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Physics

Radiation

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  • Published Date
Displaying 226 - 250 of 259

Supplementary comparison CCR(IK)-S2 of standards for absorbed dose to water Co-60 gamma radiation at radiation processing dose levels

July 25, 2011
Author(s)
Marc F. Desrosiers, D T. Burns, P J. Allisy-Roberts, P H. Sharpe, M. Pimpinella, V. Lourenco, Y. L Zhang, A Miller, V Generalova, V. Sochor
Eight national standards or absorbed dose to water in Co-60 gamma radiation at the dose levels used in radiation processing have been compared over the range from 1 kGy to 30 kGy using the alanine dosimeters of the NIST and the NPL as the transfer

Synchrotron radiation-based bilateral intercomparison of ultraviolet source calibrations

July 7, 2011
Author(s)
Uwe Arp, Zhigang Li, Ping-Shine Shaw, Mathias Richter, Roman Klein, Wolfgang Paustian, Reiner Thornagel
We report on a successful bilateral inter-comparison between the Physikalisch-Technische Bundesanstalt (PTB) and the National Institute of Standards and Technology (NIST). In both laboratories deuterium lamps were calibrated using the calculability of

Energetic Photon Spectra from Targets Irradiated by Picoseconds Lasers

April 30, 2011
Author(s)
Lawrence T. Hudson, John F. Seely, Csilla Szabo, Uri Feldman, Hui Chen, Albert Henins
Photon spectra in the energy range 60 keV to 1 MeV were recorded from targets irradiated by the LLNL Titan and LLE EP picosecond lasers. The radiation consisted of K shell radiation, Bremsstrahlung radiation from MeV electrons, and preliminary evidence for

A Collaborative Enterprise for Multi-Stakeholder Participation in the Advancement of Quantitative Imaging

March 1, 2011
Author(s)
Lisa R. Karam, Andrew Buckler, Hugo J. Aerts, Bernard Bendriem, Claus Bendtsen, Ronald Boellaard, John M. Boone, Linda Bresolin, Deborah Burstein, William Bushnell, Patricia E. Cole, James J. Conklin, Gary S. Dorfman, Pamela S. Douglas, N. R. Dunnick, Willy Eidsaunet, Cathy Elsinger, Richard F. Frank, Constantine Gatsonis, Maryellen L. Giger, David Gustafson, Sandeep N. Gupta, Otto S. Hoekstra, Edward F. Jackson, Gary J. Kelloff, Paul E. Kinahan, Geoffrey McLennan, Colin G. Miller, P D. Mozley, Keith E. Muller, Kevin O'Donnell, Rick Patt, Divid Raunig, Mark Rosen, Heren Rupani, Lawrence H. Schwartz, Barry A. Siegel, A. G. Sorensen, Richard L. Wahl, John C. Waterton, Walter Wolf, Gudrun Zahlmann, Brian E. Zimmerman, Daniel C. Sullivan
Medical imaging has seen significant and rapid technical advances over the last decade, including image acquisition devices, processing and analysis software, and agents to enhance specificity. Traditionally medical imaging has defined anatomy, but

A Dosimetric Uncertainty Analysis for Photon-Emitting Brachytherapy Sources: Report of the AAPM Task Group No. 138 and GEC-ESTRO

February 1, 2011
Author(s)
Larry A. DeWerd, Geoffrey S. Ibbott, Ali S. Meigooni, Michael G. Mitch, Mark J. Rivard, Kurt E. Stump, Bruce R. Thomadsen, Jack L. Venselaar
This report addresses uncertainties pertaining to brachytherapy source dosimetry. The ISO Guide to the Expression of Uncertainty in Measurement (GUM) and the NIST Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties

Bilateral NIST-PTB Comparison of Spectral Responsivity in the VUV

January 20, 2011
Author(s)
Uwe Arp, Ping-Shine Shaw, Zhigang Li, Alexander Gottwald, Mathias Richter
To compare the calibration capabilities for the spectral responsivity in the vacuum-ultraviolet spectral region between 135 nm and 250 nm, PTB and NIST agreed on a bilateral comparison. Calibrations of semiconductor photodiodes as transfer detectors were

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

Scaling studies with the dual crystal spectrometer at the OMEGA-EP laser facility

October 26, 2010
Author(s)
Lawrence T. Hudson, C.I Szabo, J. Workman, K. Flippo, Uri Feldman, Albert Henins
The dual crystal spectrometer (DCS) is an approved diagnostic at the OMEGA and the OMEGA-EP laser facilities for the measurement of high energy x-rays in the 11 90 keV energy range, e.g., for verification of the x-ray spectrum of backlighter targets of

Laser-produced MeV electrons and hard X-ray spectroscopic diagnostics

July 21, 2010
Author(s)
Lawrence T. Hudson, John F. Seely
A new spectroscopic technique for the measurement of the sizes of hard X-ray sources produced by the irradiation of solid-density targets by intense laser radiation is discussed. The technique is based on the source broadening of K shell spectral lines

Monte-Carlo Reaction Rate Evaluation for Astrophysics

June 2, 2010
Author(s)
Ryan P. Fitzgerald, A. Coc, R Longland, A E. Champagne
We present a new evaluation of thermonuclear reaction rates for astrophysics involving proton and a-particle induced reactions, in the target mass range between A=14 and 40, including many radioactive targets. A method based on Monte Carlo techniques is

Optimal filtering, record length, and count rate in transition-edge-sensor microcalorimeters

December 16, 2009
Author(s)
William B. Doriese, Gene C. Hilton, Kent D. Irwin, Francis J. Schima, Joel N. Ullom, Joseph S. Adams, Caroline A. Kilbourne
In typical algorithms for optimally filtering transition-edge-sensor-microcalorimeter pulses, the average value of a filtered pulse is set to zero. The achieved energy resolution of the detector then depends strongly on the chosen length of the pulse

An Automated Ionization Chamber for Secondary Radioactivity Standards

December 8, 2009
Author(s)
Ryan P. Fitzgerald
We report on the operation and characterization of a new ionization chamber system, called AUTOIC, featuring a commerical digital electrometer and a commerical robotic sample changer. The ralative accuracy of the electrometer was improved significantly

High contract femtosecond laser-driven intense hard X-ray source for imaging application

November 18, 2009
Author(s)
Lawrence T. Hudson, L.M Chen, W.M. Wang, M. Kando, F Liu, X.X. Lin, J.L Ma, Y.T. Li, S.V. Bulanvo, T. Tajima, Y. Kato, Z.M. Sheng, J Zhang
In this report we address the current situation of laser-driven hard X-ray sources for imaging applications,especially the saturation of X-ray conversion efficiency and the serious impact upon imaging quality.By employing high contrast laser pulses,the

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

Effects of high intensity neutron flux on in-situ spin-exchange optical pumping of He-3

September 17, 2009
Author(s)
Thomas R. Gentile, E Babcock, Stephen Boag, C. Becham, T E. Chupp, Gordon L. Jones, A K. Petukhov, T G. Walker
Prior studies revealed neutron beam-induced alkali-metal spin relaxation in 3He cells polarized in-situ by spin-exchange optical pumping. These effects are minor for neutron beams of low to moderate intensity, but become important at the highest neutron

Optimizing the Dynamic Range Extension of a Radiochromic Film Dosimetry System

February 28, 2009
Author(s)
Slobodan Devic, Tomic Nada, Christopher G. Soares, Ervin Podgorsak
We present a radiochromic film dosimetry protocol for a multi-color channel radiochromic film dosimetry system consisting for the EBT model GAFCHROMIC(TM) film and the Epson Expression 1680 flat-bed document scanner. Instead of extracting only the red
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