Neutron Activation Analysis NAA Alexis Popkow H 191
- Slides: 10
Neutron Activation Analysis (NAA) Alexis Popkow H 191 - Neutron Physics - 4/7/10
What is NAA? l l 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 l l 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 l l l Arsenic Chromium Selenium Chlorine Mercury Magnesium
Used to Find: l l l 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? l l l Hit source with neutrons Sources become radioactive Then decay in predictable ways
How? l l Detect the gamma-rays (prompt and delayed) - with gas detector, scintillators, semiconductors Bin number of counts at each energy
Gamma-ray Spectroscopy l l Gamma spectrum is characteristic of the nuclides in the source (or elements that are activated in NAA) Equipment: l l l Detector (Na. I, HPGe) - voltage pulse Amplifiers or multi-channel analyzers - shape the pulse ADCs - collects data, produces spectrum
Benefits l l l Small sample sizes (. 1 m. L or. 001 gm) Non-destructive Can analyze multiple element samples Doesn’t need chemical treatment High sensitivity, high precision
Resources l l l N. C. State University Reactor Program University of Wisconsin Nuclear Reactor Wikipedia Reed Research Reactor University of Missouri Research Reactor
