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Chemical reaction and equilibration mechanisms in detonation waves

Description: Experimental and theoretical evidence for the nonequilibrium Zeldovich-von Neumann-Doring (NEZND) theory of self-sustaining detonation is presented. High density, high temperature transition state theory is used to calculate unimolecular reaction rate constants for the initial decomposition of gaseous norbornene, liquid nitromethane, and solid, single crystal pentaerythritol tetranitrate as functions of shock temperature. The calculated rate constants are compared to those derived from experimental induction time measurements at various shock and detonation states. Uncertainties in the calculated shock and von Neumann spike temperatures are the main drawbacks to calculating these reaction rates. Nanosecond measurements of the shock temperatures of unreacted explosives are necessary to reduce these uncertainties.
Date: July 1, 1997
Creator: Tarver, C. M., LLNL
Partner: UNT Libraries Government Documents Department

Proceedings of the workshop on triggering and data acquisition for experiments at the Supercollider

Description: This meeting covered the following subjects: triggering requirements for SSC physics; CDF level 3 trigger; D0 trigger design; AMY trigger systems; Zeus calorimeter first level trigger; data acquisition for the Zeus Central Tracking Detector; trigger and data acquisition aspects for SSC tracking; data acquisition systems for the SSC; validating triggers in CDF level 3; optical data transmission at SSC; time measurement system at SSC; SSC/BCD data acquisition system; microprocessors and other processors for triggering and filtering at the SSC; data acquisition, event building, and on-line processing; LAA real-time benchmarks; object-oriented system building at SSC; and software and project management. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.
Date: April 1, 1989
Creator: Donaldson, R.
Partner: UNT Libraries Government Documents Department

Dynamic Holographic Lock-In Imaging of Ultrasonic Waves

Description: A laser imaging approach is presented that utilizes the adaptive property of photorefractive materials to produce a real-time measurement of ultrasonic traveling wave surface displacement and phase in all planar directions simultaneously without scanning. The imaging method performs optical lock-in operation. A single antisymmetric Lamb wave mode image produces direct quantitative determination of the phase velocity in all planar directions showing plate stiffness anisotropy. Excellent agreement was obtained with modeling calculations of the phase velocity in all planar directions for an anisotropic sheet material. The approach functions with diffusely scattering surfaces, subnanometer motions and at frequencies from Hz to GHz.
Date: May 1, 1999
Creator: Telschow, K. L.; Datta, S. K. & Deason, V. A.
Partner: UNT Libraries Government Documents Department

Method and apparatus for detecting timing errors in a system oscillator

Description: This invention is comprised of a method of detecting timing errors in a system oscillator for an electronic device, such as a power supply, includes the step of comparing a system oscillator signal with a delayed generated signal and generating a signal representative of the timing error when the system oscillator signal is not identical to the delayed signal. An LED indicates to an operator that a timing error has occurred. A hardware circuit implements the above-identified method.
Date: December 31, 1991
Creator: Gliebe, R.J. & Kramer, W.R.
Partner: UNT Libraries Government Documents Department

A CMOS delay locked loop and sub-nanosecond time-to-digital converter chip

Description: Many high energy physics and nuclear science applications require sub-nanosecond time resolution measurements over many thousands of detector channels. Phase-locked loops have been employed in the past to obtain accurate time references for these measurements. An alternative solution, based on a delay-locked loop (DLL) is described. This solution allows for a very high level of integration yet still offers resolution in the sub-nanosecond regime. Two variations on this solution are outlined. A novel phase detector, based on the Muller C element, is used to implement a charge pump where the injected charge approaches zero as the loop approaches lock on the leading edge of an input clock reference. This greatly reduces timing jitter. In the second variation the loop locks to both the leading and trailing clock edges. In this second implementation, software coded layout generators are used to automatically layout a highly integrated, multi-channel, time to digital converter (TDC). Complex clock generation can be, achieved by taking symmetric taps off the delay elements. The two circuits, DLL and TDC, were implemented in a CMOS 1.2{mu}m and 0.8{mu}m technology, respectively. Test results show a timing jitter of less than 35 ps for the DLL circuit and better solution for the TDC circuit.
Date: December 1, 1995
Creator: Santos, D.M.; Dow, S.F. & Levi, M.E.
Partner: UNT Libraries Government Documents Department

SAO HMC photodetector/event timer engineering model test report

Description: The test unit is a custom photodetector/event timer, PET, built for the Smithsonian Astrophysical Observatory, SAO, by Los Alamos which records elapsed time in 10 ps steps. The 1 Kg, 12 cm diameter PET unit uses 10 watts of electrical power and was tested to SAO`s specified flight conditions. The event timer has two inputs -- a reference clock oscillator input and a stop signal. Like a stop watch with split timing capability, the event timer records the instant a stop signal arrives. At that sample instant, the number of elapsed clock cycles are stored and the sample instant position between two reference clock edges is interpolated and stored. Then that stored data can be shifted serially to an external computer. The photodetector part of the PET responds to an optical input and provides the electrical output signal to the event timer specifying the sample instant. This test report discusses the event timer test results. Test equipment is shown for most of the operational tests. The relay rack contains test pursers and clocks. The environmental chamber controls temperature. The computer reads and records the serial data from the PET. Reported testing topics include: Pulse shapes to be used as test inputs, test results obtained using the electrical source`s input, optical test results which are the best simulation of specified operational conditions, heat sink operation in vacuum. Vibration tests performed to SAO`s specification.
Date: October 5, 1994
Partner: UNT Libraries Government Documents Department

A Cray T3D performance study

Description: We carry out a performance study using the Cray T3D parallel supercomputer to illustrate some important features of this machine. Timing experiments show the speed of various basic operations while more complicated operations give some measure of its parallel performance.
Date: May 1, 1996
Creator: Nallana, A. & Kincaid, D.R.
Partner: UNT Libraries Government Documents Department

A new pulse arrival-time recording system

Description: We describe a new pulse arrival-time recording system that is being developed at Los Alamos. The new PATRM/PCI (Pulse Arrival-Time Recording Module/Peripheral Component Interconnect) has had several features added. These features enhance our time-correlation measurement capabilities. By applying the latest advances in electronics and computer technology we are able to increase capability over existing instrumentation while lowering the per channel cost. The modular design approach taken allows easy configuration of both small and large systems.
Date: December 31, 1996
Creator: Arnone, G.J.
Partner: UNT Libraries Government Documents Department

NVLAP gap analysis. Final report

Description: The capabilities of AlliedSignal Metrology were compared to the requirements contained in the National Voluntary Laboratory Accreditation Program (NVLAP) Calibration Laboratories Handbook and NVLAP Calibration Laboratories Technical Guide. The initial analyses demonstrated a need for improved measurement uncertainty analyses, additional control artifacts, and improved statistical process control. The analysis also revealed the need for a formalized customer complaint system and a calibration quality manual.
Date: April 1, 1997
Creator: Shroyer, K.A.
Partner: UNT Libraries Government Documents Department

Early-time measurements of soft x-ray emission in an omega-upgrade laser-produced plasma. Semi-annual report, October 1, 1996--March 31, 1997

Description: Beginning in January 1997 (following arrival of the FY-97 funding) we have been preparing for our first series of experiments under this grant at the University of Rochester Laboratory for Laser Energetics (LLE) on the Omega Upgrade laser facility, now scheduled to commence June 2, 1997. For these experiments we have purchased (just arrived) a four-channel gated-stripline microchannel plate (MCP) detector to be coupled to our soft x-ray flat-field grazing incidence spectrograph used previously at LLE. This will permit time-resolved `snapshots` of the complete spectra with a resolution to times as short as 180 ps per strip. An advantage of this technique over the streak camera used previously is the lack of any carbon absorbers such as in the thin plastic cathode required for the streak camera. This eliminates absorption in the 30-44 {angstrom} spectral region in which we are interested for intermediate-Z target materials such as Mg, Al and Si. An auxiliary turbomolecular-drag pump has also been installed in order to obtain the necessary vacuum for optimum MCP operation.
Date: March 31, 1997
Creator: Griem, H.R.; Elton, R.C. & Welch, B.L.
Partner: UNT Libraries Government Documents Department

Early-time measurements of laser-plasma conditions in omega-upgrade ICF targets. Semi-annual report, October 1, 1997--March 31, 1998

Description: Since arrival of FY-98 funding under this grant in December, we have been preparing for our first series of experiments under this grant at the University of Rochester Laboratory for Laser Energetics (LLE) on the Omega laser facility, now scheduled the week beginning May 4, 1998. We will again be fielding our flat-field, grazing-incidence extreme-ultraviolet (euv) spectrograph with a four-channel gated-stripline microchannel plate (MCP) detector, which is mounted on the outside of the vacuum chamber approximately 60 inches from the center. In addition, we will be using for the first time our newly constructed flat field spectrograph covering the spectral range of 30-250 {angstrom} (hv = 50-400 eV), designed to fit into a Ten Inch Manipulator (TIM). As such, it can be located closer to the central target position, with an expected enhancement in sensitivity of at least a factor-of-ten. It is the preparation of this instrument that mainly has occupied our attention so far in this grant period and discussed in this report.
Date: April 4, 1998
Creator: Griem, H.R. & Elton, R.C.
Partner: UNT Libraries Government Documents Department

Calibration and evaluation of Blackbeard time tagging capability

Description: During November and December of 1996, the Los Alamos Portable Pulser (LAPP) facility was used to evaluate the accuracy of time tags produced by the Blackbeard instrument, a payload on the ALEXIS (Array of Low Energy X-ray Imaging Sensors) satellite. Over a two-month period, LAPP transmitted 65 broadband electromagnetic pulses to Blackbeard during satellite passes over North America. Of the 65 pulses transmitted, 31 were successfully received by Blackbeard. Ground-based diagnostics and a timing system disciplined by GPS allowed precise determinations of LAPP firing times to be made. Knowledge of the range to ALEXIS for each of the pulser shots allowed them to determine pulse propagation delays. The firing times were used in conjunction with propagation delays to compute estimated times of arrival (ETOAs) for pulses reaching Blackbeard. ETOAs were compared to Blackbeard reported times of arrival (RTOAs), which were computed from information returned by Blackbeard using an algorithm presented in this paper. For the 31 pulser shots received by Blackbeard, the mean difference between ETOA and RTOA was 1.97 milliseconds, with RTOAs occurring later than ETOAs. The standard deviation of the difference was 0.43 milliseconds. As a result of the study, the algorithm used for accurate Blackbeard time tat studies has been modified to subtract 1.97 milliseconds from reported times of arrival. The 0.43 ms error standard deviation is now used to describe the uncertainty of Blackbeard time tags.
Date: December 1, 1997
Creator: Smith, D.A.; DeLapp, D.M.; Holden, D.N.; Stelzer, G.L. & Klingner, P.L.
Partner: UNT Libraries Government Documents Department

Early-time measurements of laser-plasma conditions in OMEGA-Upgrade ICF Targets. Final report, April 1, 1997--March 31, 1998

Description: Under this FY-97 NLUF grant, we primarily carried out spectral line and continuum diagnostics at early times and in the coronal region of the plasma using our flat-field grazing-incidence spectrograph, improved to incorporate time resolution at wavelengths extending below the carbon K-absorption edge using a gated microchannel plate detector. These experiments were carried out on the OMEGA facility. Fifty-nine beams were focused onto the target, providing nominally 18 kJ of energy in a 1 ns pulse for an irradiance of {approximately}2{times}10{sup 14}/cm{sup 2}. Some beam smoothing, provided by spectral dispersion, was used, but may not have been particularly effective alone, i.e., without the presence of distributed phase plates in the beams. The plastic microballoon targets were nominally 900 {mu}m in diameter with 10- and 20-{mu}m thick walls, and were filled with neon to a pressure of 10 atm. Overcoatings of Mg and Al in thicknesses ranging from 0.2 to 4 {mu}m were applied. A 1-{mu}m thick layer of CH was added in some early shots to reduce the rate of expansion of the metallic coatings. In the extreme ultraviolet (euv) spectral region, we observed n=3 to n=2 emissions from Li-, He- and H-like ions from the Mg and Al coatings. We also obtained evidence confirming our previously-published laser-field-induced satellites lines at 53.1 {Angstrom} and 62.8 {Angstrom}, apparently at the peak of the Gaussian drive pulse. Both the Mg-line and the continuum euv emissions are high during the radial collapse. The metallic coating materials appear to be in place to some degree during the compression phase, i.e., are not all blown away as coronal plasma at earlier times as modeled. This also is apparent in the Al Lyman-{alpha} x-ray measurements before and after compression. Here, however, higher line opacity made it difficult to track the resonance lines through the compression phase. ...
Date: April 4, 1998
Creator: Griem, H.R. & Elton, R.C.
Partner: UNT Libraries Government Documents Department

Implementation of detonation electric effects. [Quarterly report], January--March 1971

Description: Detonation electric effect measurement was applied to a stack of PMMA discs on the output of an explosive PWL to resolve some anomalies previously observed in the arrival times of a shock wave as it passes through the various interfaces. A brief description of the experiments and some comments on the results are included.
Date: December 31, 1971
Creator: Boettner, J.K.
Partner: UNT Libraries Government Documents Department

Observation of cosmological time dilation using type Ia supernovae as clocks

Description: This work is based on the first results from a systematic search for high redshift Type Ia supernovae. Using filters in the R-band we discovered seven such SNe, with redshift z = 0.3-0.5, before or at maximum light. Type Ia SNe are known to be a homogeneous group of SNe, to first order, with very similar light curves, spectra and peak luminosities. In this talk we report that the light curves we observe are all broadened (time dilated) as expected from the expanding universe hypothesis. Small variations from the expected 1 + z broadening of the light curve widths can be attributed to a width-brightness correlation that has been observed for nearby SNe (z < 0.1). We show in this talk the first clear observation of the cosmological time dilation for macroscopic objects.
Date: September 1, 1998
Creator: Goldhaber, G., FNAL
Partner: UNT Libraries Government Documents Department

Strong motion duration and earthquake magnitude relationships

Description: Earthquake duration is the total time of ground shaking from the arrival of seismic waves until the return to ambient conditions. Much of this time is at relatively low shaking levels which have little effect on seismic structural response and on earthquake damage potential. As a result, a parameter termed ``strong motion duration`` has been defined by a number of investigators to be used for the purpose of evaluating seismic response and assessing the potential for structural damage due to earthquakes. This report presents methods for determining strong motion duration and a time history envelope function appropriate for various evaluation purposes, for earthquake magnitude and distance, and for site soil properties. There are numerous definitions of strong motion duration. For most of these definitions, empirical studies have been completed which relate duration to earthquake magnitude and distance and to site soil properties. Each of these definitions recognizes that only the portion of an earthquake record which has sufficiently high acceleration amplitude, energy content, or some other parameters significantly affects seismic response. Studies have been performed which indicate that the portion of an earthquake record in which the power (average rate of energy input) is maximum correlates most closely with potential damage to stiff nuclear power plant structures. Hence, this report will concentrate on energy based strong motion duration definitions.
Date: June 1, 1992
Creator: Salmon, M.W.; Short, S.A. & Kennedy, R.P.
Partner: UNT Libraries Government Documents Department

One dimensional time-to-explode (ODTX) in HMX spheres

Description: In a series of papers researchers at Lawrence Livermore National Laboratory (LLNL) have reported measurements of the time to explosion in spheres of various high explosives following a rapid, uniform increase in the surface temperature of the sphere. Due to the spherical symmetry, the time-dependent properties of the explosive (temperature, chemical composition, etc.) are functions of the radial spatial coordinate only; thus the name one-dimensional time-to-explosion (ODTX). The LLNL researchers also report an evolving series of computational modeling results for the ODTX experiments, culminating in those obtained using a sophisticated heat transfer code incorporating accurate descriptions of chemical reaction. Although the chemical reaction mechanism used to describe HMX decomposition is quite simple, the computational results agree very well with the experimental data. In addition to reproducing the magnitude and temperature dependence of the measured times to explosion, the computational results also agree with the results of post reaction visual inspection. The ODTX experiments offer a near-ideal example of a transport process (heat transfer in this case) tightly coupled with chemical reaction. The LLNL computational model clearly captures the important features of the ODTX experiments. An obvious question of interest is to what extent the model and/or its individual components (specifically the chemical reaction mechanism) are applicable to other experimental scenarios. Valid exploration of this question requires accurate understanding of (1) the experimental scenario addressed by the LLNL model and (2) details of the application of the model. The author reports here recent work addressing points (1) and (2).
Date: June 2, 1997
Creator: Breshears, D.
Partner: UNT Libraries Government Documents Department

Development of inexpensive continuous emission monitors for feedback control of combustion devices that minimize greenhouse gases, toxic emissions, and ozone damaging products

Description: This is the final report of a three-year, Laboratory Directed Research and Development project at the Los Alamos National Laboratory. Combustion is the major cause of poor urban air quality, of depletion of the ozone layer, and a major source of the greenhouse gas, carbon dioxide. Careful control of combustor conditions is important for minimizing the effects of combustion on the environment. The authors have developed sensitive, inexpensive continuous emission monitors that will assist in direct feedback of turbine power systems and provide assurance to the public and the operators of the facilities that their facility emissions lie within the accepted bounds. These include a robust solid-state Fourier transform spectrometer for rapid gas analysis, based on the use of ferroelectric liquid crystal technology, and an infrared helium-neon probe for real time measurement of combustor air-to-fuel ratios.
Date: November 1, 1998
Creator: Funk, D.J.; Moore, D.S.; Mongia, R.K.; Tomita, E.; Hsu, F.K.; Talbot, L. et al.
Partner: UNT Libraries Government Documents Department

Graphical Analysis of PET Data Applied to Reversible and Irreversible Tracers

Description: Graphical analysis refers to the transformation of multiple time measurements of plasma and tissue uptake data into a linear plot, the slope of which is related to the number of available tracer binding sites. This type of analysis allows easy comparisons among experiments. No particular model structure is assumed, however it is assumed that the tracer is given by bolus injection and that both tissue uptake and the plasma concentration of unchanged tracer are monitored following tracer injection. The requirement of plasma measurements can be eliminated in some cases when a reference region is available. There are two categories of graphical methods which apply to two general types of ligands--those which bind reversibly during the scanning procedure and those which are irreversible or trapped during the time of the scanning procedure.
Date: November 18, 1999
Creator: Logan, Jean
Partner: UNT Libraries Government Documents Department

A method for calculating longitudinal phase space distribution when given the time profile of the bunch

Description: We will show in this paper a method for calculating the longitudinal phase space distribution when the time profile of the bunch as measured by a wall current monitor is given. The key to this method is the assumption that the bunch is matched to the bucket. With this assumption, we will show that the method boils down to solving a simple upper triangular matrix equation. We will also illustrate the method with two examples and show the method's shortcomings.
Date: July 30, 2001
Creator: Tan, Cheng-Yang
Partner: UNT Libraries Government Documents Department


Description: A271 COMPLETE SUPPRESSION OF THE M=2/N-1 NEOCLASSICAL TEARING MODE USING ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D. The first suppression of the important and deleterious m=2/n=1 neoclassical tearing mode (NTM) is reported using electron cyclotron current drive (ECCD) to replace the ''missing'' bootstrap current in the island O-point. Experiments on the DIII-D tokamak verify the maximum shrinkage of the m=2/n=1 island occurs when the ECCD location coincides with the q = 2 surface. The DIII-D plasma control system is put into search and suppress mode to make small changes in the toroidal field to find and lock onto the optimum position, based on real time measurements of dB{sub {theta}}/dt, for complete m=2/n=1 NTM suppression by ECCD. The requirements on the ECCD for complete island suppression are well modeled by the modified Rutherford equation for the DIII-D plasma conditions.
Date: March 1, 2003
Partner: UNT Libraries Government Documents Department


Description: We describe a new ASIC for accurate and efficient processing of high-rate pulse signals from highly segmented detectors. In contrast to conventional approaches, this circuit affords a dramatic reduction in data volume through the use of analog techniques (precision peak detectors and time-to-amplitude converters) together with fast arbitration and sequencing logic to concentrate the data before digitization. In operation the circuit functions like a data-driven analog first-in, first-out (FIFO) memory between the preamplifiers and the ADC. Peak amplitudes of pulses arriving at any one of the 32 inputs are sampled, stored, and queued for readout and digitization through a single output port. Hit timing, pulse risetime, and channel address are also available at the output. Prototype chips have been fabricated in 0.35 micron CMOS and tested. First results indicate proper functionality for pulses down to 30 ns peaking time and input rates up to 1.6 MHz/channel. Amplitude accuracy of the peak detect and hold circuit is 0.3% (absolute). TAC accuracy is within 0.3% of full scale. Power consumption is less than 2 mW/channel. Compared with conventional techniques such as track-and-hold and analog memory, this new ASIC will enable efficient pulse height measurement at 20 to 300 times higher rates.
Date: November 10, 2002
Partner: UNT Libraries Government Documents Department