1999 .

[10]  G. Cooper,et al.  The NIF Total Neutron Yield Diagnostic , 2000 .

[11]  Edward I. Moses,et al.  The National Ignition Facility: Status and Plans for the Experimental Program , 2003 .

[12]  F. D. Brooks,et al.  Quasi-monoenergetic neutron reference fields in the energy range from thermal to 200 MeV. , 2004 .

[13]  T. C. Sangster,et al.  Prototypes of National Ignition Facility neutron time-of-flight detectors tested on OMEGA , 2004 .

[14]  Michael J. Moran,et al.  PROTEX: A proton-recoil detector for inertial confinement fusion neutrons , 2005 .

[15]  David C. Eder,et al.  Development of Nuclear Diagnostics for the National Ignition Facility (invited) , 2006 .

[16]  Edward I. Moses.  Ignition and inertial confinement fusion at the National Ignition Facility , 2010 .

[17]  Charles Lion,et al.  The LMJ program: An overview , 2010 .