Upload
ulysses-mcdaniel
View
26
Download
3
Tags:
Embed Size (px)
DESCRIPTION
The Silicon Track Trigger (STT) at D Ø. Beauty 2005 in Assisi, June 2005. Tag. fast …. beauty. Sascha Caron for the D Ø collaboration. The Silicon Track Trigger at D Ø. OUTLINE - D0 detector D0 trigger What is the STT? dataflow clustering and tracking B identification - PowerPoint PPT Presentation
Citation preview
The Silicon Track Trigger The Silicon Track Trigger (STT) at D(STT) at DØØ
Beauty 2005 in Assisi, June 2005Beauty 2005 in Assisi, June 2005
Sascha Caronfor the DØ collaboration
Tag beauty
fast …
page 1page 1
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
OUTLINEOUTLINE
- D0 detector- D0 trigger- What is the STT?- dataflow- clustering and tracking- B identification- Performance- Summary
Sascha CaronSascha Caron
page 2page 2
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
D0 in Run IID0 in Run II
The Silicon Track The Silicon Track Trigger is based Trigger is based on informationon informationof the :of the :
Silicon Microstrip Silicon Microstrip TrackerTracker
Central Fiber Central Fiber Tracker Tracker
page 3page 3
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
D0 in Run IID0 in Run II
The Silicon Track The Silicon Track Trigger is based Trigger is based on informationon informationof the :of the :
Silicon Microstrip Silicon Microstrip TrackerTracker
Central Fiber Central Fiber TrackerTracker
o 50 50 μμm pitch strips (parallel to beam)m pitch strips (parallel to beam)o 800000 readout channels800000 readout channelso Only axial strips used for STT tracksOnly axial strips used for STT tracks
o Scintillating fibersScintillating fiberso Coverage: |Rapidity| < 1.7Coverage: |Rapidity| < 1.7
page 4page 4
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
Events forEvents for L=100 E30 cmL=100 E30 cm-2-2/s/s= about 8 pb= about 8 pb-1-1/day/day
1010
11
0.10.1
0.010.01
0.0010.001
Higgs->b bbarHiggs->b bbar
ZH-> bbvv, bH->bbb etc.ZH-> bbvv, bH->bbb etc.
Z-> b bbarZ-> b bbar
QCD EQCD ETT>30 GeV >30 GeV dijet productiondijet production
b-jets Eb-jets ETT>30 GeV>30 GeV
0.00010.0001
Events Events per per
secondsecond
Find b-events Find b-events early to keep early to keep high efficiencyhigh efficiency
at an acceptableat an acceptableraterate
Find b-events Find b-events early to keep early to keep high efficiencyhigh efficiency
at an acceptableat an acceptableraterate
Aim: High EAim: High ETT
Z->bb, HZ->bbvv, Z->bb, HZ->bbvv, H->bb, etc.H->bb, etc.Hopefully B Hopefully B
physicsphysics
page 5page 5
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
Principal IdeaPrincipal Idea
B B decay length is mm
decay length is mm
Impact parameterImpact parameter(2d in x-y plane)(2d in x-y plane)
B decay productsB decay products
o Silicon Improved Tracks withSilicon Improved Tracks with 2d impact parameter2d impact parameter
o Select events with large impact parameter tracksSelect events with large impact parameter tracks
Interaction point Interaction point is mean beam spotis mean beam spot
page 6page 6
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
L1 TriggerL1 Trigger decision timedecision time
about 4 about 4 μμss
(1500) (1500) 5000 Hz5000 Hz
(700)(700)1000Hz1000Hz 50 Hz50 Hz2.5MHz2.5MHz L2 TriggerL2 Trigger
decision timedecision timeabout 200 about 200 μμss
L3 TriggerL3 Trigger decision timedecision timeabout 50 msabout 50 ms
Trigger SystemTrigger System
p p bunchp p bunch
crossing crossing frequencyfrequency
¯̄
o Hardware basedHardware basedo CTT tracks, CTT tracks, calorimeter towers, calorimeter towers, muonsmuons
o Hardware/Software Hardware/Software o simple jets, electrons, simple jets, electrons, muons, tausmuons, tauso Silicon Microvertex Silicon Microvertex improved tracks (STT)improved tracks (STT)o global processor to global processor to combine informationcombine information (e.g. STT tracks for Bid)(e.g. STT tracks for Bid)
o Software basedSoftware basedo partial event partial event reconstructionreconstruction
page 7page 7
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
SiliconSiliconMicro Micro
DetectorDetector
CentralCentralFiberFiber
TrackerTracker
L2L2STTSTT
L1L1CTTCTT
L2L2CTTCTT
L2L2GlobalGlobal
otherotherL2 pre- L2 pre-
processorsprocessors
DetectorDetector Level 1Level 1 Level 2Level 2Level 1Level 1DetectorDetector
Data flow chart L2 tracksData flow chart L2 tracks
page 8page 8
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
How is the How is the tracking improved?tracking improved?
o Tracks found at L1 with the Central Fiber Tracks found at L1 with the Central Fiber Tracker are used to define roads into the Tracker are used to define roads into the Silicon Silicon
o Silicon hits are clusteredSilicon hits are clustered
o Track is re-fit within the roadTrack is re-fit within the road
page 9page 9
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
Silicon Track Trigger cardsSilicon Track Trigger cards
Road data toRoad data toFiber Road CardFiber Road Card
SMT data to SMT data to 9 Silicon Trigger9 Silicon Trigger
CardsCards
Fitting done Fitting done in Track Fit Card in Track Fit Card
L2CTTL2CTT
Done in parallel for each of the 12 sectors
2 sectors in 1 crate-> 6 Crates with1 Fiber Road Card9 Silicon Trigger Cards2 Track Fit Cards
page 9page 9
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
Silicon Track Trigger cardsSilicon Track Trigger cards Road data toRoad data toFiber Road CardFiber Road Card
- Receives and distributes L1 - Receives and distributes L1 trackstracks- Communicates with TriggerCommunicates with Trigger frameworkframework
SMT data to SMT data to Silicon TriggerSilicon Trigger
CardsCards
- Perform clustering and cluster-road matching
- Clusters SMT hits + pedestal correction
- Axial clusters are matched to the roads
Fitting done Fitting done in Track Fit Card in Track Fit Card
- receives road and axial clusters- receives road and axial clusters- convert to physics coordinates via LUTconvert to physics coordinates via LUT- perform track fit perform track fit φφ(r)= b/r+kr+(r)= b/r+kr+φφ00 - beam spot correctionbeam spot correction- output tracks to L2CTToutput tracks to L2CTT
page 10page 10
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
Performance studies STT tracksPerformance studies STT tracks
Impact Parameter resolution Impact Parameter resolution Correlation to RECO Correlation to RECO
ppTT(GeV)(GeV)
Res
olut
ion
in
Res
olut
ion
in
μμmm
PurityPurity
Including beam spot size 35 Including beam spot size 35 μμm m and 15 and 15 μμm SMT resolutionm SMT resolution
page 11page 11
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
- Fast, simple and efficient technique- Time needed is 2 operations per track and goes linear with the number of tracks -> about 1-5 μs- Degrades bad tracks without cutting them
Store 2d signal (b events) to background (light quarks) ratio into a lookup table
Defi ne “good tracks”
Loop over tracks i and derive the product R= ∏Ri
or use max(Ri)
Likelihood as a discriminator: L= R/ (R+1)
B B identification identification Signal to Signal to Background Background
ratioratio
b/db b/db
1.5 1.5 mmmm
RRii
page 12page 12
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
Performance studiesPerformance studies
Very well separation of signal and Very well separation of signal and background eventsbackground events
Large background reductionLarge background reductionwith L2 b-ID algorithmswith L2 b-ID algorithms
efficiency Z->bbefficiency Z->bbL2 B-id likelihoodL2 B-id likelihood
Red : Red : Simple CutSimple Cut
BlueBlue//GreenGreen: : B-idB-id
page 13page 13
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
First studiesFirst studiesusing datausing data
Max IP Significance Max IP Significance Likelihood Likelihood
L2 data well correlated with offline dataL2 data well correlated with offline data-> proof of b-id principle -> Much more studies on their way-> proof of b-id principle -> Much more studies on their way
Jet dataJet data Offline B-tagged Offline B-tagged
data data
Likelihood shifted toLikelihood shifted tohigher values duehigher values due
to e.g. min bias effectsto e.g. min bias effects
DDØØpreliminarypreliminary
Using MC pdfsUsing MC pdfs
DDØØpreliminarypreliminary
page 14page 14
The Silicon Track Trigger at DThe Silicon Track Trigger at DØØ
Sascha CaronSascha Caron
SummarySummary
o The STT is operating routinely and smooth The STT is operating routinely and smooth o High Impact Parameter resolutionHigh Impact Parameter resolutiono Data is understoodData is understoodo Very fast L2 b-id is (almost) implemented Very fast L2 b-id is (almost) implemented o We expect a high potential forWe expect a high potential for Z->bb and Higgs physics now and at L=200E30cmZ->bb and Higgs physics now and at L=200E30cm-2-2/s/s
OutlookOutlook
o Implementation of new Layer 0 (r=22mm) into STT Implementation of new Layer 0 (r=22mm) into STT -> further increase in precision and stability -> further increase in precision and stability