Tracking detectors/2 F.Riggi
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
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
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
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 - 1.3 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!
ATLAS Vertex detector
ATLAS Vertex detector
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 11 - 20cm 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
ATLAS Vertex detector
CMS Vertex detector
CMS Vertex detector
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
CMS Vertex detector silicon strip detectors barrel 10 layers, radii 22-115cm layers 1, 2, 5, 6 and 7 quasi double sided other layers single sided layers 1 - 5 inner silicon detector (22 - 60cm) 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 6 - 10 outer silicon detector (70 -115cm) 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
CMS Vertex detector
LHCb Vertex detector
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
LHCb Vertex detector
ALICE Vertex detector
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
ALICE Vertex detector
ALICE Vertex detector
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