Transcript Document
The Fiber Tracker Option for MICE Spectrometers
The D0 Central Fiber Tracker – Experience and Implications for MICE A. Bross Fermilab
MICE Collaboration MTG IIT – Feb 2002
Fiber Tracker Option for MICE
In its simplest implementation, a FT for MICE could consist of two upstream and two downstream x-y tracking planes (assumes no or low background!) u-v-t option gives more redundancy With 500 micron round fiber and a fiber doublet structure (detail later) – 30 cm active width
600 fibers/layer X 2 layers/doublet X 2/3 measurements (x&y or u-v-t) X 2 (stations) X 2 (up/downstream) yields
9600 channels (x-y) 14,400 channels (u-v-t) Expect
m point-set resolution extrapolated from D0 results ( 90 mm ) with 835
m fiber This would require 10-14 D0-type VLPC cassettes
Basically all D0 spares However, IF BACKGROUNDS ARE LOW – 4:1 multiplexing possible with 1 mm D0 pixel Tremendous Premium in lowering backgrounds
MICE Collaboration MTG IIT – Feb 2002
D0 Central Fiber Tracker
8 layers
Outer 6
2.52 m Inner 2
1.66 m r - .2 to .51 m Axial readout to south VLPC Readout
77,000 channels Waveguide system
8-11.5 m “Pipes” light from detector to VLPCs
MICE Collaboration MTG IIT – Feb 2002
Central Fiber Tracker Channel Mirror Scintillating Fiber Optical connector Waveguide VLPC cassette Electronics Cryostat
MICE Collaboration MTG IIT – Feb 2002
Scintillating Fiber Ribbons
Interlocking doublet 835
m 3HF scintillating fiber
Fluorescence 525 nm (peak) to 610 nm Grooved substrate - machined Delrin
Pitch between 915 and 990
m Substrate put into curved backbone
Fibers glued together with polyurethane adhesive Ribbons is then QC’ed using scanning X-ray source Technique is very fast
All MICE planes require
4 MM effort + Tooling
MICE Collaboration MTG IIT – Feb 2002
CFT Tracker Mechanical
3500 3000 2500 2000 1500 All axial layers, r and r (incl. correct.) Mean RMS Constant Mean Sigma 0.3375E-05 0.1455E-02 2284.
0.2749E-04 0.1323E-02 1000 500 0 -0.01 -0.008 -0.006 -0.004 -0.002
( r ) measured 0 - ( r 0.002 0.004 0.006 0.008 0.01
) predicted inch 4000 3500 3000 2500 2000 1500 1000 500 0 -0.02
-0.015
-0.01
-0.005
0 Mean RMS Constant Mean Sigma 0.005
( r ) measured - ( r ) 0.01
-0.6468E-03 0.2633E-02 2903.
-0.6892E-03 0.2527E-02 0.015
0.02
inch
Global precision » 33
m (Measured vs Desired)
MICE Collaboration MTG IIT – Feb 2002
Fiber Tracker Status
MICE Collaboration MTG IIT – Feb 2002
Waveguide Bundle Fabrication and Routing 2-FRONT FORWARD DETECTORS FORWARD PRE-SHOWER ICD LEVEL ZERO CFE CENTER BEAM WAVE GUIDE PATCH PANEL ECS TRACKER CABLING SLOT CFW VLPC CRYOSTAT INSTALLATION SEPT 98 WAVE GUIDE FIBER BUNDLE INSTALLATION
Waveguide bundles consist of 256 fibers in light-tight nylon sheath
Curved connector (256 ch.) at detector 2 128 ch. Connector at cassette end VLPC CASSETTE VLPC CASSETTE VLPC CRYOSTAT VLPC CRYOSTAT SILICON TRACKER POWER SUPPLIES
MICE Collaboration MTG IIT – Feb 2002
Routing, strain relief, etc for CFT (+CPS) CFT Waveguide Routing
MICE Collaboration MTG IIT – Feb 2002
Fiber Tracker Status
South (Axial) side complete
MICE Collaboration MTG IIT – Feb 2002
VLPC (Visible Light Photon Counter)
Cryogenic APD operating @ 9K Characterization/test/s ort Cassette Assignment
As shown CFT - Readout System
MICE Collaboration MTG IIT – Feb 2002
VLPCs
VLPC
HISTE VI
High QE
80%
Low noise <5X10 4 Hz High Rate capability
>40 MHz (@ High production yield
70% (vs. 27% projected)
1.0 pe)
MICE Collaboration MTG IIT – Feb 2002
1024 Channel VLPC Cassettes
Engineering Design
8 – 128 channel modules Cassette carries two 512 ch readout boards
Front-end amp/discriminator Analog – SVX IIe 3 ’
MICE Collaboration MTG IIT – Feb 2002
Cassette Performance
Noise low
Good uniformity CFT - Readout III
MICE Collaboration MTG IIT – Feb 2002
The VLPC Cryostats
The VLPC cryostats at DØ accommodate up to 102 cassettes. The full complement of 99 cassettes necessary to instrument D0 are installed on the platform.
MICE Collaboration MTG IIT – Feb 2002
CFT: System Performance ~14.5 pe
Pulse Height Abid Patwa Como-Italy 2001
Read-out Platform: Waveguides and VLPCs
MICE Collaboration MTG IIT – Feb 2002
Lab 3 CRT (Singlet) Light Yield Lab 3 CRT Light Yield Summary Covers Waveguide lengths 7.7-11.4m
MICE Collaboration MTG IIT – Feb 2002
First Events of Run II
Tracking in the CFT is working although we still have a long way to go to fully optimize
Alignment VLPC operating point optimization Threshold setting Etc….
MICE Collaboration MTG IIT – Feb 2002
MICE Fiber Tracker VLPC Cryostat
Could envision a single VLPC cryostat reading out both up and downstream spectrometers
If multiplexing was an option
D0 test cryostat can hold required number of channels Waveguide length about 5 m
Yield with VLPCs
[exp(-5/8)]/[exp(-11.4/8)]X7
pe However
This assumes multiplexing
0.5 mm scintillating fiber coupled to 0.835 mm waveguide fiber
– Could use 1 mm fiber also and
get small improvement
MICE Collaboration MTG IIT – Feb 2002
MICE Fiber Tracker Attenuation vs. wavelength of Kuraray clear fiber
Conventional Blue 3 HF
Conventional FT using MAPMT With same length of readout fiber
If waveguides are used
L
430 nm = 1300 dB/km (1/e = 3.4m)
L
525 nm = 450 dB/km (1/e = 9.6m)
– D0 measured 8.1m @ l
f p = 525 nm QE = 20% Yield =
16 X 20/80 X exp(-5/3.4)/exp(-5/8)
2 pe Effective tracking can likely be done @ 2 pe, but would be more difficult
Depends on backgrounds Minimum acceptable waveguide length
MICE Collaboration MTG IIT – Feb 2002
Conclusions
A Fiber tracker is an attractive option for MICE
Material presented to beam acceptable
As small as 0.15% RL per doublet (smaller if can multiplex – channel count) Excellent resolution (<50
m) High light yield
efficient tracking possible VLPC (or other SS photodetector) has major advantage vz a vz light yield, but MAPMT can likely be made to work If backgrounds can be kept low, multiplexing can reduce channel count
MICE Collaboration MTG IIT – Feb 2002