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Title: Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography

Abstract

Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments, and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro channel plate) to provide gating and high DQE at the 40–200keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Here, experiments were performed at energies relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.

Authors:
 [1];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2];  [2];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. National Security Technologies, Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1258550
Report Number(s):
LLNL-PROC-694818
Journal ID: ISSN 0034-6748; RSINAK
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Conference: Proceedings of the 21st Topical Conference on High-Temperature Plasma Diagnostics, Madison, WI (United States), 5-9 Jun 2016; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS

Citation Formats

Hall, G. N., Izumi, N., Landen, O. L., Tommasini, R., Holder, J. P., Hargrove, D., Bradley, D. K., Lumbard, A., Cruz, J. G., Piston, K., Lee, J. J., Romano, E., Bell, P. M., Carpenter, A. C., Palmer, N. E., Felker, B., Rekow, V., and Allen, F. V.. Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography. United States: N. p., 2016. Web. doi:10.1063/1.4959948.
Hall, G. N., Izumi, N., Landen, O. L., Tommasini, R., Holder, J. P., Hargrove, D., Bradley, D. K., Lumbard, A., Cruz, J. G., Piston, K., Lee, J. J., Romano, E., Bell, P. M., Carpenter, A. C., Palmer, N. E., Felker, B., Rekow, V., & Allen, F. V.. Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography. United States. doi:10.1063/1.4959948.
Hall, G. N., Izumi, N., Landen, O. L., Tommasini, R., Holder, J. P., Hargrove, D., Bradley, D. K., Lumbard, A., Cruz, J. G., Piston, K., Lee, J. J., Romano, E., Bell, P. M., Carpenter, A. C., Palmer, N. E., Felker, B., Rekow, V., and Allen, F. V.. Wed . "Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography". United States. doi:10.1063/1.4959948. https://www.osti.gov/servlets/purl/1258550.
@article{osti_1258550,
title = {Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography},
author = {Hall, G. N. and Izumi, N. and Landen, O. L. and Tommasini, R. and Holder, J. P. and Hargrove, D. and Bradley, D. K. and Lumbard, A. and Cruz, J. G. and Piston, K. and Lee, J. J. and Romano, E. and Bell, P. M. and Carpenter, A. C. and Palmer, N. E. and Felker, B. and Rekow, V. and Allen, F. V.},
abstractNote = {Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments, and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro channel plate) to provide gating and high DQE at the 40–200keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Here, experiments were performed at energies relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.},
doi = {10.1063/1.4959948},
journal = {Review of Scientific Instruments},
number = 11,
volume = 87,
place = {United States},
year = {Wed Aug 03 00:00:00 EDT 2016},
month = {Wed Aug 03 00:00:00 EDT 2016}
}

Journal Article:
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  • Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro-channel plate) to provide gating and high DQE at the 40–200 keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Experiments were performed at energiesmore » relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.« less
  • An x-ray light valve (XLV) coupled with an optical scanner has the potential to meet the need for a low-cost, high quality digital imaging system for general radiography. The XLV/scanner concept combines three well-established, and hence, low-cost technologies: An amorphous selenium (a-Se) layer as an x-ray-to-charge transducer, a liquid crystal (LC) cell as an analog display, and an optical scanner for image digitization. The XLV consists of an a-Se layer and LC cell in a sandwich structure which produces an optical image in the LC layer upon x-ray exposure. The XLV/scanner system consists of an XLV in combination with anmore » optical scanner for image readout. Here, the effect of each component on the spatial resolution of an XLV/scanner system is investigated. A theoretical model of spatial resolution of an XLV is presented based on calculations of the modulation transfer function (MTF) for a-Se and a LC cell. From these component MTFs, the theoretical MTF of the XLV is derived. The model was validated by experiments on a prototype XLV/scanner system. The MTF of the scanner alone was obtained by scanning an optical test target and the MTF of the XLV/scanner system was measured using x rays. From the measured MTF of the scanner, the theoretical MTF of the XLV/scanner system was established and compared with the experimental results. Good general agreement exists between experimental and theoretical results in the frequency range of interest for general radiography, although the theoretical curves slightly overstate the measured MTFs. The experimental MTF of the XLV was compared with the MTF of two clinical systems and was shown to have the capability to exceed the resolution of flat-panel detectors. From this, the authors can conclude that the XLV has an adequate resolution for general radiography. The XLV/scanner also has the potential to eliminate aliasing while maintaining a MTF that exceeds that of a flat-panel imager.« less
  • Digital x-ray radiographic systems are desirable as they offer high quality images which can be processed, transferred, and stored without secondary steps. However, current clinical systems are extraordinarily expensive in comparison to film-based systems. Thus, there is a need for an economical digital imaging system for general radiology. The x-ray light valve (XLV) is a novel digital x-ray detector concept with the potential for high image quality and low cost. The XLV is comprised of a photoconductive detector layer and liquid crystal (LC) cell physically coupled in a sandwich structure. Upon exposure to x rays, charge is collected at themore » surface of the photoconductor, causing a change in the reflective properties of the LC cell. The visible image so formed can subsequently be digitized with an optical scanner. By choosing the properties of the LC cell in combination with the appropriate photoconductor thickness and bias potentials, the XLV can be optimized for various diagnostic imaging tasks. Specifically for chest radiography, we identified three potentially practical reflective cell designs by selecting from those commonly used in LC display technology. The relationship between reflectance and x-ray exposure (i.e., the characteristic curve) was determined for all three cells using a theoretical model. The results indicate that the reflective electrically controlled birefringence (r-ECB) cell is the preferred choice for chest radiography, provided that the characteristic curve can be shifted towards lower exposures. The feasibility of the shift of the characteristic curve is shown experimentally. The experimental results thus demonstrate that an XLV based on the r-ECB cell design exhibits a characteristic curve suitable for chest radiography.« less
  • Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detectormore » for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV–200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.« less
  • A flash X-ray source developed using pulsed electron accelerator with electron energy range of 400keV to 1030keV and a field emission cathode is characterized using X-ray imaging plates. Spatial resolution of the imaging system is measured using edge spread function fitted to data obtained from radiograph of Pb step wedge. A spatial resolution of 150±6 µm is obtained. The X-ray beam size is controlled by the anode-cathode configuration. Optimum source size of ∼13±2 mm diameter covering an area with intensity of ∼27000 PSL/mm{sup 2} is obtained on the imaging plate kept at a distance of ∼200 mm from the tip of the anode.more » It is used for recording radiographs of objects like satellite cable cutter, aero-engine turbine blade and variety of pyro-devices used in aerospace industry.« less