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1. Determination of photon emission probabilities for the main gamma-rays of 223Ra in equilibrium with its progeny
Published: 3/11/2015
Authors: Leticia S Pibida, Brian Edward Zimmerman, Ryan P Fitzgerald, Lynne Emily King, Jeffrey T Cessna, Denis E Bergeron
Abstract: The currently published 223Ra gamma-ray emission probabilities display a wide variation in the values depending on the source of the data. The National Institute of Standards and Technology performed activity measurements on a 223Ra solution that was ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=916239

2. A review of NIST primary activity standards for 18F: 1982 to 2013
Series: Journal of Research (NIST JRES)
Published: 8/27/2014
Authors: Denis E Bergeron, Jeffrey T Cessna, Bert M Coursey, Ryan P Fitzgerald, Brian Edward Zimmerman
Abstract: The new NIST activity standardization for 18F differs from results obtained between 1998 and 2008 by 4 %. The new results are considered to be very reliable; they are based on a battery of robust primary measurement techniques and bring the NIST sta ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=915421

3. The Half-Life of 209Po : Revisited
Published: 8/13/2014
Authors: Ronald Colle, Ryan P Fitzgerald, Lizbeth Laureano-Perez
Abstract: A substantial 25 % error in the then known and accepted (102  5) year half-life of 209Po was reported on in 2007. This error was detected from decay data from two separate primary standardizations of a 209Po solution standard, which were perf ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=916048

4. A New NIST Primary Standardization of 18F
Published: 2/1/2014
Authors: Ryan P Fitzgerald, Brian Edward Zimmerman, Denis E Bergeron, Jeffrey T Cessna, Leticia S Pibida, Denise S Moreira
Abstract: A new primary standardization of 18F by NIST is reported. The standard is based on live-timed beta- gamma anticoincidence counting with confirmatory measurements by three other methods: (i) liquid scintillation (LS) counting using CIEMAT/NIST 3H e ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=914677

5. Standardization of 237Np
Published: 12/4/2013
Authors: Lizbeth Laureano-Perez, Ryan P Fitzgerald, Ronald Colle
Abstract: The standardization of 237Np was investigated. The certified massic activity for 237Np was obtained by 4 liquid scintillation (LS) counting with correction for the 233Pa daughter using the CIEMAT/NIST efficiency tracing method ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=913828

6. 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

7. The effect of impurities on calculated activity in the triple-to-double coincidence ratio liquid scintillation method
Published: 3/4/2012
Authors: Denis E Bergeron, Ryan P Fitzgerald, Brian Edward Zimmerman, Jeffrey T Cessna
Abstract: In the triple-to-double coincidence ratio (TDCR) method of liquid scintillation counting, unaccounted or improperly accounted impurities can result in lower-than-expected or higher-than-expected recovered activities, depending on the counting efficie ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=909218

8. NIST Ionization Chamber "A" Sample-Height Corrections
Series: Journal of Research (NIST JRES)
Report Number: 117.003
Published: 2/2/2012
Author: Ryan P Fitzgerald
Abstract: For over 30 years scientists in the NIST radioactivity group have been using their ionization chamber ,AŠ to make measurements of radioactivity and radioactive half-lives. We now have evidence that some of those reported measurements were incorre ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=909843

9. Investigation into the Standardization of Tc-99
Published: 7/30/2010
Authors: Lizbeth Laureano-Perez, Ronald Colle, Ryan P Fitzgerald, Brian Edward Zimmerman, Lonnie Talmadge Cumberland
Abstract: The standardization of 99Tc by several primary methods was investigated. This was performed to support a new 99Tc transfer standard that has been developed and will be disseminated by the National Institute of Standards and Technology (NIST) as Stan ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=902971

10. Resonance Strength in 22Ne(p,gamma)23Na from Depth Profiling in Aluminum
Published: 4/30/2010
Authors: R Longland, C. Iliadis, J. Cesaratto, A E Champagne, S Daigle, J.R. Newton, Ryan P Fitzgerald
Abstract: The novel method for extracting absolute resonance strengths has been investigated. By implanting 22Ne ions into a thick aluminum backing, and simultaneously measuring the 22Ne + p and 27Al+p reactions, the strength of the Elab,r = 479 keV resonance ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=905839



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