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Title: Omega Neutron Bang Time Diagnostic Calibrations July 2007.


Abstract not provided.

Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the GC LDRD Workshop held January 23-25, 2007 in Livermore, CA.
Country of Publication:
United States

Citation Formats

Chandler, Gordon Andrew. Omega Neutron Bang Time Diagnostic Calibrations July 2007.. United States: N. p., 2007. Web.
Chandler, Gordon Andrew. Omega Neutron Bang Time Diagnostic Calibrations July 2007.. United States.
Chandler, Gordon Andrew. Mon . "Omega Neutron Bang Time Diagnostic Calibrations July 2007.". United States. doi:.
title = {Omega Neutron Bang Time Diagnostic Calibrations July 2007.},
author = {Chandler, Gordon Andrew},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}

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  • The time interval between the beginning of the laser pulse and the peak of neutron emission (bang time) is an important characteristic of inertial confinement fusion (ICF) implosions, directly comparable to numerical simulation. For this reason, neutron bang time (NBT) detectors have been successfully operated on ICF facilities such as the Nova and OMEGA lasers, and have been proposed as a core diagnostic for the Natinal Ignition Facility (NIF). Prototypes of the NBT detector suitable for the NIF have been built and tested on the 60-beam OMEGA laser system.
  • A simple, low-cost, high-yield neutron bang time (HYNBT) detector has been developed and implemented on the 60-beam, 30 kJ OMEGA Laser Facility at the University of Rochester's Laboratory for Laser Energetics. The HYNBT consists of three chemical-vapor deposition diamond detectors of different sizes and sensitivities placed in a lead-shielded housing. The HYNBT is located in a reentrant tube 50 cm from the center of the target chamber. The HYNBT has been temporally cross calibrated against the streak-camera-based neutron temporal diagnostic (NTD) for both D2 and DT implosions. The HYNBT has an internal time resolution better than 20 ps and ismore » able to measure bang time for yields above 10^10 for DT and 5 x 10^10 for D2 implosions. The implementation of the HYNBT on the National Ignition Facility will be discussed.« less
  • The time of peak fusion reactivity with respect to the impingement of laser light on an ICF capsule is known as Bang Time (BT). This is an essential parameter in the understanding of ICF implosions. Traditionally, BT has been determined through temporal measurements of 14 MeV fusion neutrons. Because the neutron energy spectrum is Doppler broadened, the detector must be positioned close to target-chamber center in order to minimize the neutron temporal spreading which can compromise such a measurement. Fusion gammas, on the other hand, are not subject to temporal spreading, making proximity of the detector to the source amore » lesser concern. However, the low branching ratio for DT fusion reactions producing gammas ({approx}1e-4) presents detector sensitivity challenges.« less
  • The particle-time-of-flight (pTOF) diagnostic, fielded alongside a Wedge Range-Filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted {rho}R measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT-Exploding Pusher and D{sup 3}He implosions using DD or DT neutrons with an accuracy better than {+-}70 ps. In the second phase of the project, a deflecting magnet will be incorporated into the pTOF design for simultaneous measurements of shock- and compression-bang times in D{sup 3}He-filled surrogatemore » implosions using D{sup 3}He protons and DD-neutrons, respectively.« less
  • The south pole bang-time (SPBT) diagnostic views National Ignition Facility (NIF) implosions through the lower hohlraum laser entrance hole to measure the time of peak x-ray emission (peak compression) in indirect drive implosions. Five chemical-vapor-deposition (CVD) diamond photoconductive detectors (PCD's) with different filtrations and sensitivities record the time-varying x rays emitted by the target. Wavelength-selecting highly oriented pyrolytic graphite (HOPG) crystal mirror monochromators increase the x-ray signal-to-background ratio by filtering for 11-keV emission. Diagnostic timing and the in-situ temporal instrument response function are determined from laser impulse shots on the NIF. After signal deconvolution and background removal, the bang timemore » is determined to 45-ps accuracy. The x-ray 'yield' (mJ/sr/keV at 11 keV) is determined from the total area under the peak.« less