Publications by authors named "S G Dannhoff"
The Particle Time of Flight (PTOF) diagnostic is a chemical vapor deposition diamond-based detector and is the only diagnostic for measuring nuclear bang times of low yield (<1013) shots on the National Ignition Facility. Recently, a comprehensive study of detector impulse responses revealed certain detectors with very fast and consistent impulse responses with a rise time of <50 ps, enabling low yield burn history measurements. At the current standoff of 50 cm, this measurement is possible with fast 14 MeV neutrons from deuterium-tritium (DT) fusion plasmas.
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- CR-39 proton radiography is a method used to image electric and magnetic fields in plasma at facilities like OMEGA and NIF, relying on a process called etching to prepare the CR-39 material.
- The etch time significantly affects the background-to-signal ratio (BSR) and detection efficiency across different fluence levels, leading to errors in signal measurements as high as 15% if only one etch time is used.
- Experiments at MIT determined how changing etch times impacts BSR and efficiency, showing that combining both short and long etch times improves the accuracy of field reconstructions by reducing mean squared error significantly.
Article Synopsis
- The paper examines how higher neutron fluences affect the detection efficiency of protons using CR-39, a common particle detection method, particularly in inertial fusion diagnostics.
- Experiments revealed that as neutron fluence increases, the recovery of proton signals decreases, with added complications from longer etching times.
- Notably, at 3 hours of etching, a 17% signal loss was observed with high neutron tracks, escalating to 67% at 6 hours, though improved signal isolation techniques can mitigate some of this loss.
Image plate multi-scan response to fusion protons in the range of 1-14 MeV.
Rev Sci Instrum
September 2024
Image plates (IPs) are a quickly recoverable and reusable radiation detector often used to measure proton and x-ray fluence in laser-driven experiments. Recently, IPs have been used in a proton radiography detector stack on the OMEGA laser, a diagnostic historically implemented with CR-39, or radiochromic film. The IPs used in this and other diagnostics detect charged particles, neutrons, and x-rays indiscriminately.
View Article and Find Full Text PDFCharacterization of the image plate multi-scan response to mono-energetic x-rays.
Rev Sci Instrum
September 2024
Image plates (IPs), or phosphor storage screens, are a technology employed frequently in inertial confinement fusion (ICF) and high energy density plasma (HEDP) diagnostics because of their sensitivity to many types of radiation, including, x rays, protons, alphas, beta particles, and neutrons. Prior studies characterizing IPs are predicated on the signal level remaining below the scanner saturation threshold. Since the scanning process removes some signal from the IP via photostimulated luminescence, repeatedly scanning an IP can bring the signal level below the scanner saturation threshold.
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