Phase I Water Rental Pilot Project : Snake River Resident Fish and Wildlife Resources and Management Recommendations. (open access)

Phase I Water Rental Pilot Project : Snake River Resident Fish and Wildlife Resources and Management Recommendations.

The Idaho Water Rental Pilot Project was implemented as a part of the Non-Treaty Storage Fish and Wildlife Agreement (NTSA) between Bonneville Power Administration and the Columbia Basin Fish and Wildlife Authority. The goal of the project is to improve juvenile and adult salmon and steelhead passage in the lower Snake River with the use of rented water for flow augmentation. The primary purpose of this project is to summarize existing resource information and provide recommendations to protect or enhance resident fish and wildlife resources in Idaho with actions achieving flow augmentation for anadromous fish. Potential impacts of an annual flow augmentation program on Idaho reservoirs and streams are modeled. Potential sources of water for flow augmentation and operational or institutional constraints to the use of that water are identified. This report does not advocate flow augmentation as the preferred long-term recovery action for salmon. The state of Idaho strongly believes that annual drawdown of the four lower Snake reservoirs is critical to the long-term enhancement and recovery of salmon (Andrus 1990). Existing water level management includes balancing the needs of hydropower production, irrigated agriculture, municipalities and industries with fish, wildlife and recreation. Reservoir minimum pool maintenance, water quality and …
Date: October 1, 1992
Creator: Riggin, Stacey H. & Hansen, H. Jerome
Object Type: Report
System: The UNT Digital Library
Dworshak Dam Impact Assessment and Fishery Investigation and Trout, Bass and Forage Species: Combined Project Completion Report. (open access)

Dworshak Dam Impact Assessment and Fishery Investigation and Trout, Bass and Forage Species: Combined Project Completion Report.

The Nez Perce Tribe (NPT) and the Idaho Department of Fish and Game (IDFG) entered into separate intergovernmental agreements with the Bonneville Power Administration in a cooperative four-year effort to study impacts of Dworshak Dam operation on resident fisheries. The NPT Department of Fisheries Management focused on rainbow trout, smallmouth bass and forage fish. The IDFG's segment of the project was to document kokanee population dynamics, relate it to the changing nutrient status of the reservoir, evaluate kokanee losses through Dworshak Dam, and make kokanee management recommendations. This final report includes findings for 1990 and 1991 and relates these data to information previously presented in annual reports for 1987, 1988 and 1989.
Date: October 1, 1992
Creator: Maiolie, Melo; Statler, David P. & Elam, Steve
Object Type: Report
System: The UNT Digital Library
Effect of flow leakage on the benchmarking of FLOWTRAN with Mark-22 mockup flow excursion test data from Babcock and Wilcox (open access)

Effect of flow leakage on the benchmarking of FLOWTRAN with Mark-22 mockup flow excursion test data from Babcock and Wilcox

This report presents a revised analysis of the Babcock and Wilcox (B and W) downflow flow excursion tests that accounts for leakage between flow channels in the test assembly. Leak rates were estimated by comparing results from the downflow tests with those for upflow tests conducted using an identical assembly with some minor modifications. The upflow test assembly did not contain leaks. This revised analyses shows that FLOWTRAN with the SRS working criterion conservatively predicts onset of flow instability without using a local peaking factor to model heat transfer variations near the ribs.
Date: October 1, 1992
Creator: Chen, Kuo-Fu.
Object Type: Report
System: The UNT Digital Library
Anticipated soil selenium concentrations at Kesterson Reservoir (open access)

Anticipated soil selenium concentrations at Kesterson Reservoir

Temporal trends from soil monitoring data collected at Kesterson Reservoir have been reviewed to shed light on anticipated concentrations of total and water-extractable selenium in surface and subsurface soils. Based on these data, a mass balance model for selenium has been developed and employed to evaluate the rate of leaching, remobilization and volatilization that has occurred since the Reservoir was dried out in 1987. Results from a series of calibration runs were then extrapolated 25 years in the future to forecast the evolution and redistribution of selenium within the soil profile. Projected water-extractable selenium concentrations within the 0.15 to 1 m depth interval were then used to drive a food-chain based risk-assessment model described in a separate report (CH2M Hill, 1992). Inventories of water-extractable selenium in the root zone increased in 4 of the 5 scenarios investigated. However, predicted values for the average concentration of water-extractable selenium in the root zone fall within the range of values observed at Kesterson today. Consequences of these projected increases on wildlife residing in and around Kesterson are addressed in CH2M Hill (1992).
Date: October 1, 1992
Creator: Benson, S.M.; Tokunaga, T.K. & Zawislanski, P.
Object Type: Report
System: The UNT Digital Library
Design report: SCDAP/RELAP5 reflood oxidation model (open access)

Design report: SCDAP/RELAP5 reflood oxidation model

Current SCDAP/RELAP5 oxidation models have proven to under-predict oxidation, and therefore hydrogen production, when modeling reflood during in-pile tests. As an example, while OECD LOFT Experiment LP-FP-2 shows significant increases in temperature and pressure during reflood due to increased oxidation, only minimal additional oxidation is currently predicted with SCDAP/RELAP5. Since SCDAP/RELAP5 predicts a steam rich environment during reflood, the parameter limiting oxidation must be the availability of zircaloy. Two phenomena, not currently modeled, may provide the necessary unoxidized zircaloy during reflood: (1) localized steam starvation prior to reflood, caused by debris blockage or hydrogen generation, or (2) shattering of oxidized cladding during reflood. The objective of this design report is to develop new models to accurately predict zircaloy cladding oxidation during the temperature transients prior to and during reflood. Evidence compiled from postirradiation examination (PIE) of fuel bundles subjected to severe accident conditions from several in-pile tests is used to identify mechanisms for additional cladding oxidation during reflood and to develop specific criteria to determine when these mechanisms are applicable.
Date: October 1, 1992
Creator: Coryell, E. W.; Chavez, S. A.; Davis, K. L. & Mortensen, M. H.
Object Type: Report
System: The UNT Digital Library
High resolution studies of atoms and small molecules (open access)

High resolution studies of atoms and small molecules

High resolution, continuous wave lasers have been utilized successfully in studies of small molecules. Examples of two-photon excitation schemes and of multiple resonance excitation sequences will be discussed within the framework of the spectroscopy and dynamics of selected Rydberg states of nitric oxide. Initial results on the circular dichroism of angular distributions in photoelectron spectra of individual hyperfine states of cesium will also be discussed, but no data given.
Date: October 1, 1992
Creator: Bushaw, B. A.; Tonkyn, R. G. & Miller, R. J.
Object Type: Article
System: The UNT Digital Library
National Geothermal Association Trade Mission to Central America (open access)

National Geothermal Association Trade Mission to Central America

The United States (US) geothermal industry, the world's most technically proficient, has been unable to achieve penetration into the markets of the developing nations. This report details the findings of an industry Trade Mission to Central America, tasked with determining the reasons for this shortfall and with developing a US industry geothermal export strategy designed to achieve immediate and long-term export benefits.
Date: October 1, 1992
Creator: unknown
Object Type: Report
System: The UNT Digital Library
A sparse architecture low power gated integrator for use with germanium gamma-ray spectrometers in remote geochemistry measurements (open access)

A sparse architecture low power gated integrator for use with germanium gamma-ray spectrometers in remote geochemistry measurements

Prototypical circuits of a low power gated integrator for use with germanium gamma-ray spectrometers in remote locations have been developed. The gated integrator is constructed from three very simple sub circuits. With a power consumption of <250mW the low count rate spectroscopy performance of this gated integrator is comparable to that of a conventional pulse shaping amplifier at energies of 1 MeV and greater.
Date: October 1, 1992
Creator: Madden, N.; Landis, D.; Adachi, R.; Pehl, R.; Abott, R. & Stogsdill, E.
Object Type: Article
System: The UNT Digital Library
Environmental risks and future generations: Criteria for public policy (open access)

Environmental risks and future generations: Criteria for public policy

This paper examines alternative normative approaches to the policy challenges posed by long-term environmental problems such as toxic and radioactive waste disposal, stratospheric ozone depletion, and climate change. The paper argues that cost-benefit analysis is limited in its ability to handle the issues of intergenerational equity and uncertainty that are intrinsic to such problems. Also considered is the precautionary principle, which holds that policies should seek to reduce threats to the welfare of future generations if the costs of doing so would not significantly reduce the subjective well-being of existing persons. Although the precautionary principle depends on an explicit value judgement, it yields a policy criterion that is operationally decisive under a wide array of circumstances.
Date: October 1, 1992
Creator: Howarth, R.B.
Object Type: Article
System: The UNT Digital Library
Results of the radiological survey at 48 Schlosser Drive, Rochelle Park, New Jersey (RJ005) (open access)

Results of the radiological survey at 48 Schlosser Drive, Rochelle Park, New Jersey (RJ005)

Maywood Chemical Works (MCW) of Maywood, New Jersey, generated process wastes and residues associated with the production and refining of thorium and thorium compounds from monazite ores from 1916 to 1956.MCW supplied rare earth metals and thorium compounds to the Atomic Energy Commission and various other government agencies from the late 1940s to the mid-1950s. Area residents used the sandlike waste from thisthorium extraction process mixed with tea and cocoa leaves as mulch in their yards. Some of these contaminated wastes were also eroded from the site into Lodi Brook. At the request of the US Department of Energy(DOE), a group from Oak Ridge National Laboratory conducts investigative radiological surveys of properties in the vicinity of MCW to determine whether a property is contaminated with radioactive residues, principally [sup 232]Tb, derived from the MCW site. The survey typically includes direct measurement of gamma radiation levels and soil sampling for radionuclide analyses. The survey of this site, 48 Schlosser Drive, Rochelle Park, New Jersey (RJO05), was conducted on July 14, 1991. Results of the survey demonstrated no radionuclide concentrations in excess of the DOE Formerly Utilized Sites Remedial Action Program criteria. The radionuclide distributions were not significantly different from normal background …
Date: October 1, 1992
Creator: Foley, R.D. & Brown, K.S.
Object Type: Report
System: The UNT Digital Library
Drift chamber tracking with neural networks (open access)

Drift chamber tracking with neural networks

We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed.
Date: October 1, 1992
Creator: Lindsey, C.S.; Denby, B. & Haggerty, H.
Object Type: Article
System: The UNT Digital Library
Bracketing to speed convergence illustrated on the von Newmann algorithm for finding a feasible solution to a linear program with a convexity contraint (open access)

Bracketing to speed convergence illustrated on the von Newmann algorithm for finding a feasible solution to a linear program with a convexity contraint

Analogous to gunners firing trial shots to bracket a target in order to adjust direction and distance, we demonstate that it is sometimes faster not to apply an algorithm directly, but to roughly approximately solve several perturbations of the problem and then combine these rough approximations to get an exact solution. To find a feasible solution to an m-equation linear program with a convexity constraint, the von Neumann Algorithm generates a sequence of approximate solutions which converge very slowly to the right hand side b[sup 0]. However, it can be redirected so that in the first few iterations it is guaranteed to move rapidly towards the neighborhood of one of m + 1 perturbed right hand sides [cflx b][sup i], then redirected in turn to the next [cflx b][sup i]. Once within the neighborhood of each [cflx b][sup i], a weighted sum of the approximate solutions. [bar x][sup i] yields the exact solution of the unperturbed problem where the weights are found by solving a system of m + 1 equations in m + 1 unknowns. It is assumed an r > 0 is given for which the problem is feasible for all right hand sides b whose distance [parallel]b …
Date: October 1, 1992
Creator: Dantzig, G.B.
Object Type: Report
System: The UNT Digital Library
An investigation of scramming the outer shutdown rods of the ANS with no reversal of flow in the manifold inlet lines (open access)

An investigation of scramming the outer shutdown rods of the ANS with no reversal of flow in the manifold inlet lines

This report provides calculations and calculation checks on the outer shutdown system, consisting of eight shutdown rods located on the outside of the core. The function of the system is to scram the reactor, or to break the chain reaction of the fission process. The shutdown rods are clad with a neutron-absorbing material (i.e., hafnium) to achieve scram. During normal operation, the outer shutdown rods (Fig. 1) are in a nonscram, withdrawn position. This means that they are not close enough to the core to absorb a significant number of the neutrons that cause the fission process. In the case of a malfunction or an emergency, the outer control rods are moved to a position near the core. The outer shutdown system is operated with the use of springs and hydraulics. During normal operation, a constant flow of heavy water is circulated through the reflector vessel. A part of this flow provides a pressure high enough to keep the rods in their withdrawn or upper position, a nonscram status. If any signs of abnormal operation occur, the valves in the hydraulic system cut off the flow, and the springs push the rods into the scram position, stopping the chain reaction. …
Date: October 1, 1992
Creator: Morsk, K. (Royal Inst. of Tech., Stockholm (Sweden))
Object Type: Report
System: The UNT Digital Library
Results of the radiological survey at 27 Schlosser Drive, Rochelle Park, New Jersey (RJ004) (open access)

Results of the radiological survey at 27 Schlosser Drive, Rochelle Park, New Jersey (RJ004)

Maywood Chemical Works (MCW) of Maywood, New Jersey, generated process wastes and residues associated with the production and refining of thorium and thorium compounds from monazite ores from 1916 to 1956. MCW supplied rare earth metals and thorium compounds to the Atomic Energy Commission and various other government agencies from the late 1940s to the mid-1950s. Area residents used the sandlike waste from this thorium extraction process mixed with tea and cocoa leaves as mulch in their yards. Some of these contaminated wastes were also eroded from the site into Lodi Brook. At the request of the US Department of Energy (DOE), a group from Oak Ridge National Laboratory conducts investigative radiological surveys of properties in the vicinity of MCW to determine whether a property is contaminated with radioactive residues, principally [sup 232]Tb, derived from the MCW site. The survey typically includes direct measurement of gamma radiation levels and soil sampling for radionuclide analyses. The survey of this site, 27 Schlosser Drive, Rochelle Park, New Jersey (RJ004), was conducted on July 14, 1991. Results of the survey demonstrated no radionuclide concentrations in excess of the DOE Formerly Utilized Sites Remedial Action Program criteria. The radionuclide distributions were not significantly different …
Date: October 1, 1992
Creator: Foley, R.D. & Brown, K.S.
Object Type: Report
System: The UNT Digital Library
Status report on the geology of the Oak Ridge Reservation (open access)

Status report on the geology of the Oak Ridge Reservation

This report provides an introduction to the present state of knowledge of the geology of the Oak Ridge Reservation (ORR) and a cursory introduction to the hydrogeology. An important element of this work is the construction of a modern detailed geologic map of the ORR (Plate 1), which remains in progress. An understanding of the geologic framework of the ORR is essential to many current and proposed activities related to land-use planning, waste management, environmental restoration, and waste remediation. Therefore, this report is also intended to convey the present state of knowledge of the geologic and geohydrologic framework of the ORR and vicinity and to present some of the available data that provide the basic framework for additional geologic mapping, subsurface geologic, and geohydrologic studies. In addition, some recently completed, detailed work on soils and other surficial materials is included because of the close relationships to bedrock geology and the need to recognize the weathered products of bedrock units. Weathering processes also have some influence on hydrologic systems and processes at depth.
Date: October 1, 1992
Creator: Hatcher, R.D. Jr.; Lemiszki, P.J.; Foreman, J.L. (Tennessee Univ., Knoxville, TN (United States). Dept. of Geological Sciences); Dreier, R.B.; Ketelle, R.H.; Lee, R.R. et al.
Object Type: Report
System: The UNT Digital Library
Weak ferromagnetism in [kappa]-(ET)[sub 2]Cu[N(CN)[sub 2]]Cl (open access)

Weak ferromagnetism in [kappa]-(ET)[sub 2]Cu[N(CN)[sub 2]]Cl

We present magnetization measurements at ambient pressure on [kappa]-(ET)[sub 2]Cu[N(CN)[sub 2]]Cl, an organic salt that is superconducting under pressure ([Tc] = 12.8 K at 0.3 kbar). An antiferromagnetic transition near 45 K and, for the first time in this class of materials, a transition near 22 K to a state displaying weak ferromagnetic hysteresis with a saturation moment of 8 x 10 [sup [minus]4][mu][sub B]/formula are observed. This low temperature state is characterized by a sequence of first order magnetization jumps.
Date: October 1, 1992
Creator: Welp, U.; Kwok, W. K.; Crabtree, G. W.; Carlson, K. D.; Wang, H. H.; Geiser, U. et al.
Object Type: Article
System: The UNT Digital Library
Well log evaluation of natural gas hydrates (open access)

Well log evaluation of natural gas hydrates

Gas hydrates are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas hydrates are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane hydrates appear to be the most common in nature. The amount of methane sequestered in gas hydrates is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the hydrate reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas hydrates also represent a significant drilling and production hazard. A fundamental question linking gas hydrate resource and hazard issues is: What is the volume of gas hydrates and included gas within a given gas hydrate occurrence Most published gas hydrate resource estimates have, of necessity, been made by broad extrapolation of only general knowledge of local geologic conditions. Gas volumes that may be attributed to gas hydrates are dependent on a number of reservoir parameters, including the areal extent ofthe gas-hydrate occurrence, reservoir thickness, hydrate number, reservoir …
Date: October 1, 1992
Creator: Collett, T.S.
Object Type: Report
System: The UNT Digital Library
Magnetic ring for stripping enhancement (open access)

Magnetic ring for stripping enhancement

A ring designed to recycle ions through a stripping medium offers the possibility for increasing output of the desired charge state by up to 4x. This could be a very important component of a Radioactive Nuclear Beam Facility. In order for such a ring to work effectively it must satisfy certain design conditions. These include achromaticity at the stripper, a dispersed region for an extraction magnet, and a number of first and higher order optics constraints which are necessary to insure that the beam emittance is not degraded unduly by the ring. An example is given of a candidate design of a stripping ring.
Date: October 1, 1992
Creator: Selph, F.
Object Type: Article
System: The UNT Digital Library
The reduction of NO[sub x] by HNCO. [RAPRENOx process] (open access)

The reduction of NO[sub x] by HNCO. [RAPRENOx process]

A chemical mechanism for the reduction of NO[sub x] by HNCO has been constructed to model NO[sub x] reduction in exhausts typical of natural gas combustion with the addition of radical boosters (fuel). Variables considered were the initial concentrations of NO, NO[sub 2], CO, O[sub 2], CH[sub 4], H[sub 2], and HNCO as well as initial temperatures. The chemical model was validated by comparing results with earlier model calculations of Miller and Bowman and with the experiments of Caton and Siebers and Lyon and Cole. Agreement with experiments was satisfactory. The reduction chemistry must be preceded by thermal ignition chemistry which generates radicals. The lowest temperature for which ignition occurs is the optimum temperature for reduction and defines the beginning of the temperature window. Reduction was not achieved for the natural gas exhaust'' for a reasonable residence time. Additional H[sub 2] added to the exhaust mixture enhanced reduction, but the addition of CO and CH[sub 4] did not. Under some conditions the computed sensitivity coefficient for nitrogen species and temperature exhibited self-similarity. Four reaction paths were identified which controlled the fate of the NO: the conversion of NO to NO[sub 2] via HO[sub 2], the conversion of NO[sub 2] to …
Date: October 1, 1992
Creator: Brown, N. J. & Garay, J.
Object Type: Article
System: The UNT Digital Library
Source calibrations and SDC calorimeter requirements (open access)

Source calibrations and SDC calorimeter requirements

Several studies of the problem of calibration of the SDC calorimeter exist. In this note the attempt is made to give a connected account of the requirements on the source calibration from the point of view of the desired, and acceptable, constant term induced in the EM resolution. It is assumed that a local'' calibration resulting from exposing each tower to a beam of electrons is not feasible. It is further assumed that an in situ'' calibration is either not yet performed, or is unavailable due to tracking alignment problems or high luminosity operation rendering tracking inoperative. Therefore, the assumptions used are rather conservative. In this scenario, each scintillator plate of each tower is exposed to a moving radioactive source. That reading is used to mask'' an optical cookie'' in a grey code chosen so as to make the response uniform. The source is assumed to be the sole calibration of the tower. Therefore, the phrase global'' calibration of towers by movable radioactive sources is adopted.
Date: October 1, 1992
Creator: Green, D.
Object Type: Report
System: The UNT Digital Library
Advanced separation technology for flue gas cleanup. [Hollow fiber contactors] (open access)

Advanced separation technology for flue gas cleanup. [Hollow fiber contactors]

The objective of this work is to develop a novel system for regenerable S0[sub 2] and NO. scrubbing of flue gas that focuses on (a) a novel method for regeneration of spent S0[sub 2] scrubbing liquor and (b) novel chemistry for reversible absorption of NO[sub x]. In addition, high efficiency hollow fiber contactors (HFC) are proposed as die devices for scrubbing the S0[sub 2] and NO[sub x] from the flue gas. The system will be designed to remove more than 95% of the SO[sub x] and more than 75% of the NO[sub x] from flue gases typical of pulverized coal-fired power plants at a cost that is at least 20% less than combined wet limestone scrubbing of SO[sub x] and selective catalytic reduction of NO[sub x]. In addition, the process will make only marketable byproducts, if any (no waste streams). The major cost item in existing technology is capital investment therefore, our approach is to reduce the capital cost by using high efficiency hollow fiber devices for absorbing and desorbing the SO[sub 2] and NO[sub x]. We will also introduce new process chemistry to minimize traditionally well-known problems with SO[sub 2] and NO[sub x] absorption and desorption. For example, we …
Date: October 1, 1992
Creator: unknown
Object Type: Report
System: The UNT Digital Library
A carbon-carbon composite materials development program for fusion energy applications (open access)

A carbon-carbon composite materials development program for fusion energy applications

Carbon-carbon composites increasingly are being used for plasma-facing component (PFC) applications in magnetic-confinement plasma-fusion devices. They offer substantial advantages such as enhanced physical and mechanical properties and superior thermal shock resistance compared to the previously favored bulk graphite. Next-generation plasma-fusion reactors, such as the International Thermonuclear Experimental Reactor (ITER) and the Burning Plasma Experiment (BPX), will require advanced carbon-carbon composites possessing extremely high thermal conductivity to manage the anticipated extreme thermal heat loads. This report outlines a program that will facilitate the development of advanced carbon-carbon composites specifically tailored to meet the requirements of ITER and BPX. A strategy for developing the necessary associated design data base is described. Materials property needs, i.e., high thermal conductivity, radiation stability, tritium retention, etc., are assessed and prioritized through a systems analysis of the functional, operational, and component requirements for plasma-facing applications. The current Department of Energy (DOE) Office of Fusion Energy Program on carbon-carbon composites is summarized. Realistic property goals are set based upon our current understanding. The architectures of candidate PFC carbon-carbon composite materials are outlined, and architectural features considered desirable for maximum irradiation stability are described. The European and Japanese carbon-carbon composite development and irradiation programs are described. The Working …
Date: October 1, 1992
Creator: Burchell, T.D.; Eatherly, W.P. (Oak Ridge National Lab., TN (United States)); Engle, G.B. (Nuclear and Aerospace Materials Corp., Poway, CA (United States)) & Hollenberg, G.W. (Battelle Pacific Northwest Lab., Richland, WA (United States))
Object Type: Report
System: The UNT Digital Library
The role of the Federal Relighting Initiative in emission controls (open access)

The role of the Federal Relighting Initiative in emission controls

The Department of Energy's (DOE) Federal Relighting Initiative (FRI), under the Federal Energy Management Program (FEMP), has developed a comprehensive process to assist federal agencies in meeting the nation's energy mandate. This mandate states that federal facilities must use 20% less energy by the year 2000, based on 1985 consumption levels. Because lighting accounts for about 40% of total federal electricity consumption, the FRI was conceived to help reduce energy use in this important area while improving lighting quality and increasing productivity through relighting. Selected federal rules and regulations provide guidance on the types of energy efficiency techniques required, life-cycle costing methods and lighting levels that should be employed to achieve the federal mandate. Although the central focus of this paper is on the environment, this paper takes the perspective that the energy efficiency gains achieved through the FRI would produce both environmental and economic benefits for the United States. For example, improvements in energy efficiency would reduce electricity demand, and would consequently reduce the emissions associated with fossil fuel combustion for power production. These reduced emissions include carbon dioxide, which is associated with the potential for global climate change, and heavy metals, which pose a potential health threat to …
Date: October 1, 1992
Creator: Nicholls, A.K.; Purcell, C.W. & Friedman, J.R.
Object Type: Article
System: The UNT Digital Library
Design of a pulsed x-ray system for fluorescent lifetime measurements with a timing accuracy of 109 ps (open access)

Design of a pulsed x-ray system for fluorescent lifetime measurements with a timing accuracy of 109 ps

We describe the design of a table-top pulsed x-ray system for measuring fluorescent lifetime and wavelength spectra of samples in both crystal and powdered form. The novel element of the system is a light-excited x-ray tube with a tungsten anode at +30 kV potential. The S-20 photocathode is excited by a laser diode with a maximum rate of 10 MHz, each pulse having [lt]100 ps fwhm (full-width at half-maximum) and [gt]107 photons. In a collimated 2 mm [times] 2 mm beam spot 40 mm from the anode we expect [gt]1 x-ray per pulse. A sample is exposed to these x-rays and fluorescent photons are detected by a microchannel PMT with a photoelectron transit time spread of 60 ps fwhm, a sapphire window, and a bialkali photocathode (wavelength range 180--600 nm). The combined time spread of a laser diode, the x-ray tube, and a microchannel tube has been measured to be 109 ps fwhm. To measure wavelength spectra, a reflection grating monochromator is placed between the sample and the PMT.
Date: October 1, 1992
Creator: Derenzo, S. E.; Moses, W. W.; Blankespoor, S. C. (Lawrence Berkeley Lab., CA (United States)); Ito, M. & Oba, K. (Hamamatsu Photonics K.K., Hamamatsu City (Japan))
Object Type: Article
System: The UNT Digital Library