MICE Fiber Tracker Design Update

1
MICE Fiber Tracker Design Update

• Requirements and Proposed Detector
  Implementations
• A. Bross
• Fermilab

2
Detector Options

• Letter of Intent based the trackers on four
  planes of scintillating fiber

3
Fiber Tracker Option for MICE

• At this point we have taken a VERY conservative
  approach to the Fiber Tracker
• Assume
• Backgrounds are extremely high!
• Requires use of smallest fiber diameter possible
• 350 micron
• Under these assumptions, the Fiber option may be
  the only one that will work
• uvt readout station
• Doublet structure
• 0.3 Xo per station
• 5 stations/spectrometer
• This yields a system with about 45k channels!
• VLPC readout
• lt3 m light piping fibers from detector to VLPC
• MAJOR EFFORT And COST
• 5M
• Of course, other assumptions can reduce the
  cost/effort significantly!

4
Fiber Tracker Channel
Optical connector
Mirror
Scintillating Fiber
Waveguide
VLPC cassette
Electronics
Cryostat
5
Scintillating Fiber Ribbons

• Interlocking doublet
• 835 mm 3HF scintillating fiber
• Fluorescence 525 nm (peak) to 610 nm
• Grooved substrate - machined Delrin
• Pitch between 915 and 990 mm
• Optimal P/d 1.2
• Substrate put into curved backbone
• Fibers glued together with polyurethane adhesive
• Ribbons is then QCed using scanning X-ray source
• Technique is very fast
• All MICE planes require 4 MM effort Tooling

6
VLPC Readout Option

• VLPC (Visible Light Photon Counter)
• Cryogenic APD operating _at_ 9K
• Characterization/test/sort Cassette Assignment
• As shown

7
1024 Channel VLPC Cassettes

• Engineering Design
• 8 128 channel modules
• Cassette carries two 512 ch readout boards
• Front-end amp/discriminator
• Analog SVX IIe

8
Lab 3 CRT (Singlet) Light Yield
Lab 3 CRT Light Yield Summary Covers Waveguide
lengths 7.7-11.4m
9
MICE Fiber Tracker

• Conventional FT using MAPMT
• With same length of readout fiber
• If waveguides are used
• L430 nm 1300 dB/km (1/e 3.4m)
• L525 nm 450 dB/km (1/e 9.6m)
• D0 measured 8.1m _at_ lfp 525 nm
• QE 20
• Yield
• 9 X 20/80 X exp(-5/3.4)/exp(-5/8)
• 1 pe
• Waveguide length would have to be limited to 2 to
  3 meters

Attenuation vs. wavelength of Kuraray clear fiber
Conventional Blue
3 HF
10
On-Going Work

• We have prototyped ribbons
• 500 and 350 micron diameter
• Will measure light yield with VLPCs at Fermilab
• Trying to put together small test system (128 ch)
  for use at KEK test beam in Dec.
• Negotiated with Fermilab management for support
• Most parts exist, however need to assemble new
  cassette
• 128 ch VLPC cassette based on D0 parts
• Cryo system exists
• Commercial Oxford flow cryostat
• Can measure
• Light yield
• Resolution
• Timing performance