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Author: Michael Unterweger

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1. UPDATE OF NIST HALF-LIFE RESULTS CORRECTED FOR IONIZATION CHAMBER SOURCE-HOLDER INSTABILITY
Published: 11/4/2013
Author: Michael P Unterweger
Abstract: As reported at ICRM 2011, it was discovered that the source holder used for calibrations in the NIST 4π ionization chamber (IC) was not stable. This has affected a large number of half-life measurement results previously reported and use ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=914278

2. Justification of Shielding Requirements for Plutonium Sources
Series: Technical Note (NIST TN)
Report Number: 1758
Published: 9/12/2012
Authors: Leticia S Pibida, Michael P Unterweger
Abstract: This report provides a justification for shielding plutonium sources when testing radiation detection instruments against standard performance requirements and test methods. The use of copper as a shielding material is proposed to provide compara ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=912144

3. Technical Note on Unexpected Bias in NIST 4¿¿ Ionization Chamber Measurements
Published: 4/4/2012
Authors: Michael P Unterweger, Ryan P Fitzgerald
Abstract: The NIST 4π pressurized ionization chamber ,AŠ (PIC ,AŠ) has been the mainstay for secondary calibrations of liquid and gaseous gamma-ray emitting sources for the last 40-45 years. It has also been the main instrument used to measure th ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=910074

4. NIST Handbook 150-23, 2010 ed., National Voluntary Laboratory Accreditation Program (NVLAP) Homeland Security Applications: Radiation Detection Instruments
Series: Handbook (NIST HB)
Report Number: 150-23
Published: 4/13/2010
Authors: Betty A Sandoval, Leticia S Pibida, Gordon Gillerman, Michael P Unterweger
Abstract: NIST Handbook 150-23, NVLAP Homeland Security Applications: Radiation Detection Instruments, presents the technical requirements and guidance for the accreditation of laboratories that test radiation detection instruments used in homeland security ap ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=905638

5. Half-life Measurements of Sr82
Published: 1/30/2009
Authors: Leticia S Pibida, Ryan P Fitzgerald, Michael P Unterweger, Michelle M. Hammond, Daniel B. Golas
Abstract: Half-life measurements of 82Sr were performed at the National Institute of Standards and Technology (NIST) using gamma-ray spectrometry and a 4 pressurized ionization chamber. The 82Sr half-life was determined to be 25.36 &plu ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=842553

6. Assessing the 210At Impurity in the Production of ^u211^At for Radiotherapy by ^u210^At Analysis via Isotope Dilution Alpha Spectrometry
Published: 1/1/2006
Authors: M K Schultz, Michelle M. Hammond, Jeffrey T Cessna, P Plascjak, Brian Edward Zimmerman, B Norman, L Szajek, K Garmestani, Michael P Unterweger
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=103325

7. Calibration of HPGe Gamma-ray Detectors for Measurement of Radioactive Noble Gas Sources
Published: 1/1/2006
Authors: Leticia S Pibida, S S Nafee, Michael P Unterweger, Michelle M. Hammond, Lisa R Karam, I Abbas m
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=101346

8. Development of Gamma-ray Emitting Test Sources for Portal Monitors
Published: 1/1/2006
Authors: Leticia S Pibida, Michael P Unterweger, Lisa R Karam
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=103291

9. Results of Test and Evaluation of Commercially Available Personal Radiation Detectors (PRDs) and Radiation Pagers for the Department of Homeland Security - Round 2 Testing
Published: 1/1/2006
Authors: Leticia S Pibida, Michael P Unterweger, Lisa R Karam
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=103606

10. Results of the Test and Evaluation of Commercially Available Portal Monitors for the Department of Homeland Security - Round 2 Testing
Published: 1/1/2006
Authors: Leticia S Pibida, Michael P Unterweger, Lisa R Karam
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=103608



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