Gain Monitoring System

2008 13th Jun. Fri.

Kobe Univ.

Hiroko Ikeda

Ideas• Fiber (connected to the acrylic plate with

optical cement) distribution.

• Side-emitting fibers

• Optical fibers with notches

I have tested above 3 methods to decidewhich one we will adopt for the FNAL beam test.

SetupⅠ. Fiber distribution (with acrylic plate)

Acrylic plate Acrylic plate

LED

Acrylic plates(0.8mm thick)

Hole(1.1mmφ)

Acrylic plate(27cm long)

Fiber distribution

• 0.02 ●:1 fiber (on bundle1)

●:1 fiber (on bundle2)

●:2 fibers (on bundle2)

Dark noise level (0.02p.e.)

Ⅱ． ESKA (side-emitting fiber =0.8 mm)Hole for MPPC (3mmX5mm)

Hole for ESKA (2mmX86mm)2mm

① ②

③

Reflector film

Black sheet

Hole for MPPC (3mmX90mm)

Hole for ESKA (3mmX90mm)

27.5mm

90mm

④ESKA

Ⅲ ． Optical fiber (with notches)

Optical fiber

28mm

Notch made with a file

Comparison●:acrylic plate

●:ESKA1

●:ESKA2

●:optical fiber with

notches

Dark noise level (0.02 p.e.)

Proposed setup for the FNAL BT ① ESKA Only

② ESKA and optical fiber

Optical fiber

ESKA

ESKA

Summary & Plans• Either ESKA or notched optical fiber are likely

candidates for the gain monitoring system.• To do (within a few days):

– Check connection between fiber and hole for fiber.– Examine position dependence of ESKA’s light decrease.

• Then we will decide the light distribution method and whole design of the system.

●:w/o light shield

●:w/ light shield

Try covering first half of acrylic bar