Construction, Installation and Commissioning of a High- Efficiency and High-Resolution Straw Tube Tracker for the Experiment ●Introduction ○B-physics at

Construction, Installation and Commissioning of a High-Efficiency and High-Resolution Straw Tube Tracker for the

Experiment

● Introduction○ B-physics at LHCb○ The LHCb experiment

● The LHCb Outer Tracker○ Design and construction○ Installation and commissioning

Fabian Jansen (Nikhef)On behalf of the LHCb Outer Tracker group

11th Pisa meeting on advanced detectorsLa Biodola, Isola d’Elba (Italy), May 24-30 2009

May 25, 2009 11th Pisa Meeting on Advanced Detectors

2/

28

B-physics

● The physics of hadrons containing b-quarks

1. CP-violation (Charge-Parity asymmetry) with B-mesons○ measurable through B/anti-B mixing and decay

2. New physics with rare B decays○ B decays with small conventional

branching fractions involving loop diagrams○ New physics may contribute at the

same scale as conventional physicsVtb

Vtb

Nobel prize 2008: 1. spontaneous symmetry breaking + 2. at least three families of quarks =

possible CP violation

B mixing

new physics?

K*B0

μ+

μ-

b s

rare decay B0 → K* μ+ μ-


3/

28

B-physics at LHCb

● The LHC will act as a B factory with large b-quark production rate○ σbb ~ 500μb for pp collisions at s = 14TeV

● B hadrons are produced predominantly forward/backward

● LHCb ○ forward spectrometer (10-300 mrad)○ dedicated to B physics○ “modest” luminosity L~ 2 1032cm-2s-1 ○ expected 1012 bb/year (107 sec)

100 b

230 b

ppb

b

p p

collisioncollision

250mrad


4/

28

LHCb detector: overview● One-arm forward spectrometer: subdetectors cascade in beam direction

proton beam

collision point

~1 cm

B

proton beam


5/

28

LHCb detector: vertex locater● contains the pp-collision point

● precise determination of primary and secondary vertices (B lifetime)

~1 cm

B


6/

28

LHCb detector: RICH1,RICH2● Particle IDentification; kaon-pion separation


7/

28

LHCb detector: calorimeter system● particle identification; electron, photon, hadron

● trigger (at 40MHz)


8/

28

LHCb detector: muon system● muon tracking

● trigger (at 40MHz)


9/

28

LHCb detector: tracking stations● charged particle momentum determination

● TT before magnet, Inner and Outer Tracker after magnet


10/

28

OT expected occupancy:

Average = 4.5%

Hottest region = 9%

Outer tracker performance requirements

● High speed○ 25ns bunch crossing cycle

● Momentum resolution (Δp/p) better than 0.5% (2-100GeV tracks)○ precise (B-)mass reconstruction ○ =► spatial resolution less than 200μm

● Occupancy below 10% ○ efficient track reconstruction

● High efficiency○ efficient B reconstruction

beam pipe and Inner Tracker

expected J/ψ mass distribution

σ=11MeV!


11/

28

The Outer Tracker consists of 3 stations ~0.5m apart

● Station○ 2 support frames (C-frames) mounted vertically

with 2 layers of detector modules○ =► 4 layers of modules with orientation 00,+50,-50,00

○ Every C-frame is in two halves that can be moved

horizontally in and out around the beam pipe

● Layer○ 14 type F modules; full height○ 4 type S modules; half height outside the hot region

Outer Tracker module design and production

2400 mm

Type F

S1

3070 mm

S3S2

2900 mm

00

00

+50-50

Inner Tracker


12/

28


● Module○ 2 staggered layers of 64 straw tubes○ split in electrically independent upper and

lower sections with Front End electronics on both sections

○ 1module: X/X0 = 0.37%!

● Straw○ 5mm radius○ 25μm anode wire at 1550V

○ Ar(70%)/CO2(30%)

module top view

aluminum laminated kapton wound on carbon doped kapton-XC

4800

mm

340 mm


13/

28


● 2004-2005: OT module production

● Quality assurance during production○ wire tension (<7%)○ wire position (<100μm)○ dark current (<10nA at 1600V)

● Quality assurance after production○ gas tightness (<1mbar/minute)

○ dark current (<10nA at 1600V and Ar(70%)/CO2(30%) )

● Detector response to 90Sr source; full scan (every cm) of all OT modules

● Module production summary○ dead channels: disconnected shorts (0.6‰)○ “noisy” channels: high dark current (0.7‰), often cured after HV training

• Cracow: all straw-support panels• Warsaw: 124 type S modules• Heidelberg: 62 type F modules• Nikhef: 130 type F modules

Detector Module massconstruction ~ assembly of:- 56,000 straws- 56,000 wires- 200,000 soldered joints- 620 panels- 185 F and 124 S Modules

LHCb note: lhcb-2004-078


14/

28

OT Front End electronics design and production● HV circuit board

○ 330 pF capacitors decouple signal from HV○ embedded capacitors reduce leakage currents

● ASDBLR amplifier○ discriminate signal against threshold○ high speed through elimination of long ion tail by shaping and baseline restoring of

signal; dead time ~20ns○ low noise through differential logic swing○ low threshold =► good efficiency & resolution

● OTIS time-to-digital converter○ 25ns LHC bunch clock into 64 TDC bins○ incorporate up to three BX drift time

● GOL○ Transfer of data of 128 channels

(+headers) via optical fiber at 1.6Gb/s

See poster: The FE Electronics of the LHCb Straw Tube Tracker


15/

28

OT Front End electronics design and production

● 2005-2008 OT FE electronics production

● All components tested and selected individually before assembly

● All FE boxes tested after assembly on○ threshold characteristics○ timing behavior○ noise and cross talk○ trigger latency response

threshold scanthreshold scan

insensitive channelsASDBLR’s replaced

nonlinear channelOTIS replaced

All Front End electronics components with bad

characteristics/behavior/response were replaced!

LHCb note: lhcb-2007-122

linearity scanlinearity scan

rejected co

mponents


16/

28

Test beam at Desy● Beginning of 2005: beam test at Desy

● First four half-length OT modules

● Final prototype FE electronics

LHCb Note: lhcb-2005-076

● Efficiency● Resolution● Noise & Cross Talk

● High Voltage● Amplifier threshold● Position along straw

VS


17/

28

Test beam results (1)

r (mm)

Drif

t tim

e (n

s)RT-relation

2.45 mm 2.45 mm

r (mm)

Eff

icie

ncy

efficiency profile

next slide resolution and efficiency for different HV and amplifier threshold

results for 1550V HV, 800mV threshold


18/

28

Test beam results (2)

100

0.2

0

0

0.6

HV(V)1400 15501200

1400

Good efficiency and resolution for HV > 1550V

ε 98%

σ 200 µm

o Corresponds to Gain > 50,000

Re

solu

tion

(mm

)

Eff

icie

ncy


19/

28

Outer tracker module installation (1)

bridge

beam pipe

module support frame (C-frame)• 2x9 detector modules• 4x9 FE boxes• cooling, gas• Low Voltage, High Voltage, etc.


20/

28

Outer Tracker module installation (2)

● 2006-2007: Assembly of modules into C-frames and installation of C-frames in detector

● Before assembly of modules, C-frames tested for○ gas tightness of gas distribution system <1mbar/minute at 10mbar CO2

○ High Voltage leakage currents <10nA/RMS<1nA○ Low Voltage connections OK○ optical fiber attenuation <30dBm

● After assembly of modules into C-frame, modules tested for○ gas tightness: <1mbar/minute & matching production

○ High Voltage leakage currents <100nA/channel at 3 minutes 1.8kV-CO2

● Functionality test with 55Fe source○ >2700 straws (~½OT) individually tested○ 13 dead channels; 11 known at production

● 2008: Installation of FE electronics

LHCb note lhcb-2008-033


21/

28

Outer Tracker commissioning overview

ok

FE not installed

I2C problem

BxID mismatch

QPLL not locked

other problem

optical link problem

desynchronisation

all TELL1 OK

this is a snap shot,work is ongoing!


22/

28

Data taking (1)

● During the last months OT was taking data in global LHCb commissioning○ random and calibration triggers (test pulse possibility)○ cosmic muons triggered by CALO/MUON○ “media day” (beam!)

media day


23/

28

Data taking (2)

● Look at various type of data with various goals○ Random trigger for noise, FE debugging, …○ Calibration test pulse trigger for threshold characteristics, timing behavior,…o Cosmics trigger for

○ t0 calibration/time alignment

○ RT calibration○ Alignment○ track reconstr.○ …

cosmics event

Next slides: first t0 & RTcalibrations with cosmics


24/

28

Cosmics data (1)

● Use calorimeter to trigger cosmic muons

● Correct for downstream (early OT hits) or upstream (late OT hits)

● Correct for Time Of Flight and wire propagation time

TDC = tcosmic + tTOF + tdrift + tprop + t0


25/

28

● t0 calibration with cosmics: a first analysis

Cosmic data (2)

Faulty CLK fan-outs,now replaced!

mod

ule

t 0 (

ns)

module average t0 (ns)

module

<3ns variation in t0’s!


26/

28

Cosmic data (3)

● RT relation with cosmics: a first analysis

RT-relation in beam testRT-relation from cosmics

calibration with cosmics ongoing work!


27/

28

Summary

● LHCb will be ready to collect data with its full detector as LHC turns on:o Test of Charge-Parity asymmetry

o probe rare B decays

● Tracking system performance of crucial importanceo Outer Tracker consisting of straw-tubes modules

o All OT modules and electronics built and tested• Quality Assurance during production• Beam tests

● All OT modules and electronics installed and re-tested in situ o Commissioning well advanced

• Electronics debugging• Cosmic trigger for OT commissioning: track reconstruction, T0 and RT

calibration, alignment, etc

Beam for B physics


28/

28

Documents

Construction, Installation and Commissioning of a High- Efficiency and High-Resolution Straw Tube Tracker for the Experiment ●Introduction ○B-physics at