This document discusses different types of solid state radiation detectors, including scintillation detectors, thermoluminescent dosimeters (TLD), and semiconductor detectors. Scintillation detectors detect radiation via light emission in inorganic crystal materials like NaI or organic crystals like anthracene. TLDs "capture" radiation dose information and release light when heated, allowing dose measurement. Common TLD materials are LiF:Mg,Ti and Li2B4O7:Mn. Semiconductor detectors like silicon and germanium act as solid state ionization chambers and are used for high resolution energy measurement of alpha and beta particles.

1. SOLID STATE DETECTOR
1 MAMITA SAKHAKARMI
B.Sc.MIT
4th BATCH 1ST YEAR
Chitwan Medical College

2. DETECTORS
An instrument responsible for detection of
ionizing radiations by interacting with matter or
to measure radiation or to do both.
Types
 Gas filled detector
 Solid state detector
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3. SOLID STATE DETECTOR
This consists of the solid materials with fluorescence,
phosphorescence and semiconducting properties.
Types
 Scintillation Detector
 Thermo luminescent dosimeter
 Semiconductor Detector
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4. Scintillation detectors:
 Detectors based on scintillation (light emission)
Working Principle
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5. Types
 Inorganic crystals
 Organic crystals
 Inorganic crystals
 Generally, high atomic number and high density materials
 NaI, CsI, Lithium glasses, ZnS
 Commonly used for gamma-ray detection
 High light yield (60,000/ Mev)
 Can’t be used in liquid form.
 Low decay time about 1 microsecond
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6. INORGANIC SCINTILLATORS
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7. Organic crystals
 low atomic numbers, relatively low density.
 Low light yield (1000photons/ Mev)-power signal
 Can be used in both liquid and solid form.
 Economic
 Fast decay time about 10 nanosecond
 Commonly used for Beta particles detection
E.g. trans-stilbene, Anthracene, Naphthalene etc.
Generally, in our department inorganic crystals are
used because of their high at. no. n high densities
that make them good x-ray n gamma ray detector.
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8. ORGANIC SCINTILLATORS COME IN MANY
FORMS
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9. THERMO LUMINESCENT DOSIMETER
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• TLD is excellent personnel and environmental
dosimeter.
• It is based on Thermoluminescence.

10. Measurement of Thermoluminescence
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11.  “Captures” radiation dose information in a crystal
matrix.
 Releases light when heated, light intensity
proportional to radiation dose absorbed.
 Information destroyed when processed.
 Should be annealed before reused.
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12. TYPES OF TLD MATERIAL
Commonly used
LiF:Mg,Ti, LiF:Mg,Cu,P and Li2B4O7:Mn, because of
their tissue equivalence.
Most widely used is LiF.
 Atomic no. is 8.2 that is nearly tissue equivalent (7.4 for
soft tissue)
 LiF is relatively sensitive and can measure as low as 5
mRad with modest accuracy.
 CaF2 has higher effective atomic no. (z= 16.3)
 TLDs are available in various forms (e.g. powder,
chips, rods and ribbons).
 Can be expensive (reusable chips)
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15. Glow curve : graph obtained by plotting phosphor
temperature (ºC) against intensity of emitted light.
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Phosphor temperature (C)
EmittedLightIntensity

16. Practical consideration :
 Must be calibrated before use.
 Since the response of the TLD material is affected
by their previous radiation history and thermal
history, the material must be annealed to removed
residual effect.
 Should be worn at chest position.
 Changed in every 3 months.
 Should be stored away from light, radiation and
dust when it is not used.
 Should not be used beside concern personnel.
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17. SEMICONDUCTOR DETECTOR
 Detector of choice of very high resolution
energy measurement
 Response that varies linearly with the
energy deposited in the detector and
doesn't depend upon the type of radiation
that deposits the energy
 Negligible absorption of energy
 Small detector size
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 Act as a solid state ionization chamber.
 Operation depends on having either an excess
of electrons or an excess of holes

19. Semiconductor Detectors
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 Common materials of choice
Silicon and Geranium
 Generally, used for the detection of alpha and
beta particles.
 Light radiation can be detected in
semiconductors through release of charges
across the band gap
 Higher energy radiation can be expected to do
so at much higher efficiencies.
 A metal-oxide semiconductor field effect
transistor (MOSFET) is a miniature silicon
transistor.
 Use as vivo dosimeter in rectum and urinary
bladder

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