U.S. Radioecology Research Programs of the Atomic Energy Commission in the 1950s (open access)

U.S. Radioecology Research Programs of the Atomic Energy Commission in the 1950s

This report contains two companion papers about radiological and environmental research that developed out of efforts of the Atomic Energy Commission in the late 1940s and the 1950s. Both papers were written for the Joint U.S.-Russian International Symposium entitled ''History of Atomic Energy Projects in the 1950s--Sociopolitical, Environmental, and Engineering Lessons Learned,'' which was hosted by the International Institute for Applied Systems Analysis in Laxemberg, Austria, in October 1999. Because the proceedings of this symposium were not published, these valuable historic reviews and their references are being documented as a single ORNL report. The first paper, ''U.S. Radioecology Research Programs Initiated in the 1950s,'' written by David Reichle and Stanley Auerbach, deals with the formation of the early radioecological research programs at the U.S. Atomic Energy Commission's nuclear production facilities at the Clinton Engineering Works in Oak Ridge, Tennessee; at the Hanford Plant in Richland, Washington; and at the Savannah River Plant in Georgia. These early radioecology programs were outgrowths of the environmental monitoring programs at each site and eventually developed into the world renowned National Laboratory environmental program sponsored by the Office of Biological and Environmental Research of the U.S. Department of Energy. The original version of the first …
Date: January 12, 2004
Creator: Reichle, D.E.
System: The UNT Digital Library
Small-Column Ion-Exchange Alternative to Remove 137Cs from Low-Curie Salt Waste: Summary of Phase 1 (open access)

Small-Column Ion-Exchange Alternative to Remove 137Cs from Low-Curie Salt Waste: Summary of Phase 1

A Small-Column Ion-Exchange (SCIX) system is being evaluated for removing cesium from the Type 2 and/or Type 3 dissolved saltcake wastes at the Savannah River Site (SRS) to ensure that the dissolved saltcake meets the waste acceptance criteria at the Saltstone Facility. Both crystalline silicotitanate (CST) and IONSIV{trademark} IE-96 zeolite were evaluated as the ion-exchange media. The accelerated alternative, using CST in the SCIX, could save as much as $3 billion in operating and storage costs and {approx}20 years in processing time compared to the current baseline. With its proven high cesium-loading capacity for the expected dissolved saltcake compositions and temperatures, CST is the preferred sorbent for SCIX. The low-cost alternative sorbent, zeolite, greatly increases the volume of sorbent required because of its much lower cesium-loading capacity. Thus, zeolite greatly increases the cost for the alternative, mainly because of the increased number of Defense Waste Processing Facility canisters required to dispose of the loaded sorbent (potentially over 7000 for zeolite, compared with <500 for CST). The models previously developed for predicting cesium loading on CST compared favorably with laboratory measurements of equilibrium distribution ratios and column loading performance using dissolved saltcake simulants. These models predict that a column of 432 …
Date: May 12, 2004
Creator: Walker, J. F. Jr.
System: The UNT Digital Library
Computation Directorate Annual Report 2003 (open access)

Computation Directorate Annual Report 2003

Big computers are icons: symbols of the culture, and of the larger computing infrastructure that exists at Lawrence Livermore. Through the collective effort of Laboratory personnel, they enable scientific discovery and engineering development on an unprecedented scale. For more than three decades, the Computation Directorate has supplied the big computers that enable the science necessary for Laboratory missions and programs. Livermore supercomputing is uniquely mission driven. The high-fidelity weapon simulation capabilities essential to the Stockpile Stewardship Program compel major advances in weapons codes and science, compute power, and computational infrastructure. Computation's activities align with this vital mission of the Department of Energy. Increasingly, non-weapons Laboratory programs also rely on computer simulation. World-class achievements have been accomplished by LLNL specialists working in multi-disciplinary research and development teams. In these teams, Computation personnel employ a wide array of skills, from desktop support expertise, to complex applications development, to advanced research. Computation's skilled professionals make the Directorate the success that it has become. These individuals know the importance of the work they do and the many ways it contributes to Laboratory missions. They make appropriate and timely decisions that move the entire organization forward. They make Computation a leader in helping LLNL achieve …
Date: March 12, 2004
Creator: Crawford, D L; McGraw, J R; Ashby, S F; McCoy, M G; Michels, T C & Eltgroth, P G
System: The UNT Digital Library
On The Use Of Models To Assess Foot-And-Mouth Disease Transmission And Control (open access)

On The Use Of Models To Assess Foot-And-Mouth Disease Transmission And Control

The 2001 outbreaks of foot-and-mouth disease (FMD) in Europe (Ferguson et al. 2001a, 2001b; Bouma et al. 2003) and concern about the possibility of an intentional introduction of a devastating foreign animal disease triggered renewed interest in both theoretical and experimental research related to FMD. Theoretical models of disease transmission, which influenced the tactical decisions of the United Kingdom (UK) government during the epidemic (Taylor 2003), resulted in large numbers of uninfected animals being slaughtered. After the epidemic, the adopted control policies were sharply criticized (Kitching 2004;, Taylor 2003). Still, the role of computationaL modeling for analyzing the scope of the epidemic and devising control strategies was recognized as substantial and necessary.
Date: July 12, 2004
Creator: Kostova-Vassilevska, Tanya
System: The UNT Digital Library
Validation of the Use of the NMR MOUSE for Detection of Inhomogeneities in DC745 at Production (open access)

Validation of the Use of the NMR MOUSE for Detection of Inhomogeneities in DC745 at Production

In an effort to develop a QA/QC protocol to be used in the development of new pads, we are employing a tabletop unilateral NMR relaxometer called the NMR MOUSE (MObile Universal Surface Explorer). Model materials of varying crosslink density first demonstrated the applicability of the method. Analysis of deformed pads returned from service has been shown to be clearly distinguishable by the NMR MOUSE. Finally, we have quantified the variables associated with taking the relevant measurements and believe that the NMR MOUSE is a viable production and surveillance tool for screening of future DC745 parts.
Date: November 12, 2004
Creator: Chinn, S.; Sawvel, A. & Maxwell, R.
System: The UNT Digital Library
User Instructions for the Systems Assessment Capability, Rev. 1, Computer Codes Volume 1: Inventory, Release, and Transport Modules (open access)

User Instructions for the Systems Assessment Capability, Rev. 1, Computer Codes Volume 1: Inventory, Release, and Transport Modules

This document contains detailed user instructions for the transport codes for Rev. 1 of the System Assessment Capability.
Date: September 12, 2004
Creator: Eslinger, Paul W.; Miley, Terri B.; Engel, David W.; Nichols, William E.; Gerhardstein, Lawrence H.; Strenge, Dennis L. et al.
System: The UNT Digital Library
Borehole Data Package for Four CY 2003 RCRA Wells 299-E27-4, 299-E27-21, 299-E27-22, and 299-E27-23 at Single-Shell Tank, Waste Management Area C, Hanford Site, Washington (open access)

Borehole Data Package for Four CY 2003 RCRA Wells 299-E27-4, 299-E27-21, 299-E27-22, and 299-E27-23 at Single-Shell Tank, Waste Management Area C, Hanford Site, Washington

Four new Resource Conservation and Recovery Act (RCRA) groundwater monitoring wells were installed at the single-shell tank farm Waste Management Area (WMA) C in fiscal year 2003 to fulfill commitments for well installations proposed in the draft Hanford Federal Facility Agreement and Consent Order milestone M-24-00. Well 299-E27-22, installed upgradient, was drilled through the entire uppermost unconfined aquifer to the basalt and wells 299-E27-4, 299-E27-21 and 299-E27-23 were drilled approximately 40 feet into the uppermost unconfined aquifer and installed downgradient of the WMA. Specific objectives for these wells include monitoring the impact, if any, that potential releases from inside the WMA may have on current groundwater conditions (i.e., improved network coverage) and differentiating upgradient groundwater contamination from contaminants released at the WMA. This report supplies the information obtained during drilling, characterization, and installation of the four new groundwater monitoring wells. This document also provides a compilation of hydrogeologic and well construction information obtained during drilling, well development, aquifer testing, and sample collection/analysis activities.
Date: May 12, 2004
Creator: Williams, Bruce A. & Narbutovskih, Susan M.
System: The UNT Digital Library
Atmospheric Dispersal and Dispostion of Tephra From a Potential Volcanic Eruption at Yucca Mountain, Nevada (open access)

Atmospheric Dispersal and Dispostion of Tephra From a Potential Volcanic Eruption at Yucca Mountain, Nevada

The purpose of this model report is to provide documentation of the conceptual and mathematical model (ASHPLUME) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. The ASHPLUME conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The ASHPLUME mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report will improve and clarify the previous documentation of the ASHPLUME mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model.
Date: February 12, 2004
Creator: Keating, G. & W.Statham
System: The UNT Digital Library
Topical Report: Task 2.1 "Aphron Visualization" (open access)

Topical Report: Task 2.1 "Aphron Visualization"

The Acoustic Bubble Spectrometer has been identified as a potential method for monitoring the size distribution of aphrons in situ, such as in an oil well drilling fluid flowline.1 Research was continued from Task 1.1 of this Project, Aphron Visualization,2 in which ABS was tested against laser light scattering (Coulter Counter) and optical (visual) imaging to determine the bubble size distribution (BSD) of the aphrons at ambient temperature and pressure. Task 2.1 continued this investigation by measuring the bubble size distribution via ABS and optical imaging at elevated pressures up to 2000 psig.
Date: December 12, 2004
Creator: O'Connor, Bob & Growcock, Fred
System: The UNT Digital Library
Minority Summer Research Program in the Plant Sciences (open access)

Minority Summer Research Program in the Plant Sciences

Gutierrez and Larcom (2000) suggest that ''According to the National Science Foundation/Division of Science Resources Studies in 1997, the percentage distribution of scientists and engineers in the labor force by race/ethnicity changed little between 1993 and 1997''. According to this report, Black, non-Hispanic went from 3.6 in 1993 to 3.4 in 1997. Hispanic went from 3.0 in 1993 to 3.1 in 1997; and American Indian/Alaskan Native stayed the same at 0.3 during the same period. The only exceptions were a slight increase in the percentage of Asian from 9.2 in 1993 to 10.4 in 1997, while a slight decrease in percentage White from 83.9 in 1993 to 82.8 in 1997. Overall, no major changes in minorities were present in the science and engineering fields during that period. These data shows that major efforts are needed in order to improve and achieve better results for diversity in the workplace (Gutierrez & Larcom, 2000). This does not mean that major steps have not been taken over this period. For example, the Minority Summer Research Program in Plant Sciences (also funded in part by NSF under the title, ''Undergraduate Researchers in Plant Sciences Program'') was established in an effort to enhance the diversity …
Date: August 12, 2004
Creator: Poff, Kenneth L.
System: The UNT Digital Library
Analysis of KEK-ATF Optics and Coupling Using LOCO (open access)

Analysis of KEK-ATF Optics and Coupling Using LOCO

LOCO is a code for analysis of the linear optics in astorage ring based on the closed orbit response to steering magnets. Theanalysis provides information on focusing errors, BPM gain and rotationerrors,and local coupling. Here, we report the results of an applicationof LOCO to the KEK-ATF. Although the analysis appears to have provideduseful information on the optics of the machine, it appears that one ofthe main aims of the study to reduce the vertical emittance by correctingthe local coupling was not successful, and we discuss some possiblereasons for this.
Date: January 12, 2004
Creator: Wolski, Andrzej; Ross, Marc; Woodley, Mark; Nelson, Janice & Mishra, Shekhar
System: The UNT Digital Library
Aluminum Leaching of ''Archived'' Sludge from Tanks 8F, 11H, and 12H (open access)

Aluminum Leaching of ''Archived'' Sludge from Tanks 8F, 11H, and 12H

Aluminum can promote formation or dissolution of networks in hydroxide solid solutions. When present in large amounts it will act as a network former increasing both the viscosity and the surface tension of melts. This translates into poor free flow properties that affect pour rate of glass production in the Defense Waste Processing Facility (DWPF). To mitigate this situation, DWPF operations limit the amount of aluminum contained in sludge. This study investigated the leaching of aluminum compounds from archived sludge samples. The conclusions found boehmite present as the predominant aluminum compound in sludge from two tanks. We did not identify an aluminum compound in sludge from the third tank. We did not detect any amorphous aluminum hydroxide in the samples. The amount of goethite measured 4.2 percentage weight while hematite measured 3.7 percentage weight in Tank 11H sludge. The recommended recipe for removing gibbsite in sludge proved inefficient for digesting boehmite, removing less than 50 per cent of the compound within 48 hours. The recipe did remove boehmite when the test ran for 10 days (i.e., 7 more days than the recommended baseline leaching period). Additions of fluoride and phosphate to Tank 12H archived sludge did not improve the aluminum …
Date: March 12, 2004
Creator: Fondeur, Fernando F.; Hobbs, D. T. & Fink, S. D.
System: The UNT Digital Library
Stability analysis of the laser system for the TTF photoinjector at Fermilab (open access)

Stability analysis of the laser system for the TTF photoinjector at Fermilab

A solid-state laser system that produces a 1MHz pulse train of 800 pulses with 18 {micro}J per pulse at {lambda} = 263.5 nm has been developed to meet the requirements of the TESLA Test Facility (TTF) at Fermilab and in operation since 1998.[1,2] Besides the production of high charges, high brightness electron beams, the need for high bunch charge stability requires that each laser pulse in the pulse train must have the same energy, and the energy per laser pulse should not vary significantly from shot to shot. This motivates the stability analysis of the laser system for the TTF photoinjector.
Date: May 12, 2004
Creator: Yang, Xi
System: The UNT Digital Library
INTEGRATING P-WAVE AND S-WAVE SEISMIC DATA TO IMPROVE CHARACTERIZATION OF OIL RESERVOIRS (open access)

INTEGRATING P-WAVE AND S-WAVE SEISMIC DATA TO IMPROVE CHARACTERIZATION OF OIL RESERVOIRS

During this period, the principal investigator wrote an abstract and research accomplishments which was published in the journal of the historically black colleges and universities and other minority institutions contract review meeting of June 2003. Interpretations and analysis of data from the study area shows that incident full-elastic seismic wavefield reflected four different wave modes, P, fast-S (SH) , slow-S (SV) and C. These four wave modes image unique geologic stratigraphy and facies and at the same time reflect independent stratal surfaces. It was also observed that P-wave and S-wave do not always reflect from the same stratal boundaries. At inline coordinate 2100 and crossline coordinates of 10,380, 10430, 10480 and 10,520 the P-wave stratigraphy shows coherency at time slice 796 m/s and C-wave stratigraphy shows coherency at time slice 1964 m/s at the same inline coordinate and crossline coordinates of 10,400 to 10470. At inline coordinate 2800 and crossline coordinate 10,650, P-wave stratigraphy shows coherency at time slice 792 m/s and C-wave stratigraphy shows coherency at time slice 1968 m/s.
Date: January 12, 2004
Creator: Aluka, Innocent J.
System: The UNT Digital Library
Amorphous Silicon Based Neutron Detector (open access)

Amorphous Silicon Based Neutron Detector

Various large-scale neutron sources already build or to be constructed, are important for materials research and life science research. For all these neutron sources, neutron detectors are very important aspect. However, there is a lack of a high-performance and low-cost neutron beam monitor that provides time and temporal resolution. The objective of this SBIR Phase I research, collaboratively performed by Midwest Optoelectronics, LLC (MWOE), the University of Toledo (UT) and Oak Ridge National Laboratory (ORNL), is to demonstrate the feasibility for amorphous silicon based neutron beam monitors that are pixilated, reliable, durable, fully packaged, and fabricated with high yield using low-cost method. During the Phase I effort, work as been focused in the following areas: 1) Deposition of high quality, low-defect-density, low-stress a-Si films using very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) at high deposition rate and with low device shunting; 2) Fabrication of Si/SiO2/metal/p/i/n/metal/n/i/p/metal/SiO2/ device for the detection of alpha particles which are daughter particles of neutrons through appropriate nuclear reactions; and 3) Testing of various devices fabricated for alpha and neutron detection; As the main results: · High quality, low-defect-density, low-stress a-Si films have been successfully deposited using VHF PECVD on various low-cost substrates; · …
Date: December 12, 2004
Creator: Xu, Liwei
System: The UNT Digital Library
Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipline Leak Detection Semi-Annual Report: October 2003 - April 2004 (open access)

Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipline Leak Detection Semi-Annual Report: October 2003 - April 2004

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The third six-month technical report contains a summary of the progress made towards finalizing the design and assembling the airborne, remote methane and ethane sensor. The vendor has been chosen and is on contract to develop the light source with the appropriate linewidth and spectral shape to best utilize the Ophir gas correlation software. Ophir has expanded upon the target reflectance testing begun in the previous performance period by replacing the experimental receiving optics with the proposed airborne large aperture telescope, which is theoretically capable of capturing many times more signal return. The data gathered from these tests has shown the importance of optimizing the fiber optic receiving fiber to the receiving optic and has helped Ophir to optimize the design of the gas cells and narrowband optical filters. Finally, Ophir will discuss remaining project issues that may impact the success of the project.
Date: May 12, 2004
Creator: Myers, Jerry
System: The UNT Digital Library
DWPF Glass Air-Lift Pump Life Cycle Testing and Plant Implementation (open access)

DWPF Glass Air-Lift Pump Life Cycle Testing and Plant Implementation

Due to the accelerated cleanup at the Savannah River Site (SRS), efforts are underway to increase the glass melt rate and hence the high level waste processing throughput at the SRS Defense Waste Processing Plant Facility (DWPF). One of the proposed process/equipment improvements is a glass air-lift pump. The use of a glass air-lift pump to increase melt rate in the DWPF Melter has been investigated via several techniques including lab scale testing on various melters. The final test before implementation in DWPF was a long-term life cycle test (several months in duration) on a full size pump. The air-lift pump was successfully tested and no major problems were found. Based on this test a unit was designed and fabricated for DWPF and was installed in the DWPF Melter in February 2004.
Date: May 12, 2004
Creator: SMITH, MICHAEL
System: The UNT Digital Library
Filtration of a Hanford AW-101 Waste Sample (open access)

Filtration of a Hanford AW-101 Waste Sample

The objectives of this test were: determine the optimum filter operating parameters to maximize filter flux; determine whether the mean filter flux across the dewatering cycle matches or exceeds the plant design throughput; dewater the feed sample to 20 wt percentage insoluble solids; wash the sample to determine which species are removed during the washing process; provide filtrate to the ion exchange test program; the project flowsheet for the separation of LAW entrained solids assumes the entrained solids slurry from ultrafiltration contains 20 wt percentage insoluble solids by weight. These tests must therefore confirm that the slurry rheology is compatible with this requirement. No solids must pass into the ultrafiltration permeate; and after the filtration stage is complete, the rig will be chemically cleaned to determine if the clean water flux can be returned to pre-operation (clean) levels.
Date: May 12, 2004
Creator: POIRIER, M.R.
System: The UNT Digital Library
Statistical Comparison of Gross Alpha and Radium Measurement Between Background and Point of Compliance (POC) Wells at the SRS Sanitary Landfill (SLF) (open access)

Statistical Comparison of Gross Alpha and Radium Measurement Between Background and Point of Compliance (POC) Wells at the SRS Sanitary Landfill (SLF)

Statistical analyses were performed on groundwater monitoring data obtained for gross alpha, radium 226, and 228 from the SRS Sanitary Landfill (SLF). Several inference tests were performed using the prescribed statistical methods of the Resource Conservation and Recovery Act Part B Permit regulations (US EPA 1992). Test results show that the LFW 29R, LFW 57B and LFW 62B wells have significantly elevated concentrations of all three radiological constituents above background. However, isotopic ratios of Ra228 to Ra226 are consistent with naturally occurring concentrations of each. In addition, corresponding pH data for these same three wells suggests that acidic conditions may have effected a mobilization of naturally occurring radium from the soils associated with the SLF. In fact, there is a statistically significant and negative correlation between gross alpha, Ra226, and Ra228 measurements vs pH.
Date: July 12, 2004
Creator: TUCKFIELD, RICHARD
System: The UNT Digital Library
Fermilab drift tube Linac revisited (open access)

Fermilab drift tube Linac revisited

Using the PARMILA code running under PC-WINDOWS, the present performance of the Fermilab Drift Tube Linac has been analyzed in the light of new demands on the Linac/Booster complex (the Proton Source). The Fermilab Drift Tube Linac (DTL) was designed in the sixties as a proton linac with a final energy of 200 MeV and a peak current of 100mA. In the seventies, in order to enable multi-turn charge exchange injection into the Booster, the ion source was replaced by an H- source with a peak beam current of 25mA. Since then the peak beam current was steadily increased up to 55mA. In the early nineties, part of the drift tube structure was replaced with a side-coupled cavity structure in order to increase the final energy to 400 MeV. The original and still primary purpose of the linac is to serve as the injector for the Booster. As an added benefit, the Neutron Therapy Facility (NTF) was built in the middle seventies. It uses 66MeV protons from the Linac to produce neutrons for medical purposes. The Linac/Booster complex was designed to run at a fundamental cycling rate of 15Hz, but beam is accelerated on every cycle only when NTF is …
Date: May 12, 2004
Creator: Popovic, Milorad
System: The UNT Digital Library
Resistive Drift Waves in a Bumpy Torus (open access)

Resistive Drift Waves in a Bumpy Torus

A computational study of resistive drift waves in the edge plasma of a bumpy torus is presented. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.
Date: January 12, 2004
Creator: Lewandowski, J.L.V.
System: The UNT Digital Library
Spectrometric Analysis for Pulse Jet Mixer Testing (open access)

Spectrometric Analysis for Pulse Jet Mixer Testing

The Analytical Development Section (ADS) was tasked with providing support for a Hanford River Protection Program-Waste Treatment Program (RPP-WTP) project test involving absorption analysis for non-Newtonian pulse jet mixer testing for small scale (PJM) and prototype (CRV) tanks with sparging. Tanks filled with clay were mixed with various amounts of powdered dye as a tracer. The objective of the entire project was to determine the best mixing protocol (nozzle velocity, number of spargers used, total air flow, etc.) by determining the percent mixed volume through the use of an ultraviolet-visible (UV-Vis) spectrometer. The dye concentration within the sample could be correlated to the volume fraction mixed in the tank. Samples were received in vials, a series of dilutions were generated from the clay, allowed to equilibrate, then centrifuged and siphoned for the supernate liquid to analyze by absorption spectroscopy. Equilibration of the samples and thorough mixing of the samples were a continuous issue with dilution curves being difficult to obtain. Despite these technical issues, useful data was obtained for evaluation of various mix conditions.
Date: July 12, 2004
Creator: ZEIGLER, KRISTINE
System: The UNT Digital Library
Gamma Ray Imaging for Environmental Remediation (open access)

Gamma Ray Imaging for Environmental Remediation

This program is the development of germanium strip detectors for environmental remediation. It is a collaboration between the Naval Research Laboratory and Lawrence Berkeley National Lab. The goal is to develop detectors that are simultaneously capable of excellent spectroscopy and imaging of gamma radiation.
Date: November 12, 2004
Creator: Philips, B.F.; Johnson, R.A. Kroeger: J.D. Kurfess: W.N.; Wulf, E.A. & Novikova, E. I.
System: The UNT Digital Library
Reaching sub-Angstrom resolution with a mid-voltage TEM (open access)

Reaching sub-Angstrom resolution with a mid-voltage TEM

Phase-contrast imaging in the high-resolution electron microscope produces images with peaks at atom positions by extracting the spatial distribution of the relative phase from the electron wave. Usually, the electron wave is imaged by direct interference of diffracted beams at optimum focus. Instead, the One-Angstrom Microscope uses focal-series reconstruction software to derive the relative electron phase from a series of images taken over a range of focus, with peaks that correspond to the atom positions at a resolution that extends to the microscope information limit. Tests using a silicon specimen tilted into [112] orientation show that the O Angstrom M has achieved a world-record resolution of 0.78 Angstrom.
Date: April 12, 2004
Creator: O'Keefe, Michael A.; Hetherington, Crispin J.D. & Nelson, E. Chris
System: The UNT Digital Library