proton

Muons and why don’t we know about these guys?

Muons and why don’t we know about these guys? 2

I like particle physics (muons aren’t a tribe in the amazon). But it’s all from a distance…meaning, I’m really fascinated with how we discovered these particles and figured out if they are elementary but I’m no physicist. We all know about the two particles in the nucleus of an atom….the proton and neutron. Those aren’t elementary. They are made of quarks; up, down, charmed and others. But let’s just talk about muons and I’ll start by saying that maybe a hundred just went through your body since reading this.

We’ve known about muons for more than 70 years. Is it important to know about them? Maybe, I don’t recall hearing about them until I started reading astronomy texts. When we take classes in high school, someone (some committee) decides what we should learn and I guess they figured we need to know the “basics.” My son is learning the basics I think in 2nd grade. He brought home a bar chart that he completed. I think he could go to work and make at least minimum wage now. They seem to be learning more than we used to a long time ago. I wish they’d teach a kids physics course to him.

A muon is an elementary particle which means we don’t think it’s made of anything else. What’s interesting about muons is that we can use them to our benefit. And people are doing that now. As a matter of fact, 50 years ago someone used them to find out what was inside a pyramid. This is where this gets interesting. It’s all the sun’s fault. Particles like the muon are spraying down on us all the time and we know if they hit something in particular they might scatter slightly. Why not put a detector under the pyramid and see how those muons scatter. It was thought that this one pyramid in Egypt might have a special burial chamber. Instead of disturbing the Great Pyramid of Chefren they put detectors underneath it to find out how those muons behave after going through the pyramid.

Science is way ahead of most of us (it’s not too late to learn I tell myself). But, can you imagine how ingenius you’d be if you thought of applying something so simple as putting a detector underneath a pyramid? That guy, Luis Alvarez (Nobel Laureate), didn’t find a hidden chamber but he was seen as brilliant to come up with that idea (he was brilliant in plenty of other ways). So today we use muons in a similar way to detect what we can’t see. It’s one of the ways we search cargo for nuclear material. Muons behave a certain way when they go through high density materials. We can thank the Department of Homeland Security for applying this method to check for this stuff.

Here’s sort of a list of elementary particles, in case you wondered.

quarks, neutrinos, muons, electrons, photons, gluons, gravitons (hypothetical) and bosons (yeah, the Higgs is one of those guys).

Wow! So the protons and neutrons and electrons are all I learned in school but there are a huge number of other particles…that are known knowns…thanks for the phrase Donald R.

Here’s an interesting study using muon tomography (detection), http://www2.mate.polimi.it/ocs/viewpaper.php?id=70&cf=8

 

muon detector

muon detector

 

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Zealand to New Zealand, Rutherford to protons

Zealand to New Zealand, Rutherford to protons 0

If there’s a New Zealand there’s got to be an old one. We keep a lot of old things around, even countries and cities. A little later in this post I’m going to talk about a New Zealander named Ernest Rutherford. He did an amazing experiment. His “microscope” was as phenomenal as the LHC….Large Hadron Collider. And to me my little light microscope is pretty amazing but worlds apart from subatomic particle microscopes.

Back to part of the post title, Zealand. This is where I started getting confused. But let me try to explain this. Zealand is the largest island in Denmark. It’s Danish. Not Dutch. If you are from the Netherlands, you’re referred to as Dutch (apparently Dutch people are really a native ethnic group from the Netherlands). Let’s not go any further because I’m sure I’ll probably say something that isn’t correct (right). But there are some very famous Dutch people…very famous….van Gogh is probably someone practically everyone knows about.

On to Ernest Rutherford who is neither Dutch nor Dane. He was born in New Zealand however (a Kiwi 🙂 ). And what his microscope did (in the UK) was find that the center of the atom (we call the nucleus) had a positive charge. If you remember anything about an atom, you probably remember that electrons carry a negative charge and the protons (in the nucleus) have a positive charge. It makes you wonder how over 100 years ago someone figured that out. To me it just doesn’t seem like someone without an iphone could possibly have figured that out. I know that sounded stupid but it’s just amazing what science has known for a long time. You know where we stand…on the shoulders…..

A tad bit more about his “microscope.” There is no way to see an atom with ordinary light. An atom is too small to see with visible wavelengths. He sent alpha particles (radium decayed positively charged helium particles that had no electrons) through a thin sheet of gold and measured what came out on the other side. He also measured what was reflected and didn’t go through. That was his microscope. He expected all the alpha particles would go through the other side but not all did. Some bounced back. Remember, positive repels positive. But there is a large empty space in an atom so most particles went through. And just remember, any ordinary light hitting a thin sheet of gold doesn’t go through the gold. It takes a way smaller particle to do that.

So, a patient I had some years ago had a tumor in his eye. I found it and took a picture of it. Showed it to the patient.  He ended up seeing a doctor somewhere in California for proton beam radiation treatment. Yep, thanks to all the scientific discoveries, protons were eventually harnessed for our benefit. And thanks to the Zealands, new and old. May they keep adding on to our rich wealth of history and discovery.

Here’s a fun website that compares the various sizes of things in our universe…big to small. http://htwins.net/scale2/

 

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