Wavefunction collapse on degenerate states

1. Jul 20, 2011

osturk

Hello, I am a beginner on the sbject so please correct if I'm using some sloppy terminology. I'll try to be clear.

Consider a Hamiltonian with degenerate energy eigenstates (say the degeneracy is on angular momentum as in hydrogen atom).

Which of the degenerate eigenstates would the wave function collapse on, after an energy measurement?

Would the resulting wave function be a linear combination of the degenerate eigenstates (which has different angular momentum numbers m,l)?
If so, how are the coefficients of the linear combination determined?