Tube Indexing and Symsets - Closeup
Tubes in symset “t” shown.
+/- 3 * (gap-1) tubes covers 3s scattering for lowest momentum particles that can penetrate to gap i.
Coverage improves dramatically with increasing momentum since the bulk of scattering occurs in the last penetrable gap. So the tubes included in a symset span the space of tubes which could be fired by a vertex muon entering at the center of that symset.