A5042481611- Nuclear Physics and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Photocathodes and Microchannel Plates
- Radiation Detection and Scintillator Technologies
- Electron and X-Ray Spectroscopy Techniques
- Advanced X-ray Imaging Techniques
- Fluid Dynamics and Thin Films
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Particle Detector Development and Performance
- Electrostatic Discharge in Electronics
- Pulsed Power Technology Applications
- Atomic and Molecular Physics
- Solidification and crystal growth phenomena
- Laser-induced spectroscopy and plasma
- nanoparticles nucleation surface interactions
- Particle Dynamics in Fluid Flows
- Gyrotron and Vacuum Electronics Research
- Heat Transfer and Optimization
- Magnetic confinement fusion research
- Space Science and Extraterrestrial Life
- Digital Radiography and Breast Imaging
- Distributed and Parallel Computing Systems
- Silicon and Solar Cell Technologies
- Advanced X-ray and CT Imaging
Nevada National Security Site
2018-2024
Sandia National Laboratories
2021
Subsea Technologies (United Kingdom)
2017
National Security Technologies (United States)
2008-2014
Bechtel (United States)
2001-2006
Emcore (United States)
1993-1994
University of California System
1981
Understanding of microchannel plate (MCP) detectors with x-ray energy is important for applications in high density research such as broadband imaging and spectroscopy. The relative sensitivity photon Cu∕Au coated MCPs the range 250eV<hν<5000eV has been measured at National Synchrotron Light Source. A model this response that includes contributions from secondary photoelectron yield interactions multiple channels presented. This shown to agree MCP <20% over majority...
The DARHT-II linear-induction accelerator has been successfully operated at 1.2-1.3 kA and 12.5-12.7 MeV to demonstrate the production acceleration of an electron beam. Beam pulse lengths for these experiments were varied from 0.5 /spl mu/s 1.2 full-width half-maximum. A low-frequency inductance-capacitance (LC) oscillation diode voltage current resulted in beam position through interaction with accidental (static) magnetic dipole region. There was no growth amplitude this after propagating...
Deuterium–tritium (DT) reaction rates of imploding capsules have historically been measured using neutron detectors. Temporal resolution is limited by the size detector and distance from source to detector. The can also be 16.7 MeV gamma ray, which produced same DT reaction, but statistically far less often than 14.1 neutron. Cherenkov detectors detect rays converting electrons, in turn produce light record this visible a fast optical These scaled large volumes order increase detection...
A gas Cerenkov detector with a 12-MeV threshold for gamma-ray detection has been built use on the OMEGA laser system to record high-energy gamma rays emitted during DT burn. Recording 16.7-MeV ray while discriminating against lower energy 14-MeV neutron-induced gammas is an important objective using this system. Detector design, sensitivity, and background studies were possible Integrated Tiger Series Monte Carlo code modified include production full time-history of all particles. The...
Neutron time-of-flight (nTOF) detectors have been used on Sandia National Laboratories' Z-Machine for inertial confinement fusion and magnetized liner experiments to infer physics parameters including the apparent fuel-ion temperature, neutron yield, magnetic-radius product (BR), rho-r. Single-paddle, dual-paddle, co-axial scintillation nTOF are in axial lines-of-sight (LOS) LOS that 12° from midplane. Detector fabrication, characterization, calibration discussed.
A new time-resolved opacity spectrometer (OpSpecTR) is currently under development for the National Ignition Facility (NIF) campaign. The utilizes Icarus version 2 (IV2) hybridized complementary metal–oxide–semiconductor sensors to collect gated data at time of transmission signal, unlocking ability higher-temperature measurements on NIF. Experimental conditions achieve higher temperatures are feasible; however, backgrounds will dominate collected by current time-integrating spectrometer....
The second axis of the Dual Axis Radiographic HydroTest (DARHT) facility will provide up to four short (< 150 ns) radiation pulses for flash radiography high-explosive driven implosion experiments. To accomplish this DARHT-II linear induction accelerator (LIA) produce a 2-kA electron beam with 18-MeV kinetic energy, constant within /spl plusmn/ 0.5% 2-/spl mu/s. A fast kicker cleave out mu/s flattop, bulk diverted into dump. then be transported final-focus magnet, and focused onto tantalum...
Microchannel plates (MCPs) are a standard detector for fast-framing x-ray imaging and spectroscopy of high-temperature plasmas. The MCP is coated with conductive striplines that carry short duration voltage pulses to control the timing amplitude signal gain. This gain depends on large exponent so small reflections or impedance losses along can have significant impact position-dependent pulse width Understanding pulsed response therefore requires careful measurements position- time-dependent...
We present here results of continued efforts to understand the performance microchannel plate (MCP)-based, high-speed, gated, x-ray detectors. This work involves improvement a Monte Carlo simulation code describe MCP coupled with experimental better characterize such Our goal is quantitative description saturation behavior in both static and pulsed modes. A new model charge buildup on walls channels briefly described. The are compared data obtained short-pulse, high-intensity ultraviolet...
When compared with the National Ignition Facility's (NIF) original soft x-ray opacity spectrometer, which used a convex cylindrical design, an elliptically shaped design has helped to increase signal-to-noise ratio and eliminated nearly all reflections from alternate crystal planes. The success of elliptical geometry in experiments driven new spectral range covering 520-1100 eV. coupled primary geometry, spans 1000-2100 eV, sub-keV helps cover full iron L-shell major oxygen transitions...
MCP detector performance at hard x-ray energies from 6 to 25 keV was recently investigated using NSLS beamline X15A BNL. Measurements were made with an NSTec Gen-II (H-CA-65) framing camera, based on a Photonis ∼10 μm in diameter pores, ∼12 center-center spacing, L/D ratio of 46, and bias angle 8°. The characterizations focused (1) energy dependent sensitivity, (2) spatial resolution, (3) gain performance, (4) dynamic range. These measurement corroborated simulation results Monte Carlo model...
When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2 kA, 18 MeV electron beam with more than 1500 ns current/energy "flat-top." In initial tests has already accelerated beams current pulse lengths from 500 to 1200 full-width at half maximum (FWHM) 1.2 kA peak and 12.5 energy. Experiments soon begin ∼ 1600 flat-top pulse, but reduced These are all significantly longer any other multi-MeV LIA, they define novel regime for high-current dynamics, especially regard...
This work illustrates predominant measureable nonlinearities in photomultiplier tubes (PMTs) and introduces a controllable one called "Superlinearity," signifying both positive nonlinear response the ability to extend linear operation by counteracting gain saturation mechanisms - charge depletion, space-charge field limitation, secondary emission surface effects. Recognizing superlinearity its effect on temporal step leads true definition of linearity, free small-signal assumption....
The National Ignition Facility uses a soft x-ray opacity spectrometer for spectral imaging in high-energy-density experiments. increased demand better resolution prompted the investigation into Agfa D4 film. Characterization is already under way A Manson source using six different anodes was used to expose film linear optical density (OD) region. This continuation of previous work, and updated analysis process communicated here. identified uncertainties have been reduced with steps that...
Opacity measurements are being carried out at the Z-facility Sandia National Laboratories and Ignition Facility (NIF) Lawrence Livermore Laboratory. The current soft x-ray Spectrometer (OpSpec) used on NIF uses two elliptically bent crystals in time-integrated mode either an image plate or a film. Plans under way to expand these opacity into of time-resolved detection, called OpSpecTR. Previously, considerations for available hCMOS detector size photometrics led crystal geometry redesign use...
When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2-kA, 18-MeV electron beam with more than 1500-ns current/energy "flat-top." In initial tests has already accelerated beams current pulse lengths from 500-ns to 1200-ns full- width at half maximum (FWHM) 1.2- kA, 12.5-MeV peak and energy. New experiments are planned ~1600-ns length but reduced These all significantly longer any other multi-MeV LIA, they define novel regime for high-current dynamics, especially...
High-speed microchannel plate (MCP)-based imagers are critical detectors for x-ray diagnostics employed on Z-experiments at Sandia National Laboratories (SNL) to measure time-resolved spectra and image dynamic hohlraums. A multiframe design using eight half strips in one imager permits recordings of radiation events discrete temporal snapshots yield a time-evolved movie. We present data various facilities characterize the performance this design. These characterization studies include DC...
We present the results of Monte Carlo simulations microchannel plate (MCP) response to x rays in 250 eV 25 keV energy range as a function both x-ray and impact angle their comparisons with experimental from X8A beamline at National Synchrotron Light Source Brookhaven Laboratory. Incoming interact lead glass plate, producing photoelectrons. Transport photoelectrons is neglected this model, it assumed that deposit all point they are created. This deposition leads generation many secondary...