13.5 mm

15.8 mm

Unique L0 trigger capability• Prompt FastOR signal in each chip• Extract and synchronize 1200 FastOR

signals from the 120 half-staves• User defined programmable algorithms

• 2 layer barrel• Total surface: ~0.24m2

• Power consumption ~1.5kW

• Evaporative cooling C4F10

• Room temperature• Material budget per layer ~1%

X0

Inner surface: 40 half-staves

Outer surface: 80 half-staves

MCM

5 Al layer bus + extender

Ladder 1 Ladder 2 MCM + extender + 3 fiber link

Grounding foil

• ALICELHCb1 readout chip• mixed signals• 8192 cells• 50x425m2

Half-stave

Highlights of the ALICE Silicon Pixel Detector

~1200 wire-bonds

SPD installed in ALICE in Jun‘07

Final checks (top-right), installation around the Be beam pipe (bottom-left) and last sight (bottom-right)

Commissioning started-up in Dec ’07 First cosmic event detected in the SPD on 21 Feb ’08 SPD prompt trigger (≈800 ns latency) to ALICE L0 installed and commissioned in Apr

‘08 Data taking for the inner alignment of the ITS modules and ITS vs TPC from May

’08, trigger provided by the SPD

SPD residual misalignment < 10 m (detector position resolution 12 m)

SPD Online Event Display - Cosmic RunSelf-triggered (FastOr) coincidence of top outer and bottom outer

layer

Side view View along z Side view View along z

First sign of life in LHC seen by the ALICE SPD on 15 Jun ‘08 during a transfer line injection test

- cover and LHC focus article in the Jul/Aug issue of the CERN Courier

SPD operational during the beam injection tests since Aug ‘08 in self-triggering mode

- study of the LHC screen related background in ALICE

On 10 Sep ‘08 the SPD lights up with first beam in LHC

Longitudinal tracks along up two ladders (14 cm)

First beam-induced interaction in LHC recorded by the ALICE Inner tracking System on 11 Sep ’08

- Beam 1 captured by RFs and circulating up to 30’- SPD triggering - ITS standalone tracking, 7 track event

SPD ready to record the first collisions in LHC in Sep ’09.

«It's 9 a.m. and the Silicon Pixel Detector in ALICE lights up with particle “debris“ created as beam in the transfer line from the SPS hits the beam stop before Point 2.» From CERN Courier –Nov. ’08 – LHC focus: “LHC first beam: a day to remember”