Transcript Neutron Activation Analysis (NAA)

Neutron Activation
Analysis (NAA)
Alexis Popkow
H191 - Neutron Physics - 4/7/10
What is NAA?
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Determine the chemical composition of a
sample
Lunar samples, artifacts, forensics
Can identify up to 74 different elements in
gases, liquids, solids, and mixtures
Can also determine the concentration of the
elements of interest:
Requires Neutrons
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A nuclear reactor
A source that emits
neutrons by fission
(e.g. Californium)
Alpha Source (like
Radium) with
Beryllium
D-T fusion
Some elements of interest
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Arsenic
Chromium
Selenium
Chlorine
Mercury
Magnesium
Used to Find:
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Impurities in industrial products and foods
Poisons in human hair
Hazardous material at dumps
Trace elements in archaeological remains
Testing for elements in air filters
How?
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Hit source with neutrons
Sources become radioactive
Then decay in predictable ways
How?
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Detect the gamma-rays (prompt and delayed) - with
gas detector, scintillators, semiconductors
Bin number of counts at each energy
Gamma-ray Spectroscopy
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Gamma spectrum is characteristic of the
nuclides in the source (or elements that are
activated in NAA)
Equipment:
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Detector (NaI, HPGe) - voltage pulse
Amplifiers or multi-channel analyzers - shape the
pulse
ADCs - collects data, produces spectrum
Benefits
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Small sample sizes (.1mL or .001gm)
Non-destructive
Can analyze multiple element samples
Doesn’t need chemical treatment
High sensitivity, high precision
Resources
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N.C. State University Reactor Program
University of Wisconsin Nuclear Reactor
Wikipedia
Reed Research Reactor
University of Missouri Research Reactor