t. bowcock1 can cp save life? lhcb and its applications…
TRANSCRIPT
T. Bowcock 1
Can CP save life?
“LHCb and its applications…”
T. Bowcock 2
Overview
• CP physics and the LHCb experiment
• LHCb vertex detector technology• Optimization• MAP project• Applications• Summary
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CPz
x
yP: )( rr C:(particle antiparticle)
CP violated only rarely … compensated by T violation (CPT)
e.g KLe±
±
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Why study CP violation?
• Origin of CP (T) violation? – Matter/AntiMatter
Asymmetry• Sakharov
• CP violation– Only observed in
K system. – CP effects in B
system in SM
CosmologyParticle Physics
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CP studies • 1st Generation B -sector studies
<2005. Two possibilities:– either: there will be already a sign of
new physics– or: measurements will look “consistent”
with the Standard model.
• A dedicated experiment at LHC is needed. A “CP-interferometer”. About 10x more sensitive.
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CP studies
Bd+-
Bds
BsDsK
B
s mixing
V ub/V
cb
Bs
First generation of experiments will study Vub/Vcb and BdKs.
To study all angles/decay modes need a specialized detector.
Detailed Bs studies out of reach of Generation 1 experiments.
Bd JS Bs JBs DSK (PID)Bd DK (PID,Trigger)Bd D* (PID)Bd (PID)Bd K (PID)Bd Bs KBs Kll Bs 75 38Bs
LHCb ATLAS/CMS
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B-hadron productionB-hadron production
323222
CP effects 10K events
About 11012 BB produced/year (108 Gen. 1)
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LHCb Detector
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Vertex Detector
• Precision tracking that: – identification of B vertices– measurement of lifetime (40fs)
Bs Ds K
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Geometry
10cm
Detectors separated 6cm during injection
series of 17 1/2 disks
smalloverlap
Positioning and movement to 5m
Precision detectors: Very high radiation doses
£3M project
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Vertex Detector
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Radiation Environment
cm
1013
1014
1 M
eV e
quiv
alen
t neu
tron
s/cm
2
1 2 3 4 5 6
station 6
Dose after 1yr • Including effects of walls, vessel
• High doses at tips– (1/r2)
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150 micron thin n on n detectors with double metal layer (multiple scattering, radiation)
r phi z geometry (reflects forward symmetry of the events, optimizes resolution / channel numbers, ease L1 trigger)
Baseline Solution
r-measuring detector-measuring detector
5 ° “stereo” tilt resolves ambiguities
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Detectors fabricated on 100mm wafer
-measuringdetectors
r-measuringdetectors
inner radius 10mm
readout tracksspaced 50m
UK prototypes
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Testbeam
Testbeam
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Resolution
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Noise
• S/N with VA2 (slow) electronics
• Noise – readout line
length– strip length
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Module Design
0 50 100 150 200 250 300
W/mm2
0
-4
-8Tem
pera
ture
at T
ip (
°C)
Thermal Model: hold cooling at -10°C
Thermal Runaway
LHCbthick detectors
Single Sided r and module
LHCbUK
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Irradiation
• 4 Detectors Irradiated 11/98– Heidelberg 20MeV
p
• Lab test• Awaiting test
beam– stored at -25C
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First Test with a Fast Readout Chip (SCTA 128)
Main goal: Noise Study Over Spill
19.10.1998:first output from one SCTA chip
Now: 4 SCTA/hybrid uniform pedestals Noise: 600 ENC 26.4.1999:
Next testbeam
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Summary 1998
• Prototype in test beam• LHCb like events produced with a
target• Alignment issues
– design modifications
• Noise Studies• Resolution
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Physics Performance
Bs decays
B->
Level 1 Trigger
z positions+radii
#planes
tilt angle
material effects
pitch vs. r
break positions
stereo angle
Use LINUX farm at Liverpool + VX fast simulation
Optimization
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Some ideas for improvement need to be investigated:
smaller pitches -> p on n technology improve resolution, (price )
vary pitch as function of radius optimize occupancy / number of channels / resolution
move closer to beam axis
reduce outer radius to fit on one wafer reduces number of individual detector modules, ease alignment
Improvements?
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Simulation
• Radiation damage• Signal
– ISE(3D)/Kurata– full 3D diode
• Thermal analysis
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New p-strip design
• reduced inner radius: 8 mm
• reduced outer radius: 40 mm requires a few extra stations
• 182o modules with 45.5o sectors (r-detector)
• inner strip pitch 25 (26) micron, strip pitch increases with r outer strip pitch 99 (131) micron
r-detector2048 strips
phi-detector2048 strips
Try different thickness 300, 200 and 140 micron
40.0mm
21.2mm 17.9mm
8mm
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1999
• Tests of irradiated n-strips in Lab• Tests of irradiated detectors (with
SCT128A) in test beam
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1999 Irradiation
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Irradiated Detector
Irradiated (200V) unirradiated
(V. Prelim) Irradiation at 3*1014
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Module
Precision Mount to platformdesigned
Hybrid Design
L’pool +IDE
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Mechanics
• Can adjust to <10microns in space.
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Thermal Model
• Heat Conduction Away from module– separate cooling and mechanical path– no cooling pipes?
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Biases?
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VD Milestones
• Technology Choice 9/00• Technical Design Report 01/01?
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Current Work
• SCTa electronics• Cosmic Ray & Laser setups• Evaluation of Irradiated Detectors
– comparison with testbeam
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Computing
• In operation 1PByte stored/year– LCB has set up MONARC
• Short term– data sets of about 108 events
• optimize detector design• background suppression
• “Monte-Carlo Array Processor
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MAP operation• Run for several weeks 106-107 events
– data will reside on disk!
• Model for use has been developed– “commodity disk” servers -1TByte each`– 8 TBytes at MAP– 5 mirror sites with 0.5TBytes each
• Minimum required for UK LHCb program– RICH and VD design and optimization
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MAP+analysis
Institutes
Liverpool
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Summary• Responsibility for LHCb Si• Extensive programme of R&D• Computing for LHCb-UK
– solve immediate optimization problems
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Need for Monte Carlo
• At LHCb about 1 interaction /25ns !– 4*1014/year– if you want to do physics you need to
know the backgrounds• generating just the signals doesn’t work
– need to generate large MC samples•O(107) to O(108) events.
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Summary
• LHCb recommended for funding by PPESP !
• Intense programme of work to TDR until 2001
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MAP cont’d
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MAP status
• Method– Linux– Batch System– Broadcast
• point to point transfers for “broken sockets”
– complex code– handling failed/dropped packets.
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MAP hardware
• 300 processors– 400MHz PII– 128 Mbytes memory– 3 Gbytes disk– 100BaseT ethernet +hubs– commercial units BUT
• custom boxes for packing and cooling
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MAP use
• Prepare a job • Submit to Batch Queue
– at the moment suppress o/p
• Histograms/Ntuples transmitted back at end of job
• Random Numbers handled automatically
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MAP
• Performance– About 120s/event GEANT +
reconstruction
• Produce about 200,000 events/day• Results
– move into production
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MAP capabilites
• Can be used in “throwaway” mode– just keep Ntuples
• MAP possesses 1Tbyte internal storage – 3 Gbytes/machine– events stored locally (1million events)– repeatedly analyse QUICKLY
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MAP+COMPASS
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COMPASS
• Meant to give large storage capability for use of all UK institutes– RICH/VELO studies– PHYSICS
• DELL prototype in place– 1TByte + High End Server (600MHz)
• transfer rates• reliability
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COMPASS
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COMPASS
• Purpose– Will show this in place and working
with MAP– Model for LHC analysis
• store events on disks (cheap!)• move JOB to the DATA• NO HSM
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BACKUP SLIDES
BACKUP slides
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Technology Options for LHCb Vertex Detector
pro con
p strip Single sided processing Rapidly falling efficiencyReduced cost (30%)and ease of handling below partial depletion
Minimum pitch 12 m High field region on opposite surface to readout
Thin detectors advantageous for Needs to be thinner for givenmultiple scattering operating voltage.(Lower signal)
Handling(cost) of thin detectors.
n strip High efficiency at partial depletion gives Lithographic processing of backlower operating voltage and lower power (Cost and handling)High field region (after irradiation) at Minimum pitch 40m.readout strips.
Operating partially depleted at tip still allows full depletion (high CCE) elsewhere.
both Material Difficult to handleCharge Correlation Offset voltages on one side of
detector for electronics.Thermal contact - sensitive face?
Proto
type
1998
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RF shieldprimary ->
secondary Vacuum2100 micron / detector station
Best case: 100 micron once
Worst case: 2.4100 micron/detector station for low angle tracks (but high p)
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Noise Study
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Noise Study
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pictures of rf shield
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Expected Resolution
LHCb 97-020 TRAC
6 micron for theta = 0o
LHCb 97-020 TRAC
6 micron for theta = 0o