U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: John D. Gillaspy (Fed)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 1 - 25 of 157

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

EUV spectra of Rb-like to Ni-like dysprosium ions in an electron beam ion trap

August 12, 2014
Author(s)
Deirdre Kilbane, G. O'Sullivan, Yuri A. Podpaly, John D. Gillaspy, Joseph Reader, Yuri Ralchenko
Extreme ultraviolet radiation emitted from highly-charged dysprosium ions was measured at the National Institute of Standards and Technology. The ions were created, trapped, and excited in an electron beam ion trap (EBIT), and the spectra were recorded

Extreme ultraviolet spectra and analysis of ?n=0 transitions in highly charged barium

July 4, 2014
Author(s)
Joseph Reader, John D. Gillaspy, Dmitry D. Osin, Yuri Ralchenko
Extreme ultraviolet spectra of highly charged barium atoms were produced with an electron beam ion trap (EBIT) and recorded with a flat-field grazing-incidence spectrometer. The spectra were measured in the wavelength range 4 nm to 24 nm with the beam

EUV spectra from N-shell ions of Gd, Dy and W

September 23, 2013
Author(s)
Deirdre Kilbane, John D. Gillaspy, Yuri Ralchenko, Joseph Reader, G. O'Sullivan
Measurements of extreme ultraviolet radiation from gadolinium, dysprosium and tungsten ions with an open n=4 shell were performed at the National Institute of Standards and Technology. The ions were produced and confined in an electron beam ion trap and

Magnetic-dipole lines in 3dn ions of high-Z elements: identification, diagnostic potential, and dielectronic resonances

September 23, 2013
Author(s)
Yuri Ralchenko, John D. Gillaspy, Joseph Reader, Dmitry D. Osin, John J. Curry, Yuri A. Podpaly
We present a review of measurements and analyses of extreme-ultraviolet magneticdipole (M1) lines in 50-60-times ionized atoms of tungsten, hafnium, tantalum, and gold with an open 3d shell. The spectra were measured with the electron beam ion trap at the

Anisotropic LMN dielectronic resonances from ratios of magnetic-dipole lines

July 13, 2013
Author(s)
Yuri Ralchenko, John D. Gillaspy
Signatures of multi-keV LMN dielectronic resonances in highly-charged 3dn ions of tungsten were detected in the intensity ratios of extreme-ultraviolet magnetic-dipole lines within ground configurations. The measurements were performed with an electron

Transition Energies of the D-lines in Na-like Ions

June 5, 2013
Author(s)
John D. Gillaspy, Dmitry D. Osin, Yuri Ralchenko, Joseph Reader, S A. Blundell
The NIST electron beam ion trap (EBIT) was used to measure the D1 (3s-3p1/2) and D2 (3s-3p3/2) transitions in Na-like ions of xenon, barium, samarium, gadolinium, dysprosium, erbium, tungsten, platinum, and bismuth. New relativistic many-body perturbation

Reply to “Comment on "Testing Three-body Quantum Electrodynamics with Trapped Ti20+ Ions: Evidence for a Z-Dependent Divergence between Experiment and Calculation"

April 12, 2013
Author(s)
Lawrence T. Hudson, C T. Chantler, M N. Kinnane, John D. Gillaspy, A.T. Payne, L F. Smale, Albert Henins, Joshua M. Pomeroy, J A. Kimpton, E Takacs, K Makonyi
We find that Epp’s [1] hypothesis - namely that the current experimental data set is well represented by a small constant or zero offset from the predictions of Artemyev et al. [2] - is not supported by standard statistical analysis. We find that adding

Light polarization and quantum interference effects in unresolvable atomic lines: application to a precise measurement of the 6,7Li D2 lines.

March 7, 2013
Author(s)
Roger C. Brown, Saijun Wu, James V. Porto, Craig J. Sansonetti, Clayton Simien, Samuel M. Brewer, Joseph N. Tan, John D. Gillaspy
We characterize the effect of quantum interference of light scattering on the line shapes and measured line positions in atomic spectra. These effects occur when the excited state splittings are of order the excited state line widths, and represent an

EUV magnetic-dipole lines from highly-charged high-Z ions with an open $3d$ shell

November 27, 2012
Author(s)
Yuri Ralchenko, John D. Gillaspy, Joseph Reader, Dmitry D. Osin
The electron beam ion trap (EBIT) at the National Institute of Standards and Technology was used to produce highly-charged ions of hafnium, tantalum and gold with an open $3d$ shell. The extreme-ultraviolet (EUV) spectra from these ions were recorded with

Testing Three-body Quantum Electrodynamics with Trapped Ti-20 Ions: Evidence for a Z-Dependent Divergence between Experiment and Calculation

October 10, 2012
Author(s)
Lawrence T. Hudson, C T. Chantler, Mark N. Kinnane, John D. Gillaspy, A.T. Payne, L F. Smale, Albert Henins, Joseph N. Tan, J A. Kimpton, E Takacs, K Makonyi, Joshua M. Pomeroy
We report the measurement of the w (1s2p 1P1 ! 1s2 1S0) resonance line transition energy in helium-like titanium. Our result, 4749.85(7) eV, deviates from the most recent ab initio prediction by three times our experimental uncertainty and by many times

EUV spectra of Rb-like to Cu-like gadolinium ions in an electron beam ion trap

October 8, 2012
Author(s)
Yuri Ralchenko, Deirdre Kilbane, G. O'Sullivan, John D. Gillaspy, Joseph Reader
Measurements of extreme ultraviolet radiation from highly-charged gadolinium ions were made at the National Institute of Standards and Technology. The ions were produced and confined in an electron beam ion trap (EBIT) and the spectra were recorded with a

Overview of Recent Atomic Spectroscopy At The NIST EBIT

May 5, 2012
Author(s)
John D. Gillaspy
Seven papers published by the NIST EBIT spectroscopy team and collaborators from mid-2009 to mid-2011 are summarized. Previous discussions of the D-lines in Na-like ions and the Lyman-alpha lines in H-like ions are updated with new information. Nine issues

Resource Letter SS-1: The Spin-Statistics Connection

April 4, 2012
Author(s)
Catalina Curceanu, John D. Gillaspy, R. C. Hilborn
This Resource Letter provides a guide to the literature on the Spin-Statistics Connection and related issues such as the Pauli Exclusion Principle and particle indistinguishability. Journal articles and books are cited for the following topics: basic

Absolute transition frequencies and quantum interference in a frequency comb based measurement of the 6,7Li D lines

July 6, 2011
Author(s)
Craig J. Sansonetti, Clayton Simien, John D. Gillaspy, Joseph N. Tan, Samuel M. Brewer, Roger C. Brown, Saijun Wu, James V. Porto
Optical frequencies of the D lines of 6,7Li were measured with a relative accuracy of 5x10-11 using an optical comb synthesizer. Quantum interference in the laser induced fluorescence for the partially-resolved D2 lines was found to produce polarization

Fe xvii X-ray Line Ratios for Accurate Astrophysical Plasma Diagnostics

February 20, 2011
Author(s)
John D. Gillaspy, E. H. Silver, L. Tedesco, Joseph N. Tan, Joshua M. Pomeroy, J M. Laming, G.-X. Chen, T. Lin
New laboratory measurements of the Ne-like Fe xvii x-ray lines in the 15-17 Angstrom range are presented, along with new theoretical predictions. These results establish consistency between independent laboratories and opens the door to trustworthy