Types of Detectors

1. Overview of Gas Ion chamber
and Scintillating
Particle Detectors
Erich Wanzek

2. Detectors
• Particle Detectors can
measure the
• Particle energy
• momentum
• charge,
• presence of a particle.
• Trajectory

3. Gaseous Ionization Detectors
• Use the ionizing effects of radiation
upon a gas-filled sensor.
• If a particle has enough energy
to ionize a gas atom or molecule,
• the electrons and ions will cause a
current flow which can be measured.
• The three basic types of gaseous
ionization detectors are
• 1) ionization Chambers
• 2) Proportional Counters
• 3) Geiger Tubes

4. Gas Ion Chamber Detectors
• Common Ion Detectors
chambers contain a mixture
of these gases:
• Argon
• Isobutene
• Freon
• Xenon
• Tetramethlsilane
• Tetrakis dimethylamine
ethylene vapor

5. Ionization Chambers
• Simplest of all gas-filled radiation
detectors
• widely used for the detection and
measurement high amounts of
Gamma rays, beta particles
• Collect the charges created by direct
ionization within the gas through the
application of an electric field.
• It only uses the discrete charges
created by each interaction between
the incident radiation and the gas
• Does not involve the gas
multiplication Ion chambers have a
good uniform response to radiation
over a wide range of energies and are
the preferred means of measuring
high levels of gamma radiation.
• They are widely used in the nuclear
power industry, research labs,
radiography, radiobiology, and
environmental monitoring.

6. Proportional Counters
• Operate at a higher voltage
• Voltage is set such that
discrete avalanches are generated.
• Each ion pair produces a single
avalanche so that an output current
pulse is generated which is proportional
to the energy deposited by the radiation.
• This is in the "proportional counting"
region.
• able to detect particle energy
• It is widely used where energy levels of
incident radiation must be known, such
as in the discrimination between alpha
and beta particles

7. Geiger Tube
• Operate at very high voltage so that each ion
pair creates an avalanche, with the emission of
UV photons, multiple avalanches are created
which spread along the anode wire, and the
adjacent gas volume ionizes from as little as a
single ion pair event.
• This is the "Geiger region" of operation.
• to produce an easily detectable electronic pulse
from as little as a single ionizing event due to a
radiation particle. It is used for the detection
of gamma radiation, x-rays, and alpha and beta
particles
• The current pulses produced by the ionizing
events are passed to processing electronics
which can derive count rate

8. Multi Wire proportional
Chamber
• A multi-wire-proportional is a type
of proportional counter that detects charged
particles and photons
• Can give positional information on trajectory
of particles by tracking the trails of gaseous
ionization.
• In 1968, Georges Charpak invented and
developed the MWPC and this led to his
Nobel Prize in 1992.
• The chamber was an advancement of the
earlier bubble chamber rate of detection of
only one or two particles every second to
1000 particle detections every second.
• The MWPC produced electronic signals from
particle detection allowing scientists to
examine data via computers.
• For high energy experiments, it is used to
observe a particle's path.

9. MWPCs

10. Scintillation Counter
• Detects and measures ionizing
radiation by using the excitation effect of
incident radiation on a scintillator
material, and detecting the resultant
light pulses.
• Consists of a scintillator which generates
photons in response to incident
radiation, and sensitive photomultiplier
tube (PMT) which converts the light to an
electrical signal and electronics to
process this signal.
• Scintillation counters are widely used
because they can be made inexpensively
yet with good quantum efficiency, and
can measure both the intensity and the
energy of incident radiation.

11. Types of Scintillating Crystals
• Organic
• Liquids
• crystals
• Plastics
• Inorganic
• Gases
• Operate on the principle of
fluorescence and phosphorescence

12. Scintillation Detector

13. Scintillating Fiber Detectors