Recent content by Astrofiend

Homework Statement For an assignment question, I am trying to work out an approximate formula for the average recoil energy of an electron involved in a Compton scattering event (averaged over all scattering angles theta). Note that there are other ways to do this problem than the formula I...

Ahhh - OK. It didn't even occur to me that the wording could be taken in that way - that makes a great deal more sense. Cheers for that!

Homework Statement I have an assignment question that asks the me to look up the partial mass attenuation coefficients for Beryllium for Rayleigh Scattering, Compton Scattering, the Photoelectric Effect, and Pair Production in both the nuclear and electron fields on the NIST database for...

Cheers mate - appreciate the response! I'll have to go away and think it over a bit...

I've been studying relativity and standard model physics, and I don't understand how it is determined what 'things' go together to form a 4-vector. For example, there is the familiar energy momentum 4-vector, the charge-current density four vector, the phi-A (scalar/vector potential) 4-vector...

Damn it! Still not seeing it...

Homework Statement I'm having problems seeing how the transformation to Eddington-Finkelstein in the Schwarzschild geometry works. Any help would be great! Homework Equations So we have the Schwarzschild Geometry given by: ds^2 = -(1-2M/r)dt^2 + (1-2M/r)^-^1 dr^2 +...

Thanks for that - yep, I had come around to that conclusion. What about the other conditional probability assignments that I made? Are they valid?

Homework Statement I am trying to work out what I believe to be a fairly simple 'odds ratio' problem using Bayesian probability for my physics class. Here is the statement of the problem: "Two criminals have left traces of their own blood at the scene of a crime. A suspect, Oliver, is tested...

"(You forgot to take the square root of the RHS!)" Der! Must be tired - or just plain dumb... Thanks a lot Doc Al - I got it out easily after that little hint. I appreciate it a lot!

Homework Statement I am trying to show that the velocity of an ultra-relativistic particle can be approximated by the following expressions: v \approx c \left[1-\frac{1}{2}\left(\frac{mc^2}{E}\right) ^2 \right] and \frac{1}{v} \approx \frac{1}{c}...

Done! (only took 5 hours of staring at it waiting for my slow brain to tick over...) I didn't actually need to go through all of that ungodly expanding. Thanks to those who helped! Much appreciated.

OK - I think I'm really not getting how the maths goes on this. If anyone can have even a brief look at this and tell me what I'm doing wrong, that'd be great. I've tried to expand out the first (kinetic) part of the primed Lagrangian as described above, and got (using g = \frac{g1}{2}...

Thanks guys. I'll try to nut it out this afternoon... Thanks for picking up that typo...

Homework Statement I want to show explicitly that the Lagrangian... L_\Phi = (D_\mu \Phi)^\dagger (D^\mu \Phi) - \frac{m^2}{2\phi_0 ^2} [\Phi^\dagger \Phi - \phi_0 ^2]^2 where \Phi is a complex doublet of scalar fields, and D_\mu = (\partial_u + i \frac{g_1}{2} B_\mu) is the...