  The activation probe is a robust tool to measure flux of fusion products from
a magnetically confined plasma. A carefully chosen solid sample is exposed to
the flux, and the impinging ions transmute the material making it radioactive.
Ultra-low level gamma-ray spectroscopy is used post mortem to measure the
activity and, thus, the number of fusion products.
  This contribution presents the numerical analysis of the first measurement in
the ASDEX Upgrade tokamak, which was also the first experiment to measure a
single discharge. The ASCOT suite of codes was used to perform adjoint/reverse
Monte Carlo calculations of the fusion products. The analysis facilitates, for
the first time, a comparison of numerical and experimental values for
absolutely calibrated flux. The results agree to within a factor of about two,
which can be considered a quite good result considering the fact that all
features of the plasma cannot be accounted in the simulations.
  Also an alternative to the present probe orientation was studied. The results
suggest that a better optimized orientation could measure the flux from a
significantly larger part of the plasma.
