Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Acceleration of electrons.

  1. Apr 19, 2006 #1
    Hi all,
    Is the next quote true? If it has already been discussed here can anyone show the thread. Thanks.

     
  2. jcsd
  3. Apr 19, 2006 #2

    Meir Achuz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    "Innumerable linear accelerator experiments confirm that atomic orbiters DO NOT RADIATE at c/137."
    You'll have to give more of the quote, or a reliable source.
     
  4. Apr 19, 2006 #3
    www.newphysics2000.org/facts.htm

    The reason I didn’t give the full reference is that this place looks a bit suspect to say the least. But I singled out point 5 of the fact sheet because of the assertion that many experiments had it confirmed.
     
  5. Apr 19, 2006 #4
    You're right when you say "suspect to say the least". I wouldn't bother trying to use that site to understand any facts that may actually be contained there.
     
  6. Apr 19, 2006 #5

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    To be blunt, the statement you quoted is rather stupid. Linear accelerators, by definition, accelerate FREE particles. These particles aren't in any bound state. So how could there be ANY "orbitals" or "orbiters" (whatever those are). Without such a thing, how could linear accelerators confirm or disprove whether such a thing radiate at ANY value?

    In other words, the site put several things that simply do NOT make any sense together into a sentence.

    Zz.
     
  7. Apr 19, 2006 #6
    Thanks a lot guys. So I can again trust the standard text books, which as far as I know never put restrictions at any speed on radiation from an accelerating charge.
    "Innumerable linear accelerator experiments confirm” what a claim to make!

    While I’m on the subject of suspect sites have any of you come across the work of Dr. Paul Marmet?
     
  8. Apr 20, 2006 #7

    arivero

    User Avatar
    Gold Member

    Still it is interesting to step a little about the classical relativistic speed of a circular orbiter in a coulomb potential. It happens that the product of angular momentum times speed is equal to the coupling constant, Lv=K. Thus a fascinating phenomena happens: as the maximum speed is c, it implies that the minimum angular momentum is K/c. This minimum is reached for radious->0.

    Now if the coupling is K=hc/137 and the angular momentum is the smallest quantum one, h, then the speed of the circular orbit is K/h=c/137, and greater angular momenta have smaller speeds. This is the source of the statement in the webpage, and it comes from old good Bohr quantum mechanics.

    [In fact I do not know how to define precisely the speed of a circular orbiting (s state?) particle in modern quantum mechanics. It is possible to define the period of the orbit, and is is possible to calculate the average radious, so one could just divide, but it is a very ad-hoc method; one could have different definitions of the period, and different ways to choose radiouses.]

    The combination of the quantum minimum, h, and the relativistic minimum, K/c, is the first hint to claim that there could be no exist point-like nuclei with Z > 137, as then K/c>h and a state of angular momentum h can not exist (with r>0); I suppose that electrons are then trapped in the nuclei and then Z becomes less than 137 again :smile:
     
    Last edited: Apr 20, 2006
  9. Apr 20, 2006 #8

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    But this has absolutely nothing to do with a "linear accelerator"!

    Zz.
     
  10. Apr 20, 2006 #9
    From: http://fr.physics.sunysb.edu/francium_news/production.htm

    The Stony Brook group creates Fr atoms with atomic weight 210, (half-life of 3.2 minutes) by bombarding a gold target with beams of oxygen from the linear accelerator in the basement of the physics building at Stony Brook.
     
  11. Apr 20, 2006 #10
  12. Apr 21, 2006 #11
    Arivero, your answer reminded me of a thread in PF some months ago about ionisation energies. I stated something like that the ionisation energy of the first electron of an atom can be worked out using good old Bohr, taking in account relativistic mass. However the calculated values are always a bit too high. Do you or anyone know why?
     
  13. Apr 21, 2006 #12

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Note: An ACCELERATOR is NOT a COLLIDER!

    When you say something is an accelerator, it doesn't mean you are doing high energy particle collider experiment! I work at an accelerator. I study the beam physics and acceleration mechanism. I do ZERO particle collision other than the beam dump at the end of the beamline. Synchrotron centers all over the world also have an accelerator to get electrons up to speed before they are dumped into the storage ring - no study of collisions there either!

    Zz.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Acceleration of electrons.
  1. Accelerating electrons (Replies: 4)

  2. Electron capture (Replies: 2)

  3. Electrons in nucleus? (Replies: 5)

  4. Electron's Mass (Replies: 3)

Loading...