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Title: Performance evaluation of an energy tuning assembly for neutron spectral shaping

Abstract

An energy tuning assembly (ETA) was designed here to be fielded at the National Ignition Facility (NIF) to modify the characteristic D-T fusion spectrum to include a prompt fission neutron spectral component. The ETA was characterized at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory to measure the shaped spectrum from an incident deuteron breakup neutron source, test the proposed neutron spectroscopy techniques used to inform the flux measurements at NIF, and validate the ability to predict ETA performance using a Monte Carlo Neutral Particle (MCNP) simulation. Activation foils (i.e., Ni, In, Au, Al) were exposed to a collimated 33-MeV deuteron-breakup beam originating from a tantalum breakup target. The source spectrum absent the ETA was characterized using a set of activation foils and the STAYSL unfolding code. Finally, the ETA-modified spectrum was obtained using activation foil unfolding with a χ 2 ν = 0 . 92 . The ETA-modified unfolded spectrum agreed with the MCNP-simulated prediction in the energy range of 0.1–14 MeV, but exhibited disagreements in the 10 eV–100 keV region. This work demonstrates shaping of the NIF neutron spectrum via the ETA to be a viable path forward for tailored neutron beams at NIF.

Authors:
 [1];  [2];  [2];  [3];  [3];  [4];  [3];  [3]
  1. Air Force Inst. of Technology, Wright Patterson AFB, OH (United States). Dept. of Engineering Physics
  2. Univ. of California, Berkeley, CA (United States). Dept. of Physics
  3. Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Berkeley, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20); National Science Foundation (NSF)
OSTI Identifier:
1513143
Alternate Identifier(s):
OSTI ID: 1547841
Report Number(s):
LLNL-JRNL-767547
Journal ID: ISSN 0168-9002; 957398
Grant/Contract Number:  
AC52-07NA27344; AC02-05CH11231; NA0003180; NSF 11-582
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 923; Journal ID: ISSN 0168-9002
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; neutron energy tuning; beam shaping; neutron activation analysis; spectrum unfolding; fast neutrons; surrogate debris

Citation Formats

Bevins, James E., Sweger, Z., Munshi, N., Goldblum, B. L., Brown, J. A., Bleuel, D. L., Bernstein, L. A., and Slaybaugh, R. N. Performance evaluation of an energy tuning assembly for neutron spectral shaping. United States: N. p., 2019. Web. doi:10.1016/j.nima.2019.01.049.
Bevins, James E., Sweger, Z., Munshi, N., Goldblum, B. L., Brown, J. A., Bleuel, D. L., Bernstein, L. A., & Slaybaugh, R. N. Performance evaluation of an energy tuning assembly for neutron spectral shaping. United States. doi:10.1016/j.nima.2019.01.049.
Bevins, James E., Sweger, Z., Munshi, N., Goldblum, B. L., Brown, J. A., Bleuel, D. L., Bernstein, L. A., and Slaybaugh, R. N. Mon . "Performance evaluation of an energy tuning assembly for neutron spectral shaping". United States. doi:10.1016/j.nima.2019.01.049. https://www.osti.gov/servlets/purl/1513143.
@article{osti_1513143,
title = {Performance evaluation of an energy tuning assembly for neutron spectral shaping},
author = {Bevins, James E. and Sweger, Z. and Munshi, N. and Goldblum, B. L. and Brown, J. A. and Bleuel, D. L. and Bernstein, L. A. and Slaybaugh, R. N.},
abstractNote = {An energy tuning assembly (ETA) was designed here to be fielded at the National Ignition Facility (NIF) to modify the characteristic D-T fusion spectrum to include a prompt fission neutron spectral component. The ETA was characterized at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory to measure the shaped spectrum from an incident deuteron breakup neutron source, test the proposed neutron spectroscopy techniques used to inform the flux measurements at NIF, and validate the ability to predict ETA performance using a Monte Carlo Neutral Particle (MCNP) simulation. Activation foils (i.e., Ni, In, Au, Al) were exposed to a collimated 33-MeV deuteron-breakup beam originating from a tantalum breakup target. The source spectrum absent the ETA was characterized using a set of activation foils and the STAYSL unfolding code. Finally, the ETA-modified spectrum was obtained using activation foil unfolding with a χ2ν=0.92. The ETA-modified unfolded spectrum agreed with the MCNP-simulated prediction in the energy range of 0.1–14 MeV, but exhibited disagreements in the 10 eV–100 keV region. This work demonstrates shaping of the NIF neutron spectrum via the ETA to be a viable path forward for tailored neutron beams at NIF.},
doi = {10.1016/j.nima.2019.01.049},
journal = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},
issn = {0168-9002},
number = ,
volume = 923,
place = {United States},
year = {2019},
month = {1}
}

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