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Physics

Radiation

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  • Published Date
Displaying 126 - 150 of 259

Muffin tin potentials in EXAFS analysis

September 1, 2015
Author(s)
Bruce D. Ravel
Muffin tin potentials are the standard tool for calculating the potential surface of a cluster of atoms for use in the analysis of extended x-ray-absorption fine-structure (EXAFS) data. The set of Cartesian coordinates used to define the positions of atoms

Compact X-ray and Extreme-Ultraviolet Light Sources

July 10, 2015
Author(s)
Lahsen Assoufid, Uwe Arp, Patrick Naulleau, Sandra Biedron , William Graves
Bringing the brightness and power of vast synchrotron and free-electron laser sources to the scale of the lab and clinic marks an important next frontier—and could transform the landscape of X-ray science and technology.

Experimentally, How Does Cu TSV Diameter Influence its Stress State?

May 27, 2015
Author(s)
Chukwudi A. Okoro, Lyle E. Levine, Yaw S. Obeng, Ruqing Xu
In this work, an experimental study of the influence of Cu through-silicon via (TSV) diameter on stress build up was performed using synchrotron-based X-ray microdiffraction technique. Three Cu TSV diameters were studied; 3 µm, 5 µm and 8 µm, all of which

Uncertainties in Internal Gas Counting

May 22, 2015
Author(s)
Michael P. Unterweger, L Johansson, M Rodriques, A Yunoki, Lisa R. Karam
The uncertainties in internal gas counting can, for the most part, be split into two areas: counting and sample gas measurement uncertainties and the counting uncertainties. The former includes measurements of counting and sample gas quantities and

Uncertainties in Surface Emission Rate Measurements

May 22, 2015
Author(s)
Michael P. Unterweger
The uncertainties in surface emission rates determined by gas-flow proportional counters (multiwired) will be broken down into alpha and beta emission rate determinations. Counting statistics, spectrum analysis, and electronic uncertainties will be

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

Measurement of the 240Pu/239Pu Mass Ratio Using a Transition-Edge-Sensor Microcalorimeter for Total Decay Energy Spectroscopy

February 27, 2015
Author(s)
Daniel R. Schmidt, Douglas A. Bennett, James P. Hays-Wehle, Daniel S. Swetz, Joel N. Ullom, Andrew Hoover, Mark Croce, Michael W. Rabin, Evelyn Bond, Terry Holesinger, Gerd Kunde, Laura Wolfsbereg
We have developed a new category of sensor for measurement of the 240Pu/239Pu mass ratio from aqueous solution samples with advantages over existing methods. Aqueous solution plutonium samples were evaporated and encapsulated inside of a gold foil absorber

Understanding the blue color in antique mosaic mirrored glass from the Temple of the Emerald Buddha, Thailand

February 4, 2015
Author(s)
Bruce D. Ravel, Wantana Klysubun, Christoph Hauzenberger, Prapong Klysubun, Yuying Huang, Weeraya Wongtepa, Panidtha Sombunchoo
Two samples of the blue glass produced in the middle 19th century from the Temple of the Emerald Buddha in Bangkok, Thailand, were studied in order to understand the origin of its blue color. The oxide components and trace elements are quantitatively

SIM.RI(I)-K3 Comparison of Calibration Coefficients at Radiotherapy Level for Orthovoltage X-ray Beams

February 2, 2015
Author(s)
C M. O'Brien, J.P. McCaffrey, H Shen, M Saravi, G M. Ortiz, G Stefanic, M Carlos, C.N.M. da Silva, J L. Alvarez, V Tovar
Air-kerma calibration coefficients were compared at the radiotherapy level for orthovoltage x-ray beams in the SIM.RI(I)-K3 comparison for members of the Sistema Interamericano de Metrología (SIM). Five SIM laboratories participated in the comparison: NIST

Beyond the International Year of Crystallography

February 1, 2015
Author(s)
Andrew J. Allen, Janos Hajdu, Anke R. Kaysser-Pyzalla
It is now one year since all International Union of Crystallography (IUCr) journals became online only, and this is just one of the developments during the International Year of Crystallography, IYCr 2014. Perhaps, most conspicuously, IUCr’s new flagship

Alanine-EPR High-Dose Radiation Metrology

January 25, 2015
Author(s)
Marc F. Desrosiers
A comprehensive guide to the calibration, use, and maintenance of the alanine-EPR metrology system for high-dose radiation dosimetry is presented. Alanine dosimetry is the system of choice for calibration services for all major primary and secondary

New x-ray measurements shed light on discrepancy between experiment and QED

December 15, 2014
Author(s)
Lawrence T. Hudson, C T. Chantler, A.T. Payne, M N. Kinnane, John D. Gillaspy, L F. Smale, Albert Henins, J A. Kimpton, E Takacs
Quantum Electro-Dynamics (QED) is the best tested theory of our physical world, yet significant disagreements have emerged between attempts to apply QED to exotic atomic systems. A recent 15 parts-per-million (ppm) experiment on muonic hydrogen, in which

New Methods for Measurement of Neutron Detector Efficiency up to 20 MeV

December 1, 2014
Author(s)
Fred B. Bateman, Allan D. Carlson, N. A. Kornilov, S M. Grimes, T N. Massey, C E. Brient, D E. Carter, J E. O'Donnell, R. C. Haight, N Boukharouba
A new approach to neutron detector effciency has been taken. A neutron detector has been calibrated with a Cf-252 source at low energy. The calibration was extended to higher neutron energies by use of symetric reactions such as A + A ! (2A - 1) + n:

Potential Hazard Due to Induced Radioactivity Secondary to Radiotherapy: The Report of AAPM Task Group 136

December 1, 2014
Author(s)
Fred B. Bateman, Bruce R. Thomadsen, Ravinder Nath, Jonathan Farr, Cal Glisson, Mohammad K. Islam, T. LaFrance, M. E. Moore, X. G. Xu, Mark Yudelev
External-beam radiation therapy mostly uses high-energy photons (x-rays) produced by medical accelerators but many facilities now use proton beams and a few use neutrons. High energy photons offer several advantages over lower energy photons in terms of

The Metrology of a Rastered Spot of X Rays used in Security Screening

November 6, 2014
Author(s)
Lawrence T. Hudson, Jack L. Glover, Ronaldo Minniti
In recent times, ionizing radiation has been used around the world to screen persons for non- medical purposes, namely to detect bulk explosives or other contraband hidden on the body including materials not registered by metal detectors. In contrast to

Structural and Dynamical Studies of Acid Mediated Conversion in Amorphous-Calcium-Phosphate Based Dental Composites

October 31, 2014
Author(s)
Fan Zhang, Andrew Allen, Lyle E. Levine, Mark D. Vaudin, Drago Skrtic, Joseph M. Antonucci, Kathleen Hoffman, Anthony A. Giuseppetti, Jan Ilavsky
Amorphous calcium phosphate (ACP) based composites are promising restorative dental materials attributable to ACP's capacity to release calcium and phosphate ions through a complex reaction in which ACP is converted to its crystalline, apatitic form

Path degeneracy and EXAFS analysis of disordered materials

October 24, 2014
Author(s)
Bruce D. Ravel
The analysis of EXAFS data measured on a material with a disordered local configuration environment around the absorbing atom can be challenging due to the proliferation of photoelectron scattering paths that must be considered in the analysis. In the case

New National Air-Kerma Standard for Low-Energy Electronic Brachytherapy Sources

October 6, 2014
Author(s)
Stephen M. Seltzer, C M. O'Brien, Michael G. Mitch
The purpose of this report is to document the NIST air-kerma measurement standard for the electronic brachytherapy sources, i.e., the Axxent sources of Xoft, Inc., which operate at tube potentials of 50 kV and anode currents of 300 μA. The use of such

Bromination of marine particulate organic matter through oxidative mechanisms

September 14, 2014
Author(s)
Bruce D. Ravel, Alessandra C. Leri, Kathleen Thornton, Lawrence M. Mayer
Although bromine is considered conservative in seawater, it exhibits a well established correlation with organic carbon in marine sediments. This carbon-bromine association was recently attributed to covalent bonding, with organobromine in sinking
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