The expected performance of various neutrino beam configurations
has been studied. The so-called `reference beam', shown
in Figure4 and outlined in Appendix A of
reference [5], has been investigated in detail and the
results are discussed below. The `reference beam' should be
considered as a preliminary variant from which an optimised
scheme to match the requirements for the LBL and SBL
appearance experiments will be developed.
Figure 4: Components of the proposed neutrino beam.
A full Monte Carlo simulation of the `reference beam', called NGSSIM and based on the CHORUS and NOMAD application, has been made using the hadronic production model FLUKA97 [8] specifically integrated into GEANT 3.21 for this simulation. The neutrino parents are tracked in detail to their point of decay and realistic values based on the reference beam parameters have been used for the definition of the geometry together with the material thicknesses, magnetic field strengths etc.
Figure 5 shows the predicted 
flux spectrum
produced by the NGS `reference beam'
while Table 1 gives the average energies, contamination
and expected number of events for TOSCA.
The TOSCA fiducial mass and area are 2.4 t and
, respectively.
It should be noted that NGSSIM predicts about a 
higher
flux than the FLUKA97 simulation detailed in reference [5].
The difference seems to be explainable by the different amount of material
along the beamline assumed in the FLUKA97 simulation. A detailed comparison
is presently in progress.
A number of different beam optics have already been tried and various beam
configurations more favourable than the `reference beam' for appearance experiments
have been identified. This optimisation work is presently in progress.
Table 1: Predicted Performance of the NGS `reference beam' at the Location of TOSCA.
Figure 5: Energy distribution of the flux at the TOSCA detector.