ECal Layer Z-Position Bug

[SanjitMasanam]

Describe the bug
Currently, the silicon layer positions in GDML and those saved to ECalSim/RecHits are not the same. This may also result in incorrect layer weights, but further testing needs to be done.

To Reproduce
Run the script below to see the mismatch

import numpy

# Constants
PCB_dz = 1.666
Glue_dz = 0.1
Si_dz = 0.3
GlueThick_dz = 0.2
CarbonBasePlate_dz = 0.79
MotherBoardAssembly_dz = 8.166
CarbonCoolingPlane_dz = 5.7
CarbonCoolingPlane_dy = 495.3
CarbonCoolingPlane_dx = 673.1
strongback_bar_dy = 25.4
strongback_bar_dx = 838.2 - 0.6815
PCB_Motherboard_Gap = 3.5
FrontTolerance = 0.5
BackTolerance = 0.5
preshower_extra_air = 0.5
bilayer_start = 240.5
sampling_section_offset = 2*preshower_extra_air
front_pre_tungsten_dz = 2.0
cooling_pre_tungsten_dz = 2.0

# Arrays
layerZPositions = [7.932, 14.532, 32.146, 40.746, 58.110, 67.710, 86.574, 96.774, 115.638, 125.838, 144.702, 154.902, 173.766, 183.966, 202.830, 213.030, 231.894, 242.094, 260.958, 271.158, 290.022, 300.222, 319.086, 329.286, 351.650, 365.250, 387.614, 401.214, 423.578, 437.178, 459.542, 473.142, 495.506, 509.106]
bilayer_absorber_cumulative = [0.0, 3.0, 8.0, 15.1, 22.2, 29.3, 36.4, 43.5, 50.6, 57.7, 64.8, 71.9, 85.9, 99.9, 113.9, 127.9, 141.9]
front_tungsten_dz = [1.0, 2.0, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 7.0, 7.0, 7.0, 7.0, 7.0]
cooling_tungsten_dz = [1.0, 1.5, 1.8, 1.8, 1.8, 1.8, 1.8, 1.8, 1.8, 1.8, 1.8, 3.5, 3.5, 3.5, 3.5, 3.5]

# Calculated constants
Flower_dz = PCB_dz + Glue_dz + Si_dz + GlueThick_dz + CarbonBasePlate_dz
bilayer_noabsorber_thickness = FrontTolerance + PCB_dz + PCB_Motherboard_Gap + Flower_dz + CarbonCoolingPlane_dz + Flower_dz + PCB_Motherboard_Gap + PCB_dz + BackTolerance

# Position of silicon modules
first_sc_z_pos = bilayer_start + FrontTolerance + PCB_dz + PCB_Motherboard_Gap + PCB_dz + Glue_dz
second_sc_z_pos = bilayer_start + FrontTolerance + PCB_dz + PCB_Motherboard_Gap + Flower_dz + preshower_extra_air + CarbonCoolingPlane_dz + CarbonBasePlate_dz + GlueThick_dz
calc_layers = [first_sc_z_pos, second_sc_z_pos]
for i in range(len(bilayer_absorber_cumulative)-1):
    odd_layer = bilayer_start + sampling_section_offset + bilayer_noabsorber_thickness*(i+1) + bilayer_absorber_cumulative[i] + BackTolerance + front_tungsten_dz[i] + FrontTolerance + PCB_dz + PCB_Motherboard_Gap
    even_layer = bilayer_start + sampling_section_offset + bilayer_noabsorber_thickness*(i+1) + bilayer_absorber_cumulative[i] + BackTolerance + front_tungsten_dz[i] + FrontTolerance + PCB_dz + PCB_Motherboard_Gap + Flower_dz + cooling_tungsten_dz[i] + CarbonCoolingPlane_dz + cooling_tungsten_dz[i] + CarbonBasePlate_dz + GlueThick_dz
    calc_layers.append(odd_layer)
    calc_layers.append(even_layer)

# print results
print("True  Given  Diff")
for i in range(len(layerZPositions)):
    print(round(calc_layers[i] - 240, 3), round(layerZPositions[i], 3), round(numpy.abs(calc_layers[i] - layerZPositions[i] - 240), 3))

Desired behavior
We want the GDML and defined positions to match and an easier way to check if this issue arises again with new versions of the geometry. #1482 addresses the check.