379 Matching Results

Search Results

Advanced search parameters have been applied.

Distinguishing between Dirac and Majorana neutrinos withtwo-particle interferometry

Description: Two-particle interferometry, a second-order interferenceeffect, is explored as another possible tool to distinguish betweenmassive Dirac and Majorana neutrinos. A simple theoretical framework isdiscussed in the context of several gedanken experiments. The method canin principle provide both the mass scale and the quantum nature of theneutrino for a certain class of incoherent left-handed sourcecurrents.
Date: March 2, 2006
Creator: Gutierrez, Thomas D.
Partner: UNT Libraries Government Documents Department

Lithographic characterization of low-order aberrations in a 0.3-NAEUV microfield exposure tool

Description: Although tremendous progress has been made in the crucial area of fabrication of extreme ultraviolet (EUV) projection optics, the realization diffraction-limited high numerical aperture (NA) optics (above 0.2 NA) remains a concern. The highest NA EUV optics available to date are the 0.3-NA Microfield Exposure Tool (MET) optics used in an experimental exposure station at Lawrence Berkeley National Laboratory [1] and commercial METs [2] at Intel and SEMATECH-North. Even though these optics have been interferometrically demonstrated to achieve diffraction-limited wavefront quality, the question remains as to whether or not such performance levels can be maintained after installation of the optics into the exposure tool. Printing-based quantitative aberration measurements provide a convenient mechanism for the characterization of the optic wavefront error in the actual lithography tool. We present the lithographic measurement of low-order aberrations in the Berkeley MET tool, including a quantitative measurement of astigmatism and spherical error and a qualitative measurement of coma. The lithographic results are directly compared to interferometry results obtained from the same optic. Measurements of the Berkeley MET indicate either an alignment drift or errors in the interferometry on the order of 0.5 to 1 nm.
Date: March 1, 2006
Creator: Naulleau, Patrick; Cain, Jason; Dean, Kim & Goldberg, Kenneth A.
Partner: UNT Libraries Government Documents Department

Development of diagnostics for high-energy petawatt pulses

Description: Applications accessed by high energy petawatt (HEPW) lasers require complete, single-shot characterization of pulse spatial, temporal, and energy characteristics. We describe techniques that enable single-shot characterization of the temporal shape and pulse contrast of HEPW pulses with >10{sup 8} dynamic range over a ns-temporal window. Approaches to measure pulse durations that span two orders of magnitude will be discussed. Finally, we describe a novel implementation of spectrally dispersed two-beam interferometry for measurement of the phase difference between two HEPW pulses. This technique can be applied to dispersion and B-integral measurements in a HEPW system, as well as to achieve precise timing of nanosecond pulses. Lastly, spectrally dispersed interferometry represents an ideal technique to enable coherent addition of HEPW pulses for production of ultrahigh intensities.
Date: June 15, 2006
Creator: Jovanovic, I; Hernandez, J; Appel, G; Barker, D; Betts, S; Brewer, W et al.
Partner: UNT Libraries Government Documents Department

Identification of mine collapses, explosions and earthquakes using INSAR: a preliminary investigation

Description: Interferograms constmcted from satellite-borne synthetic aperture radar images have the capability of mapping sub-cm ground surface deformation over areas on the order of 100 x 100 km with a spatial resolution on the order of 10 meters. We investigate the utility of synthetic aperture radar interferomehy (InSAR) used in conjunction with regional seismic methods in detecting and discriminating different types of seismic events in the context of special event analysis for the CTBT. For this initial study, we carried out elastic dislocation modeling of underground explosions, mine collapses and small (M<5.5) shallow earthquakes to produce synthetic interferograms and then analyzed satellite radar data for a large mine collapse. The synthetic modeling shows that, for a given magnitude each type of event produces a distinctive pattern of ground deformation that can be recognized in, and recovered from, the corresponding interferogram. These diagnostic characteristics include not only differences in the polarities of surface displacements but also differences in displacement amplitudes from the different sources. The technique is especially sensitive to source depth, a parameter that is crucial in discriminating earthquakes from the other event types but is often very poorly constrained by regional seismic data alone. The ERS radar data analyzed is from a M<sub>L</sub> 5.2 seismic event that occurred in southwestern Wyoming on February 3,1995. Although seismic data from the event have some characteristics of an underground explosion, based on seismological and geodetic data it has been identified as being caused by a large underground collapse in the Solvay Mine. Several pairs of before-collapse and after-collapse radar images were phase processed to obtain interferograms. The minimum time separation for a before-collapse and after-collapse pair was 548 days. Even with this long time separation, phase coherence between the image pairs was acceptable and a deformation map was successfully obtained. Two images, separated ...
Date: July 7, 1998
Creator: Foxall, B; Sweeney, J J & Walter, W R
Partner: UNT Libraries Government Documents Department

Foundations of VISAR analysis.

Description: The Velocity Interferometer System for Any Reflector (VISAR) is a widely used diagnostic at Sandia National Laboratories. Although the operating principles of the VISAR are well established, recently deployed systems (such as the fast push-pull and air delay VISAR) require more careful consideration, and many common assumptions about VISAR are coming into question. This report presents a comprehensive review of VISAR analysis to address these issues. Detailed treatment of several interferometer configurations is given to identify important aspects of the operation and characterization of VISAR systems. The calculation of velocity from interferometer measurements is also described. The goal is to derive the standard VISAR analysis relationships, indicate when these relationships are valid, and provide alternative methods when the standard analysis fails.
Date: June 1, 2006
Creator: Dolan, Daniel H.
Partner: UNT Libraries Government Documents Department

Single pulse phase-control interferometric coherent anti-StokesRaman scattering spectroscopy (CARS)

Description: In coherent anti-Stokes Raman scattering spectroscopy (CARS) experiments, usually the amplitude of the signal is measured and the phase information is lost. With a polarization- and phase-controlled pulse shaping technique, the relative phase between the resonant and non-resonant CARS signals is controlled, and spectral interferometry is performed without an interferometer. Both the real and imaginary parts of the background-free resonant CARS spectrum are measured via spectral interferometry between the resonant and non-resonant signals from the same sample. The resonant signal is amplified significantly by homodyne mixing with the non-resonant signal as a local oscillator, greatly improving the detection limit.
Date: September 28, 2005
Creator: Lim, Sang-Hyun; Caster, Allison G. & Leone, Stephen R.
Partner: UNT Libraries Government Documents Department

Neutral Kaon Interferometry in Au+Au collisions at sqrt(s_NN) =200 GeV

Description: We present the first statistically meaningful results fromtwo-K0s interferometry in heavy-ion collisions. A model that takes theeffect of the strong interaction into account has been used to fit themeasured correlation function. The effects of single and coupled channelwere explored. At the mean transverse mass m_T = 1.07 GeV, we obtain thevalues R = 4.09 +- 0.46 (stat.) +- 0.31 (sys) fm and lambda = 0.92 +-0.23 (stat) +- 0.13 (sys), where R and lambda are the invariant radiusand chaoticity parameters respectively. The results are qualitativelyconsistent with m_T systematics established with pions in a scenariocharacterized by a strong collective flow.
Date: August 5, 2006
Creator: Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D. et al.
Partner: UNT Libraries Government Documents Department

A FEMTOSECOND-LEVEL FIBER-OPTICS TIMING DISTRIBUTION SYSTEM USING FREQUENCY-OFFSET INTERFEROMETRY

Description: An optical fiber-based frequency and timing distribution system based on the principle of heterodyne interferometry has been in development at LBNL for several years. The fiber drift corrector has evolved from an RF-based to an optical-based system, from mechanical correctors (piezo and optical trombone) to fully electronic, and the electronics from analog to fully digital, all using inexpensive off-the-shelf commodity fiber components. Short-term optical phase jitter and long-term phase drift are both in the femtosecond range over distribution paths of 2 km or more.
Date: October 17, 2009
Creator: Staples, J.W.; Byrd, J.; Doolittle, L.; Huang, G. & Wilcox, R.
Partner: UNT Libraries Government Documents Department

Design and fabrication of advanced EUV diffractive elements

Description: As extreme ultraviolet (EUV) lithography approaches commercial reality, the development of EUV-compatible diffractive structures becomes increasingly important. Such devices are relevant to many aspects of EUV technology including interferometry, illumination, and spectral filtering. Moreover, the current scarcity of high power EUV sources makes the optical efficiency of these diffractive structures a paramount concern. This fact has led to a strong interest in phase-enhanced diffractive structures. Here we describe recent advancements made in the fabrication of such devices.
Date: November 16, 2003
Creator: Naulleau, Patrick P.; Liddle, J. Alexander; Salmassi, Farhad; Anderson, Erik H. & Gullikson, Eric M.
Partner: UNT Libraries Government Documents Department

Wide baseline optical interferometry with Laser Guide Stars

Description: Laser guide stars have been used successfully as a reference source for adaptive optics systems. We present a possible method for utilizing laser beacons as sources for interferometric phasing. The technique would extend the sky coverage for wide baseline interferometers and allow interferometric measurement and imaging of dim objects.
Date: March 1, 1998
Creator: Gavel, D. T., LLNL
Partner: UNT Libraries Government Documents Department

Pion Interferometry in AU+AU Collisions at the AGS

Description: Two-pion Bose-Einstein correlations have been studied using the BNL-E866 Forward Spectrometer in 11.6 A {center_dot} GeV/c Au + Au collisions. The data were analyzed using three-dimensional correlation parameterizations to study transverse momentum-dependent source parameters. The freeze-out time and the duration of emission were derived from the source radii parameters.
Date: January 9, 1999
Creator: Lee, J. H.
Partner: UNT Libraries Government Documents Department

Experimental measurements of shock properties of stishovite

Description: We have synthesized, characterized and performed Hugoniot measurements on monolithic samples of stishovite, a high pressure polymorph of silica. Synthesis was accomplished in a multianvil press with pyrophyllite gaskets and carbon heaters. The samples had densities ranging from 3.80 to 4.07, corresponding to stishovite volume fractions of 0.7 to 0.87, a range confirmed by NMR analysis. They had no significant impurities except less than 1% carbon. Samples {approximately} 1 mm thick and 3 mm diameter were tested in reverse- and forward-ballistics modes on a two-stage light gas gun, using velocity interferometry diagnostics. Impact velocities ranged from 4.0 to 6.5 km/sec. Hugoniot stresses for the four successful tests ranged from 65 to 225GPa. At higher stresses significant uncertainties arise due to impact tilt/nonplanariy issues. Results are consistent with earlier predictions of the stishovite Hugoniot based on quartz-centered Hugoniot data, static-compression (diamond-anvil cell) data and hydrostatic multianvil cell data. Release behavior appears to be frozen. These results are remarkable in view of the small size of the samples used.
Date: October 1, 1995
Creator: Furnish, M.D. & Ito, E.
Partner: UNT Libraries Government Documents Department

An adaptive optic for correcting low-order wavefront aberrations

Description: Adaptive Optics used for correcting low-order wavefront aberrations were tested and compared using interferometry, beam propagation, and a far-field test. Results confirm that the design and manufacturing specifications were met. Experimental data also confirms theoretical performance expectations, indicating the usefulness of these optics (especially in a laser-beam processing system), and identifying the resulting differences between the two fabrication methods used to make the optics.
Date: September 2, 1999
Creator: Thompson, C A & Wilhelmsen, J
Partner: UNT Libraries Government Documents Department

THRIVE : a data reduction program for three-phase PDV/PDI and VISAR measurements.

Description: THRIVE (THRee Interferometer VElocimetry) is an analysis package for reducing three-phase interferometry measurements. Three-phase displacement interferometry measurements are the primary application of this program, although velocity interferometry is also supported. THRIVE uses a push-pull approach to transform measured signals to a pair of quadrature signals, from which fringe shift, target position, and target velocity are inferred. The program can analyze the signals in an ideal sense or compensate for non-ideal measurement conditions using ellipse characterization. The program can be run in any current version of MATLAB (release 2007a or later) or as a Windows XP executable.
Date: June 1, 2008
Creator: Jones, Scott Christopher & Dolan, Daniel H.
Partner: UNT Libraries Government Documents Department

A 3-D SAR approach to IFSAR processing

Description: Interferometric SAR (IFSAR) can be shown to be a special case of 3-D SAR image formation. In fact, traditional IFSAR processing results in the equivalent of merely a super-resolved, under-sampled, 3-D SAR image. However, when approached as a 3-D SAR problem, a number of IFSAR properties and anomalies are easily explained. For example, IFSAR decorrelation with height is merely ordinary migration in 3-D SAR. Consequently, treating IFSAR as a 3-D SAR problem allows insight and development of proper motion compensation techniques and image formation operations to facilitate optimal height estimation. Furthermore, multiple antenna phase centers and baselines are easily incorporated into this formulation, providing essentially a sparse array in the elevation dimension. This paper shows the Polar Format image formation algorithm extended to 3 dimensions, and then proceeds to apply it to the IFSAR collection geometry. This suggests a more optimal reordering of the traditional IFSAR processing steps.
Date: March 1, 2000
Creator: DOERRY,ARMIN W. & BICKEL,DOUGLAS L.
Partner: UNT Libraries Government Documents Department

Shock analysis using the multi point velocimeter (VISAR).

Description: The velocity of short duration high-amplitude shock waves and high-speed motion created by sources such as explosives, high energy plasmas and other rapid-acceleration devices are difficult to measure due to their fast reaction times. One measurement tool frequently used is VISAR (Velocity Interferometer System for Any Reflector). VISAR is an optical-based system that utilizes Doppler interferometry techniques to measure the complete time-history of the motion of a surface. This technique is gaining worldwide acceptance as the tool of choice for measurement of shock phenomena. However, one limitation of the single point VISAR is that it measures only one point on a surface. The new Multi Point VISAR remedies the single point VISAR's limitation by using multiple fiber optics and sensors to send and receive information. Upcoming programs that need analysis of large diameter flyers prompted the concept and design of a single cavity-multiple fiber optic Multi Point VISAR (MPV). Preliminary designs and the testing of a single cavity prototype in 1996 supported the theory of compact fiber optic bundle systems for development into the Multi Point VISAR. The new MPV was used to evaluate the performance of two components; a piezo-driven plane wave generating isolator, and a slim-loop ferroelectric (SFE)-type fireset.
Date: October 1, 2003
Creator: Fleming, Kevin James & Broyles, Theresa A.
Partner: UNT Libraries Government Documents Department

Resist-based measurement of contrast transfer function in a 0.3-NAmicrofield optic

Description: Although extreme ultraviolet (EUV) lithography offers the possibility of very high-resolution patterning, the projection optics must be of extremely high quality in order to meet this potential. One key metric of the projection optic quality is the contrast transfer function (CTF), which is a measure of the aerial image contrast as a function of pitch. A static microfield exposure tool based on the 0.3-NA MET optic and operating at a wavelength of 13.5 nm has been installed at the Advanced Light Source, a synchrotron facility at the Lawrence Berkeley National Laboratory. This tool provides a platform for a wide variety of research into EUV lithography. In this work we present resist-based measurements of the contrast transfer function for the MET optic. These measurements are based upon line/space patterns printed in several different EUV photoresists. The experimental results are compared with the CTF in aerial-image simulations using the aberrations measured in the projection optic using interferometry. In addition, the CTF measurements are conducted for both bright-field and dark-field mask patterns. Finally, the orientation dependence of the CTF is measured in order to evaluate the effect of non-rotationally symmetric lens aberrations. These measurements provide valuable information in interpreting the results of other experiments performed using the MET and similar systems.
Date: January 11, 2005
Creator: Cain, Jason P.; Naulleau, Patrick & Spanos, Costas J.
Partner: UNT Libraries Government Documents Department

2010 CORRELATED ELECTRON SYSTEMS GORDON RESEARCH CONFERENCE, JUNE 13-18, 2010 For

Description: The 2010 Gordon Conference on Correlated Electron Systems will present cutting-edge research on emergent properties arising from strong electronic correlations. The Conference will feature a wide range of topics, such as the role of topology in condensed matter systems, quantum Hall interferometry and non-Abelian statistics, quantum criticality, metal-insulator transition, quantum effects in conductivity, Dirac quasiparticles, and superconductivity in cuprates and pnictides. In addition, we are reserving two sessions for new developments in this field that may arise in the coming year. The Conference will bring together a collection of investigators who are at the forefront of their field, and will provide opportunities for junior scientists and graduate students to present their work in poster format and exchange ideas with leaders in the field. We intend to have talks by established leaders in the field and also by young researchers who have made seminal contributions to various aspects of correlated electron physics, The collegial atmosphere of this Conference, with programmed discussion sessions as well as opportunities for informal gatherings in the afternoons and evenings, provides an avenue for scientists from different disciplines to brainstorm and promotes cross-disciplinary collaborations in the various research areas represented.
Date: June 18, 2010
Creator: Basov, Dmitri
Partner: UNT Libraries Government Documents Department

Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry

Description: New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase.
Date: January 2, 2010
Creator: Wilcox, R.; Byrd, J. M.; Doolittle, L.; Huang, G. & Staples, J. W.
Partner: UNT Libraries Government Documents Department

OTR interferometry diagnostic for the A0 photoinjector

Description: OTR interferometry (OTRI) is an attractive diagnostic for investigation of relativistic electron beam parameters. The diagnostic is currently under development at the A0 Photoinjector. This diagnostic is also applicable for NML accelerator test facility that will be built at Fermilab. The experimental setup of the OTR Interferometer for the FNAL A0 Photoinjector is described in the report. Results of simulations and measurements are presented and discussed.
Date: June 1, 2007
Creator: Kazakevich, G.; /Novosibirsk, IYF; Edwards, Helen Thom; Fliller, R.; Lebedev, V.; Nagaitsev, S. et al.
Partner: UNT Libraries Government Documents Department

Gouy Interferometry: Properties of Multicomponent System Omega Graphs

Description: We consider the properties of {Omega} graphs ({Omega} vs f(z)) obtained from Gouy interferometry on multicomponent systems with constant diffusion coefficients. We show that they must have (a) either a maximum or else a minimum between f(z)=0 and f(z)=1 and (b) an inflection point between the f(z) value at the extremum and f(z)=1. Consequently, an {Omega} graph cannot have both positive and negative {Omega} values.
Date: January 24, 2007
Creator: Miller, D G
Partner: UNT Libraries Government Documents Department

Ternary Isothermal Diffusion Coefficients of NaCl-MgCl2-H2O at 25 C. 7. Seawater Composition

Description: The four diffusion coefficients D{sub ij} of the ternary system NaCl-MgCl{sub 2}-H{sub 2}O at the simplified seawater composition 0.48877 mol {center_dot} dm{sup -3} NaCl and 0.05110 mol {center_dot} dm{sup -3} MgCl{sub 2} have been remeasured at 25 C. The diffusion coefficients were obtained using both Gouy and Rayleigh interferometry with the highly precise Gosting diffusiometer. The results, which should be identical in principle, are essentially the same within or very close to their combined 'realistic' errors. This system has a cross-term D{sub 12} that is larger than the D{sub 22} main-term, where subscript 1 denotes NaCl and 2 denotes MgCl{sub 2}. The results are compared with earlier, less-precise measurements. Recommended values for this system are (D{sub 11}){sub V} = 1.432 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}, (D{sub 12}){sub V} = 0.750 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}, (D{sub 21}){sub V} = 0.0185 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}, and (D{sub 22}){sub V} = 0.728 x 10{sup -9} m{sup 2} {center_dot} sec{sup -1}.
Date: February 12, 2007
Creator: Miller, D G; Lee, C M & Rard, J A
Partner: UNT Libraries Government Documents Department

Two-wave pattern shift aberration monitor for centrally obscuredoptical systems

Description: An aberration monitoring technique based on lateral shifts of two-wave interference patterns in centrally obscured optical systems is presented, and simulations are used to evaluate the performance of such a technique. The technique is being explored as a convenient means for monitoring the aberration level in the 0.3-NA Micro Exposure Tool (MET) optic over time. A binary mask was designed for observing phase differences across the MET optic on cut-lines at 0, 45, 90 and 135 degrees across the pupil. The mask consists of 5 line-and space patterns in a dark field that measure the side-to-side phase difference across the pupil at 7 equally spaced radial points extending from 35% to 95% of the pupil radius. For near on-axis illumination the blockage of the zero-order creates a two-wave, interferometric pattern at the wafer with half of the period expected under normal imaging conditions. The optical path difference between the two orders produces an image shift of one full period of the (frequency doubled) interference pattern per 360 degrees of side-to-side path difference. Shifts on the order of 5 to 20 nm are expected and are measured using a reference target of an array of 5 medium sized dots. Aerial image simulation is being utilized to predict the expected performance and to improve the initial design. The aberrations measured by interferometry are being used for this purpose. Also the quality of images at low partial coherence with the wavefront convergence present in the MET illumination is being studied. In addition to theory and simulation results, practical considerations in implementing this technique on actual lithography tools based upon MET-type optics are addressed, including pattern design, illumination characteristics, and data analysis.
Date: January 11, 2005
Creator: Cain, Jason P.; McIntyre, Gregory; Naulleau, Patrick; Pawloski,Adam; La Fontaine, Bruno; Wood, Obert et al.
Partner: UNT Libraries Government Documents Department