| Routine ID: PHYS251 | |
|---|---|
| Author(s): | Submitted: 10.10.89 |
| Origin: G.Tromba, P.Bregant | Revised: 16.12.93 |
GRAYL generates Rayleigh scattering of a photon using the random-number composition and rejection technique to sample the momentum of the scattered photon and the scattering angle, according to the form-factor distribution. In this reaction no new particles are generated and the kinematical quantities of the scattered photon replace the original ones in the /GCTRAK/ common block.
Activation of the Rayleigh scattering is done via the FFREAD data record RAYL. If this process is activated, GRAYL is called by GTGAMA when a Rayleigh scattering occurs.