A5057480553- Atomic and Molecular Physics
- Laser-induced spectroscopy and plasma
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- Magnetic confinement fusion research
- Nuclear Physics and Applications
- Laser-Plasma Interactions and Diagnostics
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Advanced Chemical Physics Studies
- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Particle accelerators and beam dynamics
- Stellar, planetary, and galactic studies
- Plasma Diagnostics and Applications
- Astro and Planetary Science
- Nuclear physics research studies
- Superconducting Materials and Applications
- Astrophysical Phenomena and Observations
- Laser Design and Applications
- Fusion materials and technologies
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced X-ray Imaging Techniques
- Superconducting and THz Device Technology
- Astronomical Observations and Instrumentation
Lawrence Livermore National Laboratory
2016-2025
University of California, Berkeley
2012-2025
Cheetah Conservation Fund
2023-2024
Columbia University
1996-2022
Space Science Institute
2021
Atomic Weapons Establishment
2020
Princeton Plasma Physics Laboratory
1984-2017
Goddard Space Flight Center
2003-2017
University of Nevada, Reno
1995-2017
International Atomic Energy Agency
2017
We measure up to 2x10;{10} positrons per steradian ejected out the back of approximately mm thick gold targets when illuminated with short ( 1 ps) ultraintense 1x10;{20} W/cm;{2}) laser pulses. Positrons are produced predominately by Bethe-Heitler process and have an effective temperature 2-4 MeV, distribution peaking at 4-7 MeV. The angular is anisotropic. Modeling based on measurements indicate positron density be 10;{16} positrons/cm;{3}, highest ever created in laboratory.
The newly commissioned Orion laser system has been used to study dense plasmas created by a combination of short pulse heating and compression driven shocks. Thus the plasma density was systematically varied between 1 10 g/cc using aluminum samples buried in plastic foils or diamond sheets. heated electron temperatures 500 700 eV allowing conditions be diagnosed K-shell emission spectroscopy. spectra show effect ionization potential depression as function density. data are compared simulated...
The energy splitting of the $^{229}\mathrm{Th}$ ground-state doublet is measured to be $7.6\ifmmode\pm\else\textpm\fi{}0.5\text{ }\text{ }\mathrm{eV}$, significantly greater than earlier measurements. Gamma rays produced following alpha decay $^{233}\mathrm{U}$ ($105\text{ }\ensuremath{\mu}\mathrm{Ci}$) were counted in NASA/electron beam ion trap x-ray microcalorimeter spectrometer with an experimental resolution 26 eV (FWHM). A difference technique was applied gamma-ray 71.82 keV level that...
Detailed angle and energy resolved measurements of positrons ejected from the back a gold target that was irradiated with an intense picosecond duration laser pulse reveal are in collimated relativistic jet. The laser-positron conversion efficiency is ∼2×10{-4}. jets have ∼20 degree angular divergence distributions quasimonoenergetic 4 to 20 MeV beam temperature ∼1 MeV. sheath electric field on surface shown determine positron energy. distribution controlled by varying field, through...
A measurement of the ${2s}_{1/2}\ensuremath{-}{2p}_{3/2}$ x-ray transition in trapped Li-like ${\mathrm{Bi}}^{80+}$ ions was made that resolved $0.820\ifmmode\pm\else\textpm\fi{}0.026\mathrm{eV}$ hyperfine splitting $({1s}^{2}2s{)}_{F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4,5}$ ground configuration, providing first such a multielectron highly charged ion. The intensity ratio two components is shown to be new electron density diagnostic. statistically averaged...
▪ Abstract Targeted laboratory astrophysics measurements are being conducted to address the needs of X-ray astronomy. The producing large sets reliable atomic data, which include ionization and recombination cross sections for charge balance calculations, as well line lists, excitation sections, dielectronic rates interpreting formation. Additional experiments focus on resolving specific puzzles posed by astrophysical observations, calibrating existing developing new diagnostics. We discuss...
We report the first direct laboratory measurement of spontaneous emission due to hyperfine splitting ground state a highly charged hydrogenlike ion excited by electron collisions. The transition between $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4$ and $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3$ levels $1s^{2}S_{1/2}$ configuration $^{165}H{o}^{65+}$ was observed its wavelength determined $5726.4\ifmmode\pm\else\textpm\fi{}1.5\AA{}$. After taking into account...
In laboratory experiments using the engineering spare microcalorimeter detector from ASTRO-E satellite mission, we recorded x-ray emission of highly charged ions carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy in solar wind neutral gases cometary comae. The spectra are complex do not readily match predictions. We developed a model that successfully reproduces soft spectrum comet Linear C/1999 S4, observed with Chandra X-ray Observatory.
Using the SuperEBIT electron beam ion trap, we have measured $2{s}_{1/2}\mathrm{\text{\ensuremath{-}}}2{p}_{1/2}$ transitions in ${\mathrm{U}}^{88+}$ and ${\mathrm{U}}^{89+}$. The value of $280.645\ifmmode\pm\else\textpm\fi{}0.015\text{ }\text{ }\mathrm{eV}$ for Li-like ${\mathrm{U}}^{89+}$ improves available precision by nearly an order magnitude establishes a new benchmark testing total QED contribution to transition energy within fractional accuracy...
The strengths of individual 1s2l2l' resonances for dielectronic recombination heliumlike iron are measured on an electron-beam ion trap using high-resolution x-ray spectroscopy. An energy resolution \ensuremath{\Delta}E/E better than 0.1% is achieved by monitoring the exit channel process. Dielectronic-resonance relative to cross section nonresonant radiative electron capture Fe xxv, and overall uncertainty 20% achieved. Good agreement with theory found strongest resonances; however, less...
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}$${\mathit{S}}_{1}$. The were made with Electron Beam Ion Trap at two electron-beam energies: 4.36 5.62 keV. lines is strongly influenced by...
In the autumn of 1986, first electron beam ion trap, EBIT, was put into service as a light source for spectroscopy highly charged ions. On occasion twentieth anniversary we review its early uses spectroscopy, from measurements X-rays L-shell xenon ions in 1986 to conversion SuperEBIT 1992 and rebirth EBIT-I 2001. Together with their sibling, EBIT-II, these machines have been used at Livermore perform multitude seminal studies physics ions.PACS Nos.: 01.65.+g, 32.30.–r, 32.30,Rj, 39.10.+j
The linear polarization of the 1s2p${\mathrm{}}^{1}$${\mathit{P}}_{1}$\ensuremath{\rightarrow}1${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$ resonance line, 1s2p${\mathrm{}}^{3}$${\mathit{P}}_{1,2}$\ensuremath{\rightarrow}1${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$ intercombination lines, and 1s2s${\mathrm{}}^{3}$${\mathit{S}}_{1}$\ensuremath{\rightarrow}1${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$ forbidden line was measured in heliumlike Fe XXV excited near...
The $F=3$ to $F=2$ hyperfine transitions in the $1s$ ground state of two isotopes ${}^{185}{\mathrm{Re}}^{74+}$ and ${}^{187}{\mathrm{Re}}^{74+}$ were measured be $(4560.5\ifmmode\pm\else\textpm\fi{}3)\AA{}$ $(4516.9\ifmmode\pm\else\textpm\fi{}3)\AA{},$ respectively, using emission spectroscopy an electron beam ion trap. After applying appropriate corrections for nuclear charge distribution QED effects, a Bohr-Weisskopf effect \ensuremath{\varepsilon}=2.23(9)% 2.30(9)% are found...
Using x-ray spectroscopic techniques, we have investigated the properties of an electron beam ion trap (EBIT) after is switched off. In absence beam, bare, and hydrogenlike Kr35+ Kr36+ ions remain trapped due to externally applied magnetic electric fields for at least 5 s; xenon with open L shell, i.e., Xe45+–Xe52+, as long 20 s. The storage time in this ‘‘magnetic trapping mode’’ depends on pressure background atoms well value potential, even longer times appear possible. mode enables a...
The first Doppler-shift-free crystal-spectrometer measurement of stationary highly stripped uranium ions from a high-energy electron beam ion trap is presented. Thirteen 2${\mathit{s}}_{1/2\mathrm{\ensuremath{-}}}$2${\mathit{p}}_{3/2}$ transitions in eight ionization states bteween Li-like ${\mathrm{U}}^{89+}$ and Ne-like ${\mathrm{U}}^{82+}$ are identified measured with an accuracy as high 37 ppm, providing benchmarks for testing relativistic correlation quantum electrodynamic effects...
The hyperfine splitting of the $1s$ ground state hydrogenlike Tl has been measured for two stable isotopes using emission spectroscopy in SuperEBIT electron-beam ion trap, giving $3858.22\ifmmode\pm\else\textpm\fi{}0.30 \AA{}$ ${}^{203}{\mathrm{Tl}}^{80+}$ and $3821.84\ifmmode\pm\else\textpm\fi{}0.34 ${}^{205}{\mathrm{Tl}}^{80+}$ with a wavelength difference $\ensuremath{\Delta}\ensuremath{\lambda}=36.38\ifmmode\pm\else\textpm\fi{}0.35 \AA{}.$ This is consistent estimates based on anomaly...
At the Livermore electron-beam ion-trap facility, extreme-ultraviolet spectra of tungsten have been recorded in wavelength range 4085 Å. The energy was varied systematically to identify individual Rb-like W 37+ Cu-like 45+ . About 60 spectral features identified. PACS Nos.: 32.30Rj, 39.30+w, 31.50+w
A high-throughput von Hámos-type Bragg crystal spectrometer is described that operated with the Livermore electron beam ion trap. The employed to measure high-resolution x-ray spectra from highly charged heliumlike and neonlike ions. Data Ti20+ Fe24+ Au69+ are presented demonstrate utility of new instrument.
The mention of few-electron atoms usually brings to mind hydrogen, helium or other light elements in neutral form. However, these simple are part a sequence ions having the same number electrons but different nuclear charges. For example, hydrogen-like spans hydrogen through uranium, U91+. Both atomic physics and applications most highly charged such isoelectronic sequences receiving increasing attention. Recently electronbeam ion trap has made it possible produce study any modest-sized...
Wavelength measurements of n=3 to n=2 transitions in neonlike ${\mathrm{Xe}}^{44+}$, ${\mathrm{La}}^{47+}$, ${\mathrm{Nd}}^{50+}$, and ${\mathrm{Eu}}^{53+}$ have been made using a high-resolution Bragg-crystal spectrometer on the Princeton Large Torus tokamak. The cover wavelength regions 2.00--3.00 A\r{} include electric dipole magnetic quadrupole transitions. measured wavelengths are compared energy levels obtained from multiconfigurational Dirac-Fock calculation. Systematic differences...