A 600 MeV cyclotron for radioactive beam production (open access)

A 600 MeV cyclotron for radioactive beam production

The magnetic field design for a 600 MeV proton cyclotron is described. The cyclotron has a single stage, a normal conducting magnet coil and a 9.8 m outside yoke diameter. It has 8 sectors, with a transition to 4 sectors in the center region. The magnetic field design was done using 1958 Harwell rectangular ridge system measurements and was compared with recent 3-dimensional field calculations with the program TOSCA at NSCL. The center region 4--8 sector transition focussing was also checked with TOSCA.
Date: May 17, 1993
Creator: Clark, D. J.
Object Type: Article
System: The UNT Digital Library
Assist in the Recovery of Bypassed Oil From Reservoirs in the Gulf of Mexico. Summary Annual Report, February 18, 1992--February 18, 1993 (open access)

Assist in the Recovery of Bypassed Oil From Reservoirs in the Gulf of Mexico. Summary Annual Report, February 18, 1992--February 18, 1993

The objective of this research is to assist the recovery of non-contacted oil from known reservoirs on the Outer Continental Shelf in the Gulf of Mexico. Thus far, research has consisted of data collection from Minerals Management Service (MMS); literature and operators; screening of reservoirs for detailed studies; modification of two public domain simulators; development of a predictive model; and design of several laboratory experiments for studying attic oil recovery. The methodology for data collection from MMS, literature and operators is keyed on 208 sands containing 1,289 reservoirs, representing 60% of the original oil in place (OOIP) in the Gulf of Mexico. This data collection is presently in progress after several delays concerning confidentiality agreements between MMS, DOE, and LSU and its subcontractors. Modifications on two public domain computer reservoir simulators, BOAST II and MASTER, is underway. Modifications will consist of developing a code to handle steeply dipping oil reservoirs and a radial grid format for near wellbore studies. Modifications for steeply dipping reservoirs have been successfully implemented. At present, modifications to BOAST II for radial grid systems are producing acceptable results in a reasonable, though long, period of time. Research of all phases listed above are in progress; therefore, …
Date: March 17, 1993
Creator: Schenewerk, P. A.
Object Type: Report
System: The UNT Digital Library
Audit of Mound Plant`s reduction in force (open access)

Audit of Mound Plant`s reduction in force

Objective of this audit was to determine whether the Mound Plant`s Fiscal Year 1992 reduction in force (RIF) was effectively managed and implemented properly by DOE. DOE established policy to encourage contractors to reduce staffing by voluntary separations without unreasonable separation costs. EG&G Mound`s FY 1992 RIF was accomplished by voluntary separations; however, its implementation unreasonably increased costs because DOE did not have adequate criteria or guidelines for evaluating contractors` RIF proposals, and because EG&G Mound furnished inaccurate cost data to DOE evaluators. The unreasonable costs amounted to at least $21 million. Recommendations are made that DOE develop and implement guidelines to impose limitations on voluntary separation allowances, early retirement incentive payments, and inclusion of crucial employee classifications in voluntary RIFs.
Date: May 17, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Carbollide solubility and chemical compatibility summary (open access)

Carbollide solubility and chemical compatibility summary

This report examines the value of the cobalt dicarbollide anion as an effective form of in-tank precipitation. The cobalt dicarbollide anion (CDC) has been investigated for the possible replacement of tetraphenyl borate anion (TPB) for precipitation of cesium in SRS High Level Waste (HLW). The solubility of the cesium CDC in 5 M salt solutions and the reactivity with caustic have been studied extensively. The solubility of CSCDC in a mixture of 4 M sodium nitrate and 1 m sodium hydroxide is {approximately}2 {times} 10{sup {minus}3} M at 40{degrees}C. Furthermore, the CDC decomposes in 1 M sodium hydroxide solution with apparent first order kinetics with a half-life of 7.3 days at 60 {degrees}C and 94 days at 40{degrees}C. Tank temperatures are currently estimated to approach 60{degrees}C during the ITP filtration cycle. This solubility and rapid decomposition of the CDC under highly alkaline conditions and high temperature would require increasing the quantity of CDC and nonradioactive cesium which must be added, increasing the cost of production. Increasing the quantity of CDC would necessitate recovery of the material, probably using a solvent extraction system. Due to the large amount of nonradioactive cesium which must be added, the total amount of precipitate formed …
Date: August 17, 1993
Creator: McCabe, D. J.
Object Type: Report
System: The UNT Digital Library
Catalyst and process development for synthesis gas conversion to isobutylene. Quarterly report, January 1, 1993--March 31, 1993 (open access)

Catalyst and process development for synthesis gas conversion to isobutylene. Quarterly report, January 1, 1993--March 31, 1993

The objectives of this project are to develop a new catalyst, the kinetics for this catalyst, reactor models for trickle bed, slurry and fixed bed reactors, and simulate the performance of fixed bed trickle flow reactors, slurry flow reactors, and fixed bed gas phase reactors for conversion of a hydrogen lean synthesis gas to isobutylene. The six main accomplishments for the quarter are the following: (1) activity testing with the 7% (wt) Ce-ZrO{sub 2}, (2) activity testing the same catalyst with CO from an aluminum cylinder, (3) preparation of ZrO{sub 2} by heating zirconyl nitrate, (4) preparation of an active zirconia prepared by a modified sol gel procedure and evaluation of the catalytic activity of a commercial zirconia and the catalysts prepared by the sol gel procedure, (5) determining the effect of separator temperatures and oil flow rate on the performance of a trickle bed reactor, and (6) calculation of the equilibrium composition of the C{sub 2} to C{sub 5} olefins, and initiation of the development of a macrokinetic model. The details of each of these accomplishments are discussed.
Date: April 17, 1993
Creator: Anthony, R. G. & Akgerman, A.
Object Type: Report
System: The UNT Digital Library
Combining nonlinear multiresolution system and vector quantization for still image compression (open access)

Combining nonlinear multiresolution system and vector quantization for still image compression

It is popular to use multiresolution systems for image coding and compression. However, general-purpose techniques such as filter banks and wavelets are linear. While these systems are rigorous, nonlinear features in the signals cannot be utilized in a single entity for compression. Linear filters are known to blur the edges. Thus, the low-resolution images are typically blurred, carrying little information. We propose and demonstrate that edge-preserving filters such as median filters can be used in generating a multiresolution system using the Laplacian pyramid. The signals in the detail images are small and localized to the edge areas. Principal component vector quantization (PCVQ) is used to encode the detail images. PCVQ is a tree-structured VQ which allows fast codebook design and encoding/decoding. In encoding, the quantization error at each level is fed back through the pyramid to the previous level so that ultimately all the error is confined to the first level. With simple coding methods, we demonstrate that images with PSNR 33 dB can be obtained at 0.66 bpp without the use of entropy coding. When the rate is decreased to 0.25 bpp, the PSNR of 30 dB can still be achieved. Combined with an earlier result, our work demonstrate …
Date: December 17, 1993
Creator: Wong, Y.
Object Type: Article
System: The UNT Digital Library
Cretaceous shallow drilling, US Western Interior: Core research (open access)

Cretaceous shallow drilling, US Western Interior: Core research

This project is a continuing multidisciplinary study of middle to Upper Cretaceous marine carbonate and clastic rocks in the Utah-Colorado-Kansas corridor of the old Cretaceous seaway that extended from the Gulf Coast to the Arctic during maximum Cretaceous transgressions. It is collaborative between in the US Geological Survey (W.E. Dean, P.I.) and University researchers led by The Pennsylvania State University(M.A. Arthur, P.I.) and funded by DOE and the USGS, in part. Research focusses on the Greenhom, Niobrara and lower Pierre Shale units and their equivalents, combining biostratigraphic/paleoecologic studies, inorganic, organic and stable isotopic geochemical studies, mineralogical investigations and high-resolution geophysical logging. This research requires unweathered samples and continuous smooth exposures'' in the form of cores from at least 4 relatively shallow reference holes (i.e. < 1000m) in transect from east to west across the basin. The major initial effort was recovery in Year 1 of the project of continuous cores from each site in the transect. This drilling provided samples and logs of strata ranging from pelagic sequences that contain organic-carbon-rich marine source rocks to nearshore coal-bearing units. This transect also will provide information on the extent of thermal maturation and migration of hydrocarbons in organic-carbon-rich strata along a burial …
Date: February 17, 1993
Creator: Arthur, Michael A.
Object Type: Report
System: The UNT Digital Library
Cretaceous shallow drilling, US Western Interior: Core research. Technical progress report (open access)

Cretaceous shallow drilling, US Western Interior: Core research. Technical progress report

This project is a continuing multidisciplinary study of middle to Upper Cretaceous marine carbonate and clastic rocks in the Utah-Colorado-Kansas corridor of the old Cretaceous seaway that extended from the Gulf Coast to the Arctic during maximum Cretaceous transgressions. It is collaborative between in the US Geological Survey (W.E. Dean, P.I.) and University researchers led by The Pennsylvania State University(M.A. Arthur, P.I.) and funded by DOE and the USGS, in part. Research focusses on the Greenhom, Niobrara and lower Pierre Shale units and their equivalents, combining biostratigraphic/paleoecologic studies, inorganic, organic and stable isotopic geochemical studies, mineralogical investigations and high-resolution geophysical logging. This research requires unweathered samples and continuous smooth ``exposures`` in the form of cores from at least 4 relatively shallow reference holes (i.e. < 1000m) in transect from east to west across the basin. The major initial effort was recovery in Year 1 of the project of continuous cores from each site in the transect. This drilling provided samples and logs of strata ranging from pelagic sequences that contain organic-carbon-rich marine source rocks to nearshore coal-bearing units. This transect also will provide information on the extent of thermal maturation and migration of hydrocarbons in organic-carbon-rich strata along a burial …
Date: February 17, 1993
Creator: Arthur, M. A.
Object Type: Report
System: The UNT Digital Library
Design of a high activity and selectivity alcohol catalyst (open access)

Design of a high activity and selectivity alcohol catalyst

Preliminary investigations of these manganese oxide materials show that the different oxides exhibit different selectivity toward methanol and other products. It seems that there is a correlation between the initial O/Mn ratio of the oxide and methanol selectivity. These conclusions are supported by the results displayed in Figures 1 and 2. The main product of the manganese oxide-catalyzed CO hydrogenation is methanol except on Mao, which shows the lowest methanol selectivity, but the highest CO[sub 2] yield. Preliminarily, the results suggest that the higher the O/Mn ratio of the precursor oxide, the higher will be the methanol selectivity, while the CO[sub 2] and methane selectivities will be lower. The higher CO[sub 2] and C[sub 2], C[sub 3] and C[sub 4] hydrocarbon selectivities over the Mao catalyst compared to the other manganese oxides tested, indicates that Mao acts more like a water-gas shift and Fischer-Tropsch catalyst.
Date: February 17, 1993
Creator: Foley, Henry C. & Mills, G. Alex
Object Type: Report
System: The UNT Digital Library
Design of a high activity and selectivity alcohol catalyst. Tenth quarterly report, November 7, 1992--February 7, 1993 (open access)

Design of a high activity and selectivity alcohol catalyst. Tenth quarterly report, November 7, 1992--February 7, 1993

Preliminary investigations of these manganese oxide materials show that the different oxides exhibit different selectivity toward methanol and other products. It seems that there is a correlation between the initial O/Mn ratio of the oxide and methanol selectivity. These conclusions are supported by the results displayed in Figures 1 and 2. The main product of the manganese oxide-catalyzed CO hydrogenation is methanol except on Mao, which shows the lowest methanol selectivity, but the highest CO{sub 2} yield. Preliminarily, the results suggest that the higher the O/Mn ratio of the precursor oxide, the higher will be the methanol selectivity, while the CO{sub 2} and methane selectivities will be lower. The higher CO{sub 2} and C{sub 2}, C{sub 3} and C{sub 4} hydrocarbon selectivities over the Mao catalyst compared to the other manganese oxides tested, indicates that Mao acts more like a water-gas shift and Fischer-Tropsch catalyst.
Date: February 17, 1993
Creator: Foley, H. C. & Mills, G. A.
Object Type: Report
System: The UNT Digital Library
Development and testing of industrial scale, coal fired combustion system, Phase 3. Fifth quarterly technical progress report, January 1, 1993--March 31, 1993 (open access)

Development and testing of industrial scale, coal fired combustion system, Phase 3. Fifth quarterly technical progress report, January 1, 1993--March 31, 1993

In the present reporting period, the first quarter of calendar year 1993, the effort was divided between Task 2. ``Pre Systems Tests`` and Task 4 ``Economics and Commercialization Plan.`` A major part of the task 2 effort was devoted converting the nozzle from adiabatic to air cooted operation. This conversion will allow immediate implementation of the longer duration task 3.2 tests after the completion of the task 2 tests. Therefore, a significant pan of the exit nozzle conversion effort is also part of task 3.1, ``Combustor Refurbishment.`` In task 1 the only activity remaining is to receive the results of the BYU combustion modeling. The results are anticipated this Spring. One of the three remaining tests in task 2 was implemented in late January under freezing weather and snow conditions. Ice plugged the coal feed lines and stack scrubber water outlet and ice jammed and damaged the coal metering auger. While these lines were thawed, the combustor was fired with oil. The coal used in this test contained fine fibrous tramp material which passed through the two tramp material retaining screens and eventually plugged several of the coal feed lines to the combustor. This cut the planned coal feed rate …
Date: May 17, 1993
Creator: Zauderer, B.
Object Type: Report
System: The UNT Digital Library
The development of coal-based technologies for Department of Defense Facilities. Semiannual technical progress report, March 28, 1993--September 27, 1993 (open access)

The development of coal-based technologies for Department of Defense Facilities. Semiannual technical progress report, March 28, 1993--September 27, 1993

The US DOD, through an Interagency Agreement with the US DOE, has initiated a three-phase program with the Consortium for Coal-Water Slurry Fuel Technology, with the aim of decreasing DOD`s reliance on imported oil by increasing its use of coal. The program is being conducted as a cooperative agreement between the Consortium and DOE and the first phase of the program is underway. A team of researchers has been assembled from Penn State, ABB Combustion Engineering Systems (CE), AMAX Research and Development Center (AMAX), and Energy and Environmental Research Corporation (EER). These four organizations are the current members of the Consortium. Phase 1 activities are focused on developing clean, coal-based combustion technologies for the utilization of both micronized coal-water slurry fuels (MCWSFs) and dry, micronized coal (DMC) in fuel oil-designed industrial boilers. Phase 2 research and development activities will continue to focus on industrial boiler retrofit technologies by addressing emissions control and pre-combustion strategies for the utilization of high ash, high sulfur coals. Phase 3 activities will examine coal-based fuel combustion systems that cofire wastes. Each phase includes an engineering cost analysis and technology assessment. The activities and status of Phase 1 are described in this report. The objective of …
Date: December 17, 1993
Creator: Miller, B. G.; Morrison, J. L. & Sharifi, R.
Object Type: Report
System: The UNT Digital Library
Development of measurement capabilities for the thermophysical properties of energy-related fluids. Annual report, December 1, 1993--November 30, 1994 (open access)

Development of measurement capabilities for the thermophysical properties of energy-related fluids. Annual report, December 1, 1993--November 30, 1994

Objectives are to develop state-of-the-art experimental apparatus for measuring the thermophysical properties of a wide range of fluids and fluid mixtures important to the energy, chemical, and energy-related industries, and carry out benchmark measurements on key systems. Measurement capabilities to be developed cover transport properties, thermodynamic properties, phase equilibria properties, and dielectric properties. The new apparatus will make it possible to study a wide range of complex fluid systems under conditions that have been previously inaccessible. Specific measurement capabilities to be developed are: Thermal Conductivity Apparatus, Vibrating Wire Viscometer, Dual-Sinker Densimeter, High-Temperature Vibrating Tube Densimeter, Dynamic Phase Equilibria Apparatus, Apparatus for Dilute Solutions, Total-Enthalpy Flow Calorimeter, Dielectric Constant Apparatus. The research also includes benchmark experimental measurements on pure and mixed alternative refrigerants, aqueous solutions, and carefully selected systems consisting of species of diverse size (methane + neopentane) and polarity (methane + ammonia) important for development of predictive models for energy-related fluids.
Date: August 17, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Development of {sup 129}I AMS for the LLNL spectrometer (open access)

Development of {sup 129}I AMS for the LLNL spectrometer

The Multi-user Tandem Laboratory at LLNL was designed to be a versatile facility which could be configured to develop new capabilities as determined by the requirements of sponsoring agencies and experimental programs. The initial design made some compromises, driven by both the usual budgetary constraints and uncertainties in program needs and support. We were recently funded by the Office of Arms Control in the US DOE to develop an {sup 129}I AMS capability. The first {sup 129}I measurements were performed this year after upgrades and modifications to the initially installed components were completed. The configuration of the present spectrometer and performance achieved to date will be described. Planned improvements to the injector and high energy spectrometer will be outlined.
Date: September 17, 1993
Creator: Proctor, I. D.; Southon, J. R. & Roberts, M. L.
Object Type: Article
System: The UNT Digital Library
Direct mass and lifetime measurements of neutron-rich nuclei up to A[approximately]100 using the TOFI spectrometer at LAMPF (open access)

Direct mass and lifetime measurements of neutron-rich nuclei up to A[approximately]100 using the TOFI spectrometer at LAMPF

This project was directed toward the study of neutron-rich nuclei using the experimental facilities at LAMPF, which is a part of LANL. The principal results of the investigation include the discovery of many new isotopes along with a measurement of their masses and in particular those nuclides in the Z = 7--19 and 14 --26 regions of the chart of the nuclides.Thirty-four new nuclides were detected and studied with their masses being measured with relatively high accuracy, and an additional twenty-six that were previously known and measured were remeasured to an improved accuracy. Besides providing new information about the mass surface in new and extended redons of the chart of the nuclides, this investigation enabled properties and previously unknown structure of some of the nuclei to be determined such as nuclear deformation among some of the nuclides. Also a study of the neutron pairing gaps and the proton pairing gaps among these nuclides was made. Other developments also achieved included instrument (TOFI) improvements and upgrades and theoretical investigations into the masses of the hadrons.
Date: June 17, 1993
Creator: Lind, V. G.
Object Type: Report
System: The UNT Digital Library
Direct mass and lifetime measurements of neutron-rich nuclei up to A{approximately}100 using the TOFI spectrometer at LAMPF. Final report, April 15, 1986--March 14, 1992 (open access)

Direct mass and lifetime measurements of neutron-rich nuclei up to A{approximately}100 using the TOFI spectrometer at LAMPF. Final report, April 15, 1986--March 14, 1992

This project was directed toward the study of neutron-rich nuclei using the experimental facilities at LAMPF, which is a part of LANL. The principal results of the investigation include the discovery of many new isotopes along with a measurement of their masses and in particular those nuclides in the Z = 7--19 and 14 --26 regions of the chart of the nuclides.Thirty-four new nuclides were detected and studied with their masses being measured with relatively high accuracy, and an additional twenty-six that were previously known and measured were remeasured to an improved accuracy. Besides providing new information about the mass surface in new and extended redons of the chart of the nuclides, this investigation enabled properties and previously unknown structure of some of the nuclei to be determined such as nuclear deformation among some of the nuclides. Also a study of the neutron pairing gaps and the proton pairing gaps among these nuclides was made. Other developments also achieved included instrument (TOFI) improvements and upgrades and theoretical investigations into the masses of the hadrons.
Date: June 17, 1993
Creator: Lind, V. G.
Object Type: Report
System: The UNT Digital Library
Direct probability mapping of contaminants (open access)

Direct probability mapping of contaminants

Exhaustive characterization of a contaminated site is a physical and practical impossibility. Descriptions of the nature, extent, and level of contamination, as well as decisions regarding proposed remediation activities, must be made in a state of uncertainty based upon limited physical sampling. Geostatistical simulation provides powerful tools for investigating contaminant levels, and in particular, for identifying and using the spatial interrelationships among a set of isolated sample values. This additional information can be used to assess the likelihood of encountering contamination at unsampled locations and to evaluate the risk associated with decisions to remediate or not to remediate specific regions within a site. Past operation of the DOE Feed Materials Production Center has contaminated a site near Fernald, Ohio, with natural uranium. Soil geochemical data have been collected as part of the Uranium-in-Soils Integrated Demonstration Project. These data have been used to construct a number of stochastic images of potential contamination for parcels approximately the size of a selective remediation unit. Each such image accurately reflects the actual measured sample values, and reproduces the univariate statistics and spatial character of the extant data. Post-processing of a large number of these equally likely, statistically similar images produces maps directly showing the …
Date: September 17, 1993
Creator: Rautman, C. A.
Object Type: Article
System: The UNT Digital Library
Electric power monthly, September 1993 (open access)

Electric power monthly, September 1993

The Electric Power Monthly (EPM) presents monthly electricity statistics. The purpose of this publication is to provide energy decisionmakers with accurate and timely information that may be used in forming various perspectives on electric issues that lie ahead. The EPM is prepared by the Survey Management Division; Office of Coal, Nuclear, Electric and Alternate Fuels, Energy Information Administration (EIA), Department of Energy. This publication provides monthly statistics at the US, Census division, and State levels for net generation, fossil fuel consumption and stocks, quantity and quality of fossil fuels, cost of fossil fuels, electricity sales, revenue, and average revenue per kilowatthour of electricity sold. Data on net generation, fuel consumption, fuel stocks, quantity and cost of fossil fuels are also displayed for the North American Electric Reliability Council (NERC) regions.
Date: September 17, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Emission from ferroelectric cathodes (open access)

Emission from ferroelectric cathodes

We have recently initiated an investigation of electron emission from ferroelectric cathodes. Our experimental apparatus consisted of an electron diode and a 250 kV, 12 ohm, 70 ns pulsed high voltage power source. A planar triode modulator driven by a synthesized waveform generator initiates the polarization inversion and allows inversion pulse tailoring. The pulsed high voltage power source is capable of delivering two high voltage pulses within 50 ns of each other and is capable of operating at a sustained repetition rate of 5 Hz. Our initial measurements indicate that emission current densities above the Child-Langmuir Space Charge Limit are possible. We explain this effect to be based on a non-zero initial energy of the emitted electrons. We also determined that this effect is strongly coupled to relative timing between the inversion pulse and application of the main anode-cathode pulse. We also have initiated brightness measurements of the emitted beam. As in our previous measurements at this Laboratory, we performed the measurement using a pepper pot technique. Beam-let profiles are recorded with a fast phosphor and gated cameras. We describe our apparatus and preliminary measurements.
Date: May 17, 1993
Creator: Sampayan, S. E.; Caporaso, G. J.; Holmes, C. L.; Lauer, E. J.; Prosnitz, D.; Trimble, D. O. et al.
Object Type: Article
System: The UNT Digital Library
Evaluation of an x-ray fluorimeter for measuring lead in paint (open access)

Evaluation of an x-ray fluorimeter for measuring lead in paint

A laboratory analysis of key performance features of the Warrington Microlead I XRF Analyzer was conducted. This analysis included the determination of instrument accuracy and precision as measured against standard reference materials as well as the instrument's ability to provide information for multiple layers of a lead-based paint.
Date: March 17, 1993
Creator: Klein, R.C.; Horn, F.T. & Wilson, R.D.
Object Type: Report
System: The UNT Digital Library
Evaluation of an x-ray fluorimeter for measuring lead in paint (open access)

Evaluation of an x-ray fluorimeter for measuring lead in paint

A laboratory analysis of key performance features of the Warrington Microlead I XRF Analyzer was conducted. This analysis included the determination of instrument accuracy and precision as measured against standard reference materials as well as the instrument`s ability to provide information for multiple layers of a lead-based paint.
Date: March 17, 1993
Creator: Klein, R. C.; Horn, F. T. & Wilson, R. D.
Object Type: Report
System: The UNT Digital Library
Fabrication of scintillator ``multitiles`` for the LBL SDC ECEM ``4 {times} 4`` test module (open access)

Fabrication of scintillator ``multitiles`` for the LBL SDC ECEM ``4 {times} 4`` test module

None
Date: August 17, 1993
Creator: Hoff, M. D.
Object Type: Report
System: The UNT Digital Library
Fast pulsars, compact stars, and the strange matter hypothesis (open access)

Fast pulsars, compact stars, and the strange matter hypothesis

Part one of this paper deals with the recent finding of the possible existence of a mixed phase of baryon matter and quark matter inside neutron stars. In part two we review the theoretically determined minimum rotational periods of neutron stars, which serve to distinguish between pulsars that can be understood as rotating neutron stars and those that can not. Likely candidates for the latter are hypothetical strange stars. Their mass-radius relationship is discussed in the last part. It is pointed out that strange stars with a nuclear crust can give rise to the observed phenomena of pulsar glitches, thus passing the only astrophysical test of the strange-matter hypothesis existing to date.
Date: March 17, 1993
Creator: Weber, F. & Glendenning, N. K.
Object Type: Article
System: The UNT Digital Library
The first data from the MACHO experiment (open access)

The first data from the MACHO experiment

MAssive Compact Halo Objects such as brown dwarfs, Jupiters, and black holes are prime candidates to comprise the dark halo of our galaxy. Paczynski noted that objects (dubbed MACHOS) with masses in the range 10{sup {minus}6} M{circle_dot} < M {approx_lt} 100M{circle_dot} can be detected via gravitational microlensing of stars in the Magellanic Clouds with the caveat that only about one in 10{sup 6} stars will be lensed at any given time. Our group has recently begun a search for microlensing using a refurbished 1.27 meter telescope at the Mount Stromlo Observatory in Australia. Since the summer of 1992, we have been imaging up to 10{sup 7} stars a night in the Large Magellanic Cloud using our large format two-color 3.4 {times} 10{sup 7} pixel CCD camera. Here I report on our first results based on an analysis of {approximately}10{sup 6} of these stars. Although this is not enough data to make definitive statements about the nature of the dark matter, we are able to conclude that the rate of variable star background events is not larger than the expected MACHO signal.
Date: March 17, 1993
Creator: Bennett, D. P.; Cook, K. H.; Akerlof, C.; Perlmutter, S.; Sutherland, W.; Alcock, C. et al.
Object Type: Article
System: The UNT Digital Library