* Reference
(0,0,0) is taken at the center of the target chamber (not at the center of the target)

* Survey Numbers:
- gem and hycal positions: https://wiki.jlab.org/pcrewiki/images/0/0b/B1721.pdf
- target positions: https://wiki.jlab.org/pcrewiki/images/a/a2/B1718.pdf
- hycal surface: https://logbooks.jlab.org/entry/3467294
- target center: https://logbooks.jlab.org/entry/3458879

* Target Material
radius: 2.5 cm
length: 4.0 cm
center: (0,0,89 mm) 
material: H2 gas, 19.5 K, 62.7 Pa, 7.79 kg/m3

* Target Cell
box: 3.5 x 3.5 x 4 cm3 surrounding the material
material: copper
center: (0,0,89 mm) 

* Target Cell Windows
doc: https://drive.google.com/file/d/0B1LlET0ObD0MREc2aEhfMmNhMzQ/view
at both end of the cell (0,0,69 mm) and (0,0,109 mm)
hole radius: 2 mm
thickness: 7.5 um
material: kapton

* Downstream Chamber and Tube
doc: https://userweb.jlab.org/~mezianem/PRAD/2nd_chamber_final.pdf
cylindrical polygon
z planes: (16.3 cm, 49.13 cm, 49.13 cm, 51.67 cm, 51.67 cm, 87.3 cm)
inner radii: (7.56 cm, 7.56 cm, 7.56 cm, 7.56 cm, 17.30 cm, 17.30 cm)
outer radii: (8.00 cm, 8.00 cm, 17.78 cm, 17.78 cm, 17.78 cm, 17.78 cm)
material: aluminum

* Downstream Chamber Window
position: (0,0, 16.3 cm)
hole radius: 22.8 mm
thickness: 7.5 um
material: kapton

* Vacuum Box
doc: https://userweb.jlab.org/~mezianem/PRAD/PRad_Vacuum_box.pdf and https://userweb.jlab.org/~mezianem/PRAD/PRad_window.pdf
cylindrical polygon
z planes: (87.3 cm, 94.1 cm, 104.9cm , 302.6 cm, 316.8 cm, 512.47 cm)
inner radii: (17.3 cm, 17.3 cm, 50.17 cm, 50.17 cm, 78.11 cm, 78.11 cm) 
outer radii: (17.78 cm, 17.78 cm, 50.8 cm, 50.8 cm, 78.74 cm, 78.74 cm)
material: aluminium

* Vacuum Box Window
doc:
- https://wiki.jlab.org/pcrewiki/images/1/1f/Operational_safety_procedure_form_58956.pdf
- https://userweb.jlab.org/~mezianem/PRAD/PRad_window.pdf

* Vacuum Tube
start at (0,0, 506.88 cm) till the end
outer radius: 1.9 cm
thickness: 1.2446 mm
material: stainless steel

* Flange on Vacuum Tube
start at (0,0, 506.88 cm) till (0,0, 507.88 cm)
outer radius: 3 cm
thickness: 1.1 cm
material: stainless steel

* GEM
gem z centers : 518.3 cm and 522.3 cm
gem x centers: -25.32 cm and 25.32 cm
gem dimension (x2): 55.04cm x 122.88 cm x 1.4 cm
hole radius: 2.2 cm
external frame width: 1.5 cm
center frame width: 7.4 cm
gem gas material: ArCO2 (70% Ar, 30% CO2)
- 5 gem foils (-4 mm, -1 mm, +1 mm, +3 mm, +5 mm)
  gem foil thickness: 50 um
  gem foil material: kapton
- 8 gem copper foils  
  gem copper foil thickness: 5 um
  gem copper foil material: copper
- 2 gem windows (-7 mm, +7 mm)
  gem window thickness: 15 um
  gem window material: kapton

* HyCal
doc: https://userweb.jlab.org/~mezianem/PRAD/HyCal_Drawings.pdf