The energy spectrum of X-rays from rocket-triggered lightning

What is it about?

It is known that X-rays are routinely produced by natural and rocket-triggered lightning leaders. The energy spectrum of such X-rays has never been well measured because they are emitted in very short but intense bursts that result in pulse pileup in the detectors. We have recently developed and operated the first spectrometer for the energetic radiation from lightning. Using X-ray pulses preceding 48 return strokes in 8 rocket-triggered lightnings, for the first time, we accurately measured the energy spectrum of X-rays from rocket-triggered lightning leaders.

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Why is it important?

The energy spectrum X-rays from lightning leaders is important because it provides information about the source mechanism for producing the energetic runaway electrons and about the electric fields that they traverse. We found that the spectrum of X-rays from leaders is too soft to be consistent with the Relativistic Runaway Electron Avalanche mechanism.