18 Matching Results

Search Results

Advanced search parameters have been applied.

Inductively coupled plasma spectrometry: Noise characteristics of aerosols, application of generalized standard additions method, and Mach disk as an emission source

Description: This dissertation is focused on three problem areas in the performance of inductively coupled plasma (ICP) source. The noise characteristics of aerosols produced by ICP nebulizers are investigated. A laser beam is scattered by aerosol and detected by a photomultiplier tube and the noise amplitude spectrum of the scattered radiation is measured by a spectrum analyzer. Discrete frequency noise in the aerosol generated by a Meinhard nebulizer or a direct injection nebulizer is primarily caused by pulsation in the liquid flow from the pump. A Scott-type spray chamber suppresses white noise, while a conical, straight-pass spray chamber enhances white noise, relative to the noise seen from the primary aerosol. Simultaneous correction for both spectral interferences and matrix effects in ICP atomic emission spectrometry (AES) can be accomplished by using the generalized standard additions method (GSAM). Results obtained with the application of the GSAM to the Perkin-Elmer Optima 3000 ICP atomic emission spectrometer are presented. The echelle-based polychromator with segmented-array charge-coupled device detectors enables the direct, visual examination of the overlapping lines Cd (1) 228.802 nm and As (1) 228.812 nm. The slit translation capability allows a large number of data points to be sampled, therefore, the advantage of noise averaging is gained. An ICP is extracted into a small quartz vacuum chamber through a sampling orifice in a water-cooled copper plate. Optical emission from the Mach disk region is measured with a new type of echelle spectrometer equipped with two segmented-array charge-coupled-device detectors, with an effort to improve the detection limits for simultaneous multielement analysis by ICP-AES.
Date: October 6, 1995
Creator: Shen, Luan
Partner: UNT Libraries Government Documents Department

Determination of toxic material penetrations for wildland respirator filters

Description: Thousands of wildland firefighters are exposed to high levels of toxic materials every year. Carbon monoxide, formaldehyde and acrolein gases, along with high particulate concentrations, are the major toxics encountered. Currently, the only respiratory protection wildland firefighters use is a bandanna over the mouth and nose. In this study, a modem activated carbon cartridge with an electrostatic prefilter was compared to a typical bandanna for its ability to filter wildland smoke toxics such as formaldehyde and particulates. The results of the tests were disappointing; neither filter performed very well. The activated carbon cartridge and prefilter efficiently collected formaldehyde gas for up to 60 minutes; however, it only collected 85 percent of the challenge particulate. ]Me bandanna, as expected, was only partially effective at collecting smoke particulate and filtered no toxic gases.
Date: May 1, 1994
Creator: Foote, K.L.
Partner: UNT Libraries Government Documents Department

Measurements and analysis of end-to-end Internet dynamics

Description: Accurately characterizing end-to-end Internet dynamics - the performance that a user actually obtains from the lengthy series of network links that comprise a path through the Internet - is exceptionally difficult, due to the network`s immense heterogeneity. At the heart of this work is a `measurement framework` in which a number of sites around the Internet host a specialized measurement service. By coordinating `probes` between pairs of these sites one can measure end-to-end behavior along O(N{sup 2}) paths for a framework consisting of N sites. Consequently, one obtains a superlinear scaling that allows measuring a rich cross-section of Internet behavior without requiring huge numbers of observation points. 37 sites participated in this study, allowing the author to measure more than 1,000 distinct Internet paths. The first part of this work looks at the behavior of end-to-end routing: the series of routers over which a connection`s packets travel. Based on 40,000 measurements made using this framework, the author analyzes: routing `pathologies` such as loops, outages, and flutter; the stability of routes over time; and the symmetry of routing along the two directions of an end-to-end path. The author finds that pathologies increased significantly over the course of 1995 and that Internet paths are heavily dominated by a single route. The second part of this work studies end-to-end Internet packet dynamics. The author analyzes 20,000 TCP transfers of 100 Kbyte each to investigate the performance of both the TCP endpoints and the Internet paths. The measurements used for this part of the study are much richer than those for the first part, but require a great degree of attention to issues of calibration, which are addressed by applying self-consistency checks to the measurements whenever possible. The author finds that packet filters are capable of a wide range of measurement errors, some of ...
Date: April 1, 1997
Creator: Paxson, V.
Partner: UNT Libraries Government Documents Department

Development in the design and performance of gas avalanche microdetectors (MSGC, MGC, and MDOT)

Description: There has been continuing development of generic classes of microstrip gas chambers (MSGCs), microgap gas chambers (MGCs) and microdot gas chambers (MDOTs) at Lawrence Berkeley National Laboratory (LBNL) over the past few years, to improve such detectors beyond their present capabilities, to produce detectors suitable for use in current or upcoming experiments, and to allow a basis for new R&D developments which may incorporate these detectors as part of the system. All of these new detectors are collectively referred to as {open_quotes}gas avalanche microdetectors{close_quotes}. The MSGC, which was motivated by the pioneering work of A. Oed, has many attractive features, especially excellent spatial resolution ({approximately}30 {mu}m rms at normal incidence) and high rate capability ({approximately}10{sup 6} mm{sup -2}{center_dot}s{sup -1}). Moreover, the MGC seems to have certain advantages over the MSGC in speed, stability and simplicity, and the MDOT has larger gain (>10{sup 4}) and the intrinsic advantages of two-dimensional readout. Because of these attractive properties, they have received a great deal of attention for nuclear and high energy physics experiments, medical X-ray imaging and many other fields requiring radiation detection and measurement.
Date: December 1, 1997
Creator: Cho, Hyo-Sung
Partner: UNT Libraries Government Documents Department

[The Waste Package Project. Final report, July 1, 1995--February 27, 1996]: Volume 2, Experimental verification of structural response of a flexible three-link hydraulic steel robot

Description: This report presents experimental techniques for determining the static and dynamic response, in three dimensional space, of a flexible three-link hydraulic steel robot. The flexible robot was originally built under a grant from the Army Research Office (ARO) and has been the subject of a six year research project involving 12 graduate students and four faculty members. The research was continued under grant from the U.S. Department of Energy which is considering the use of robot in remote handling, placement and retrievability of H.L.N.W. canisters in geological formations. A series of static and dynamic experiments was conducted under two different loads at various angular positions of the robot links.
Date: June 1, 1996
Creator: Ladkany, S.G. & Channarayapatna, S.S.
Partner: UNT Libraries Government Documents Department

Strange meson spectroscopy in K{omega} and K{phi} at 11 GeV/c and Cherenkov ring imaging at SLD

Description: This thesis consists of two independent parts; development of Cherenkov Ring Imaging Detector (CRID) system and analysis of high-statistics data of strange meson reactions from the LASS spectrometer. Part 1: The CRID system is devoted to charged particle identification in the SLAC Large Detector (SLD) to study e{sup +}e{sup {minus}} collisions at {radical}s = m{sub Z{sup 0}}. By measuring the angles of emission of the Cherenkov photons inside liquid and gaseous radiators, {pi}/K/p separation will be achieved up to {approximately}30 GeV/c. The signals from CRID are read in three coordinates, one of which is measured by charge-division technique. To obtain a {approximately}1% spatial resolution in the charge-division, low-noise CRID preamplifier prototypes were developed and tested resulting in <1000 electrons noise for an average photoelectron signal with 2 {times} 10{sup 5} gain. To help ensure the long-term stability of CRID operation at high efficiency, a comprehensive monitoring and control system was developed. Part 2: Results from the partial wave analysis of strange meson final states in the reactions K{sup {minus}}p {yields} K{sup {minus}}{omega}p and K{sup {minus}}p {yields} {bar K}{sup 0}{phi}n are presented. The analyses are based on data from a 4.1 event/nb exposure of the LASS spectrometer in K{sup {minus}}p interactions at 11 GeV/c. The data sample of K{sup {minus}}{omega}p final state contains {approximately}10{sup 5} events. From the partial wave analysis, resonance structures of J{sup P} = 2{sup {minus}}, 3{sup {minus}} and 2{sup +} amplitudes are observed in the K{omega} system. The analysis of 2{sup {minus}} amplitudes provides an evidence for two strange meson states in the mass region around 1.75 GeV/c{sup 2}. The appropriate branching fractions are calculated and compared with the SU(3) predictions. The partial wave analysis of {bar K}{sup 0}{phi} system favors J{sup P} = 1{sup {minus}} and 2{sup +} states in the 1.9--2.0 GeV/c{sup 2} region.
Date: January 1993
Creator: Kwon, Youngjoon
Partner: UNT Libraries Government Documents Department

Chemical dynamics in time and energy space

Description: The development of a versatile picosecond ultraviolet/vacuum ultraviolet temporal spectrometer and its potential use for measuring internal energy redistribution in isolated molecules are described in detail. A detailed description of the double-pass Nd:YAG amplifier and the dye amplifiers is given with the pulse energies achieved in the visible, ultraviolet, and vacuum ultraviolet. The amplified visible pulses are shown to be of sub-picosecond duration and near transform limited. The instrument`s temporal response ({le}10 ps) is derived from an instrument limited measurement of the dissociation lifetime of methyl iodide at 266 nm. The methyl iodide experiment is used to discuss the various sources of noise and background signals that are intrinsic to this type of experiment. Non-time-resolved experiments measuring the branching ratio and kinetic energy distributions of products from the 193 nm photodissociation of cyclopentadiene and thiophene are presented. These studies were done using the molecular beam Photofragment Translational Spectroscopy (PTS) technique. The results from the cyclopentadiene experiment confirm that H atom elimination to yield the cyclopentadienyl radical is the dominant dissociation channel. A barrier of {ge}5 kcal/mol can be understood in terms of the delocalization of the radical electron of the cyclopentadienyl fragment. A concerted elimination yielding cyclopropene and acetylene was also observed and is proposed to occur via a bicyclo-[2.1.0]pent-2-ene intermediate. Two other channels, yielding acetylene plus the CH{sub 2}CHCH triplet carbene, and CH{sub 2} plus 1-buten-3-yne, are postulated to occur via ring opening. The implications of the experimental results for bulk thermal oxidation and pyrolysis models are discussed. The thiophene experiment shows six competing dissociation channels. The postulated intermediates for the various thiophene dissociation channels include bicyclo, ring opened, and possibly ring contracted forms.
Date: April 1, 1993
Creator: Myers, J. D.
Partner: UNT Libraries Government Documents Department

Signal and noise analysis of a-Si:H radiation detector-amplifier system

Description: Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was {approximately}400 MHz and the noise charge {approximately}1000 electrons at a 1 {mu}sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of {approximately}0.02 mV/electron with a pulse rise time less than 100 ...
Date: March 1, 1992
Creator: Cho, Gyuseong
Partner: UNT Libraries Government Documents Department

Leaks in nuclear grade high efficiency aerosol filters

Description: Nuclear grade high efficiency aerosol filters, also known as high efficiency particulate air (HEPA) filters, are commonly used in air cleaning systems for removal of hazardous aerosols. Performance of the filter units is important in assuring health and environmental protection. The filter units are constructed from pleated packs of fiberglass filter media sealed into rigid frames. Results of previous studies on such filter units indicate that their performance may not be completely predicted by ideal performance of the fibrous filter media. In this study, departure from ideal performance is linked to leaks existing in filter units and overall filter unit performance is derived from independent performance of the individual filter unit components. The performance of 14 nuclear grade HEPA filter units (size 1, 25 cfm) with plywood frames was evaluated with a test system that permitted independent determination of penetration as a function of particle size for the whole filter unit, the filter unit frame, and the filter media pack. Tests were performed using a polydisperse aerosol of di-2-ethylhexyl phthalate with a count median diameter of 0.2 {mu}m and geometric standard deviation of 1.6. Flow rate and differential pressure were controlled from 1% to 100% of design values. Particle counts were made upstream and downstream of the filter unit with an optical particle counter (OPC). The OPC provided count information in 28 size channels over the particle diameter range from 0.1 to 0.7 {mu}m. Results provide evidence for a two component leak model of filler unit performance with: (1) external leaks through filter unit frames, and (2) internal leaks through defects in the media and through the seal between the media pack and frame. For the filter units evaluated, these leaks dominate overall filter unit performance over much of the flow rate and particle size ranges tested.
Date: July 1, 1994
Creator: Scripsick, R. C.
Partner: UNT Libraries Government Documents Department

The crosswell electromagnetic response of layered media

Description: Crosswell electromagnetic measurements are a promising new geophysical technique for mapping subsurface electrical conductivity which can provide information about the subsurface distribution of water, oil or steam. In this work the fields from a low frequency vertical magnetic dipole have been examined from the specific point of view of their application to the determination of the conductivity of a layered medium. The source and the receiver were placed inside two separate boreholes. The range of penetration of such a crosswell system for typical earth resistivities and for currently available transmitter and receiver technologies was found to be up to 1,000 meters so problems in ground water and petroleum reservoir characteristics can be practically examined. An analysis of the behavior of the magnetic fields at the boundary between two half-spaces showed that the horizontal magnetic field component, H{rho}, and the vertical derivative of a vertical component, {delta}H{sub z}/{delta}z, are more sensitive to conductivity variations than H{sub z}. The analysis of derivatives led to the concept of measuring the conductivity directly using a second vertical derivative of H{sub z}. Conductivity profiles interpreted from field data using this technique reproduced accurately the electrical logs for a test site near Devine, Texas. It was found in this study that the inversion techniques are more stable when the first vertical derivative of H{sub z} is used rather than H{sub z} itself. Using data from a salt water injection experiment at the Richmond Field test site in Berkeley it was also found that these robust layer inversions were successful in identifying the preferential flow direction of the injected brine to four boreholes surrounding the injection well.
Date: April 1, 1994
Creator: Deszcz-Pan, M.
Partner: UNT Libraries Government Documents Department

The use of micellar solutions for novel separation techniques

Description: Surfactant based separation techniques based on the solubilization of organic compounds into the nonpolar interior of a micelle or electrostatic attraction of ionized metals and metal complexes to the charged surface of a micelle were studied in this work. Micellar solutions were used to recover two model volatile organic compounds emitted by the printing and painting industries (toluene and amyl acetate) and to investigate the effect of the most important variables in the surfactant enhanced carbon regeneration (SECR) process. SECR for liquid phase applications was also investigated in which the equilibrium adsorption of cetyl pyridinium chloride (CPC) and sodium dodecyl sulfate (SDS) on activated carbon were measured. Micellar-enhanced ultrafiltration (MEUF) was investigated using spiral wound membranes for the simultaneous removal of organic compounds, metals and metal complexes dissolved in water, with emphasis on pollution control applications. Investigations of MEUF to remove 99+ per cent of trichloroethylene (TCE) from contaminated groundwater using criteria such as: membrane flux, solubilization equilibrium constant, surfactant molecular weight, and Krafft temperature led to the selection of an anionic disulfonate with a molecular weight of 642 (DOWFAX 8390). These data and results from supporting experiments were used to design a system which could clean-up water in a 100,000 gallon/day operation. A four stage process was found to be an effective design and estimated cost for such an operation were found to be in the range of the cost of mature competitive technologies.
Date: December 31, 1993
Creator: Roberts, B. L.
Partner: UNT Libraries Government Documents Department

Gas proportional detectors with interpolating cathode pad readout for high track multiplicities

Description: New techniques for position encoding in very high rate particle and photon detectors will be required in experiments planned for future particle accelerators such as the Superconducting Super Collider and new, high intensity, synchrotron sources. Studies of two interpolating cathode ``pad`` readout systems are described in this thesis. They are well suited for high multiplicity, two dimensional unambiguous position sensitive detection of minimum ionizing particles and heavy ions as well as detection of x-rays at high counting rates. One of the readout systems uses subdivided rows of pads interconnected by resistive strips as the cathode of a multiwire proportional chamber (MWPC). A position resolution of less than 100 {mu}m rms, for 5.4 keV x-rays, and differential non-linearity of 12% have been achieved. Low mass ({approximately}0.6% of a radiation length) detector construction techniques have been developed. The second readout system uses rows of chevron shaped cathode pads to perform geometrical charge division. Position resolution (FWHM) of about 1% of the readout spacing and differential non-linearity of 10% for 5.4 keV x-rays have been achieved. A review of other interpolating methods is included. Low mass cathode construction techniques are described. In conclusion, applications and future developments are discussed. 54 refs.
Date: December 1, 1991
Creator: Yu, Bo
Partner: UNT Libraries Government Documents Department

Response of the D0 calorimeter to cosmic ray muons

Description: The D0 Detector at the Fermi National Accelerator Laboratory is a large multipurpose detector facility designed for the study of proton-antiproton collision products at the center-of-mass energy of 2 TeV. It consists of an inner tracking volume, hermetic uranium/liquid argon sampling calorimetry, and an outer 47{pi} muon detector. In preparation for our first collider run, the collaboration organized a Cosmic Ray Commissioning Run, which took place from February--May of 1991. This thesis is a detailed study of the response of the central calorimeter to cosmic ray muons as extracted from data collected during this run. We have compared the shapes of the experimentally-obtained pulse height spectra to the Landau prediction for the ionization loss in a continuous thin absorber in the four electromagnetic and four hadronic layers of the calorimeter, and find good agreement after experimental effects are folded in. We have also determined an absolute energy calibration using two independent methods: one which measures the response of the electronics to a known amount of charge injected at the preamplifiers, and one which uses a carry-over of the calibration from a beam test of central calorimeter modules. Both absolute energy conversion factors agree with one another, within their errors. The calibration determined from the test beam carryover, relevant for use with collider physics data, has an error of 2.3%. We believe that, with further study, a final error of {approx}1% will be achieved. The theory-to-experiment comparison of the peaks (or most probable values) of the muon spectra was used to determine the layer-to-layer consistency of the muon signal. We find that the mean response in the 3 fine hadronic layers is (12 {plus_minus} 2%) higher than that in the 4 electromagnetic layers. These same comparisons have been used to verify the absolute energy conversion factors. The conversion factors work well ...
Date: October 1, 1992
Creator: Kotcher, J.
Partner: UNT Libraries Government Documents Department

D0 central tracking chamber performance studies

Description: The performance of the completed DO central tracking chamber was studied using cosmic rays at the State University of New York at Stony Brook. Also studied was a prototype tracking chamber identical in design to the completed DO tracking chamber. The prototype chamber was exposed to a collimated beam of 150 GeV pions at the Fermilab NWA test facility. Results indicate an R{Phi} tracking resolution compatible with the limitations imposed by physical considerations, excellent 2 track resolution, and a high track reconstruction efficiency along with a good rejection power against {gamma} {yields} e {sup +} e{sup {minus}} events.
Date: December 1991
Creator: Pizzuto, Domenico
Partner: UNT Libraries Government Documents Department

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

Description: The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit by studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 {plus_minus} 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker`s theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.
Date: September 1, 1991
Creator: Mears, C. A.
Partner: UNT Libraries Government Documents Department

The design and performance of a twenty barrel hydrogen pellet injector for Alcator C-Mod

Description: A twenty barrel hydrogen pellet injector has been designed, built and tested both in the laboratory and on the Alcator C-Mod Tokamak at MIT. The injector functions by firing pellets of frozen hydrogen or deuterium deep into the plasma discharge for the purpose of fueling the plasma, modifying the density profile and increasing the global energy confinement time. The design goals of the injector are: (1) Operational flexibility, (2) High reliability, (3) Remote operation with minimal maintenance. These requirements have lead to a single stage, pipe gun design with twenty barrels. Pellets are formed by in- situ condensation of the fuel gas, thus avoiding moving parts at cryogenic temperatures. The injector is the first to dispense with the need for cryogenic fluids and instead uses a closed cycle refrigerator to cool the thermal system components. The twenty barrels of the injector produce pellets of four different size groups and allow for a high degree of flexibility in fueling experiments. Operation of the injector is under PLC control allowing for remote operation, interlocked safety features and automated pellet manufacturing. The injector has been extrusively tested and shown to produce pellets reliably with velocities up to 1400 m/sec. During the period from September to November of 1993, the injector was successfully used to fire pellets into over fifty plasma discharges. Experimental results include data on the pellet penetration into the plasma using an advanced pellet tracking diagnostic with improved time and spatial response. Data from the tracker indicates pellet penetrations were between 30 and 86 percent of the plasma minor radius.
Date: May 1, 1994
Creator: Urbahn, J. A.
Partner: UNT Libraries Government Documents Department

Synthesis of higher alcohols from carbon monoxide and hydrogen in a slurry reactor

Description: Higher, i.e. C{sub 2{sup +}}, alcohols are desired as gasoline additives, feedstocks for producing ethers and as alternative fuels for automobiles. In all cases, the backbone branching of an alcohol improves octane rating, which is essential for good engine performance. These types of branched, higher alcohols are the desired products for a process converting synthesis gas, a CO and H{sub 2} mixture, often generated from coal gasification. Based on this premise, promoted ZnCr oxide catalysts appear to be as one of the best avenues for further investigation. Once this investigation is complete, a natural extension is to replace the Cr in the ZnCr oxide catalyst with Mo and W, both in the same elemental triad with Cr. Mo has already been shown as an active HAS catalyst, both on a SiO{sub 2} support and in the MoS{sub 2} form. The three catalyst combinations, ZnMo, ZnW, and MnCr oxides will be tested in the stirred autoclave system. However, if none of the three indicate any comparable activity and/or selectivity toward higher alcohols as compared with other HAS catalysts, then an investigation of the effects of Cs promotion on the ZnCr oxide methanol catalysts will be executed.
Date: August 28, 1992
Creator: McCutchen, M. S.
Partner: UNT Libraries Government Documents Department

An evaluation of the Panasonic model UD513AC-1 Thermoluminescence Dosimetry system

Description: An evaluation of the Panasonic UD513AC-1 Thermoluminescence Dosimetry system was performed to determine the system`s capabilities as a general purpose thermoluminescence dosimeter measuring device. The tests that were performed included a critique of the user`s manual, delimitation of the operating parameters, the quality of construction, and an evaluation of the features that were unique to this system. The UD513AC-1 was found to be an adequate measuring device for most dosimetric applications. It was not well suited for experimental work with thermoluminescence materials due to a low sensitivity displayed by the photomultiplier tube to commonly used materials. The system was well constructed and did not suffer hardware failure during this research. Major attributes of the UD513AC-1 were automatic data storage, highly reproducible heating ramps, an excellent infrared light filter and a unique feature to a single phosphor unit, a dose determination function. Negative aspects of the system included a limited data manipulation capability within the controlling program, a poorly written user`s manual, inadequate sensitivity on the part of the photomultiplier tube, and insufficient capability to adjust the hot N{sub 2} gas flow to desired levels.
Date: December 1, 1991
Creator: Durrer, R. E. Jr.
Partner: UNT Libraries Government Documents Department