New instrumentation for ground and airborne high-energy observations
Abstract
Terrestrial gamma-ray flashes, glows, and lightning-leader x-rays can be observed from the ground and aircraft. One of the biggest challenges in these observations is the enormous dynamic range of possible photon (or particle) intensities. We recently received funding from the Air Force Office of Scientific Research to build six copies of a detector package adaptable for ground or airborne deployment. These arrays, called THOR (Terrestrial High-energy Observations of Radiation), are designed to address the issue of dynamic range more thoroughly than prior instrumentation. They will be capable of independent outdoor operation with solar power. They will become available in 2020 and 2021 for collaborative deployments -- we welcome discussions about opportunities. Each THOR detector package will contain four plastic scintillators, of widely varying size, three of which allow counting rates > 1 MHz. The largest, of 5.7 kg, will observe glows, distant TGFs, and stepped-leader x-rays with high sensitivity. Because it is plastic, it can capture neutrons to produce deuterium in the detector and a characteristic gamma-ray of 2.2 MeV, which provides a distinctive spectral signature (Bowers et al. 2017, GRL 44, 10,063). The smallest plastic scintillator, currently planned to be approximately 0.2 g, will be read out as a digital dosimeter for the purposes of estimating the intensity of a nearby, full-luminosity TGF (e.g. 10^18 gamma-rays). By using a photodiode whose current is accumulated, via a charge-sensitive preamplifier, on a capacitor for the whole duration of the TGF, we will measure the radiation dose associated with the event in the regime when no plausible instrument would be capable of resolving individual photon counts. Finally, an inorganic scintillator will be included for better spectroscopy, e.g. for the positron annihilation line from radioactive air post-TGF (Enoto et al. 2017, Nature 551, 481).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMAE41B3157S
- Keywords:
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- 3304 Atmospheric electricity;
- ATMOSPHERIC PROCESSES;
- 3324 Lightning;
- ATMOSPHERIC PROCESSES;
- 4301 Atmospheric;
- NATURAL HAZARDS