lhcb vertex locator & displaced vertex trigger vertex detector design test beam results ...
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LHCb LHCb VEVErtex rtex LOLOcator & cator & Displaced Vertex TriggerDisplaced Vertex Trigger
Vertex Detector Vertex Detector Design Test Beam Results
Displaced Vertex TriggerDisplaced Vertex Trigger Algorithm Test Beam Emulation
ConclusionsConclusions Summary Future Plans
Chris Parkes, CERN
Beauty ‘99
Beauty ‘99 Chris Parkes
LHCb DetectorLHCb Detector
Beauty ‘99 Chris Parkes
Resolution Resolution
Secondary VerticesSecondary Vertices
B taggingB tagging
Rejection of Rejection of backgroundbackground
Primary vertex Primary vertex resolution 40 resolution 40 mm
Beauty ‘99 Chris Parkes
GeometryGeometry
10cm
Detectors separated 6cm during injection
series of discs
smalloverlap
Beauty ‘99 Chris Parkes
Vertex LocatorVertex Locator
• Detector Length 1m
• Station spacing varying
from 4 - 12cm
• Phi Overlap of detectors
• Each Station has an R and
a Phi measuring detector
• Stereo angle between
successive Phi Detector layers
Beauty ‘99 Chris Parkes
r-measuringdetectors
-measuringdetectors
Prototype DesignPrototype Design
5 ° “stereo” tilt
Both detectors utilize a double metal layer to readout inner strips whilst keeping electronics outside active area.
r-detectors
-detectors
Beauty ‘99 Chris Parkes
New DesignNew Design 180 degree R 180 degree R
& Phi & Phi DetectorsDetectors
2048 strips2048 strips
Smooth Smooth variation in variation in pitchpitch
Ready in Ready in AutumnAutumn
16 chip Hybrid16 chip Hybrid
Beauty ‘99 Chris Parkes
MechanicsMechanics
Beauty ‘99 Chris Parkes
Vacuum VesselVacuum Vesselmanipulators
window
TopHalf
primary vacuum
vessel
detectors100cm
RF shieldvacuum barrier
Beauty ‘99 Chris Parkes
Radiation EnvironmentRadiation Environment
1013
1014
1 M
eV e
quiv
alen
t neu
tron
s/cm
2
1 2 3 4 5 6cm
station 6
Dose after 1yr Including effects of Including effects of walls, vesselwalls, vessel
High doses at tipsHigh doses at tips (1/r2)
Detectors IrradiatedDetectors Irradiated Test-Beam
September
n+ on n Silicon as n+ on n Silicon as base solutionbase solution
Beauty ‘99 Chris Parkes
ModellingModelling
Cooling Required
Electric Field Distortions
Radiation Response
Beauty ‘99 Chris Parkes
SoftwareSoftware
LHCb will use C++LHCb will use C++BUT Technical Proposal work was in FORTRAN
Test Beam Test Beam used to gain experience with new language and Root
All reconstruction software in C++
Cluster Making, Event Display, Track Fit, Alignment, Noise Studies...
Software Designed for future useSoftware Designed for future useboth useful code, and class design
Beauty ‘99 Chris Parkes
Trigger LevelsTrigger Levels
Beauty ‘99 Chris Parkes
Second Level Trigger Second Level Trigger Vertex AlgorithmVertex Algorithm
Second Level Trigger Second Level Trigger Vertex AlgorithmVertex Algorithm
IDEA Separation of minimum bias events and B events by
using the signature of displaced secondary vertices.
AIM Minimum bias retention of less than 4% and a signal
efficiency of more than 50%.
Boundary Conditions Input event rate of 1 MHz or 2Gbytes/second . Average execution time of about 250 microseconds.
Implementation benchmark results show can be performed by 120 1000
MIP processors
Beauty ‘99 Chris Parkes
Present AlgorithmPresent AlgorithmPresent AlgorithmPresent Algorithm 2d2d
Track finding using triplets of r-clusters track search starts in inner r sector
Primary vertex reconstruction, x y z, by crossing tracks of opposite phi-sectors
x y - resolution given by phi-sector Selection of tracks with large impact parameter Rejection of pile-up events
z
r
Beauty ‘99 Chris Parkes
Algorithm cont.Algorithm cont.Algorithm cont.Algorithm cont.
3d3d Add phi info. for large impact parameter tracks
ambiguities resolved by stereo angle and impact parameter in xy-projection
find two track combinations which are close calculate probability that one of the two tracks
originate from the primary vertex based on impact parameter and geometry
calculate total L1 probability by multiplying the individual probabilities
Beauty ‘99 Chris Parkes
Present PerformancePresent PerformancePresent PerformancePresent Performance
2d and 3d track reconstruction efficiency of 98% and 95%.
Primary vertex resolution of 80micron and 20micron for z and x/y.
Beauty ‘99 Chris Parkes
Test BeamTest BeamSpring ‘98Spring ‘98
12 Silicon Planes
Slow Electronics
Beauty ‘99 Chris Parkes
Vertex Trigger Vertex Trigger PeformancePeformance
Use Targets to Use Targets to simulate Primary simulate Primary VertexVertex
Resolution Resolution Simulation 80m Test Beam
Extrapolated 80m
Assess sensitivity Assess sensitivity to detector to detector misalignmentsmisalignments
Beauty ‘99 Chris Parkes
Artificial B eventsArtificial B events
Virtual BVirtual B ! ! Five events form one target
“minimum bias” One From next target
B event
Good PerformanceGood Performance
Beauty ‘99 Chris Parkes
OverviewOverviewof theof the
readoutreadoutschemescheme
Analogue
readout
FE Rad. Hard
>2Mrad/yr
FADC + L1
buffers 10m away
Processing in
DSPs after L1 accept
Front End Chip
DMILL- SCTA
or
0.25m CMOS-
BEETLE
Beauty ‘99 Chris Parkes
LHC Speed Readout LHC Speed Readout ChipChip
Test-Beam Spring ‘99Test-Beam Spring ‘99 AimAim
Evaluate Evaluate
performance performance
of detectorof detector
equipped withequipped with
SCT128A 40MHzSCT128A 40MHz
FE chipFE chip
SetupSetup
6 plane Telescope6 plane Telescope
+ 2 Test Detectors+ 2 Test Detectors
Beauty ‘99 Chris Parkes
Test-Beam ResultsTest-Beam Results
Clear Signal ObservedClear Signal Observed Correlated with reference TelescopeCorrelated with reference Telescope
Beauty ‘99 Chris Parkes
Time ResponseTime Response
Rise Time ~ 25nsRise Time ~ 25ns
Pulse Remaining afterPulse Remaining after
25ns ~ third of Signal25ns ~ third of Signal40% of LHCb events are40% of LHCb events are
preceded by an eventpreceded by an event
simulation of Bsimulation of BTrigger efficiencyTrigger efficiency
drops above 30%drops above 30%
overspilloverspill
Signal:Noise ~ 20:1Signal:Noise ~ 20:1
Beauty ‘99 Chris Parkes
ConclusionsConclusions
Prototype Detectors Tested Prototype Detectors Tested New Design New Design
Displaced Vertex Trigger Displaced Vertex Trigger Future Work Future Work …..…..
So far the project is flying...
Beauty ‘99 Chris Parkes
MilestonesMilestones
2000 : Full Half station at 40MHz
2001 : Technical design Report
2003 : Construction
2004 : Commissioning
2005 : Start Data Taking
But there is still a long way to cycle…..