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  1. Article ; Online: Three-dimensional reconstruction of neutron, gamma-ray, and x-ray sources using a cylindrical-harmonics expansion.

    Volegov, P L / Batha, S H / Fittinghoff, D N / Danly, C R / Geppert-Kleinrath, V / Wilde, C H / Zylstra, A B

    The Review of scientific instruments

    2021  Volume 92, Issue 3, Page(s) 33508

    Abstract: Inertial confinement fusion capsule implosions produce neutron, gamma-ray, and x-ray emission, which are recorded by a variety of detectors, both time integrated and time resolved, to determine the performance of the implosion. Two-dimensional emission ... ...

    Abstract Inertial confinement fusion capsule implosions produce neutron, gamma-ray, and x-ray emission, which are recorded by a variety of detectors, both time integrated and time resolved, to determine the performance of the implosion. Two-dimensional emission images from multiple directions can now be combined to infer three-dimensional structures in the implosion, such as the distribution of thermonuclear fuel density, carbon ablator, and impurities. Because of the cost and complexity of the imaging systems, however, only a few measurements can be made, so reconstructions of the source must be made from a limited number of views. Here, a cylindrical-harmonics decomposition technique to reconstruct the three-dimensional object from two views in the same symmetry plane is presented. In the limit of zero order, this method recovers the Abel inversion method. The detailed algorithms used for this characterization and the resulting reconstructed neutron source from an experiment collected at the National Ignition Facility are presented.
    Language English
    Publishing date 2021-04-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/5.0042860
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Modeling of a spatially resolved ion temperature diagnostic for inertial confinement fusion.

    Danly, C R / Birge, N / Geppert-Kleinrath, V / Haines, B M / Ivancic, S / Jorgenson, H J / Katz, J / Merrill, F E / Mendoza, E F / Sorce, A / Tafoya, L R / Volegov, P L / Wilde, C H / Wilson, D C

    The Review of scientific instruments

    2023  Volume 94, Issue 4

    Abstract: The performance of modern laser-driven inertial confinement fusion (ICF) experiments is degraded by contamination of the deuterium-tritium (DT) fuel with high-Z material during compression. Simulations suggest that this mix can be described by the ion ... ...

    Abstract The performance of modern laser-driven inertial confinement fusion (ICF) experiments is degraded by contamination of the deuterium-tritium (DT) fuel with high-Z material during compression. Simulations suggest that this mix can be described by the ion temperature distribution of the implosion, given that such contaminants deviate in temperature from the surrounding DT plasma. However, existing neutron time-of-flight (nTOF) diagnostics only measure the spatially integrated ion temperature. This paper describes the techniques and forward modeling used to develop a novel diagnostic imaging system to measure the spatially resolved ion temperature of an ICF implosion for the first time. The technique combines methods in neutron imaging and nTOF diagnostics to measure the ion temperature along one spatial dimension at yields currently achievable on the OMEGA laser. A detailed forward model of the source and imaging system was developed to guide instrument design. The model leverages neutron imaging reconstruction algorithms, radiation hydrodynamics and Monte Carlo simulations, optical ray tracing, and more. The results of the forward model agree with the data collected on OMEGA using the completed diagnostic. The analysis of the experimental data is still ongoing and will be discussed in a separate publication.
    Language English
    Publishing date 2023-12-12
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/5.0101892
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Nonuniform radiation damage in permanent magnet quadrupoles.

    Danly, C R / Merrill, F E / Barlow, D / Mariam, F G

    The Review of scientific instruments

    2014  Volume 85, Issue 8, Page(s) 83305

    Abstract: We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying ... ...

    Abstract We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.
    Language English
    Publishing date 2014-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4892803
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Plastic fiber scintillator response to fast neutrons.

    Danly, C R / Sjue, S / Wilde, C H / Merrill, F E / Haight, R C

    The Review of scientific instruments

    2014  Volume 85, Issue 11, Page(s) 11E607

    Abstract: The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV ...

    Abstract The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented.
    Language English
    Publishing date 2014-11
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4891160
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Simultaneous usage of pinhole and penumbral apertures for imaging small scale neutron sources from inertial confinement fusion experiments.

    Guler, N / Volegov, P / Danly, C R / Grim, G P / Merrill, F E / Wilde, C H

    The Review of scientific instruments

    2012  Volume 83, Issue 10, Page(s) 10D316

    Abstract: Inertial confinement fusion experiments at the National Ignition Facility are designed to understand the basic principles of creating self-sustaining fusion reactions by laser driven compression of deuterium-tritium (DT) filled cryogenic plastic capsules. ...

    Abstract Inertial confinement fusion experiments at the National Ignition Facility are designed to understand the basic principles of creating self-sustaining fusion reactions by laser driven compression of deuterium-tritium (DT) filled cryogenic plastic capsules. The neutron imaging diagnostic provides information on the distribution of the central fusion reaction region and the surrounding DT fuel by observing neutron images in two different energy bands for primary (13-17 MeV) and down-scattered (6-12 MeV) neutrons. From this, the final shape and size of the compressed capsule can be estimated and the symmetry of the compression can be inferred. These experiments provide small sources with high yield neutron flux. An aperture design that includes an array of pinholes and penumbral apertures has provided the opportunity to image the same source with two different techniques. This allows for an evaluation of these different aperture designs and reconstruction algorithms.
    Language English
    Publishing date 2012-10
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4746745
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Self characterization of a coded aperture array for neutron source imaging.

    Volegov, P L / Danly, C R / Fittinghoff, D N / Guler, N / Merrill, F E / Wilde, C H

    The Review of scientific instruments

    2014  Volume 85, Issue 12, Page(s) 123506

    Abstract: The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial ... ...

    Abstract The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.
    Language English
    Publishing date 2014-12
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4902978
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography.

    Simpson, R / Cutler, T E / Danly, C R / Espy, M A / Goglio, J H / Hunter, J F / Madden, A C / Mayo, D R / Merrill, F E / Nelson, R O / Swift, A L / Wilde, C H / Zocco, T G

    The Review of scientific instruments

    2016  Volume 87, Issue 11, Page(s) 11D830

    Abstract: The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for ... ...

    Abstract The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.
    Language English
    Publishing date 2016-11
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4962040
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: A new aperture for neutron and x-ray imaging of inertial confinement fusion experiments.

    Danly, C R / Grim, G P / Guler, N / Intrator, M H / Merrill, F E / Volegov, P / Wilde, C H

    The Review of scientific instruments

    2012  Volume 83, Issue 10, Page(s) 10E522

    Abstract: Recent neutron imaging of experiments at the National Ignition Facility has provided useful information about the hotspot shape and cold-fuel distribution and has also given insight into avenues for improvement. Neutron image reconstruction depends on ... ...

    Abstract Recent neutron imaging of experiments at the National Ignition Facility has provided useful information about the hotspot shape and cold-fuel distribution and has also given insight into avenues for improvement. Neutron image reconstruction depends on accurate pointing information because the point-spread function of the neutron aperture is not shift invariant. Current pointing techniques are limited in their accuracy and rely upon detailed information about the as-built structure of the array, which is difficult to determine. We present a technique for extracting high-precision pointing information from both neutron and x-ray images, and a new aperture design with features to facilitate this technique, and allow future co-registration of neutron and x-ray images.
    Language English
    Publishing date 2012-10
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4731745
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Simultaneous neutron and x-ray imaging of inertial confinement fusion experiments along a single line of sight at Omega.

    Danly, C R / Day, T H / Fittinghoff, D N / Herrmann, H / Izumi, N / Kim, Y H / Martinez, J I / Merrill, F E / Schmidt, D W / Simpson, R A / Volegov, P L / Wilde, C H

    The Review of scientific instruments

    2015  Volume 86, Issue 4, Page(s) 43503

    Abstract: Neutron and x-ray imaging provide critical information about the geometry and hydrodynamics of inertial confinement fusion implosions. However, existing diagnostics at Omega and the National Ignition Facility (NIF) cannot produce images in both neutrons ... ...

    Abstract Neutron and x-ray imaging provide critical information about the geometry and hydrodynamics of inertial confinement fusion implosions. However, existing diagnostics at Omega and the National Ignition Facility (NIF) cannot produce images in both neutrons and x-rays along the same line of sight. This leads to difficulty comparing these images, which capture different parts of the plasma geometry, for the asymmetric implosions seen in present experiments. Further, even when opposing port neutron and x-ray images are available, they use different detectors and cannot provide positive information about the relative positions of the neutron and x-ray sources. A technique has been demonstrated on implosions at Omega that can capture x-ray images along the same line of sight as the neutron images. The technique is described, and data from a set of experiments are presented, along with a discussion of techniques for coregistration of the various images. It is concluded that the technique is viable and could provide valuable information if implemented on NIF in the near future.
    Language English
    Publishing date 2015-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4918285
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Combined neutron and x-ray imaging at the National Ignition Facility (invited).

    Danly, C R / Christensen, K / Fatherley, V E / Fittinghoff, D N / Grim, G P / Hibbard, R / Izumi, N / Jedlovec, D / Merrill, F E / Schmidt, D W / Simpson, R A / Skulina, K / Volegov, P L / Wilde, C H

    The Review of scientific instruments

    2016  Volume 87, Issue 11, Page(s) 11D703

    Abstract: X-ray and neutrons are commonly used to image inertial confinement fusion implosions, providing key diagnostic information on the fuel assembly of burning deuterium-tritium (DT) fuel. The x-ray and neutron data provided are complementary as the ... ...

    Abstract X-ray and neutrons are commonly used to image inertial confinement fusion implosions, providing key diagnostic information on the fuel assembly of burning deuterium-tritium (DT) fuel. The x-ray and neutron data provided are complementary as the production of neutrons and x-rays occurs from different physical processes, but typically these two images are collected from different views with no opportunity for co-registration of the two images. Neutrons are produced where the DT fusion fuel is burning; X-rays are produced in regions corresponding to high temperatures. Processes such as mix of ablator material into the hotspot can result in increased x-ray production and decreased neutron production but can only be confidently observed if the two images are collected along the same line of sight and co-registered. To allow direct comparison of x-ray and neutron data, a combined neutron x-ray imaging system has been tested at Omega and installed at the National Ignition Facility to collect an x-ray image along the currently installed neutron imaging line of sight. This system is described, and initial results are presented along with prospects for definitive coregistration of the images.
    Language English
    Publishing date 2016-11
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209865-9
    ISSN 1089-7623 ; 0034-6748
    ISSN (online) 1089-7623
    ISSN 0034-6748
    DOI 10.1063/1.4962194
    Database MEDical Literature Analysis and Retrieval System OnLINE

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