Transcript Radiation Detectors - Embry–Riddle Aeronautical University

Radiation Detectors
In particular,
Silicon Microstrip Detectors
by
Dr. Darrel Smith
Silicon Microstrip Detectors
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Introduction
Charged Particle Detectors
Silicon Microstrip Detectors
Their use in remote sensing
Introduction
• Since the discovery of radioactivity (1890’s),
scientists have designed detectors to record
and measure the appearance of new
particles.
• , , and  radiation ( +, -)
• n radiation (neutrons)
• p radiation (protons)
Detectors
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Photographic Film
Emulsions
Bubble Chambers
Wire Chambers
Scintillators
Cerenkov Detectors
Solid-State Detectors
Ionization Radiation
• In the case of searching for charged particles,
most of these detectors work on the principle
of energy loss, namely dE/dx.
• The Bethe-Bloch equation:
• The slower a particle moves, the more
ionization that occurs.
Ionization Radiation
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β
v
E
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c
z
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I
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=v/c
velocity of the particle
energy of the particle
distance travelled by the particle
speed of light
particle charge
charge of the electron
rest mass of the electron
electron density of the target
mean excitation potential of the target
permittivity of free space
Bragg Curve
• Stopping Power
– Type of particle
– Energy of the particle
– Properties of the material
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decompressor
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Ions Slowing Down
• A typical ion slowing down in material
due to the dE/dx energy loss.
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decompressor
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Two Basic Interactions
• Electromagnetic Interactions
– electrons, and photons lose most of their
energy through these processes.
• Hadronic Interactions
– particles containing quarks, tend to lose a
greater fraction of their energy through
nuclear interactions.
Electromagnetic Interactions
• Electrons and Photons
• A “figure of merit” describing the interaction of
electrons in materials is called the radiation length,
Xo.
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decompressor
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• Energy loss is primarily through bremsstrahlung, and
pair production down to 10’s of MeV.
• Below a few 10’s of MeV, the energy loss I primarily
through ionization.
Hadronic Interactions
• The figure of merit is called the “nuclear
interaction length.”
Detector Resolutions
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Bubble Chamber
Streamer chamber
Drift Chamber Scintillator
Emulsion
Silicon Strip
Silicon Pixel
10-150 m
300 m
50-300 m
1 m
pitch/(3-7)
2 m
Early Tests (CERN)
Early Tests (CERN)
Vertex Reconstruction
Simulation of a top
quark decay into a
B meson.
Vertex Reconstruction
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Short-lived particles (b-decays)
Lifetime
 = 1.54 x 10-12 seconds
c o = 462 m
Lo = co
Vertex Reconstruction
Next Generation Detectors
• CCDs in layers
• Pixel readout
• 3 dimensional reconstruction