Material specifications for FDC Redesign
From GlueXWiki
We are pursuing a couple of options for reducing the thickness of the FDC packages. The following items are common to both designs:
- The thickness of the Kapton in each cathode plane is 25 microns
- The thickness of the Copper in each cathode plane is 2 microns
- The strips are excluded from a 10 cm diameter region about the beam line
- There is one ground plane per cathode plane composed of 6.3 micron Mylar with 0.1 micron Aluminimum on each side of the Mylar
- The FDC frames in the inactive area are composed of a sandwich of E-glass/carbon fiber/rohacell composite, polyethylene spacers, and FR-4/G10 wire frames
as described in GlueX-doc-800.
- The chamber gas mixure is 40% Argon/60% CO2.
The two options for the rest of the material are:
- 5 mm thick low-density Rohacell backing in the active region with a 10 cm diameter hole cut out of the center (including the copper and Kapton).
- No foam backing in active region, but the Kapton goes all the way through the beam hole.
The questions we would like to address are:
- What is the effect of reducing the material in the inactive area on photon conversions?
- What is the effect of reducing the material in the active area on rates on the strips and wires near the beam line?