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You searched on: Author: ryan fitzgerald

Displaying records 11 to 20 of 28 records.
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11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. Charged-Particle Thermonuclear Reaction Rate Evaluation for A=12-40 Nuclei: I. Monte Carlo Method and Statistical Distributions
Published: 4/28/2010
Authors: Ryan P Fitzgerald, R Longland, C. Iliadis, E. Champagne, J.R. Newton, C. Ugalde
Abstract: A new method based on Monte Carlo techniques is presented for evaluating thermonuclear reaction rates. We begin by reviewing commonly applied procedures and point out that reaction rates that have been reported up to now in the literature have no rig ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=842419

20. Charged-Particle Thermonuclear Reaction Rates: II. Tables and Graphs of Reaction Rates and Probability Density Functions.
Published: 4/9/2010
Authors: C. Iliadis, R Longland, A E Champagne, A. Coc, Ryan P Fitzgerald
Abstract: Numerical values of charged-particle thermonuclear reaction rates for nuclei in the A=14-40 region are tabulated. The results are obtained using a method, based on Monte Carlo techniques, that has been described in the preceding paper of this series ...
http://www.nist.gov/manuscript-publication-search.cfm?pub_id=904290



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