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DESCRIPTION
Gamma Ray Spectroscopy Experiment
Citation preview
Scintillator Detectorand
Gamma Radiation Detection
Kailash Dhaker (09024)
MS Batch 2009
Department of Physical Science
IISER Bhopal
IntroductionGamma Radiation
Interaction of Gamma Radiation with Matter
Scintillator Detector
• NaI(Tl) Scintillator Detector
Experimental Procedure and Observations
Conclusion
References
Gamma RadiationWhen a nucleon is in a high-energy orbit while a low-
energy orbit is unfilled, it can jump to the lower-energy orbit with the energy thereby released coming of as a quantum of electromagnetic radiation, which we call a gamma ray.
These g-rays can be detected, and their energies can be measured, using several types of detectors
Interaction of Gamma RadiationA gamma ray can interact with matter in three ways-
1. Photoelectric Interaction
2. Compton Interaction
3. Pair Production
Scintillator Detector
Detector absorb incident radiation and emit there energy (photon) in the form of light
These photons are then used to release avalanche of electrons by a photomultiplier tube which can be detected to give the output pulse
Scintillator DetectorSequence of events:
1. Scintillator:
In a solid crystal, the incident radiation ionizes some of the atoms at the lattice sites knocking out electrons which on recombination releases low energy radiation (300-500 nm)
Scintillator Detector2. Photomultiplier Tube: These photons are then
directed towards the photomultiplier tube (PMT) which releases photoelectrons from the photocathode. They are then accelerated by the electric field and strikes to the dynode surface (from which more electrons can be easily knocked out). The process of striking the several dynode surfaces continues until they are collected by the anode giving it a charge which flows to the capacitor to give the output voltage.
Scintillator Detector
NaI(Tl) Scintillator Detector[Ref: http
://www.thefullwiki.org/Basic_Physics_of_Nuclear_Medicine/Scintillation_Detectors]
Scintillator Detector Two types of scintillator material is used
1. Organic: Contain molecules like Benzene, Naphthalene or Anthracene
2. Inorganic: Crystals like NaI and CsI is used as scintillator material with some impurity (as activator)
NaI(Tl) Scintillator Detector
NaI(Tl) is a second type (inorganic) scintillator detector
Sodium Iodide (NaI) crystal with small amount of Thallium (Tl) as an impurity
Tl is present as Tl+ (activator) in place of Na+ in the lattice
NaI(Tl) Scintillator Detector
NaI(Tl) is a second type (inorganic) scintillator detector
Sodium Iodide (NaI) crystal with small amount of Thallium (Tl) as an impurity
Tl is present as Tl+ (activator) in place of Na+ in the lattice
Experimental ProcedureExperimental Setup
1. NaI(Tl) Scintillator Detector
2. Radioactive Samples
3. Computer setup with pre-installed software to obtain
Gamma Spectrum
Energy calibration using Na-22 sample
Gamma Spectrum were obtained for Cs-137 and Mn-54
ObservationsGamma Ray Spectrums of Cs-137 and Mn-54 were
obtainedFrom Gamma Ray Spectrum, Gamma ray energy were
calculated and compared with literature value
Gamma Ray Energy of Na-22 (Calibration)
Gamma Ray Energy for Peak-1 Gamma Ray Energy for Peak-2
510 keV 1272 keV
ObservationsGamma Ray Spectrum of Na-22
(Calibration)
ObservationsGamma Ray Spectrum of Cs-137
ObservationsGamma Ray Spectrum of Mn-54
ObservationsGamma Ray Spectrum of Ba-133
Observations
Sample Experimental Value Literature Value
Cs-137 660 keV 661.64 keV
Mn-54 811 keV 834.83 keV
Ba-133 Peak-1 87 keV 80 keV
Peak-2 374 keV 356 keV
Gamma Ray Energy for Cs-137 , Mn-54 and Ba-133 (Calculated from Spectrum)
Conclusion
Gamma Ray Energy obtained from gamma spectrum is quit close to literature value of
gamma energy for Cs-137, Mn-54 and Ba-137
ReferencesGamma Radiation-
Bernard L Cohen – Concepts of Nuclear Physics
Scintillator Detector-
Glenn F. Knoll, Radiation Detection and Measurement
Literature value of gamma energy –
www.csupomona.edu/~pbsiegel/bio431/genergies.html
Thank You…
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