High efficiency neutron and charged particle spectrometers

1991 ◽  
Author(s):  
J. Bart Czirr ◽  
Gary L. Jensen ◽  
J. C. Wang
Keyword(s):  
Charged Particle ◽  
High Efficiency

scholarly journals Development of a low-mass and high-efficiency charged-particle detector

2016 ◽  
Vol 2016 (2) ◽  
pp. 023C01 ◽  
Author(s):  
D. Naito ◽  
Y. Maeda ◽  
N. Kawasaki ◽  
T. Masuda ◽  
H. Nanjo ◽  
...  
Keyword(s):  
Charged Particle ◽  
High Efficiency ◽  
Particle Detector ◽  
Low Mass

scholarly journals Charged particle spectra from U-235 and B-10 micropellets and slab coatings

1984 ◽  
Vol 2 (2) ◽  
pp. 201-211 ◽  
Author(s):  
A. K. Chung ◽  
M. A. Prelas
Keyword(s):  
Charged Particle ◽  
Low Power ◽  
Power Density ◽  
Fission Fragment ◽  
High Efficiency ◽  
Nuclear Reactions ◽  
Length Distribution ◽  
Laser Medium ◽  
Fissile Material ◽  
Particle Spectrum

A novel method of utilizing fluorescence generated from the products of nuclear reactions offers the prospect of compact, high efficiency, multi-megajoule lasers. To overcome the problems associated with traditional laser (or energy converter)-fissile material interfaces, such as a uranium coating (low power density and low efficiency) or a gaseous uranium compound (low power density and deleterious effects on the laser kinetics and photon transport), a method suggested elsewhere of employing a reactor using a uranium aerosol fuel, interspersed with a fluorescer medium, is briefly reviewed. The charged particles produced by nuclear reactions in the fuel produce fluorescence in the core region of the reactor, through interactions with the fluorescer. This fluorescence can then be concentrated, to increase the effective power density in the laser medium, and used to drive a photolytic laser.One key issue in the above process is the charged particle spectrum from the fissile aerosol. These issues can be addressed theoretically based on the Dirac chord length distribution technique and an Arcen's function. The charged particle spectrum from a UO2 coating has been generated and benchmarked with the experimental data of Kahn et al., and Redmond et al. Agreement is generally good except near the end of the fission fragment tracks. The validity of this simple technique in approximating the rate of ion energy loss lends confidence to the generation of fission fragment spectra for other geometries (i.e. spherical in which transport efficiencies of over 60% appear achievable) using U, UO2 and U3O8. Work is also extended to the case of B-10 in a variety of configurations which are frequently used in modern energy conversion experimental devices.

scholarly journals High-efficiency acceleration by the combination of laser and electrostatic field

2014 ◽  
Vol 32 (4) ◽  
pp. 577-581 ◽  
Author(s):  
H. Lin ◽  
C.P. Liu ◽  
C. Wang ◽  
B.F. Shen
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Charged Particle ◽  
Electric Field ◽  
Laser Field ◽  
High Efficiency ◽  
Single Body ◽  
Body Dynamics ◽  
High Kinetic Energy ◽  
Dc Electric Field

AbstractA new scheme of particle acceleration is verified by the investigation on single-body dynamics of charged particle in a compound field setup. This compound field setup contains a linear polarized laser field and a DC electric field which is along the direction of laser magnetic field. This setup can cause a charged particle to be of aperiodic motion and significantly high kinetic energy. Moreover, the contribution from the motion vertical to accelerating electric field is fully taken into account and is found to be essential to efficient acceleration. The efficiency of such a setup in acceleration is higher than that of a single laser.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

The use of high-resolution FESEM to study solid-state phase transformations and reactions

1994 ◽  
Vol 52 ◽  
pp. 1028-1029
Author(s):  
P. G. Kotula ◽  
D. D. Erickson ◽  
C. B. Carter
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Phase Transformations ◽  
High Efficiency ◽  
Sol Gel ◽  
Quantitative Information ◽  
Solid State Reactions ◽  
Critical Dimensions ◽  
Backscattered Electrons ◽  
Backscattered Electron

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

Sign in / Sign up

Export Citation Format

Share Document