accelerator physics, ju, first semester, 2010-2011 (saed dababneh). 1 principles of spectrometry
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Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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Principles of Spectrometry
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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Principles of Spectrometry• Radiation detection requires that radiation interacts with detector material.• Energy deposition (not all detectors…!).• Charged particles continuously transfer their energy to the medium.http://www.srim.org
• Gammas and X-rays interact (if they do) catastrophically.http://physics.nist.gov/PhysRefData/Xcom/Text/XCOM.html
• Photon interactions produce secondary electrons.• Neutron interactions produce secondary heavy charged particles.
Could be secondary gamma (Shielding).
Usually corresponds to net area under the full energy peak.
If not, then
build-up.Good or
bad geometry.
Collimation.
I0 I
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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Charged particles.
Gamma.
Principles of Spectrometry
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• Partial or complete transfer of photon energy to electrons.• Many types of interactions, but three (or four) are important.
Interaction of gammasInteraction of gammas
• Attenuation coefficient Attenuation coefficient and and
mass attenuation mass attenuation coefficient.coefficient.
• CompareCompare to to macroscopic cross macroscopic cross
section section for for neutronsneutrons..
What is coherent scattering.What is coherent scattering.
xeII 0
HW 2HW 2
Buildup Factor
Principles of Spectrometry
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
XteIXI 0)(
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X
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eXP
eXP
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ninteractio
ninteractiono
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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Principles of Spectrometry
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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Spectrum if all energy is captured in detector.Allows identification of gamma energy.
• Large Detector (in depth?!).• Photo Peak or Full Energy Peak…?• Doppler.• Cost.• Crystal growth.
(with atoms, why??)
Photoelectric AbsorptionPhotoelectric Absorption.
Principles of Spectrometry
Auger
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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• Spectroscopy, energy deposition.• Consider what might escape.• Size and material of detector.• Shield lining.
Considerations for shields and detectors?shields and detectors?
Principles of Spectrometry
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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HPGe
HW 3HW 3
Principles of Spectrometry
• “Probability” for photoelectric absorption:
• Strong Z dependence.• Considerations for shields and detectorsshields and detectors.
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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PracticalTheoretical
Principles of Spectrometry
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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Efficiency considerations.Efficiency considerations.
Principles of Spectrometry
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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NaI or BGO
HPGe
Efficiency vs. ResolutionEfficiency vs. Resolution
Principles of Spectrometry
Accelerator Physics, JU, First Semester, 2010-2011 (Saed Dababneh).
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Considerations for shields and detectors?
shields and detectors?
Principles of Spectrometry