1. Tracking detectors/2
F.Riggi

2. Vertex detectors
All large experiments usually include a vertex detector (inner part of the tracking system) and large volume tracking detectors (TPC).
The future experiments at LHC will make use of silicon detectors for the inner part of the tracking system
pixel detectors
silicon drift detectors
strip detectors

4. LHC Vertex detectors CMS ATLAS Strips: 61m2, 6.3 x 106 channels
Pixels: ~2m2, 80 x 106 channels
210m2, 9.6 x 106 channels
~2m2, 33 x 106 channels

5. LHC Vertex detectors ALICE LHCb Strips: 4.9m2, 2.6 x 106 channels
Drifts: 1.3m2, 1.33 x 105 channels
Pixels: 0.2m2, 9.83 x 106 channels
VELO: 0.32m2, 2 x 105 channels
Tracker: 14m2, ~8 x 105 channels
HPD: ~ 0.02m2, ~1 x 106 channels

6. Radiation Levels in LHC experiments
total dose fluence
1MeV n eq. [cm-2] after 10 years
ATLAS Pixels 50 Mrad 1.5 x 1015
ATLAS Strips 7.9 Mrad ~2 x 1014
CMS Pixels ~24Mrad ~6 x 1014 *
CMS Strips 7.5Mrad 1.6 x 1014
ALICE Pixel 500krad ~2 x 1013
LHCb VELO x 1014/year**
*Set as limit, inner layer reaches this value after ~2 years
**inner part of detector (inhomogeneous irradiation )
A radiation tolerant design is important to ensure the functionality of the read out over the full life-time!

7. ATLAS Vertex detector

8. ATLAS Vertex detector

9. ATLAS Vertex detector ATLAS has two tracking systems
inner detector (ID) which is composed of
Semiconductor tracker (SCT) - both in the barrel and in the two end-caps
silicon pixel detectors
barrel 3 layers (including 1 removable) 4, 10, 13cm
5 disks on each end-cup side from cm
pixel size 50x400 mm2
silicon strip detectors - quasi-double-sided
barrel 4 layers 30, 38, 45, 52cm
9 wheels on each end-cup side
strip pitch 80mm
stereo angle 40 mrad

10. ATLAS Vertex detector

11. CMS Vertex detector

12. CMS Vertex detector

13. CMS Vertex detector Requirements - as for ATLAS
Again two tracking systems - inner tracker and muon traker
inner tracker placed inside 4 T solenoid
all silicon solution adopted, two technologies
silicon pixel detector
in barrel 3 layers 4.3, 7.2 and 11.0 cm
pixel size 150x150 m2
each end-cap 2 disks, 32.5 and 46.5 cm from interaction point

14. CMS Vertex detector silicon strip detectors
barrel 10 layers, radii cm
layers 1, 2, 5, 6 and 7 quasi double sided
other layers single sided
layers inner silicon detector ( cm)
pitch size from 61mm to 122mm, on double sided detectors second side has pitch from 81mm to 244mm
resolution between 15 and 30mm
inner silicon detector is completed by 10 disks in each end-cap
layers outer silicon detector ( cm)
strip pitch 140mm, on double sided detectors second side has a pitch 210mm
resolution between 40 and 60mm
completed by 9 disks in each end-cap

15. CMS Vertex detector

16. LHCb Vertex detector

17. LHCb Vertex detector Silicon detector in vacuum pipe
18 stations spread over ~ 1m
each station two planes with radial and circular strips
at distance 1 to 6 cm from beam axis
strip pitch
between 40 and 104 m for radial
between 40 and 80 m for circular
radial strips have stereo angle, alternate +5° and -5°
resolution between 9 and 18 m
impact parameter resolution ~ 40 m

18. LHCb Vertex detector

19. ALICE Vertex detector

20. ALICE Vertex detector Two tracking detectors (maybe three ?)
ITS (Inner Tracking System)
six layers of silicon detectors
2 pixel layers at radii 3.8 cm and 7.4 cm
50x425 m2 pixel size
2 silicon drift layers at radii 14 cm and 24 cm
drifting in r direction
about 300 m anode pitch
2 silicon strip layers at radii 39 cm and 45 cm
strip pitch 95 m, double sided silicon detectors
amplitude readout, possibility of charge matching

21. ALICE Vertex detector

22. ALICE Vertex detector

23. Conclusions Vertex detectors at LHC will use mostly silicon
Tracking capabilities are at their limits, especially for H.I.
Powerful tracking/vertex reconstruction methods are required
Radiation damage is of special concern