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Search Publications by: Leticia Pibida (Fed)

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Displaying 26 - 50 of 81

Evidence against solar influence on nuclear decay constants

August 24, 2016
Denis E. Bergeron, Ryan P. Fitzgerald, Leticia S. Pibida, Stefaan Pomme
The exponential decay of radionuclides as a function of time is a cornerstone of nuclear physics and radionuclide metrology. Decay constants for spontaneous radioactive decay are considered invariable in time and space. This convenient trait allows

Revision of the NIST Standard for 223Ra: New Measurements and Review of 2008 Data

July 1, 2015
Denis E. Bergeron, Jeffrey T. Cessna, Leticia S. Pibida
After discovering a discrepancy in the transfer standard currently being disseminated by the National Institute of Standards and Technology (NIST), we have performed a new primary standardization of the alpha-emitter 223Ra using Live-timed Anticoincidence

Determination of photon emission probabilities for the main gamma-rays of 223Ra in equilibrium with its progeny

March 11, 2015
Leticia S. Pibida, Brian E. Zimmerman, Ryan P. Fitzgerald, Lynne E. King, Jeffrey T. Cessna, Denis E. Bergeron
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 used

Scaling of Testing Speed for Different Source-to-Detector Distances

February 13, 2015
Bruce R. Norman, Anne L. Sallaska, Leticia Pibida
Several American National Standard Institute/Institute of Electrical and Electronics Engineers (ANSI/IEEE) and International Electrotechnical Commission (IEC) standards were developed for radiation detection systems used for homeland security applications

A New NIST Primary Standardization of 18F

February 1, 2014
Ryan P. Fitzgerald, Brian E. Zimmerman, Denis E. Bergeron, Jeffrey T. Cessna, Leticia S. Pibida, Denise S. Moreira
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 efficiency

ITRAP+10 Spectroscopic Radiation Portal Monitor Testing

November 14, 2013
Anne L. Sallaska, Leticia S. Pibida, Huaiyu H. Chen-Mayer, Luc Murphy, Christina Ward
The Illicit Trafficking Radiation Assessment Program (ITRAP+10) is an international effort of the Department of Homeland Security’s Domestic Nuclear Detection Office (DHS/DNDO), the European Commission’s Joint Research Center (EC-JRC), and the

Justification of Shielding Requirements for Plutonium Sources

September 12, 2012
Leticia S. Pibida, Michael P. Unterweger
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 comparable test

NIST Handbook 150-23, 2010 ed., National Voluntary Laboratory Accreditation Program (NVLAP) Homeland Security Applications: Radiation Detection Instruments

April 13, 2010
Betty A. Sandoval, Leticia S. Pibida, Gordon Gillerman, Michael P. Unterweger
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

A New Primary Standardization of Th-229

January 7, 2010
Ryan P. Fitzgerald, Lizbeth Laureano-Perez, Michelle M. Hammond, Leticia S. Pibida, Svetlana Nour, Brian E. Zimmerman
The National Institute of Standards and Technology (NIST) has certified a high-purity Th-229 Standard Reference Material as SRM 4328C, based on live-timed 4-pi alpha,beta-gamma anticoincidence counting (LTAC) of the equilibrium solution. The LTAC system

Half-life Measurements of Sr82

January 30, 2009
Leticia S. Pibida, Ryan P. Fitzgerald, Michael P. Unterweger, Michelle M. Hammond, Daniel B. Golas
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 ± 0.03 days (k=1) using the

Performance of CdTe, HPGe and NaI(Tl) Detectors for Radioactivity Measurements

October 16, 2008
A Perez-Andujar, Leticia Pibida
The characteristics and performances of the NIST High Purity Germanium (HPGe), Sodium Iodide (NaI(Tl)) and Cadmium Telluride (CdTe) gamma-ray detectors were studied. The efficiencies, the minimum detectable activities and the energy resolutions each were