Beam dynamics studies in a high-brightness photo-injector (open access)

Beam dynamics studies in a high-brightness photo-injector

A high-brightness photo-injector has been developed at Fermilab in collaboration with the TTF project at DESY. Two systems have been commissioned, one at DESY and one at Fermilab. The injector [1] consists of a 1.625-cell cavity RF gun, a superconducting niobium cavity (both 1.3 GHz), and a magnetic chicane. The gun is designed for an electric field of up to 50 MV/m on the cathode. Emittance compensation solenoids surround the gun to correct the linear space charge emittance growth. A high quantum efficiency Cs{sub 2}Te photocathode located in the first half-cell produces electrons when illuminated by 263 nm wavelength light (fourth harmonic of the Nd:YLF laser). The laser [2] was designed to produce a train of up to 800 equal amplitude, 10 {micro}J UV pulses spaced by 1 {micro}s at 1 Hz repetition rate. The laser pulse length is adjustable between 1 and 20 ps FWHM. The superconducting cavity is a 9-cell Nb structure fabricated by industry for TTF. It was tested with RF at DESY before being sent to Fermilab. At present, the cavity is operated at {approx}11 MeV/m. Beam measurements with the injector at Fermilab are in progress. Preliminary results for emittance and bunch length will be discussed …
Date: October 25, 1999
Creator: Carneiro, Jean-Paul
Object Type: Article
System: The UNT Digital Library
The Physics of Fast Z Pinches (open access)

The Physics of Fast Z Pinches

The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizing the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 36 figures and more than 300 references.
Date: October 25, 1999
Creator: Ryutov, D. D.; Derzon, Mark S. & Matzen, M. Keith
Object Type: Article
System: The UNT Digital Library
High Voltage GaN Schottky Rectifiers (open access)

High Voltage GaN Schottky Rectifiers

Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and {ge}15 for the 2kV diodes. Reverse recovery times were <0.2{micro}sec for devices switched from a forward current density of {approx}500A{center_dot}cm{sup -2} to a reverse bias of 100V.
Date: October 25, 1999
Creator: Cao, X. A.; Cho, H.; Chu, S. N. G.; Chuo, C. C.; Chyi, J. I.; Dang, G. T. et al.
Object Type: Article
System: The UNT Digital Library
New W mass results from CDF and D0 (open access)

New W mass results from CDF and D0

This article describes recent measurements of the W mass by the CDF and D0 Collabo-rations. CDF obtains a preliminary result of 80.473 ± 0.113 GeV for the W mass in the electron channel and D0 reports a preliminary result of 80.766 ± 0.234 GeV for electrons in the more forward (Endcap) rapidities. When combined with all previous measurements, the current average for the W mass measured at the Tevatron is 80.450 ± 0.063 GeV.
Date: October 25, 1999
Creator: Carithers, B.
Object Type: Article
System: The UNT Digital Library
Proton driver study at Fermilab (open access)

Proton driver study at Fermilab

Fermilab has started the design work of a high intensity proton source called the proton driver. It would provide a 4 MW proton beam to the target for muon production. This paper discusses the basic features of this machine and the associated accelerator physics and design issues.
Date: October 25, 1999
Creator: Chou, Weiren
Object Type: Article
System: The UNT Digital Library
FPIX1: An advanced pixel readout chip (open access)

FPIX1: An advanced pixel readout chip

At Fermilab, a pixel detector for BTeV is proposed for installation a few millimeters from the beam. Its information will be used in on-line track finding for the lowest level trigger system. This requires a high-speed readout and immediate data transfer from the pixel chip to the trigger processor. It is also believed that a 2-4 bits of analog information is required to achieve the targeted spatial resolution [1] with 50{micro} wide pixels. Our first prototype, FPIX0 [2], is now being used in a beam test to confirm physics simulations and to determine the required resolution of the analog ''information''. Our 2nd prototype, FPIX1, is a 160X18 pixel readout chip compatible with the ATLAS family of detectors. We have build and tested 4 FPIX1-detector assemblies. FPIX1 is realized in the HP 0.5{micro} process. The main features of FPIX1 are: 2bit flash ADC on each cell for maximum speed; Triggered or stand alone operation; and High speed sparse and time ordered Readout.
Date: October 25, 1999
Creator: al., A. Mekkaoui et
Object Type: Article
System: The UNT Digital Library
Approximate Near-Field Blast Theory: A Generalized Approach (open access)

Approximate Near-Field Blast Theory: A Generalized Approach

A method for analyzing strong shock waves in arbitrary one-dimensional geometry is presented. An approximation to classical Taylor-Sedov theory is extended to the near-field case where source mass is not negligible, accounting for differences in the chemical properties of the source mass and ambient medium. Results from example calculations are compared with previously published analytical formulae.
Date: October 25, 1999
Creator: Hutchens, G.J.
Object Type: Article
System: The UNT Digital Library
First results of the Fermilab high-brightness RF photoinjector (open access)

First results of the Fermilab high-brightness RF photoinjector

A collaboration has been formed between FNAL, UCLA, INFN Milano, the University of Rochester, and DESY to develop the technology of an RF photoinjector, followed by a superconducting cavity, to produce high bunch charge (8 nC) with low normalized emittance (< 20 mm {center_dot} mrad) in trains of 800 bunches separated by 1{micro}s. The activities of the collaboration fall into two categories: (1) the development of Injector II for the TeSLA/TTF accelerator [1]. This photoinjector (TTF RF Gun)was tested at Fermilab in September and October 1998 and installed at DESY in November 1998; (2) the installation at the A0 Hall of Fermilab of a modified version of the TTF photoinjector, for photoinjector R&D and to study novel applications of high-brightness, pulsed electrons beams. This photoinjector (A0 RF Gun) produced its first beam in March 1999. This paper presents a summary of the tests done at Fermilab on the TTF Injector II and the first results obtained on the new Fermilab photoinjector.
Date: October 25, 1999
Creator: Carneiro, Jean-Paul
Object Type: Article
System: The UNT Digital Library
Monthly energy review, October 1995 (open access)

Monthly energy review, October 1995

This is the June report by the Energy Information Administration. The contents of the report include an energy overview, energy consumption, petroleum, natural gas, oil and gas resource development, coal, electricity, nuclear energy, energy prices, and international energy. Included are appendices containing thermal conversion factors, metric and other physical conversion factors, and carbon dioxide emission factors for coal.
Date: October 25, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Portable X-Ray, K-Edge Heavy Metal Detector (open access)

Portable X-Ray, K-Edge Heavy Metal Detector

The X-Ray, K-Edge Heavy Metal Detection System was designed and built by Ames Laboratory and the Center for Nondestructive Evaluation at Iowa State University. The system uses a C-frame inspection head with an X-ray tube mounted on one side of the frame and an imaging unit and a high purity germanium detector on the other side. the inspection head is portable and can be easily positioned around ventilation ducts and pipes up to 36 inches in diameter. Wide angle and narrow beam X-ray shots are used to identify the type of holdup material and the amount of the contaminant. Precise assay data can be obtained within minutes of the interrogation. A profile of the containerized holdup material and a permanent record of the measurement are immediately available.
Date: October 25, 1999
Creator: Fricke, V.
Object Type: Report
System: The UNT Digital Library
Cobalt Source Calibration (open access)

Cobalt Source Calibration

The data obtained from these tests determine the dose rate of the two cobalt sources in SRTC. This testing used chemical dosimetry to measure the dose rate of a radioactive source.
Date: October 25, 1999
Creator: Barnes, M.
Object Type: Report
System: The UNT Digital Library
Prospects for higgs discovery at the Tevatron (open access)

Prospects for higgs discovery at the Tevatron

This report presents the results of a Fermilab study of the sensitivity for Higgs boson production at the upgraded Tevatron in Run II. The study extends previous Tevatron results by combining all possible search channels, considering the production of higher mass Higgs bosons and interpreting the results in the context of supersymmetric Higgs production as well as Standard Model production.
Date: October 25, 1999
Creator: Roco, Maria Teresa P.
Object Type: Article
System: The UNT Digital Library
Laboratory measurements of compressional and shear wave speeds through methane hydrate (open access)

Laboratory measurements of compressional and shear wave speeds through methane hydrate

Simultaneous measurements of compressional and shear wave speeds through polycrystalline methane hydrate have been made. Methane hydrate, grown directly in a wave speed measurement chamber, was uniaxially compacted to a final porosity below 2%. At 277 K, the compacted material's compressional wave speed was 3650 {+-} 50 m/s. The shear wave speed, measured simultaneously, was 1890 {+-} 30 m/s. From these wave speed measurements, we derive Vp/Vs, Poisson's Ratio, bulk, shear and Young's moduli.
Date: October 25, 1999
Creator: Durham, W B; Waite, WF; Pinkston, J C; Stern, L A; Kirby, S H; Helgerud, M B et al.
Object Type: Article
System: The UNT Digital Library
TNX GeoSiphon Cell (TGSC-1) Phase II Minimum Flushing Velocity Deployment/Demonstration Final Report (open access)

TNX GeoSiphon Cell (TGSC-1) Phase II Minimum Flushing Velocity Deployment/Demonstration Final Report

The TNX Area is a semi-works facility for the Savannah River Technology Center (SRTC), which is located one-quarter mile from the Savannah river at the Savannah River Site. As the result of TNX operation, groundwater contamination has occurred. The predominant contaminants detected in the flood plain downgradient from TNX are trichloroethylene (TCE) and nitrate.Treatability studies into the applicability of a groundwater remediation system combining GeoSiphon Cell and zero-valent iron technologies for treatment of the TCE-contaminated groundwater at TNX have been conducted. These treatability studies have been conducted by SRTC under the sponsorship of the Environmental Restoration Department.
Date: October 25, 1999
Creator: Phifer, M. A.
Object Type: Report
System: The UNT Digital Library
Thermal Decomposition Characteristics of Orthorhombic Ammonium Perchlorate (o-AP) and an 0-AP/HTPB-Based Propellant (open access)

Thermal Decomposition Characteristics of Orthorhombic Ammonium Perchlorate (o-AP) and an 0-AP/HTPB-Based Propellant

A study to characterize the low-temperature reactive processes for o-AP and an AP/HTPB-based propellant (class 1.3) is being conducted in the laboratory using the techniques of simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and scanning electron microscopy (SEM). The results presented in this paper are a follow up of the previous work that showed the overall decomposition to be complex and controlled by both physical and chemical processes. The decomposition is characterized by the occurrence of one major event that consumes up to {approx}35% of the AP, depending upon particle size, and leaves behind a porous agglomerate of AP. The major gaseous products released during this event include H{sub 2}O, O{sub 2}, Cl{sub 2}, N{sub 2}O and HCl. The recent efforts provide further insight into the decomposition processes for o-AP. The temporal behaviors of the gas formation rates (GFRs) for the products indicate that the major decomposition event consists of three chemical channels. The first and third channels are affected by the pressure in the reaction cell and occur at the surface or in the gas phase above the surface of the AP particles. The second channel is not affected by pressure and accounts for the solid-phase reactions characteristic of …
Date: October 25, 1999
Creator: Behrens, Richard, Jr. & Minier, Leanna M. G.
Object Type: Article
System: The UNT Digital Library
Methane hydrate dissociation rates as 0.1 MPa and temperatures above 272K (open access)

Methane hydrate dissociation rates as 0.1 MPa and temperatures above 272K

We performed rapid depressurization experiments on methane hydrate under isothermal conditions above 272 K to determine the amount and rate of methane evolution. Sample temperatures rapidly drop below 273 K and stabilize near 272.5 K during dissociation. This thermal anomaly and the persistence of methane hydrate are consistent with the reported recovery of partially dissociated methane hydrate from ocean drilling cores.
Date: October 25, 1999
Creator: Durham, W. B.; Circone, S.; Stern, L. A.; Kirby, S. H. & Pinkston, J. C.
Object Type: Article
System: The UNT Digital Library
Stability Analysis of Large-Scale Incompressible Flow Calculations on Massively Parallel Computers (open access)

Stability Analysis of Large-Scale Incompressible Flow Calculations on Massively Parallel Computers

A set of linear and nonlinear stability analysis tools have been developed to analyze steady state incompressible flows in 3D geometries. The algorithms have been implemented to be scalable to hundreds of parallel processors. The linear stability of steady state flows are determined by calculating the rightmost eigenvalues of the associated generalize eigenvalue problem. Nonlinear stability is studied by bifurcation analysis techniques. The boundaries between desirable and undesirable operating conditions are determined for buoyant flow in the rotating disk CVD reactor.
Date: October 25, 1999
Creator: Lehoucq, Richard B.; Romero, Louis & Salinger, Andrew G.
Object Type: Article
System: The UNT Digital Library
Theoretical status of {epsilon}{prime}/{epsilon} (open access)

Theoretical status of {epsilon}{prime}/{epsilon}

The author gives a detailed introduction into the theoretical formalism for {epsilon}{prime}/{epsilon}, which measures direct CP-violation in K {yields} {pi}{pi} decays. The current status of hadronic matrix elements and the strange quark mass is discussed. Several possible explanations of the unexpectedly high experimental results for {epsilon}{prime}/{epsilon} are pointed out: A small strange quark mass, an enhancement of the hadronic parameter B{sub 6}{sup (1/2)} from the {sigma} resonance, an underestimate of isospin breaking and possible new physics contributions in the {bar s}dZ-vertex and the {bar s}d-gluon-vertex.
Date: October 25, 1999
Creator: Nierste, Ulrich
Object Type: Article
System: The UNT Digital Library
Development of a data management system for assistance in conducting Area of Reviews (AORs) on Class II injection wells in Oklahoma. Quarterly report, July--September, 1995 (open access)

Development of a data management system for assistance in conducting Area of Reviews (AORs) on Class II injection wells in Oklahoma. Quarterly report, July--September, 1995

Project objectives are to provide the resources and capabilities to permit the State of Oklahoma to conduct Area of Review (AOR) variance analysis on a statewide level including: (1) the analysis and identification of areas which may qualify for AOR variances; (2) the correlation of information from various databases and automation systems to conduct AORs in areas that do not qualify for variances; (3) the evaluation of the risk of pollution, during permitting and monitoring, using risk based data analysis; and (4) the ability to conduct spatial analysis of injection well data in conjunction with other geographically referenced information. The division successfully converted its mainframe computer surety system to the new client server network and implemented it on September 29, 1995. The division currently lacks sufficient storage space to bring the existing oil and gas spatially referenced data systems in-house and fully integrate the systems for use in the determination of AORs or AOR variances. The second installment of the awarded grant allows for the purchase of the developmental server that will provide the minimum computer storage space to convert the remainder of the mainframe computer systems.
Date: October 25, 1995
Creator: Schmidt, M.W.
Object Type: Report
System: The UNT Digital Library
APS runControl library (open access)

APS runControl library

This document serves as a User`s Manual and Reference for the runControl library. This library is designed to be used by closed- loop EPICS control applications which are generally run in the background on the controls workstations. It permits an application to `register` itself with an EPICS record, thereby preventing additional instances of the same application from being run. In addition, the executing application may in turn be suspended or aborted via an MEDM control screen or other standard channel access client.
Date: October 25, 1995
Creator: Saunders, C. & Borland, M.
Object Type: Report
System: The UNT Digital Library
Technology development for cobalt F-T catalysts. Final quarterly technical progress report No. 11, April 1, 1995--June 30, 1995 (open access)

Technology development for cobalt F-T catalysts. Final quarterly technical progress report No. 11, April 1, 1995--June 30, 1995

Preliminary results on the effect of reaction temperature on the performance of Co catalysts during F-T synthesis obtained during the last quarter confirmed that Co catalysts were very sensitive to temperature and deactivated significantly at temperatures above 240{degree}C both in the fixed bed and the slurry bubble column reactors. Following this preliminary investigation, a series of tests were carried out during this period in order to elucidate the nature of this deactivation process as well as determine possible means of preventing it. In order to elucidate the nature of this deactivation process, the catalysts which had undergone significant deactivation after high temperature (280{degree}C) reaction in either the fixed bed reactor or the slurry bubble column reactor were regenerated and retested in the fixed bed reactor. In both cases the catalysts recovered completely their initial activity. In addition, reactions at very high H{sub 2}CO ratios and high temperatures showed very little deactivation, suggesting that the deactivation of the Co catalysts during F-T synthesis at high temperatures was mainly due carbon formation via the Boudouard reaction. Due to the unreactive nature of this carbon, it could only be removed by calcination. A second series of experiments was carried out to investigate the …
Date: October 25, 1995
Creator: Singleton, Alan H.
Object Type: Report
System: The UNT Digital Library
Stress corrosion cracking tests using double-cantilever-beam specimens (open access)

Stress corrosion cracking tests using double-cantilever-beam specimens

Although a wide variety of degradation modes can occur in aqueous environments for corrosion-resistant metallic materials, localized corrosion such as pitting corrosion, crevice corrosion, SCC, and hydrogen embrinlement (HE) is considered to be the primary mode. The evaluation of the susceptibility of candidate corrosion-resistant container materials to pitting and crevice corrosion is well underway using electrochemical polarization techniques described in the Activity Plan E-20-43144. The proposed activity (E-20-56) is aimed at evaluating the SCC behavior of these materials in susceptible environments using the linearelastic-fracture-mechanics (LEFM) concept. The mechanical driving force for crack growth, or the stress distribution at the crack tip is quantified by the stress intensity factor, K, for the specific crack and loading geometry. The critical stress intensity factor for SCC, K<sub>ISCC</sub> for candidate materials will be evaluated in environments of interest, and their comparisons will be made to select the waste package inner container material having an optimum SCC resistance.
Date: October 25, 1996
Creator: Roy, A.
Object Type: Report
System: The UNT Digital Library
A phenomenological approach to simulating the evolution of radioactive-waste container damage due to pitting corrosion (open access)

A phenomenological approach to simulating the evolution of radioactive-waste container damage due to pitting corrosion

The damage to high-level radioactive-waste containers by pitting corrosion is an important design and performance assessment consideration. It is desirable to calculate the evolution of the pit depth distribution, not just the time required for initial penetration of the containers, so that the area available for advective of diffusive release of radionuclides through the container can be estimated. A phenomenological approach for computing the time evolution of these distributions is presented which combines elements of the deterministic and stochastic aspects of pit growth. The consistency of this approach with the mechanisms believed to control the evolution of the pit depth distribution is discussed. Qualitative comparisons of preliminary model predictions with a variety of experimental data from the literature are shown to be generally favorable. The sensitivity of the simulated distributions to changes in the input parameters is discussed. Finally, the results of the current model are compared to those of existing approaches based on extreme-value statistics, particularly regarding the extrapolation of laboratory data to large exposed surface areas.
Date: October 25, 1995
Creator: Henshall, G.A.
Object Type: Article
System: The UNT Digital Library
Acceptance Test Report for the high pressure water jet system canister cleaning fixture (open access)

Acceptance Test Report for the high pressure water jet system canister cleaning fixture

This Acceptance Test confirmed the test results and recommendations, documented in WHC-SD-SNF-DTR-001, Rev. 0 Development Test Report for the High Pressure Water Jet System Nozzles, for decontaminating empty fuel canisters in KE-Basin. Optimum water pressure, water flow rate, nozzle size and overall configuration were tested
Date: October 25, 1995
Creator: Burdin, J.R.
Object Type: Report
System: The UNT Digital Library