  Measuring fast ions, most notably fusion alphas, in ITER and future reactors
remains an issue that still lacks an adequate solution. Numerical simulations
are invaluable in testing the potential and limitations of various proposed
diagnostics. However, the validity of the numerical tools first has to be
checked against results from existing tokamaks. In this contribution, a variety
of synthetic diagnostics for fast ions (collective Thomson scattering, neutral
particle analyzer, neutron camera, infrared measurements, fast ion loss
detector and activation probe) from the orbit-following Monte Carlo code ASCOT
are compared to measurements from several tokamaks (ASDEX Upgrade, DIII-D and
JET). Within the limitations of physics included in the numerical model and
availability of input data from experiments, the agreement between synthetic
data and measurements is found to be quite good.
