Download ppt - Cosmic data 2008 Cosmic data 2009 Collision data 2009 15 dec 2009Nikhef Jamboree, N. Tuning1/33 The Outer Tracker 1.Hardware status 2.Space Alignment

Cosmic data 2008 Cosmic data 2009 Collision data 2009

15 dec 2009 Nikhef Jamboree, N. Tuning 1/33

The Outer Tracker

1. Hardware status2. Space Alignment3. Time Alignment4. Event distributions5. Ageing

InteractionPoint

Muon System

Calorimeters Tracking System

Vertex Locator

RICH Detectors

The LHCb DetectorThe LHCb Detector

15 dec 2009 2/20Nikhef Jamboree, N. Tuning

InteractionPoint

Muon System

Calorimeters Tracking System

Vertex Locator

RICH Detectors

The LHCb DetectorThe LHCb Detector



Outer Tracker

34 cm

Total nr of channels: 53.760

One module: 34 x 490 cm2

4 x 64 = 256 straw tubes

5 m


~98% channels functional !

Huge Nikhef effort:

Tom, Albert, Ad, + ½ of

PhDs in bfys group

Hardware status

• DAQ 99% of FE electronics running fine 4 (432) disabled FE boxes (replace in

Jan) 0.22% noisy channels (without HV)

• not much extra noise with HV on• 90% noisy channels in 2% of FE

• LV and HV LV: 2(912) fuses blown, replaced HV: 7(1680) channels have HV trips HV power supplies: CAEN upgrades

units from 0.2 mA to 3 mA max currents

• Gas System• Prepare to add 1-2% O2


The road to where we are now: Cosmics


• Debug DAQ• Software

Framework• Noise• Spacial alignment• Time alignment

Jan Amoraal, Thomas Bauer, Besma M’Charek, Roel Aaij

Cosmics: commission detector


2009 - collisions

2009 - cosmics

2008 - cosmics

• Hitmap: Holes are filled up in due time

Top view:

Jan Amoraal


Alignment

1) Positioning of OT Special attention to avoid

rotations Carefully checked

reproducibility At nominal to <1.5(3) mm in

x(z)2) Knowing position

Survey accuracy

to <0.5 mm

3) Software Alignment

Antonio Pellegrino

Alignment: framework


• LHCb alignment framework developed by Wouter, Gerhard and Jan Implemented generically for all subdetectors Extract misalignment from residual histograms Need to deal with correlations

Minimal chi-square method Minimize chi-square simultaneously wrt.

alignment parameters and track parameters

Find track parameters a:

With n tracks, find alignment parameters β:

• Complication… Some combination of parameters are

poorly constrained: ‘weak modes’

Jan Amoraal,Wouter Hulsbergen,Gerhard Raven

Alignment: results (cosmics 2008)


• Internal alignment of OT C-frames Fix 2 C-frames, align the rest Good agreement with survey

• Modules Allow modules to move within C-frame Checked consistency by splitting sample

• Ready for beam!

Odd/even evt nr Forward/backward

Full detail in Jan Amoraal’s t

hesis!

Jan Amoraal

A-side C-side

A-side C-side

Alignment: collisions


• Framework well tested• Now, try on collisions

Magnet on Different track distribution

• Adjustments wrt. survey <1 mm !

T1 T2 T3(IT) (IT) (IT)

C-frames:

Modules:±

1 m

mWouter Hulsbergen

Δx

(mm

)

Time alignment


• Hardware: hit needs to fall in readout window…

Raw time

drift time

parti

cle

Hit

s

Dec 2009Hit

sMiss events! Raw time

Nov 2009

Shift

• Software: determine t0 constants

Dri

ft T

ime

(ns)

Distance (mm)

5 mm

~45

ns

t0

Mod

ule

t 0 (ns

)

(Slope comes from tim

e of flight)

Aleksandr Kozlinskiy,


A look at collision dataA look at collision data

15 dec 2009 Nikhef Jamboree, N. Tuning 15/20Roel Aaij









A look at collision data: alignment


m=497.3±0.6 MeV

• Ks: close enough to the PDG…

PDG

A look at collision data: Drift time


• ~80k events from 11 Dec 2009• Drift time as expected

Inside readout window of 75ns Max drift time ~45ns

T1

T2

T3T1 T2 T3

Raw

TD

CC

alib

rate

d D

rift

Tim

e

75 ns

~45 ns

tmeas=tdrift+ttof+tprop+t0

A look at collision data: Occupancy


• Very few holes• Every hole is understood• Will be fixed in January

• More hits close to the beampipe

T1 T2 T3

Zoom Zoom Zoom

T1

T2

T3

A look at collision data: Efficiency


• Check for hit if predicted by track• Monitor plateau efficiency r<1.3

mm• Average efficiency over detector

>96%

2.45 mm

Straw length

Wire locators

Herve Terrier

A look at collision data: Efficiency


• 98% of detector working!• Three handful FE-modules have

problems:

T1 T2 T3

Herve Terrier

Long track

Upstream track

Downstream track

T track

VELO track

A look at collisions: Track types in LHCb


Long Tracks highest quality for physicsDownstream Tracks Ks finding

Upstream Tracks for RICH1 pattern recognition

T Tracks for RICH2 pattern recognition

VELO Tracks for Primary Vertex reconstruction

A look at collisions: Event distributions as expected


Nr of tracks with OT / event

Nr of tracks / event Nr of OT hits / event

Z Vertex (mm)

Area normalizedNo beam-gas correction

applied

A look at collisions: OT Track distributions as expected


Pseudo-rapidity (in T-stations) Momentum (MeV)

All tracks with T-segmentArea normalized (scaled by

+20%)

Ageing


• It’s the di-isopropyl-naphthalene (CAS

38640-62-9) inside the glue AY103-1 AY105 does not contain any plastifier Just produced one module with AY105

• Decided to add 1.5% O2 to gas

• Large currents cure! HV=1900V : large dark currents / discharges HV=1800V, with source scanning over

damage Increase argon Heating also cures same process?

After HV scan area Is it feasible to just crank up the HV

during beam for a few hours? Can the power supplies handle such an

instable situation of huge HV + LHC beam?

Barbara Storaci, Daan van Eijk+ 3 masters:Ivan Mous. Mathieu Blom, Erwin Visser

SummarySummary• Electronics in good shape• Alignment close to design requirement• Ageing stays a worry


• Data archiving and re-analysis• Data quality monitoring with reconstructed

quantities Tracking Efficiency algorithm (also for ageing detection)

• Continue comparison data / MC

OutlookOutlook

Backup


Efficiency: compare data/MC


• Data:

• MC:

Wire locators

Y (A.U) FE moduleX (pitch) X (pitch)

Y (A.U) FE moduleX (pitch) X (pitch)

Eff lower close to beampipe , due tohigher occupancy?

Ionization length 325um instead of 850 um

Plateau includesdead channels

Occupancy per Quarter


“Discrete” due to nr of tracks, 1,2,3, …


Beam Test

r (mm)

Dri

ft ti

me

(ns)

rt-relation:

2.45 mm 2.45 mm

r (mm)

Eff

icie

ncy,

ε

efficiency profile:

Resolution and efficiency for different HV and amplifier threshold

1) Reminder: effect of O2 on ageing

30 Nov 2009 LHCb week - N.Tuning 38/10

• What is the optimal amount of oxygen? Beneficial effect of O2 presumably due to ozone production

Ozone production maximal above 1% O2

Between 1% and 4% no difference in ageing rate

1% O2

NB: Need to disentangle effect of

flushing time from fraction of O2


2) Effect on Gain

0% O2 2.5% O2 4.5% O2

286 mV319 mV 229 mV

→ Summarized in LHCb-2008-064Effects of Adding Oxygen to the Outer Tracker Gas Mixture

→ Shown by Mathieu Blom in LHCb week 24 Nov 2008

• Addition of O2 to gas mixture reduces gain by ~20%: 2.5% O2 lowers response to 90Sr by 20%

2.5% O2 lowers 55Fe pulse height by 10%

Confirmed by Dirk, Yuri, Christian with O2 in test chamber in the pit

Relative gain

? Average path length is same for 5.9keV γ from 55Fe and 1MeV β from 90Sr

55Fe 90Sr

http://cdsweb.cern.ch/record/1141890?ln=en

http://indico.cern.ch/conferenceDisplay.py?confId=45903

2) Effect on Gain (Erwin)


What is fraction of clusters that reaches the wire?

r (cm)

C

lust

er s

urvi

val p

roba

bili

ty

0% O2

Avg.=86%1% O2

Avg.=76%

2% O2

Avg.=67%3% O2

Avg.=59%

Simulations agree with 90Sr

Gain loss wrt 0% O2: 90Sr55Fe

Simulation

Magboltz/Garfield simulations

2% O2 gives average gain loss of 22% compared to 0% O2

Gain loss ranges from 42% at r=2.5mm to 0% at r=0mm

3) Effect on Hit efficiency


What is probability that 0 clusters reach wire?

Use λeffective=850 µm

Simulations agree with testbeam

(λeffective=850 µm fits testbeam best)

Ar/CO2 70/30 2% O2

>5% loss for r>1.9mm >5% loss for r>1.5mm

Magboltz/Garfield simulations


