4 Expected WXM sensitivity

We have carried out Monte Carlo simulation to estimate the sensitivity of WXM to GRBs. Here, the photon energy was limited within 3-10 keV to reduce the blurring due to penetration. Then the position histogram in 0.5 mm bin was simulated for the detector geometry. The GRB direction was reconstructed by cross-correlating the simulated data with the number of templates corresponding to various incidence angles. In the simple simulation with 2 second integrations, the correct position was obtained for half of the events that occur within the field of view of the WXM with peak fluxes of 4 ph/cm²/s ($4 \ 10^{-8}$ erg/cm²/s over the 3-10 keV range) and, under favorable conditions, some events down to 0.4 ph/cm²/s. Assuming the BATSE $\log{N}-\log{P}$ relation, this sensitivity results in localization of about 30 GRBs per year.