the cms detector
DESCRIPTION
The CMS Detector. Paoti Chang National Taiwan University Workshop on LHC Physics and the Strategies for Discovery Taipei, Taiwan, Jan. 14, 2008. Detector Requirement. Good Muon identification;good dimuon mass resolution (~1% at 100 GeV); distinguish charge at 1 TeV. - PowerPoint PPT PresentationTRANSCRIPT
1/14/08 NTU, Taipei 1/14/08 NTU, Taipei The CMS Detector The CMS Detector 11
The CMS DetectorThe CMS DetectorPaoti ChangPaoti Chang
National Taiwan UniversityNational Taiwan University
Workshop on LHC Physics and the StraWorkshop on LHC Physics and the Strategies for Discoverytegies for Discovery
Taipei, Taiwan, Jan. 14, 2008Taipei, Taiwan, Jan. 14, 2008
The CMS Detector 21/14/08, NTU, Taipei
Detector Requirement Good Muon identification;good dimuon mass resolution (~1
% at 100 GeV); distinguish charge at 1 TeV. Good momentum resolution for charged tracks. Efficient trig
gering and off-line tagging on and b-jets. Good EM energy resolution; good diphoton and dielectron
mass resolution;wide geometrical coverage;rejection and efficient photon and lepton isolation
Good missing-transverse-energy and dijet mass resolution
high-field solenoid, full-silicon-based inner tracking
system and a homogenous scintillating-crystal-based
electromagnetic calorimeter
The CMS Detector 31/14/08, NTU, Taipei
Overview of the CMS Detector
The CMS Detector 41/14/08, NTU, Taipei
Superconducting Magnet
Special features:
1. Winding composed of
four layers
2. Mechanically reinforced
with aluminum alloy
3. Large dimension
6.2 m cold bore, 12.5m length,220-t mass
The CMS Detector 51/14/08, NTU, Taipei
Main parameters CMS decides to use lower field, 3.8T.
The CMS Detector 61/14/08, NTU, Taipei
CMS Barrel Yoke ready for coil and muon Detector
The CMS Detector 71/14/08, NTU, Taipei
Inner Tracking System
Provide precise measurements of track trajectories and secondary vertices.
L= 1034 cm s 1000 particles from >20 inter.
high granularity and fast response of electronics
Keeping minimum amount of material 3 layers of pixel to reduce occupancy (4.4-10.2 cm)
10 layers of silicon strip detectors (R ~ 1.1 m)
endcaps: 2 disk pixel and 3 plus 9 strip on each side
⇕
The CMS Detector 81/14/08, NTU, Taipei
Overview of the tracker layout
Acceptance ||<2.5, 200 m2 silicon area, 1440 pixel and 15148 strip modules.
pixel: 100x150 m2; Inner silicon: 10cm x 80m; outer silicon: 25cm x 180 m
The CMS Detector 91/14/08, NTU, Taipei
Expected Hadron Fluence and Radiation Dose
L = 500 fb, 10 years of LHC running
Surface damage on readout chips 0.25m CMOS chip (rad. hard)
Increasing leakage current low temperature -10C to -27C
transient phenomena
The CMS Detector 101/14/08, NTU, Taipei
Pixel DetectorLayout overview
barrel support structure
material budget
The CMS Detector 111/14/08, NTU, Taipei
Barrel Pixel Detector Modules
The CMS Detector 121/14/08, NTU, Taipei
Forward Pixel
Half cylinders
Sketches of two types of FPix panels
Sketch of of a plaquette mounted in a panel
The CMS Detector 131/14/08, NTU, Taipei
Status of Pixels
The CMS Detector 141/14/08, NTU, Taipei
Overview of Silicon Strip Detector
The CMS Detector 151/14/08, NTU, Taipei
Silicon sensor
Active region
320 m sensors
500 m sensors
The CMS Detector 161/14/08, NTU, Taipei
Silicon Tracker
Exploded views of a module of two sensors
Inner Barrel and Endcap
Three TIB modules in a shell
The CMS Detector 171/14/08, NTU, Taipei
Outer Silicon TrackerEach sector consists of 9 front petals and 9 back petals
Endcap outer silicon strip detectorsTOB wheel
d = 2.3 m
The CMS Detector 181/14/08, NTU, Taipei
Rod an Petal
Double sided rodFront and back panels for TEC
The CMS Detector 191/14/08, NTU, Taipei
Expected Performance
Impact parameter in r Impact parameter in zTransverse momentum
The CMS Detector 201/14/08, NTU, Taipei
Electromagnetic Calorimeter
The CMS ECAL consists of a hermetic homogenous calorimeter made of 61200
lead tungstate (PbWO4) crystals in the central barrel part, ~7324 crystals in each of the two endcaps, and a preshower detector in front of the endcap crystals.
Advantages of PbWO4: 1. high density (8.28 g/cm3); 2. shorter rad. Length (.89 cm) 3. short Moliere radius (2.2 cm); 4. fast radiation decay time (80% of the light in 25 ns)
fine granularity, radiation hardness and compact calor.
The CMS Detector 211/14/08, NTU, Taipei
CMS-PbWO4
The CMS Detector 221/14/08, NTU, Taipei
Layout of the CMS ECAL
Barrel: || < 1.479
360 fold in
2x85 fold in
crystal size:
front: 22x22 mm2
back: 26x26 mm2
length: 230 mm
25.8 X0
Endcap:
1.479< || < 3.0
1 unit = 5x5 crystals.
crystal size:
front: 28.62x28.62mm2
back: 30x30 mm2
length: 220 mm
24.7 X0
The CMS Detector 231/14/08, NTU, Taipei
ECAL Modules
Module of 200 crystals
Barrel supermodule (1700 crystals)
The CMS Detector 241/14/08, NTU, Taipei
ECAL-Barrel
The CMS Detector 251/14/08, NTU, Taipei
Preshower Detector
1.653<||<2.6; total length 20 cm. Twp parts: lead radiators and silicon strip sensors. Taiwan involvement: NCU: 1/4 silicon sensors NTU: System Motherboards
The CMS Detector 261/14/08, NTU, Taipei
Calibration and Resolution
channel-to-channel variation:
use lab. measurements on light yields and photo-dio. response. 5% in barrel and 10% in endcap
Beam test 0/ → in data; w →e. Laser Monitor system Energy resolution
The CMS Detector 271/14/08, NTU, Taipei
Performance of a typical 3x3 crystals
The CMS Detector 281/14/08, NTU, Taipei
Status of ECAL Endcaps & Preshower
Preshower: testing micro modules, motherboards and
preparing to install in April
The CMS Detector 291/14/08, NTU, Taipei
Longitudinal View of the CMS Det.
HCAL Barrel
HCAL Endcap HCAL Forward
The CMS Detector 301/14/08, NTU, Taipei
HCAL Barrel (HB)
The HB consists of two half-barrels, each of which contains 18 wedges. Each wedge corresponds to 4 sectors.
The absorber consists of a 40-mm thick front steel plate, 8 50.5-mm-thick brass plates, 6 56.6-mm-thick brass plate, and a 75-mm-thick steel back plate.
Half barrelwedge
16
5.82 I at 90 and 10.6 I at=1.3
The CMS Detector 311/14/08, NTU, Taipei
The HCAL Tower Segmentation
Plastic scintillators
The CMS Detector 321/14/08, NTU, Taipei
Endcap Calorimeter (HE)Yoke
Close to magnet, non-conducting absorber has to be used.
C26000 cartridge brass
The CMS Detector 331/14/08, NTU, Taipei
HCAL Endcaps
HE WedgesScintillator Tray
The CMS Detector 341/14/08, NTU, Taipei
Forward Calorimeter
Situate at || = 5 Detect particles through its Cherenkov light.
Require good EM response (electrons). Serve as luminosity monitor
Methods: zero counting and average ET per tower
The CMS Detector 351/14/08, NTU, Taipei
Expected Performance
Jet energy resolution
The CMS Detector 361/14/08, NTU, Taipei
Muon System
Identify muons, measure momentum and
trigger muon events. The muon system consists of three types of gas
eous detectors:
1. four layers of drift tubes in ||<1.2
2. cathode strip chamber covering || to 2.4
3. resistive plate chambers
6 layers in barrel and 3 in endcaps ( || < 1.6 )
The CMS Detector 371/14/08, NTU, Taipei
Layout of Drift Tube Chambers
One of the five wheels.
60 chambers in the first three layers and 70 in the last.
One layer is inside the yoke, one is outside, and the other two are embedded within the york.
The CMS Detector 381/14/08, NTU, Taipei
Sketch of Drift-Tube Cell
Top and bottom plates are grounded. The voltages applied to the electrode are +320V for wires, +1800 V for the strips and -1200 V for the cathode.
Gas:
85% Ar + 15% CO2
The CMS Detector 391/14/08, NTU, Taipei
Installation of MB1 on Wheel 2
Each DT chamber is made of 3 (or 2) superlayers, each of which is made of 4 layers of rectangular drift cells.
The CMS Detector 401/14/08, NTU, Taipei
Quarter view of the CMS Detector
The CMS Detector 411/14/08, NTU, Taipei
Layout of a CSC & a Schematic View of a Single Gap
7 trapezoidal panels forming a 6 gas gaps.
Gas:
40% Ar + 50% CO2 + 10% CF4
HV: 3.5-3.9 kV
The CMS Detector 421/14/08, NTU, Taipei
Resistive Plate Chamber Advantage: tagging the ionizing time much shorter than 25s good for triggers
Gas:
96.2% C2H2F4 + 3.5% C2H10 + 0.3% SF6
The CMS Detector 431/14/08, NTU, Taipei
Schematic Layout for Barrel RPC
r-view
The CMS Detector 441/14/08, NTU, Taipei
Layout for Endcap RPC
The CMS Detector 451/14/08, NTU, Taipei
Expected Performance
The CMS Detector 461/14/08, NTU, Taipei
Status of the Muon System
1. DT muons:
a. Install tower electronics b. Test and commission
2. CSC
a. All chambers and electronics are installed. B. Do more tests.
The CMS Detector 471/14/08, NTU, Taipei
Summary
After so many year hardwork, majority of the detector and electronics are installed and commissioned.
Problems and difficulties are foreseen before collisions.
Tight schedule for Endcap ECAL and Preshower. Keep testing and looking forward to LHC physics.