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Synchrotron characterization of high-Z, current-mode X-ray detectors

Review of Scientific Instruments

Looker, Quinn M.; Wood, Michael G.; Miceli, Antonino; Niraula, Madan; Yasuda, Kazuhito; Porter, John L.

Fast X-ray detectors are critical tools in pulsed power and fusion applications, where detector impulse response of a nanosecond or better is often required. Semiconductor detectors can create fast, sensitive devices with extensive operational flexibility. There is typically a trade-off between detector sensitivity and speed, but higher atomic number absorbers can increase hard X-ray absorption without increasing the charge collection time, provided carriers achieve high velocity. This paper presents X-ray pulse characterization conducted at the Advanced Photon Source of X-ray absorption efficiency and temporal impulse response of current-mode semiconductor X-ray detectors composed of Si, GaAs, and CdTe.

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TYPE Journal Article YEAR 2020
DOIOSTIScopus

Nano-Engineering of Detector Surfaces to Offer Unprecedented Imager Sensitivity to Soft X-rays and Low Energy Electrons

Looker, Quinn M.; Sanchez, Marcos O.

The focus of this document is to record the learning and process development achieved by the completion of the Nano-Engineering of Detector Surfaces to Offer Unprecedented Imager Sensitivity to Soft X-rays and Low Energy Electrons LDRD. The goal of this effort was to study different silicon detector surface preparation methods such as ion implant parameters, and the addition of a quantum 2-layer superlattice. Enabling the preparation of the surface of silicon detectors (front side illuminated or bonded backside illuminated) increases the responsivity of the diode to shallowly absorbed photons. This increased sensitivity in turn allows for greater fidelity in imaging events that emit low soft X-rays or low energy electrons. Prior work has focused on passivating the surface of a silicon detectors with thin layers (tens of nm thick) of materials to reduce surface recombination sites. Measurements of visible light quantum efficiency, electron responsivity, and pulsed x-ray response indicate that detectors with a 2- layer superlattice enjoy a significant benefit over equivalent detectors using an ion implant at the illuminated surface.

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TYPE SAND Report YEAR 2019
DOIOSTI

Phase modulation failsafe system for multi-kJ lasers based on optical heterodyne detection

Review of Scientific Instruments

Armstrong, Darrell J.; Looker, Quinn M.; Stahoviak, John W.; Smith, Ian C.; Shores, J.E.; Jonathon; Rambo, Patrick K.; Schwarz, Jens S.; Speas, Christopher S.; Porter, John L.

Amplification of the transverse scattered component of stimulated Brillouin scattering (SBS) can contribute to optical damage in the large aperture optics of multi-kJ lasers. Because increased laser bandwidth from optical phase modulation (PM) can suppress SBS, high energy laser amplifiers are injected with PM light. Phase modulation distributes the single-frequency spectrum of a master oscillator laser among individual PM sidebands, so a sufficiently high modulation index β can maintain the fluence for all spectral components below the SBS threshold. To avoid injection of single frequency light in the event of a PM failure, a high-speed PM failsafe system (PMFS) must be employed. Because PM is easily converted to AM, essentially all PM failsafes detect AM, with the one described here employing a novel configuration where optical heterodyne detection converts PM to AM, followed by passive AM power detection. Although the PMFS is currently configured for continuous monitoring, it can also detect PM for pulse durations ≥2 ns and could be modified to accommodate shorter pulses. This PMFS was deployed on the Z-Beamlet Laser (ZBL) at Sandia National Laboratories, as required by an energy upgrade to support programs at Sandia’s Z Facility such as magnetized liner inertial fusion. Depending on the origin of a PM failure, the PMFS responds in as little as 7 ns. In the event of an instantaneous failure during initiation of a laser shot, this response time translates to a 30–50 ns margin of safety by blocking a pulse from leaving ZBL’s regenerative amplifier, which prevents injection of single frequency light into the main amplification chain. In conclusion, the performance of the PMFS, without the need for operator interaction, conforms to the principles of engineered safety.

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TYPE Journal Article YEAR 2018
DOIOSTI

A Window-less Target for Magnetized Liner Inertial Fusion Characterized using High-Speed Solid-State Framing Cameras

Colombo, Anthony P.; Schwarz, Jens S.; Rambo, Patrick K.; Galloway, B.R.; Kimmel, Mark W.; Slutz, Stephen A.; Weis, Matthew R.; Claus, Liam D.; England, Troy D.; Fang, Lu F.; Looker, Quinn M.; Mitchell, Brandon M.; Montoya, Andrew M.; Robertson, Gideon R.; Rochau, G.A.; Sanchez, Marcos O.; Stahoviak, John W.; Hund, Jared; Sin, Justin; Porter, John L.

Abstract not provided.

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TYPE Conference Poster YEAR 2018
OSTIOSTI
Results 26–50 of 52
Results 26–50 of 52