A5017061416- Laser-Plasma Interactions and Diagnostics
- High-pressure geophysics and materials
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- Diamond and Carbon-based Materials Research
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Advanced X-ray Imaging Techniques
- Magnetic confinement fusion research
- X-ray Spectroscopy and Fluorescence Analysis
- Ion-surface interactions and analysis
- Quantum, superfluid, helium dynamics
- Laser Design and Applications
- Muon and positron interactions and applications
- Laser Material Processing Techniques
- Physics of Superconductivity and Magnetism
- Advanced Chemical Physics Studies
- Astro and Planetary Science
- Advanced Condensed Matter Physics
- Boron and Carbon Nanomaterials Research
- Electron and X-Ray Spectroscopy Techniques
- Radiation Therapy and Dosimetry
- Bacterial Identification and Susceptibility Testing
- Geological and Geochemical Analysis
- Advanced Electron Microscopy Techniques and Applications
SLAC National Accelerator Laboratory
2016-2025
Menlo School
2014-2024
Stanford University
2021-2022
University of Alberta
2016-2021
Osaka University
2021
University of Nevada, Reno
2021
Lawrence Livermore National Laboratory
2016-2021
The University of Texas at Austin
2021
École Polytechnique
2010-2018
Centre National de la Recherche Scientifique
2010-2018
Abstract The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery microscopic diamonds in remnants explosively driven graphite. Furthermore, shock synthesis lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected happen during violent meteor impacts. Here, we show unprecedented situ X-ray diffraction measurements formation on nanosecond timescales by compression pyrolytic as well...
The matter in extreme conditions end station at the Linac Coherent Light Source (LCLS) is a new tool enabling accurate pump–probe measurements for studying physical properties of high-energy density (HED) physics regime. This instrument combines world's brightest x-ray source, LCLS beam, with high-power lasers consisting two nanosecond Nd:glass laser beams and one short-pulse Ti:sapphire laser. These produce short-lived states high pressures, temperatures or densities that are important...
We report on recent experimental results deploying a continuous cryogenic hydrogen jet as debris-free, renewable laser-driven source of pure proton beams generated at the 150 TW ultrashort pulse laser Draco. Efficient acceleration reaching cut-off energies up to 20 MeV with particle numbers exceeding 10
Laser plasma-based particle accelerators attract great interest in fields where conventional reach limits based on size, cost or beam parameters. Despite the fact that cell simulations have predicted several advantageous ion acceleration schemes, laser not yet reached their full potential producing simultaneous high-radiation doses at high energies. The most stringent limitation is lack of a suitable high-repetition rate target also provides degree control plasma conditions required to...
We report experimental evidence that multi-MeV protons accelerated in relativistic laser-plasma interactions are modulated by strong filamentary electromagnetic fields. Modulations observed when a preplasma is developed on the rear side of $\ensuremath{\mu}\mathrm{m}$-scale solid-density hydrogen target. Under such conditions, fields amplified electron Weibel instability and maximized at critical density region The analysis spatial profile indicates generation $B>10\text{ }\text{...
We discuss the possibility of obtaining highly precise measurements ionization potential depression in dense plasmas with spectrally resolved x-ray scattering, while simultaneously determining electron temperature and free density. A proof-of-principle experiment at Linac Coherent Light Source, probing isochorically heated carbon samples, demonstrates capabilities this method motivates future experiments laser facilities.
Abstract We present the development and characterization of a high-stability, multi-material, multi-thickness tape-drive target for laser-driven acceleration at repetition rates up to 100 Hz. The tape surface position was measured be stable on sub-micrometre scale, compatible with high-numerical aperture focusing geometries required achieve relativistic intensity interactions pulse energy available in current multi-Hz near-future higher repetition-rate lasers ( $>$ kHz). Long-term drift...
Abstract The interaction of relativistically intense lasers with opaque targets represents a highly non-linear, multi-dimensional parameter space. This limits the utility sequential 1D scanning experimental parameters for optimization secondary radiation, although to-date this has been accepted methodology due to low data acquisition rates. High repetition-rate (HRR) augmented by machine learning present valuable opportunity efficient source optimization. Here, an automated, HRR-compatible...
The effect of pressure on nanostructured rhombohedral α-Sb2Te3 (phase I) was investigated using X-ray diffraction (XRD) and Raman spectroscopy (RS) up to 19.2 25.5 GPa, respectively. XRD patterns showed two new high phases (named II III). From a Rietveld refinement α-Sb2Te3, the unit cell volume as function obtained values were fitted Birch–Murnaghan equation state (BM-EOS). best fit for bulk modulus B0=36.1±0.9 GPa its derivative B0′=6.2±0.4 (not fixed). Using refined structural data...
We report on a high repetition rate proton source produced by high-intensity laser irradiation of continuously flowing, cryogenic hydrogen jet. The energy spectra are recorded at 1 Hz for Draco powers 6, 20, 40, and 100 TW. delivers ∼1013 protons/MeV/sr/min. find that the average number over one minute, energies sufficiently far from cut-off energy, is robust to laser-target overlap nearly constant. This work therefore first step towards pulsed laser-driven sources time-resolved radiation...
Abstract Key insights in materials at extreme temperatures and pressures can be gained by accurate measurements that determine the electrical conductivity. Free-electron laser pulses ionize excite matter out of equilibrium on femtosecond time scales, modifying electronic ionic structures enhancing scattering properties. The transient evolution conductivity manifests energy coupling from high temperature electrons to low ions. Here we combine accelerator-based, high-brightness multi-cycle...
Abstract Laser-plasma acceleration of protons offers a compact, ultra-fast alternative to conventional techniques, and is being widely pursued for potential applications in medicine, industry fundamental science. Creating stable, collimated beam at high repetition rates presents key challenge. Here, we demonstrate the generation multi-MeV proton beams from fast-replenishing ambient-temperature liquid sheet. The has an unprecedentedly low divergence 1° (≤20 mrad), resulting magnetic...
The efficiency and uniformity of heating induced by hard x-ray free-electron laser pulse is investigated for 0.5 μm silver foils using the X-ray Pump Probe instrument at Linac Coherent Light Source facility. Intense 8.9 keV pulses 60 fs duration deposit energy predominantly via inner-shell ionization to create a non-equilibrium Ag solid density plasma. are focused 14 × 17 μm2 means beryllium lenses varying total beam energy, deposition varied over range irradiances from 4.4 6.5 1015 W/cm2....
Collisionless shock acceleration of protons and ${\mathrm{C}}^{6+}$ ions has been achieved by the interaction a ${10}^{20}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$, $1\text{ }\ensuremath{\mu}\mathrm{m}$ laser with near-critical density plasma. Ablation initially solid target secondary allows for systematic control plasma profile. This enables production beams peaked spectra energies $10--18\text{ }\mathrm{MeV}/\mathrm{amu}$ energy spreads 10%--20% up to...
Radiochromic films (RCF) are commonly used in dosimetry for a wide range of radiation sources (electrons, protons, and photons) medical, industrial, scientific applications. They multi-layered, which includes plastic substrate layers sensitive that incorporate radiation-sensitive dye. Quantitative dose can be retrieved by digitizing the film, provided prior calibration exists. Here, to calibrate newly developed EBT3 HDv2 RCFs from Gafchromic™, we Stanford Medical LINAC deposit various doses...
Angularly resolved X-ray scattering measurements from fs-laser heated hydrogen have been used to determine the equilibration of electron and ion temperatures in warm dense matter regime. The relaxation rapidly cryogenic is visualized using 5.5 keV pulses Linac Coherent Light (LCLS) source a 1 Hz repetition rate pump-probe setting. We demonstrate that electron-ion energy transfer faster than quasi-classical Landau-Spitzer models use ad hoc cutoffs Coulomb logarithm.
For high-intensity laser-solid interactions, the absolute density and surface gradients of target at arrival ultrarelativistic laser peak are critical parameters. Accurate modeling leading edge-driven preexpansion is desired to strengthen predictive power associated computer simulations. The transition from an initial solid state a plasma state, i.e., breakdown solid, defines starting point subsequent preexpansion. In this work, we report on time-resolved observation transient laser-induced...
We describe a setup for performing inelastic X-ray scattering and diffraction measurements at the Matter in Extreme Conditions (MEC) endstation of Linac Coherent Light Source. This technique is capable high-, meV-resolution dynamic ion features both crystalline non-crystalline materials. A four-bounce silicon (533) monochromator was used conjunction with three diced crystal analyzers to provide an energy resolution ∼50 meV over range ∼500 single shot measurements. In addition instrument...
We report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using frequency-doubled Titan short pulse laser system Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate generation pure proton beam with maximum energy 2 MeV. Furthermore, record quasi-monoenergetic peak 1.1 MeV in spectrum emitted forward direction suggesting an alternative acceleration mechanism. solid-density mixed hydrogen-deuterium target,...
We have observed, by 2D positron annihilation, the ridge-shaped Fermi surface related to chains in compound series (R)${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ for R=Y, Dy, Ho, and Pr. In case of Y we sighted clear signature ridge fourth Brillouin zone observed effect substituting Cu with Ni, Zn, Al. The presence is also seen...
We present direct observations of acoustic waves in warm dense matter. analyze wave-number- and energy-resolved x-ray spectra taken from methane created by laser heating a cryogenic liquid jet. X-ray diffraction inelastic free-electron scattering yield sample conditions <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mn>0.3</a:mn><a:mo>±</a:mo><a:mn>0.1</a:mn></a:mrow></a:math> eV <b:math...
Intense research is being conducted into sources of laser-accelerated ions and their application. Particular attention now given to the low-density regime laser ion acceleration. In this regime, volume effects are expected dominate, while for solid foils, acceleration directly related electron surface density number accelerated limited. Simulations therefore show that it possible reach high energies with a conversion efficiency. This scheme also leads less debris than foils more adapted...
It was recently shown that a promising way to accelerate protons in the forward direction high energies is use under-dense or near-critical density targets instead of solids. Simulations have revealed acceleration process depends on gradients plasma target. Indeed, under certain conditions, most energetic are predicted be accelerated by collisionless shock mechanism significantly increases their energy. We report here results recent experiment dedicated study longitudinal ion partially...
We show efficient laser driven proton acceleration up to 14MeV from a 50 $\mu$m thick cryogenic hydrogen ribbon. Pulses of the short pulse ELFIE at LULI with length $\approx$ 350 fs an energy 8 J per are directed onto target. The results compared spectra metal and plastic foils different thicknesses similar good performance both in maximum as well number. Thus, this target type is promising candidate for experiments high repetition rate systems.
We demonstrate high repetition-rate deuteron acceleration by irradiating a continuously flowing, ambient temperature liquid heavy water jet with the high-intensity ALEPH laser. The laser delivered up to 5.5 J (120 TW, 1.2 × 1021 W/cm2) energy on target at 0.5 Hz. A Thomson parabola spectrometer measured beam spectra each shot for 60 sequential shots (two minutes). Peak fluxes of 5×1010 deuterons/sr/pulse, corresponding an average flux 1.5×1012 deuterons/sr/min, were demonstrated energies...