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Title: A fused silica Cherenkov radiator for high precision time-of-flight measurement of DT γ and neutron spectra (invited)

Abstract

A fused silica Cherenkov radiator has been utilized at the National Ignition Facility to provide a new high precision measurement of the time-of-flight spectrum of 14.1 MeV DT fusion neutrons. This detector allows a high precision (<30 ps) co-registered measurement of both a thresholded γ-ray and a neutron spectrum on a single record. Other approaches typically require γ and neutron signals to be co-registered via other diagnostics and/or dedicated timing experiments. Analysis of the co-registered γ and neutron signals allows precise extraction of the mean neutron energy and bulk hot-spot velocity, both of which were not possible with prior scintillator technologies. Initial measurements demonstrate the feasibility of this measurement and indicate that combined detection of neutrons and γ-rays on multiple lines-of-sight should enable the bulk vector velocity of the implosion hot-spot to be determined to ≈5 km/s and reduced uncertainty in the spectral width ≈0.1 keV.

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2];  [2]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Atomic Weapons Establishment (AWE), Berkshire (United Kingdom)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); UK Ministry of Defence
OSTI Identifier:
1545509
Alternate Identifier(s):
OSTI ID: 1476838
Grant/Contract Number:  
AC52-07 nA273444
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 89; Journal Issue: 10; Conference: 22. Proceedings of the Topical Conference on High-Temperature Plasma Diagnostics, San Diego, CA (United States), Apr 2018; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Moore, Alastair S., Schlossberg, D. J., Hartouni, E. P., Sayre, D., Eckart, M. J., Hatarik, R., Barbosa, F., Root, J., Waltz, C., Beeman, B., Rubery, M. S., and Grim, G. P. A fused silica Cherenkov radiator for high precision time-of-flight measurement of DT γ and neutron spectra (invited). United States: N. p., 2018. Web. doi:10.1063/1.5039322.
Moore, Alastair S., Schlossberg, D. J., Hartouni, E. P., Sayre, D., Eckart, M. J., Hatarik, R., Barbosa, F., Root, J., Waltz, C., Beeman, B., Rubery, M. S., & Grim, G. P. A fused silica Cherenkov radiator for high precision time-of-flight measurement of DT γ and neutron spectra (invited). United States. https://doi.org/10.1063/1.5039322
Moore, Alastair S., Schlossberg, D. J., Hartouni, E. P., Sayre, D., Eckart, M. J., Hatarik, R., Barbosa, F., Root, J., Waltz, C., Beeman, B., Rubery, M. S., and Grim, G. P. Tue . "A fused silica Cherenkov radiator for high precision time-of-flight measurement of DT γ and neutron spectra (invited)". United States. https://doi.org/10.1063/1.5039322. https://www.osti.gov/servlets/purl/1545509.
@article{osti_1545509,
title = {A fused silica Cherenkov radiator for high precision time-of-flight measurement of DT γ and neutron spectra (invited)},
author = {Moore, Alastair S. and Schlossberg, D. J. and Hartouni, E. P. and Sayre, D. and Eckart, M. J. and Hatarik, R. and Barbosa, F. and Root, J. and Waltz, C. and Beeman, B. and Rubery, M. S. and Grim, G. P.},
abstractNote = {A fused silica Cherenkov radiator has been utilized at the National Ignition Facility to provide a new high precision measurement of the time-of-flight spectrum of 14.1 MeV DT fusion neutrons. This detector allows a high precision (<30 ps) co-registered measurement of both a thresholded γ-ray and a neutron spectrum on a single record. Other approaches typically require γ and neutron signals to be co-registered via other diagnostics and/or dedicated timing experiments. Analysis of the co-registered γ and neutron signals allows precise extraction of the mean neutron energy and bulk hot-spot velocity, both of which were not possible with prior scintillator technologies. Initial measurements demonstrate the feasibility of this measurement and indicate that combined detection of neutrons and γ-rays on multiple lines-of-sight should enable the bulk vector velocity of the implosion hot-spot to be determined to ≈5 km/s and reduced uncertainty in the spectral width ≈0.1 keV.},
doi = {10.1063/1.5039322},
url = {https://www.osti.gov/biblio/1545509}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 10,
volume = 89,
place = {United States},
year = {2018},
month = {10}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Figures / Tables:

FIG. 1 FIG. 1: DT fit to measured time-of-flight neutron spectra resulting from different NIF implosions, highlighting the range of mean neutron energies, spectral widths, and down-scattered neutrons. N180128-002 (blue) results from a cryogenic DT-layered high-density carbon (HDC) capsule implosion. N180129-002 (red) is the broader spectrum produced by the directly driven implosionmore » of a DT gas-filled glass-shell exploding pusher, and N171120001 (black) shows the shifted mean neutron energy spectrum created by an asymmetrically driven DT gas-filled capsule. The spectra have been peak normalized.« less

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Works referenced in this record:

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    Works referencing / citing this record:

    Testing a Cherenkov neutron time-of-flight detector on OMEGA
    journal, October 2018


    Using multiple neutron time of flight detectors to determine the hot spot velocity
    journal, October 2018


    Characterization of photodetector temporal response for neutron time-of-flight (nToF) diagnostics at the National Ignition Facility
    journal, October 2018


    Ab initio response functions for Cherenkov-based neutron detectors
    journal, October 2018


    Nuclear diagnostics for Inertial Confinement Fusion (ICF) plasmas
    journal, January 2020