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Sunday, November 5, 2017

Muon


Muons in the Cathedral
The first ten seconds give you some context, so pay attention.

Some science dudes think they have found a secret chamber in the big pyramid. They claim they used a muon detector. Muons? I haven't heard anything about muons in a long time. I just barely recognize the word as a name for some kind of sub-atomic particle.

There is something wrong with Muons. On one hand they weigh (mass) 207 times as much as an electron, but when they decay all you get is an electron and two virtually massless neutrinos. What happens to all the extra mass? Does it get turned into energy? We aren't talking about very much mass here. . . pause while we figure out just how much a muon masses.

First we find that the muon mass is:
105.6583745(24) MeV/c2
MeV/c is a no unit of mass I've ever hear of, but following the link takes us to a conversion formula that translates it into atomic mass units (u). 
1 u = 931.4941 MeV/c2
So we're dealing with something like one-ninth (105 / 931) of one atomic mass unit. If all that gets turned into energy, how much is it?

Well, Wikipedia's Elevtronvolt page translates electronvolts to joules, so we don't have to do the energy to mass to energy conversion. We go straight from one form of energy to another:
1 Electron Volt = 1.6021766208(98)×10−19 Joules
Call it 1.6 x 10^19. So:
1 Me (million electron volts) = 1.6×10−13 Joules
And the mass of a muon is worth
 106 x 1.6×10−13 = 170×10−13 Joules
1 Joule is equal to 1 Watt-Second.

A square kilometer contains one million square meters. 10,000 muons impact every square meter every second. In one second, ten billion muons will impact our square kilometer of land. In a day we'll have 86.4 trillion muons, which is 86.4 x 10^12. So in one day all those muons will generate one-twentieth of a Joule, or about one Watt for 5 milliseconds. Might be enough to make an LED flash. Guess we don't need to worry.

When I started searching for information about muons, I found a couple of people who claimed to have built muon detectors for cheap, but they didn't actually tell you how they are made. The muon detectors used in the video above, and in the pyramids don't just detect the muons, they also tell you what direction they are coming from. You could do that with home made detectors, if you could find out how to make them. They would just need to be very small and you would need a bunch of them.

2 comments:

Anonymous said...

I had to listen to the video twice and I still didn't get every word clearly. She spoke extremely quickly and with a very thick Italian accent, and the closed captions were zero help. Nevertheless, it looks like an interesting project. Thanks for another great diversion.

Your pal,
James.

Chuck Pergiel said...

The thing I liked about the video is it shows what a muon detector looks like. And they used it on the cathedral in Florence, which featured in mini-series about the Medicis I saw.