Re: [Phys-L] Particle physics

[Paul Lulai <plulai@stanthony.k12.mn.us>]

> We believe leptons, quarks, and some bosons are fundamental.



What do you mean by "we", Kemosabe?



As others have pointed out, fundamentalism is in the eye of the beholder.



Besides, it's a moving target.  It changes as we learn more.

Democritus thought atoms (pretty much by definition) were fundamental.



Most importantly, who cares?  Suppose I told you that XXX was fundamental ... what would you do with the information?

The physics is what it is and does what it does.  It usually does not much care what labels we hang on things.





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I am attempting to make some materials that students can use when reviewing particles, particle detectors, and so on.  One aspect worth investigating (in my mind) is how our understanding changes over time.  I am trying to show that the target is moving and that is acceptable.  The more that is found out, the more there is to investigate and refine. I plan to include something that shows that atoms were once thought fundamental, then protons & neutrons, now we are at leptons, quarks etc...  Of course these may be fundamental, and they may not be fundamental.  If they are not, their parts aren't visible because we don't have the tools to see inside of them.  I would think this is acceptable, Kemosabe.

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  There are some labels that do matter, such as spin and

  charge and lepton number (among others).  That's because

  they connect to the real physics.  In particular, those

  labels connect to conservation laws.

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yep. We plan to discuss energy, momentum, charge, and mention lepton number.  I won't go into baryon number because the students will be at varying ages and stages of their science careers.  I hope a bit of 3, a mention of 4 and the possiblity of more is a decent intro to 9-12 graders.

There is the challenge of making materials that kids can use, that shows enough that I am not cheating anyone or lying about what is involved, but that is at the same time do-able by students that have limited backgrounds (not just my own students, but others as well)

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> must daughter particles be fundamental?



Definitely not.  For example, the thorium decay chain produces a bunch of daughters, including radium, radon, polonium, and others ... none of which are particularly "fundamental" by any post-Democritus definition.



> within the accelerator & detector, is there something like pair

> production happening?



Sure.  That's pretty much the whole point.  That's why huge energies are needed.



Also, in a proton/proton collision, you know that protons are neither charmed nor strange.  So to produce charmed and/or strange particles, you obviously cannot do it by simply rearranging the quarks you started with.

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Thanks for this example! I am drowning a bit when I combine my reading, questions, and memory. I had the positron / electron annihilation example to convince myself, but this helps.  I forgot to look at the charmed / strange quark detection. Perfect.

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If what I generate is worth the time I put into it, maybe I'll share it here.

Thanks again.



Have a good one.

Paul.

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