Recent content by kylie14

  1. K

    Decay of Pi0 Meson: Exploring EM & Annihilation

    Thank you for sorting out the thread for me- I am unfamiliar with how to do things like that. I also don't know how I missed that there was a particle physics thread. Thanks for the reply- Your response has cleared things up for me for the most part. Obviously all mesons are unstable, and if...
  2. K

    Decay of Pi0 Meson: Exploring EM & Annihilation

    About the pi0 meson: I have a vague understanding of the idea of quantum super-position giving the linear combination of uubar and ddbar, even though it is very hard to picture - if possible I would like to avoid going off onto a tangent about this... My question is: am I right in saying...
  3. K

    Dipole-dipole interaction

    I have an answer: (-mu_0 / 2 pi r^3) p1 ∙ p2 I have a problem with this answer though; while it takes into account the orientation of the two with respect to each other, shouldn't it also take into account the orientation of each with the vector joining them? My equation seems to agree with a...
  4. K

    Dipole-dipole interaction

    Actually, sorry, I think I was being stupid! Do I consider it both ways round, so treat p1 as being in an external mag field (from p2), then p2 in an external field (from p1) and then sum the energies together?
  5. K

    Dipole-dipole interaction

    Say you have two magnetic dipole moments, say p1 and p2, which are separated by a distance r, with no external magnetic fields. If you want to figure out the energy of their magnetic interaction, is it valid to figure out the energy of p1 in the magnetic field generated by p2, or vice versa...
  6. K

    Hamiltonian and spin states

    Thanks for your reply. The hamiltonian can be written as a linear combination of spin operators if that's what you mean? The problem I have is that I don't remember considering spin when I formed the hamiltonian (although I have confirmation that the hamiltonian is correct).
  7. K

    Hamiltonian and spin states

    Sorry if this question is very general/vague, but I would prefer a general answer rather than a specific solution... I'll put more detail in if necessary though. So, say we have a Hamiltonian for a system (of fermions, spin 1/2); then we find its eigenvalues and hence eigenstates. These are...
  8. K

    Representations of finite groups

    That all makes sense to me; thanks for explaining it so clearly!
  9. K

    Representations of finite groups

    Thank you, that does clarify things for me. Say you had a 1D irreducible representation of a finite group, though, and then also a 2D one for the same group; is there any advantage in using the 2D one? What I mean is, if there is a 1D representation possible, why bother with a 2D one even if...
  10. K

    Representations of finite groups

    I'm just having a little trouble getting my head around how representation theory works. Say for example we are working with the dihedral group D8. Then the degrees of irreducible representations over C are 1,1,1,1,2. So there are 4 (non-equivalent) irreduible representations of degree 1...
  11. K

    Intrinsic fermi energy of silicon

    Yes, I think that's it. Thanks again!
  12. K

    Intrinsic fermi energy of silicon

    I needed it because it appeared in an equation I needed to find how far the fermi energy is below the conduction band in n-type silicon. I've just found another equation though, and you're right. I can find the distance between E_f and E_i, using E_f - E_i = kT ln(n/n_i) and then if E_i is...
  13. K

    Intrinsic fermi energy of silicon

    Yes, but how to I find out where the what the energy is at the centre of the band gap? Thanks for your reply
  14. K

    Intrinsic fermi energy of silicon

    I've tried to look this up online, but I can't find it anywhere. I'm just looking for the intrinsic fermi energy of silicon E_i ? Can someone maybe direct me towards a website where I could look it up? Either that, or is there a way to calculate it from the energy gap for intrinsic silicon...
  15. K

    Particle Physics Struggles: Which Interactions are Most Likely?

    Brilliant, thanks, I'm sorted! I think I have enough now to be able to figure it out in general.
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