A5052208250- Atomic and Molecular Physics
- Nuclear physics research studies
- Ionosphere and magnetosphere dynamics
- Nuclear Physics and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- Neutrino Physics Research
- Geomagnetism and Paleomagnetism Studies
- Advanced Chemical Physics Studies
- Planetary Science and Exploration
- Dark Matter and Cosmic Phenomena
- Earthquake Detection and Analysis
- Calibration and Measurement Techniques
- Archaeology and ancient environmental studies
- Nuclear reactor physics and engineering
- Optical and Acousto-Optic Technologies
- Solar and Space Plasma Dynamics
- Advanced Aircraft Design and Technologies
- Astro and Planetary Science
- Methane Hydrates and Related Phenomena
- Astrophysics and Cosmic Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Atmospheric and Environmental Gas Dynamics
- Analytical chemistry methods development
- Pleistocene-Era Hominins and Archaeology
Lawrence Livermore National Laboratory
1990-2023
Media Working Group
2021
Lawrence Livermore National Security
1996-2012
Office of Scientific and Technical Information
1996
Princeton University
1979-1985
University of Bristol
1985
University of Rochester
1975-1979
U.S. National Science Foundation
1975-1979
Battelle
1965-1971
Mass spectrometric methods have long been suggested as ways of measuring (14)C/(12)C ratios for carbon dating. One problem has to distinguish between (14)N and (14)C. With negative ions a tandem electrostatic accelerator, the background is virtually absent fewer than three (14)C atoms in 10(16) (12)C easily measured.
We report the first measurements of polarization x rays emitted from bound-bound transitions in a highly ionized He-like ion. Polarization was measured for decay to ground state, 1${\mathit{s}}^{2}$ $^{1}$${\mathit{S}}_{0}$, ${\mathrm{Sc}}^{19+}$ levels 1s2p $^{1}$${\mathit{P}}_{1}$, $^{3}$${\mathit{P}}_{2}$, $^{3}$${\mathit{P}}_{1}$, and 1s2s $^{3}$${\mathit{S}}_{1}$. The were made with Electron Beam Ion Trap at two electron-beam energies: 4.36 5.62 keV. lines is strongly influenced by...
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The dielectronic recombination excitation function for He-like ${\mathrm{Ni}}^{26+}$ ions has been measured. were created and held in an electron beam ion trap, K x rays detected. Several features observed, including resonant of the transition from to direct at threshold. cross section KLL resonances relative radiative measured, agrees with theoretical sections calculated using multiconfiguration Dirac-fock model.
The recently developed direct counting technique for radiocarbon atoms has been used to measure the relative numbers of such in various geological samples which had earlier dated by beta-ray method. Sample weights ranged from 3.5 15 milligrams. dates determined two methods are consistent with each other. Further experience new method is also reported.
We present systematics of the ground-state $\ensuremath{\alpha}$-particle spectroscopic strengths for nuclei from $^{20}\mathrm{Ne}$ to $^{66}\mathrm{Zn}$, measured in ($^{6}\mathrm{Li}$, $d$) reaction. An oscillatory decrease $^{32}\mathrm{S}$, which is excellent agreement with SU(3) theory, followed by a striking and unexplained increase at $^{36}\mathrm{Ar}$ $^{40}\mathrm{Ca}$ then up $^{52}\mathrm{Ti}$, after there again rise.
An experimental investigation of the spectrum x rays emitted in electron-capture decay $^{163}\mathrm{Ho}$ is described. The data obtained are analyzed to determine their sensitivity value neutrino mass. At a 95% confidence level, an upper limit 225 eV set for electron No evidence finite found. Using available photon detectors, further improvements this result severely limited by uncertainties atomic interference effects inherent decay.
We report a measurement of the 3${\mathit{s}}_{1/2\mathrm{\ensuremath{-}}}$3${\mathit{p}}_{3/2}$ transition energy in Na-like $_{78}\mathrm{Pt}^{67+}$ ions 653.44\ifmmode\pm\else\textpm\fi{}0.02(stat) \ifmmode\pm\else\textpm\fi{}0.05(syst) eV. The x rays were observed from an electron-beam ion trap. uncertainty our result corresponds to 1% total estimated quantum electrodynamic radiative contribution this energy. This value differs significantly extrapolations based on previous lower-Z data,...
A systematic difference between the x-ray energies emitted by daughter atom produced in electron-capture radioactive decay and usual ``characteristic'' electron bombardment or photoemission is noted. Particularly, enhanced differences are predicted for certain elements, some measurements demonstrating this effect presented.
The LMM dielectronic recombination resonances of a neonlike ion (${\mathrm{Au}}^{69+}$) have been observed. ions were produced and held in an electron-beam trap. intensity the n=3\ensuremath{\rightarrow}2 x rays resulting from was measured as function energy with sufficient resolution to distinguish structure resonances. resonance strengths for 2${\mathit{p}}_{3/2}^{\mathrm{\ensuremath{-}}1}$ core are good agreement theoretical predictions, but there is some disagreement...
In a continuing effort to explore electron-capture decay properties of $^{163}\mathrm{Ho}$ as means measuring the mass neutrino, we measured half-life 4570\ifmmode\pm\else\textpm\fi{}50 yr (95% confidence level) for using isotope-dilution spectrometry. From this value infer an $Q$ approximately 2.65 keV known atomic physics factors and estimate nuclear matrix element based on systematics $\mathrm{ft}$ values other Ho isotopes.RADIOACTIVITY $^{163}\mathrm{Ho}$, electron capture decay,...
The $^{81}\mathrm{Kr}^{m}$ to $^{81}\mathrm{Br}$ electron capture rate has been measured and found have a $log\mathrm{ft}$ value of 4.58\ifmmode\pm\else\textpm\fi{}0.11. This result implies is feasible target for solar neutrino capture.RADIOACTIVITY Measured branching ratio capture, deduced capture.
The $^{81}\mathrm{Br}$($^{3}\mathrm{He}$,$t$)$^{81}\mathrm{Kr}$, reaction has been used to determine an improved value for the ground state mass of $^{81}\mathrm{Kr}$. A comparison is made with $^{51}\mathrm{V}$($^{3}\mathrm{He}$,$t$)$^{51}\mathrm{Cr}$ and implications calibration proposed bromine solar neutrino detector are presented.NUCLEAR REACTIONS $^{51}\mathrm{V}$($^{3}\mathrm{He}$,$t$)$^{51}\mathrm{Cr}$, $^{87}\mathrm{Rb}$($^{3}\mathrm{He}$,$t$)$^{87}\mathrm{Sr}$,...
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Abstract Using data from the Van Allen Probe and Swarm‐Bravo satellites, evidence for a persistent population of slow magnetosonic waves in ionosphere is presented. Dispersion relations two‐fluid analyses warm plasma are used to interpret explicate these observations. These appear be continuously present globally distributed. Their amplitudes systematically decrease with increasing altitude. The also correlated longitude manner consistent global distribution lightning strikes. Evidence...