What is it about?

Flash X-ray systems are commonly used in laboratory settings where a short burst of X-rays is needed to see inside an object during an experiment. This paper examines several commercially-available sensors as a way to determine exactly when and for how long those X-ray pulses occur.

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Why is it important?

This work examines several low-cost commercially-available photodiodes for use as direct X-ray detectors. Traditionally, short X-ray pulses may be measured in laboratory settings using a combination of a scintillator and a photodiode, but it is often difficult to record weak X-ray pulses this way. Our findings show that we can repeatably and directly measure short nanosecond duration X-ray pulses using a photodiode alone. This work provides a simple and effective method for determining the timing of X-ray pulses in any flash X-ray system.

Perspectives

I'm happy that this article has been published because it explains a simple X-ray timing trick that we've used in our lab for a few years now and that I believe few people know about. The photodiodes we talk about in this paper are commonly used for measuring visible and infrared light, but never X-rays in a benchtop flash X-ray system. The idea of using photodiodes to directly measure X-ray pulses in our lab actually originated from Lily H. Shevitz as part of her 6th grade science project. Lily wanted to see if she could record any kind of signal from discharging static electricity using a photodiode covered with black tape (to prevent it from measuring visible light). "Shockingly", the photodiodes DID record a signal, and her mother, Laura Smilowitz, went back to the lab to see if the photodiode might also be able to record a signal from X-ray pulses...and it did! I hope this back story and article prompts you to challenge the status quo and to always look for new creative solutions in your research.

Cameron Brown
Los Alamos National Laboratory

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This page is a summary of: Evaluation of silicon and indium gallium arsenide photodiodes as direct timing detectors for pulsed x-ray systems, Review of Scientific Instruments, March 2024, American Institute of Physics,
DOI: 10.1063/5.0191520.
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