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Detectors & Measurements: How we do physics without seeing…. Overview of Detectors and Fundamental Measurements: From Quarks to Lifetimes. Prof. Robin D. Erbacher University of California, Davis. References : R. Fernow, Introduction to Experimental Particle Physics, Ch. 14, 15
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Overview of Detectors and
Fundamental Measurements:
From Quarks to Lifetimes
Prof. Robin D. Erbacher
University of California, Davis
References: R. Fernow,Introduction to Experimental Particle Physics, Ch. 14, 15
D. Green, The Physics of Particle Detectors, Ch. 13
http://pdg.lbl.gov/2004/reviews/pardetrpp.pdf
Lectures from CERN, Erbacher, Conway, …
A Higgs field interacts
as well, giving particles
their masses.
H
The SM states that:
The world is made
up of quarks and
leptons that interact
by exchanging
bosons.
35 times heavier
than b quark
Lepton Masses:Me<M<M ; M~0.*
Quark Masses:Mu ~ Md < Ms < Mc< Mb << Mt
Time
Rare Events, such as Higgs production, are difficult to find!
Need good detectors, triggers, readout to reconstruct the mess into a piece of physics.
Time
Cartoon by Claus Grupen, University of Seigen
No single detector does it all…
Create detector systems
Collider Geometry
Fixed Target Geometry
End products
Modern detectors consist of many different pieces of
equipment to measure different aspects of an event.
Measuring a particle’s properties:
Particles are detected via their interaction with matter.
Many types of interactions are involved, mainly electromagnetic.
In the end, always rely on ionization and excitation of matter.
Jet (jet) n. a collimated spray of high energy hadrons
Quarks fragment into many particles to form a jet, depositing energy in both calorimeters.
Jet shapes narrower at high ET.
high pT
muon
missing ET
b-quark lifetime:
c ~ 450m
b quarks travel
~3 mm before decay
q jet 1
q jet 2
CDF Top PairEvent
Signature Detector Type Particle
Jet of hadrons Calorimeter u, c, tWb,
d, s, b, g
‘Missing’ energy Calorimeter e, ,
Electromagnetic
shower, Xo EM Calorimeter e,, We
Purely ionization
interactions, dE/dx Muon Absorber ,
Decays,c ≥ 100m Si tracking c, b,
(TOF, C, dE/dx)
v
Particle Identification MethodsConstituent Si Vertex Track PID Ecal Hcal Muon
electron primary — —
Photon primary — — — —
u, d, gluon primary — —
Neutrino — — — — — —
s primary —
c, b, secondary —
primary — MIP MIP
MIP = Minimum
Ionizing Particle
Z bosons have a very short lifetime, decaying in ~10-27 s, so that only decay particles are seen in the detector. By looking at these detector signatures, identify the daughters of the Z boson.
But some daughters can also decay:
More Fun with Z Bosons, Click Here!
Run 2 Event
Solenoid
Toroid
+ Large homogeneous field inside
- Weak opposite field in return yoke - Size limited by cost
- Relatively large material budget
+ Field always perpendicular to p
+ Rel. large fields over large volume + Rel. low material budget
- Non-uniform field
- Complex structural design
All silicon: pixels and strips!
210 m2 silicon sensors
6,136 thin detectors (1 sensor)
9,096 thick detectors (2 sensors)
9,648,128 electronics channels
All silicon sensors:
pixel/strip tracking
“imaging” calorimeter
using tungsten with Si wafers
Coming next time…
