Scales the default transverse width (xywidth 50->200 cm) and every
layer thickness across the example/production geometries (run_pbwo4,
example.py/ipynb, run_sampling configs, export_xsec) by the same
factor, so the calo grows uniformly in x, y, and z.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Builds a minimal PbWO4 geometry, forces EM physics tables via a
zero-event run, then sweeps photon energy 1 eV-10 MeV with
G4EmCalculator to dump per-process mass attenuation coefficients to CSV.
lars