SENSITIVITY ANALYSIS FOR COMET

The magnetic field can be split into the contribution from the iron and the one from the coil. We have extracted the two parts from the TOSCA model (scc_009_pre) obtained from the cyclotron manufacturer ACCEL Instruments GmbH. For this purpose, we have recalculated the model with 1 % higher current. After subtracting the new field from the old (100 % current) and multiplying the resulting field with 100 we “extracted” the coil field contribution. The difference between the total field and the coil field is then assumed to be the iron contribution. The two field contributions were saved in separate files and can be added with any desired relative spatial shift. This superposition is a simplified approach, but for small coil shifts it is a good approximation. A practical alternative does not really exist, as for some cases of coil asymmetry we would need to calculate full models and abandon the reduction to 1/8, provided by the symmetry.