20 April 2002 Bill LeeAPS
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The D0 Silicon Track Trigger
Bill LeeFlorida State University
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STT People and Institutions• Boston University
– Ulrich Heintz, Meenakshi Narain– Evgeny Popkov, Lars Sonnenschein, Jodi
Wittlin– Kevin Black, Sarosh Fatakia, Lorenzo
Feligioni, Alex Zabi– Eric Hazen, Bill Earle, Shouxiang Wu
• Columbia University– Hal Evans– Georg Steinbrück– Tulika Bose– An Qi
• Florida State University– Horst Wahl, Sue Blessing, Stephen Linn,
Harrison Prosper– Bill Lee, Sylvia Tentinto-Repond– Reginald Perry, Arvindh Lalam, Shweta
Lolage• SUNY Stony Brook
– John Hobbs– Wendy Taylor– Huishi Dong– Chuck Pancake, Bonnie Smart, Jane Wu
20 April 2002 Bill LeeAPS
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D0 Central Detector Upgrade• New silicon tracker, new fiber tracker, new preshower, and
a new 2T superconducting solenoid.
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Silicon Microstrip Tracker (SMT)
- ~800,000 total readout channels- 6 barrels (4 layers)
- ~390,000 axial channels- ~220,000 stereo channels
- 12 interspersed (F-)disks - 4 external large area (H-)disks for
forward tracking (2 < |η| < 3)
~ 2.4 m
SMT half cylinder
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D0 Central Fiber Tracker (CFT)• ~12m long clear light-guides to Visible Light Photon Counters (VLPC)
under detector• 8 layers of axial and stereo fibers (20 < r < 51 cm), 77k channels
VLPC
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D0 Trigger System
• L1CTT– Provides
tracks from axial CFT fibers
• SMT unused until L3
L2FW:Combined objects (e, µ, j)
L1FW: towers, tracks, correlations
L1CAL
GlobalL2
L2CFT
L2PS
L2Cal
L1CTT
L2Muon
L1Muon
L1FPD
Detector L1 Trigger L2 Trigger7 MHz 5-10 kHz
CAL
FPSCPS
CFT
SMT
Muon
FPD
1000 Hz
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Trigger System with STT• What if we
used the SMT to improve the tracks from the CTT?
L2FW:Combined objects (e, µ, j)
L1FW: towers, tracks, correlations
L1CAL
L2STT
GlobalL2
L2CFT
L2PS
L2Cal
L1CTT
L2Muon
L1Muon
L1FPD
Detector L1 Trigger L2 Trigger7 MHz 5-10 kHz
CAL
FPSCPS
CFT
SMT
Muon
FPD
1000 Hz
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Track Reconstruction at L2
• We could get:– Impact
parameter– Improved pT
resolution– Fake track
reduction
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Conceptual Design• L1CTT tracks in CFT
– Define road in SMT
• Find clusters in SMT hits• Select SMT clusters in
roads• Fit trajectory to
L1CTT+SMT hits. • Send results to L2
roaddata
SMTdata
SiliconTriggerCardSiliconTriggerCard
SiliconTriggerCardSiliconTriggerCardSiliconTriggerCard
FiberRoadCard
SiliconTriggerCard
TrackFit
CardL2CTT
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Fiber Road Card (FRC)
• Communicates with trigger framework and broadcasts control info to other cards.
• Fans out track data to all other cards
• manage L3 buffers– Controls the readout to
L3
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Silicon Trigger Card
• Receives raw data from SMT
• Finds clusters in axial and stereo strips
• Associates tracks with axial clusters
• Outputs clusters with tracks
Strip reader
Cluster finder
Hit filter
SMTL1CTT
RoadLUT
SCL
L3
L3
TFC via serial link
from FRC via serial link
control logic
L3
channel logic (x8)
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STC Prototype RoadLUT
RoadLUT
RoadL
UT
RoadL
UT
control logic(8x) channel logic(Xilinx Virtex E)
800k gates1.1 Mbits RAM560 pin BGA
accommodatesall 8 channels
need 1/STC
control logic(8x) channel logic(Xilinx Virtex E)
800k gates1.1 Mbits RAM560 pin BGA
accommodatesall 8 channels
need 1/STC
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Track Fit Card (TFC)• One per 30 degree
sector• Inputs tracks from
FRC and associated clusters from STC
• Farms each track out to one of eight DSPs
• Outputs input track list and expanded track list to L2
TI6202/3 (300 MHz)DSPs
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Track Fit Card (TFC)• require hits in
– at least 3 of the 4 SMT layers
– in same 30 degree sector– in at most 2 adjacent barrels
• choose hits – closest to trajectory defined
by CFT and origin• linearized χ2 fit
– φ(r) = b/r + κr + φ0– drop worst hit and refit if 4-
hit χ2 bad
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Summary
• STT will provide D0 with the ability at L2:– to reduce the background signal– to improve pT resolution– to cut on an impact parameter
• Production of boards is underway.• Our goal is to be operational in early
summer.