More FAX/PAX config parameters

[l-althueser]

I saw that in FAX/HAX there is also an option the set the drift_field and s2_mean_area_fraction_top. I don't know if we need them but we could add them to the sciencerun flag and use the actual values. At least the drift_field could be adjusted by the field macros.

[pdeperio]

I didn't add drift_field yet since fax is currently using a simple model here, which bypasses the s1_ER_recombination_time model that depends on drift_field. You can add it, but just include a note saying it's not currently used. Also, I just hardcoded the EFIELD parameter in run_sim.sh, but can be improved as you described (pulling from the G4 macro file).

Indeed we should tune s2_mean_area_fraction_top too, as well as all the correction maps as defined in hax, feeding into pax (S1: s1_light_yield_map, S2: s2_light_yield_map, FDC: rz_position_distortion_map). Would you be able to add these?

For the long term, this also ties into the implementation of run dependence for MC.

[pdeperio]

Perhaps @l-althueser is busy, how about @jpienaar13 or @pietrodigangi ?