Chapter 9. Nuclear Analysis Methods 1. Neutron Activation Analysis 2. Accelerator Mass spectrometry 3. Mossbauer Spectroscopy 4.Ion beam analysis
Chapter 9. Nuclear Analysis Methods 1.Neutron Activation Analysis 2.Accelerator Mass Spectrometry 3.Mössbauer Spectroscopy 4.Ion Beam Analysis
The Neutron activation Analysis Method 中子活化分析 Material Neutron for naa Prompt y rays Source Material radioactive βrays original nuclides y rays Gamma-ray Data analysis and esults reporting spectrometer Block diagrams of the naa method
2 The Neutron Activation Analysis Method Block diagrams of the NAA method Neutron Source Material for NAA radioactive nuclides Prompt g rays b rays Gamma-ray spectrometer Data analysis and results reporting Material original g rays 中子活化分析
Chinese naa facilities China Institute of Atomic Energy中国原子能科学研究院 Institute of High Energy physics, Chinese academy of Science f 国科学院高能物理研究所
3 Chinese NAA Facilities China Institute of Atomic Energy 中国原子能科学研究院 Institute of High Energy Physics, Chinese Academy of Science中 国科学院高能物理研究所 …
What is NAA? Hit source with neutrons The activity a of the sample A=in(t =doN(I-e)increases with bombarding time t Sources become radioactive Then decay in predictable ways Prompt Beta Gamma Ray Incident radioactive Product Compound
What is NAA? • Hit source with neutrons • Sources become radioactive • Then decay in predictable ways The activity A of the sample increases with bombarding time t
R=,A=8l,noo(l-eve R= measured gamma-ray count rate(cps) A=absolute activity of isotope A+1 Z in sample 8=absolute detector efficiency absolute gamma-ray abundance n=number of atoms of isotope Z in sample o=neutron flux(neutrons cm. sec 0= neutron capture cross section(cm)for Isotope 2=radioactive decay constant(s) for isotope A+1 - irradiation time(s) td=decay time(s) 10Ag+n→Ag 1Ag→6+lCd+y(658keV
How? Detect the gamma-rays ( prompt and delayed)-with gas detector, scintillators semiconductors Bin number of counts at each energy Channel An example of gamma ray spectrum from the activation of a human nail
How? • Detect the gamma-rays(prompt and delayed) - with gas detector, scintillators, semiconductors • Bin number of counts at each energy An example of gamma-ray spectrum from the activation of a human nail
Neutron sources A nuclear reactor a source that emits neutrons by fission ( e.g Californium) Alpha Source(like Radium) with Beryllium ·D- T fusion in a gas n source discharge tube Flament Magnet Target
Neutron sources • A nuclear reactor • A source that emits neutrons by fission (e.g. Californium) • Alpha Source (like Radium) with Beryllium • D-T fusion in a gas discharge tube
Applications 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
Applications • 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:
Advantages Small sample sizes( 1mL or. 001gm) Non-destructive Can analyze multiple element samples Doesn 't need chemical treatment h sensitivity, gl gh precision
Advantages • Small sample sizes (.1mL or .001gm) • Non-destructive • Can analyze multiple element samples • Doesn’t need chemical treatment • High sensitivity, high precision
Sensitivit Elements (picograms) DY, Eu 1-10 In lu. mn 10-100 Au, Ho Ir re, sm w 100-1000 Ag, Ar, As, Br, Cl, Co, Cs, Cu, Er, Ga, Hf, I La, Sb, Sc, Se, Ta, tb, th Tm U,v, yb 1000-10 Al, Ba, Cd, Ce, Cr, Hg Kr Gd, Ge, Mo, Na, Nd. ni, os, pd. rb. rh Ru. sr. te. Zn Zr 104-10 Bi, Ca, K, mg p pt, Si, Sn, Ti, tl, Xe , y 105-10 Fe, nb Ne 10 Pb, s
Sensitivity (picograms) Elements 1 Dy, Eu 1–10 In, Lu, Mn 10–100 Au, Ho, Ir, Re, Sm, W 100–1000 Ag, Ar, As, Br, Cl, Co, Cs, Cu, Er, Ga, Hf, I, La, Sb, Sc, Se, Ta, Tb, Th, Tm, U, V, Yb 1000–104 Al, Ba, Cd, Ce, Cr, Hg, Kr, Gd, Ge, Mo, Na, Nd, Ni, Os, Pd, Rb, Rh, Ru, Sr, Te, Zn, Zr 104–105 Bi, Ca, K, Mg, P, Pt, Si, Sn, Ti, Tl, Xe, Y 105–106 F, Fe, Nb, Ne 107 Pb, S