F. E. Merrill
A5039188145- Nuclear Physics and Applications
- Laser-Plasma Interactions and Diagnostics
- Space Technology and Applications
- Particle Detector Development and Performance
- High-pressure geophysics and materials
- Radiation Detection and Scintillator Technologies
- Quantum Chromodynamics and Particle Interactions
- Particle accelerators and beam dynamics
- Gamma-ray bursts and supernovae
- Ion-surface interactions and analysis
- Particle Accelerators and Free-Electron Lasers
- Particle physics theoretical and experimental studies
- Laser-induced spectroscopy and plasma
- Atomic and Subatomic Physics Research
- Nuclear reactor physics and engineering
- Astro and Planetary Science
- High-Energy Particle Collisions Research
- Superconducting Materials and Applications
- Magnetic confinement fusion research
- Cold Fusion and Nuclear Reactions
- X-ray Spectroscopy and Fluorescence Analysis
- Photocathodes and Microchannel Plates
- CCD and CMOS Imaging Sensors
- Electron and X-Ray Spectroscopy Techniques
- Radiation Therapy and Dosimetry
Los Alamos National Laboratory
2016-2025
SLAC National Accelerator Laboratory
2017-2020
IMDEA Materials
2020
Colorado School of Mines
2020
Argonne National Laboratory
2020
Lawrence Livermore National Laboratory
2012-2017
General Atomics (United States)
2012-2017
Massachusetts Institute of Technology
2012-2017
Fusion Academy
2012-2017
Fusion (United States)
2012-2017
Neutrons are unique particles to probe samples in many fields of research ranging from biology material sciences engineering and security applications. Access bright, pulsed sources is currently limited large accelerator facilities there has been a growing need for compact over the recent years. Short pulse laser driven neutron could be relatively cheap way produce neutrons with energies excess 10 MeV. For more than decade experiments have tried obtain numbers sufficient Our demonstrated an...
The E885 Collaboration utilized the 1.8GeV/cK− beam line at Alternating Gradient Synchrotron (AGS) to accumulate greater than 10 times world's existing data sample of (K−,K+) events on carbon. A total about 3×105(K−,K+) were collected and analyzed. Ξ hypernuclear states are expected be produced through reaction K−+12→CK++12ΞBe. signal could also result from direct production 11ΛBe+Λ without a distinct intermediate state. measured missing-mass spectrum indicates existence below threshold for...
The “High-Foot” platform manipulates the laser pulse-shape coming from National Ignition Facility to create an indirect drive 3-shock implosion that is significantly more robust against instability growth involving ablator and also modestly reduces convergence ratio. This strategy gives up on theoretical high-gain in inertial confinement fusion order obtain better control of bring experimental performance in-line with calculated performance, yet keeps absolute capsule relatively high. In...
A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important tool for inertial fusion studies NIF measuring size and shape of burning DT plasma during ignition stage Inertial Confinement Fusion (ICF) implosions. The technique utilizes a pinhole aperture, placed between source detector. detection measures two dimensional distribution neutrons passing through pinhole. designed to collect images times. long flight path this...
High Density Carbon (HDC) is a leading candidate as an ablator material for Inertial Confinement Fusion (ICF) capsules in x-ray (indirect) drive implosions. HDC has higher density (3.5 g/cc) than plastic (CH, 1 g/cc), which results thinner with larger inner radius given capsule scale. This leads to absorption and shorter laser pulses compared equivalent CH designs. paper will describe series of experiments carried out examine the feasibility using both gas filled hohlraums lower density,...
Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This made possible by using dense ablator (high-density carbon), which shortens drive duration needed to achieve convergence: measured 40% higher efficiency than typical gas-filled hohlraums, requires less laser...
We report on the first layered deuterium-tritium (DT) capsule implosions indirectly driven by a "high-foot" laser pulse that were fielded in depleted uranium hohlraums at National Ignition Facility. Recently, high-foot have demonstrated improved resistance to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into DT hot spot [Hurricane et al., Nature (London) 506, 343 (2014)]. Uranium provide higher albedo and thus an increased drive equivalent additional 25 TW...
The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring two-dimensional size and shape of neutrons produced in burning deuterium-tritium plasma during ignition stage inertial confinement fusion (ICF) implosions NIF. Since source small (∼100 μm) are deeply penetrating (>3 cm) all materials, apertures used to achieve desired 10-μm resolution 20-cm long, single-sided tapers gold. These apertures, which have triangular cross...
The first inertial confinement fusion implosion experiments with equimolar deuterium-tritium thermonuclear fuel have been performed on the National Ignition Facility. These use 0.17 mg of potential for ignition and significant yield conditions. has fielded as a cryogenic layer inside spherical plastic capsule that is mounted in center cylindrical gold hohlraum. Heating hohlraum 192 laser beams total energy 1.6 MJ produces soft x-ray field 300 eV temperature. ablation pressure produced by...
The neutron spectrum from a cryogenically layered deuterium–tritium (dt) implosion at the National Ignition Facility (NIF) provides essential information about performance. From measured primary-neutron (13–15 MeV), yield (Yn) and hot-spot ion temperature (Ti) are determined. scattered (10–12 MeV) relative to Yn, down-scatter ratio, fuel areal density (ρR) These parameters have been diagnosed an unprecedented accuracy with suite of neutron-time-of-flight spectrometers magnetic recoil...
First results from the analysis of neutron image data collected on implosions cryogenically layered deuterium-tritium capsules during 2011-2012 National Ignition Campaign are reported. The span a variety experimental designs aimed at increasing stagnation pressure central hotspot and areal density surrounding fuel assembly. Images neutrons produced by deuterium–tritium fusion reactions in presented, as well images that scatter dense compared with 1D 2D model predictions, consistency checked...
Hydrodynamic instabilities can cause capsule defects and other perturbations to grow degrade implosion performance in ignition experiments at the National Ignition Facility (NIF). Here, we show first experimental demonstration that a strong unsupported shock indirect drive implosions NIF reduces ablation front instability growth leading 3 10 times higher yield with fuel ρR>1 g/cm(2). This work shows importance of during Campaign may provide path improved high compression necessary for ignition.
The National Ignition Facility has been used to compress deuterium-tritium an average areal density of ~1.0±0.1 g cm(-2), which is 67% the ignition requirement. These conditions were obtained using 192 laser beams with total energy 1-1.6 MJ and peak power up 420 TW create a hohlraum drive shaped profile, peaking at soft x-ray radiation temperature 275-300 eV. This pulse delivered series shocks that compressed capsule containing cryogenic radius 25-35 μm. Neutron images implosion estimate...
Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165 μm in thickness, 10% 15% thinner, respectively, than nominal thickness used throughout high foot most of Campaign. These three-shock, high-adiabat, high-foot implosions demonstrated good performance, with higher velocity better symmetry control lower laser powers energies their ablator counterparts. Little to no hydrodynamic mix into DT hot...
By increasing the velocity in "high foot" implosions [Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014); Park 055001 Hurricane Nature 506, 343 Plasmas 21, 056314 (2014)] on National Ignition Facility laser, we have nearly doubled neutron yield and hotspot pressure as compared to reported upon last year. The implosion has been increased using a combination of laser (higher power energy), hohlraum (depleted uranium wall material with higher opacity lower specific heat than gold hohlraums),...
Hydrodynamic mix of the ablator into DT fuel layer and hot spot can be a critical performance limitation in inertial confinement fusion implosions. This results increased radiation loss, cooling spot, reduced neutron yield. To quantify level mix, we have developed simple model that infers contamination using ratio measured x-ray emission to The principal source for “low-foot” class implosions appears been mix. Lower convergence “high-foot” are found less susceptible allowing velocities...
The generation of dynamic high energy density plasmas in the pico- to nano-second time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At National Ignition Facility (NIF), primary goal inertial confinement fusion has led synergistic development a unique brightness neutron source, sophisticated diagnostic instrumentation, and versatile experimental platforms. These novel capabilities provide new path investigate processes structural effects...
We present a full characterization of short pulse laser-driven neutron source. Neutrons are produced by nuclear reactions ions deposited in secondary target. The emission neutrons is superposition an isotropic component into 4π and forward directed, jet-like contribution, with energies ranging up to 80 MeV. A maximum flux 4.4 × 109 neutrons/sr has been observed used for fast radiography. On-shot the ion driver beam done variety different diagnostics, including particle detectors, reaction,...
Emerging approaches to short-pulse laser-driven neutron production offer a possible gateway compact, low cost, and intense broad spectrum sources for wide variety of applications. They are based on energetic ions, driven by an laser, interacting with converter material produce neutrons via breakup nuclear reactions. Recent experiments performed the high-contrast laser at Trident facility Los Alamos National Laboratory have demonstrated ion acceleration mechanism operating in regime...
Cosmic ray muons that reach the earth's surface provide a natural source of radiation is used for radiography. In this paper, we show radiography using cosmic background provides method can be to monitor bulk aspects human anatomy. We describe measure changes in patients as function time by muon Modeling shows tomography could hourly readouts parameters such lung density with sufficient sensitivity detect inflammation lungs in, e.g., COVID patients.
The accuracy of density measurements and position resolution in flash (40 ns) radiography thick objects with 24 Gev/c protons is investigated. A global model fit to step wedge data shown give a good description spanning the periodic table. parameters obtained from are used predict transmission through French Test Object (FTO), test object nested spheres, precision better than 1%. Multiple trials have been show that systematic errors less 2%. Absolute agreement between average radiographic...
This article describes the design and performance of a magnifying magnetic-lens system designed, built, commissioned at Los Alamos National Laboratory (LANL) for 800 MeV flash proton radiography. The technique radiography has been developed LANL to study material properties under dynamic loading conditions through analysis time sequences radiographs. requirements this growing experimental program have resulted in need improvements spatial radiographic resolution. To meet these needs, new...