Laser fusion ion temperatures determined by neutron time-of-flight techniques

Lerche, R. A.; Coleman, L. W.; Houghton, J.W.; Speck, D. R.; Storm, E.

doi:10.1063/1.89509

Cited by 49 publications

(11 citation statements)

References 3 publications

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“…1.4. Because the pulse of neutrons is very intense, neutron time-of-flight measurements can be used to measure the energy spectrum of the primary 14-MeV peak, but background obscures the lower-intensity RIF neutrons [28,29]. A neutron activation technique was selected to quantify the ratio between the 14-MeV neutrons formed by the primary D-T reaction and Figure 1.3: Reaction-in-Flight production mechanisms.…”

Section: Reaction In Flight Neutron Measurementsmentioning

confidence: 99%

Experiments to Improve Nuclear Data for High Energy Density Environments

Champine¹

2016

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Section: Reaction In Flight Neutron Measurementsmentioning

confidence: 99%

Experiments to Improve Nuclear Data for High Energy Density Environments

Champine¹

2016

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“…On Inertial Confinement Fusion (ICF) facilities such as OMEGA 1 and the National Ignition Facility (NIF), 2 neutron time-of-flight (nTOF) detectors, operated in current mode, are routinely used to measure parts of the neutron spectrum from which absolute yield, [3][4][5] neutron-average ion temperature, [6][7][8][9][10] bang time (BT), [11][12][13] and areal density 14,15 are inferred. In an ICF implosion, neutrons are mainly generated from the primary fusion reactions in a deuterium (DD), or a deuterium/tritium (DT) fuel mixture, D + D → n (2.45 MeV) + 3 He (0.82 MeV),…”

Section: Introductionmentioning

confidence: 99%

A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

Waugh

Rosenberg

Zylstra

et al. 2015

Review of Scientific Instruments

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Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule.

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“…[19], no other technique has been found which has a sufficient resolution without a sacrifice of efficiency of several orders of magnitude.…”

Section: Tritium Produced In the D(dp)t Reaction Can Also React Via D-tmentioning

confidence: 99%

A fast neutron spectrometer for D-D fusion neutron measurements at the Alcator C tokamak

Fisher

Chen

Gwinn

et al. 1984

Nuclear Instruments and Methods in Physics Research

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A neutron spectrometer using a high pressure 3 He ionization chamber has been designed and used to measure the neutron spectrum from an ohmically heated deuterium plasma. The resolution of the spectrometer at 2.45 MeV is determine to be 46 keV full width at the half maximum (FWHM). Particular attention has been paid to optimizing the detector shielding and collimation to reject thermal and epithermal neutrons scattered from the tokamak structure. As a result, measurements indicate that the ratio of the number of counts in the 2.45 MeV peak to the total number of detected neutron events is 1/67.For the 8 Psec amplifier time constant used, a count rate as high as 44 counts per second has been achieved in the thermonuclear peak.The observed spectra have been compared with calculated spectra using the MCNP Monte Carlo Neutral Particle Transport code and they show good agreement. There is little evidence of neutrons produced from photoneutron reactions or electrodisintegration. It has been possible to confirm that the shape of the thermonuclear peak is consistent with the Gaussian shape predicted and that the ion temperature as determined from the line width is consistent with other Alcator C ion temperature diagnostics, and follows the trends predicted by the theory of Doppler line broadening.

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Laser fusion ion temperatures determined by neutron time-of-flight techniques

Cited by 49 publications

References 3 publications

Experiments to Improve Nuclear Data for High Energy Density Environments

Experiments to Improve Nuclear Data for High Energy Density Environments

A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

A fast neutron spectrometer for D-D fusion neutron measurements at the Alcator C tokamak

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