DEVELOPMENTS ON THE MONTE CARLO LIBRARY LEASTSQUARES MCLLS APPROACH FOR PGNAA AND EDXRF

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DEVELOPMENTS ON THE MONTE CARLO LIBRARY
LEAST-SQUARES (MCLLS) APPROACH FOR PGNAA AND EDXRF

• Robin Gardner

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TOPICS

• PGNAA DEVELOPMENTS
• EDXRF DEVELOPMENTS
• GENERAL DEVELOPMENTS

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PGNAA DEVELOPMENTS, 1

• General MCLLS Approach
• Pulse Pile-Up Corrections Can now be made with
  our Monte Carlo code CEARIPPU
• Libraries All libraries including eight sources
  of background can now be obtained by Monte Carlo
  simulation
• Detector Response Functions Can now be generated
  for NaI Detectors by Monte Carlo simulation

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GENERAL MCLLS APPROACH

• A Monte Carlo code (CEARPGA) is developed that
  provides all element and other library spectra
  for any specific case for the linear library
  least-squares (LLS) analysis.
• The experimental response for a sample is first
  corrected (if necessary) for pulse pile up with
  the CEARIPPU code.
• The CEARPGA code uses a detector response
  function (DRF) for efficiency. The present set of
  DRF codes for NaI will be modified as a patch
  in MCNP.

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PULSE PILE-UP CORRECTIONS

• Generalization of the Off-Line method by Monte
  Carlo simulation
• Investigation of the On-Line method

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CEARPPU Cubic-Spline Pulse Model
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Double Pulse Pile-up Examples
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Counting Rate Curve

• Single pulse width 10 µs
• Observations
• Pulse Pile-up limits counting rate
• It would help to reduce the pulse width.
• Facts
• Pulse width could not be so small to make pulse
  pile up negligible
• Ballistic Deficit
• S/N ratio

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Pulse Number of Pile-up
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CEARPPU Simulation Results
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CEAR Proposed Correction Approaches

• Guo, W., S.H. Lee, and R.P. Gardner, The Monte
  Carlo Approach MCPUT for Correcting Pile-up
  Distorted Pulse-height Spectra, Nuclear
  Instruments and Methods in Physics Research A,
  531(2004)pp. 520-529.
• Gardner, R. P., C.W. Mayo and W. Guo, Real Time
  Accurate Elimination of Pulse Pile-Up Distortion
  in Nuclear Radiation Spectroscopy . ANS Winter
  Meeting, 2004. Invited Paper, To be Presented.

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LIBRARIES

• ELEMENTAL LIBRARIES (17)
• NATURAL RADIOISOTOPE LIBRARIES (3)
• LIBRARY OF STRUCTURAL MATERIALS
• Cf-252 GAMMA-RAY LIBRARY SOURCE
• DETECTOR ACTIVATION LIBRARIES (3)
• EXPERIMENTAL Na AND I RADIOISOTOPE LIBRARIES
• EXPERIMENTAL PROMPT GAMMA-RAY LIBRARY
• EXPERIMENTAL VS. MCLLS CALCULATED COAL SPECTRA

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Al, C, and Ca Libraries
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Cl, Fe, and H Libraries
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K, Mg, and Mn Libraries
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N, Na, and Ni Libraries
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O, P, and S Libraries
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Si and Ti Libraries
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K-40, Th, and U Libraries
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Analyzer Structure Library
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Cf-252 Gamma-Ray Library
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I-128 and Na-24 Decay and NaI Prompt Gamma-Ray
Libraries
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Experimental I-128 and Na-24 NaI Activation
Libraries
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NaI Prompt Gamma-Ray Library
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Sample Experimental vs. MCLLS-Calculated Spectra
CHQ32
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6 X 6 NaI Spectra
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6 X 6 NaI Spectra
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6 X 6 NaI Spectra
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6 X 6 NaI Spectra
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PGNAA DEVELOPMENTS, 2

• Coincidence Counting for reducing background and
  increasing the S/N ratio
• Two-Dimensional Spectra
• Q-Value and Other Summing Methods for Bulk
  Analysis
• Summing Methods for the Well Detector for C/O
  Logs

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COINCIDENCE COUNTING

• The Sparrow System
• Two-Dimensional Spectra

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Co-60
The 1.3325 MeV Gamma in the Pop Top detector in
coincidence with the 1.1732 MeV Gamma in the 72
detector.
The 1.1732 MeV Gamma in the Pop Top detector in
coincidence with the 1.3325 MeV Gamma in the 72
detector.
Co-60 Two Dimensional Spectrum
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Co-60 2-D Scatter Plot
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DIAGONAL SUM
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Two Dimensional Diagonal Summing
Flat View of Two Dimensional Spectra Types of
Projections Whole Spectrum Horizontal or Vertical
Area Diagonal Area Irregular Area
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Sulfur Spectra
Two Dimensional Full Spectrum Projection for
Sulfur
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Sulfur Spectra
Q-Value Diagonal Summing for Sulfur (Window 1)
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Sulfur Spectra
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Sulfur Spectra
Comparison of Total and Diagonal Summing for
Sulfur
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Coal Spectra
Singles and Coincidence Spectra for Sulfur
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Coal Spectra
Two Dimensional Spectrum with Q-Value
Window
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Coal Spectra
Coincidence and Diagonal Summing Spectra for
Sulfur
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Hg Q-VALUE SPECTRUM
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Hg TOTAL Q-VALUE SPECTRA
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SCHEMATIC DIAGRAM OF PRO-POSED PGNAA SORTING
SYSTEM
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WELL DETECTOR IDEA FOR C/O OIL WELL LOGGING TOOL
Oil Well Logging. Energy Range of
Interest. Logging Tool Dimensions. MCNP
Calculations
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TYPICAL OIL WELL LOGGING C/O SPECTRA
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Concept (Patent Pending)
NaI Detector (Well Type)
PMT
PMT
The New NaI Detector Setup.
NaI Detector (Inside)
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Arrangement
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Sodium - 24
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Sodium - 24
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Sodium - 24
V-shaped spectra
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Sodium - 24
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EDXRF DEVELOPMENTS

• Lead in Bone for NIEHS (NIH)
• General Sample Analysis
• Paper 1 at DRC
• Paper 2 at DRC
• Monte Carlo Workshop

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CXRF Spectrometer 2-D Cross Sectional Diagram
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Horizontal Section
Vertical Section II
1
4
2
I
I
4
6
1
II
II
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Vertical Section I
1
3

• Bone Phantom
• 1st NaI(Tl) Detector (121mm)
• 2nd NaI(Tl) Detector(121mm)
• Photomultiplier Tube (PMT)
• Photomultiplier Tube (PMT)
• Collimated Cd-109 Radiation Source

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GENERAL DEVELOPMENTS

• RECENT
• On-Line Pulse Pile-Up Correction
• Off-Line Pulse Pile-Up Correction
• Development and Benchmarking of CEARCPG Code
• FUTURE
• Spectrum Stripping Code for Unknown Libraries in
  MCLLS
• Optimization of All Coincidence Counting
  Applications