Deal with the strip detector measurement description
For strip detectors, they usually contain double-side silicon modules in one layer. Currently we don't consider how to place the strips, e.g. include the stereo angle in building geometry. Here we use an approximate approach:
we take the double-sided strip(imagine both rotate 20 mrad) as a 2d "pixel detector", then the resolution will be:
sigma_rphi = sigma/cos(20)/sqrt(2) = 7mm/cos(20mrad)/sqrt(2) ~= 5mm
sigma_z = sigma_rphi * cot(20mrad) = 250mm
to keep consistent, 1 sensitive surfaces will be marked as "non sensitive": see #9