The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

Casey, D. T.; Frenje, J. A.; Johnson, M. Gatu; Séguin, F. H.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Katz, J.; Magoon, J.; Meyerhofer, D. D.; Sangster, T. C.; Shoup, M. J.; Ulreich, J.; Ashabranner, R.; Bionta, R. M.; Carpenter, A.; Felker, B.; Khater, H. Y.; LePape, S.; Mackinnon, A. J.; McKernan, M. A.; Moran, Mike; Rygg, J. R.; Yeoman, M. F.; Zacharias, R.; Leeper, R. J.; Fletcher, K.; Farrell, M.; Jasion, Daniel; Kilkenny, J. D.; Paguio, R. R.

doi:10.1063/1.4796042

Cited by 65 publications

(19 citation statements)

References 25 publications

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“…To investigate the impact of x-ray dose on proton track formation in CR-39, samples were irradiated with x rays, exposed to protons with various energies, and then etched in a 6 molar NaOH solution. The TasTrak® CR-39 samples used in the experiment were 1.5 mm thick sheets acquired from TASL, 36 as has been used extensively in charged particle spectrometry and imaging applications in ICF 12,16,17,19,37 and the response of which has been investigated in several related studies. 25,30,38,39 The samples were laser-cut into 5 cm round discs.…”

Section: Experimental Designmentioning

confidence: 99%

“…4 Additionally, backlighting of HED plasmas with high-energy charged particles has recently provided new insights into magnetic and electric field generation and evolution in contexts relevant to ICF, basic plasma physics, and laboratory astrophysics. [5][6][7][8][9][10] The solid-state nuclear track detector CR-39 11 has provided the basis for many neutron and charged particle diagnostics 5,[12][13][14][15][16][17][18][19][20] for HED and ICF experiments at both the OMEGA laser facility 21 and the National Ignition Facility (NIF). 22 CR-39, a transparent plastic, detects charged particles with energy on the order of 1-10 MeV with 100% efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

Rinderknecht

Rojas-Herrera

Zylstra

et al. 2015

Review of Scientific Instruments

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The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1-100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5-9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. The impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.

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Section: Experimental Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

Rinderknecht

Rojas-Herrera

Zylstra

et al. 2015

Review of Scientific Instruments

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“…Inhomogeneous and time-varying plasma conditions will affect the rate and type of interactions and hence the resulting spectra. Spectroscopy is performed experimentally by the Neutron Time of Flight detectors (nToFs) 11,12 and the Magnetic Recoil Spectrometer (MRS) 13 . Measurements by these diagnostics are used to infer ion temperatures, areal densities and fluid motion 3,6,8,9,14,15 .…”

Section: Introductionmentioning

confidence: 99%

Synthetic nuclear diagnostics for inferring plasma properties of inertial confinement fusion implosions

et al. 2018

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A suite of synthetic nuclear diagnostics has been developed to post-process radiation hydrodynamics simulations performed with the code Chimera. These provide experimental observables based on simulated capsule properties and are used to assess alternative experimental and data analysis techniques. These diagnostics include neutron spectroscopy, primary and scattered neutron imaging, neutron activation, γ-ray time histories and carbon γ-ray imaging. Novel features of the neutron spectrum have been analysed to infer plasma parameters. The nT and nD backscatter edges have been shown to provide a shell velocity measurement. Areal density asymmetries created by low mode perturbations have been inferred from the slope of the downscatter spectrum down to 10 MeV. Neutron activation diagnostics showed significant aliasing of high mode areal density asymmetries when observing a capsule implosion with 3D multimode perturbations applied. Carbon γ-ray imaging could be used to image the ablator at high convergence ratio. Time histories of both the fusion and carbon γ signals showed a greater time difference between peak intensities for the perturbed case when compared to a symmetric simulation.

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“…8 Neutron spectroscopy techniques in-use at the OMEGA and NIF facilities include neutron time-of-flight (nTOF), 9,10 nuclear activation, 11,12 and recoil spectroscopy. [13][14][15][16][17][18] The primary signature of residual kinetic energy would be a Doppler shift of the neutron spectrum; for relevant conditions the Doppler shift is approximately linear through relativistic kinematics (see Appendix B). This is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

A compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF

Zylstra

Johnson

Frenje

et al. 2014

Review of Scientific Instruments

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A compact spectrometer for measurements of the primary deuterium-tritium neutron spectrum has been designed and implemented on the OMEGA laser facility [T. Boehly et al., Opt. Commun. 133, 495 (1997)]. This instrument uses the recoil spectrometry technique, where neutrons produced in an implosion elastically scatter protons in a plastic foil, which are subsequently detected by a proton spectrometer. This diagnostic is currently capable of measuring the yield to ~±10% accuracy, and mean neutron energy to ~±50 keV precision. As these compact spectrometers can be readily placed at several locations around an implosion, effects of residual fuel bulk flows during burn can be measured. Future improvements to reduce the neutron energy uncertainty to ±15-20 keV are discussed, which will enable measurements of fuel velocities to an accuracy of ~±25-40 km/s.

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The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

Cited by 65 publications

References 25 publications

Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

Synthetic nuclear diagnostics for inferring plasma properties of inertial confinement fusion implosions

A compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF

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