Lightning Emits X-Rays

Makarand writes "Scientists have now confirmed that lightning does emit X-rays according to this BBC News article. That lightning might emit high energy radiation was first suggested in 1925, however, confirmation had proven difficult because of the sporadic nature of lightning and the electromagnetic "noise" it generates. A team at the University of Florida built a special tower allowing them to study lightning in detail by firing rockets trailed by grounded wire into storm clouds to trigger strikes. They detected X-Ray bursts that typically lasted less than 100 microseconds. The breakdown of air by strong electrical fields when the lightning creates a path from clouds to ground may generate these X-rays."

Comments

Aha!

[xyphus]

Science has finally explained why lightning always reveals Donald Duck's skeleton!

Re:Aha!

[Simon Field]

Now if we could just get him to wear pants...

Seriously, though, how do you shield your X-ray detector so you can prove to yourself that what you are seeing is not just the effect of power spikes and RF interference in your instruments?

I'm sure they did a good job of it -- but as a geek thing, I'd like to see how it was done.

Re:Aha!

[Viadd]

They had two photomultiplier tubes (PMTs): one was coupled to a scintillator (crystal that makes light when X-rays hit it), one wasn't. There was a hefty signal in the PMT that was coupled to the scintillator, the other showed a flatline.

Re:hands

[Yarn]

What a pick up line... "Want a free mammogram, my dad invented them"

You lucky, lucky man.

Re:hands (OT)

[Cy Guy]

i live in a suburb just north of dallas, from about march-november we see thunder about once a week on average.

WOW! I've never seen thunder in my life. Could you describe what it looks like?

a couple of the girls i told this to believed it, .... telling them my dad worked on the original mamogram/soft tissue imaging systems helped with my credibility considerably. a good, fairly original line that will get you far :)

So how successful was this to convince them that you were also an expert at performing manual breast exams, and they should let you demonstrate on them?

The real source is

[Technician]

Just my humble opinion, but in an X-Ray tube, the X-Rays are produced when high speed electrons strike a hard target (tungston in the tube). I wonder if the X-rays do not originate from the lightning strike itself, but from the high current striking the metal (the wire) that has been added to the mix in their test. Any data on a strike minus the added metal?
My guess if a strike hits a radio tower, the only portion of the bolt generating X-rays is at the point of the electrons striking the metal tower (assuming cloud negative strike). Just a hunch. I could be completely off base on this one.

Re:The real source is

[DrFlounder]

The radiation from an X-ray tube is a special case of bremsstrahlung, or braking radiation, that occurs when a charged particle is accelerated (or decelerated). Often this happens when an energetic electron is decelerated by hitting metal, but anything that changes a electron's trajectory will cause it to radiate.

The real story here is not that X-rays are emitted, but that there are high energy electrons produced by lightning (called runaways because they gain more energy from the accelerating electric field than they lose from collisions with the background particles). Existing models of lightning don't predict the creation of these electrons. In this sense, it doesn't matter what caused the electrons to radiate. What matters is that electrons were created that had enough energy to produce the X-rays, which means that our models need to be corrected.