We present results of test-particle simulations on both the first- and the
second-order Fermi acceleration for relativistic parallel shock waves. Our
studies suggest that the role of the second-order mechanism in the turbulent
downstream of a relativistic shock may have been underestimated in the past,
and that the stochastic mechanism may have significant effects on the form of
the particle spectra and its time evolution.Comment: Poster at "The XXII Texas Symposium on Relativistic Astrophysics",
Stanford, USA, December 2004, (TSRA04), 6 pages, LaTeX, 5 ps/eps figure