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Search Publications by: Denis E. Bergeron (Fed)

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Displaying 51 - 68 of 68

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

March 11, 2015
Author(s)
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

Secondary standards for 223Ra revised

March 5, 2015
Author(s)
Denis E. Bergeron, Jeffrey T. Cessna, Brian E. Zimmerman
Dose calibrator dial settings reported by NIST in 2010 (ARI v. 68, p. 1367) are now known to give erroneously low (by 10 %) activity readings. The original determinations were based on a chain of calibrations; a broken link in this chain was recently

A review of NIST primary activity standards for 18F: 1982 to 2013

August 27, 2014
Author(s)
Denis E. Bergeron, Jeffrey T. Cessna, Bert M. Coursey, Ryan P. Fitzgerald, Brian E. Zimmerman
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 standard

Dose calibrator manufacturer-dependent bias in assays of 123I

March 26, 2014
Author(s)
Denis E. Bergeron, Jeffrey T. Cessna, Daniel B. Golas, Rheannan K. Young, Brian E. Zimmerman
Calibration factors for commercial ionization chambers (i.e. dose calibrators) were determined for a solution of 123I; the activity was based on the 1976 NBS standard. A link between the NIST standard and the International Reference System (SIR) was

A New NIST Primary Standardization of 18F

February 1, 2014
Author(s)
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

Micelle size effect on Fe-55 Liquid Scintillation Efficiency

December 1, 2013
Author(s)
Denis E. Bergeron, Lizbeth Laureano-Perez
We used efficiency tracing techniques to study the micelle size effect on liquid scintillation counting of the low-energy Auger electron emitter, 55Fe. We determined micelle hydrodynamic diameters for specific LS cocktails via dynamic light scattering, and

Results of an international comparison for the activity measurement of 177Lu

March 6, 2012
Author(s)
Brian E. Zimmerman, Denis E. Bergeron, Jeffrey T. Cessna
An international Key Comparison of 177Lu has recently been carried out. Twelve laboratories performed assays for radioactivity content on aliquots of a common master solution of 177Lu, leading to eleven results submitted for entry into the Key Comparison

TDCR Measurements on Pu-241 at NIST

December 21, 2010
Author(s)
Denis E. Bergeron, Brian E. Zimmerman
We have performed a series of measurements on a Pu-241 solution using the triple-to-double coincidence ratio (TDCR) liquid scintillation technique. A similar series of measurements in 2007 revealed significant discord between activity values determined via

Development of secondary standards for radium-223

November 5, 2009
Author(s)
Denis E. Bergeron, Brian E. Zimmerman, Jeffrey T. Cessna
223Ra is a bone-seeking alpha emitter, and as such is currently being evaluated as a radiopharmaceutical for the treatment of skeletal metastases. In the clinical setting, dosage measurements are typically achieved with reentrant ionization chambers

Ligand Exchange Reactions in the Formation of Diphosphine-Protected Gold Clusters

August 14, 2008
Author(s)
Denis E. Bergeron, Orkid Coskuner, Jeffrey W. Hudgens, Carlos A. Gonzalez
Electrospray ionization mass spectrometry is employed to study the formation of L3- and L5-protected gold clusters (L3 = 1,3-Bis(diphenylphosphino)propane; L5 = 1,5-Bis(diphenylphosphino)pentane), and it is found that molecular complexes in which Au+ is

Glycosidic Linkage Conformation of Methyl-alpha-Mannopyranoside

July 31, 2008
Author(s)
Orkid Coskuner, Denis E. Bergeron, Luis C. Rincon, Jeffrey W. Hudgens, Carlos A. Gonzalez
We study the preferred conformation of the glycosidic linkage of methyl--mannopyranoside in the gas phase and in aqueous solution. Results obtained utilizing Car Parrinello molecular dynamics (CPMD) simulations are compared to those obtained from

Impact of Swapping Ethyl for Phenyl Groups on Diphosphine-Protected Undecagold

September 1, 2007
Author(s)
Justin Golightly, Lin Gao, A W. Castleman, Denis E. Bergeron, Jeffrey W. Hudgens, Rudolph Magyar, Carlos A. Gonzalez
1,3-Bis(diethylphosphino)propane (depp) protected gold clusters are synthesized and studied via electrospray ionization mass spectrometry. An undecagold cluster, [Au11(depp)4Cl2]+, is observed under soft ionization conditions, and is found to persist in

Ligand Dissociation and Core Fission from Diphosphine Protected Gold Clusters

May 19, 2007
Author(s)
Denis E. Bergeron, Jeffrey W. Hudgens
Highly monodisperse samples of diphosphine ligand (1,3-Bis(diphenylphosphino)propane or 1,5-bis(diphenylphosphino)pentane) protected gold nanoparticles form rapidly in a mixed methanol/chloroform solvent environment. Methanol soluble octagold, decagold