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Electro-optical streak camera system for use at 1. 3. mu. m

Description: An electro-optical streak camera for use at 1.3 ..mu..m is described, including determination of the streak tube absolute photocathode sensitivity and system dynamic range. Nonlinear response at higher input intensities suggests multi-photon photocathode absorption.
Date: January 1, 1979
Creator: Palmer, M.A. & Palmer, R.E.
Partner: UNT Libraries Government Documents Department

Geothermal investigations in Idaho. Part 12. Stable isotopic evaluation of thermal water occurrences in the Weiser and Little Salmon River drainage basins and adjacent areas, west-central Idaho with attendant gravity and magnetic data on the Weiser area

Description: Fifteen thermal springs, two thermal wells, and eight cold springs in the Weiser and Little Salmon river drainages were sampled for deuterium and oxygen-18 analysis during the fall of 1981. The straight-line fit of delta D and delta /sup 18/O versus latitude and longitude observed in the data is what would be expected if the recharge areas for the thermal and non-thermal waters were in close proximity to their respective discharge points. The discrete values of delta D and delta /sup 18/O for each thermal discharge suggest that none of the sampled thermal systems have common sources. The depleted deuterium and oxygen-18 contents of most thermal relative to non-thermal waters sampled suggests that the thermal waters might be Pleistocene age precipitation. The isotopic data suggest little or no evidence for mixing of thermal and non-thermal water for the sampled discharges. Thermal waters from Weiser, Crane Creek, Cove Creek, and White Licks hot springs show enrichment in oxygen-18 suggesting that these waters have been at elevated temperatures relative to other sampled thermal discharges in the area. Gravity and magnetic data gathered by the Idaho State University Geology Department in the Weiser Hot Springs area suggest that southeastward plunging synclinal-anticlinal couples, which underlie the hot springs, are cut south of the springs by a northeast trending boundary fault.
Date: December 1, 1984
Creator: Mitchell, J.C.; Bideganeta, K. & Palmer, M.A.
Partner: UNT Libraries Government Documents Department

SUPERCONDUCTING MAGNET NEEDS FOR THE ILC.

Description: The ILC Reference Design Report was completed early in February 2007. The Magnet Systems Group was formed to translate magnetic field requirements into magnet designs and cost estimates for the Reference Design. As presently configured, the lLC will have more than 13,000 magnetic elements of which more than 2300 will be based on superconducting technology. This paper will describe the major superconducting magnet needs for the ILC as presently determined by the Area Systems Groups, responsible for beam line design, working with the Magnet Systems Group. The superconducting magnet components include Main Linac quadrupoles, Positron Source undulators, Damping Ring wigglers, a complex array of Final Focus superconducting elements in the Beam Delivery System, and large superconducting solenoids in the e{sup +} and e{sup -} Sources, and the Ring to Main Linac lines.
Date: June 25, 2007
Creator: PARKER,B.; TOMPKINS, J.C.; KASHIKHIN, VI.; PALMER, M.A. & CLARKE, J.A.
Partner: UNT Libraries Government Documents Department

Superconducting magnet needs for the ILC

Description: The ILC Reference Design Report was completed early in February 2007. The Magnet Systems Group was formed to translate magnetic field requirements into magnet designs and cost estimates for the Reference Design. As presently configured, the ILC will have more than 13,000 magnetic elements of which more than 2300 will be based on superconducting technology. This paper will describe the major superconducting magnet needs for the ILC as presently determined by the Area Systems Groups, responsible for beam line design, working with the Magnet Systems Group. The superconducting magnet components include Main Linac quadrupoles, Positron Source undulators, Damping Ring wigglers, a complex array of Final Focus superconducting elements in the Beam Delivery System, and large superconducting solenoids in the e{sup +} and e{sup -} Sources, and the Ring to Main Linac lines.
Date: June 1, 2007
Creator: Tompkins, J.C.; Kashikhin, Vl.; /Fermilab; Parker, B.; /Brookhaven; Palmer, M.A. / et al.
Partner: UNT Libraries Government Documents Department

Methods for Quantitative Interpretation of Retarding Field Analyzer Data

Description: Over the course of the CesrTA program at Cornell, over 30 Retarding Field Analyzers (RFAs) have been installed in the CESR storage ring, and a great deal of data has been taken with them. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. Obtaining a quantitative understanding of RFA data requires use of cloud simulation programs, as well as a detailed model of the detector itself. In a drift region, the RFA can be modeled by postprocessing the output of a simulation code, and one can obtain best fit values for important simulation parameters with a chi-square minimization method.
Date: March 28, 2011
Creator: Calvey, J.R.; Crittenden, J.A.; Dugan, G.F.; Palmer, M.A.; Furman, M. & Harkay, K.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of changes in x-ray multilayer optics subjected to high radiation flux

Description: A variety of metal multilayers was exposed to high x-ray flux using Sandia National Laboratories' PROTO II machine in the gas puff mode. Fluxes incident on the multilayers above 700 MW/cm/sup 2/ in total radiation, in nominal 20 ns pulses, were realized. The neon hydrogen- and helium-like resonance lines were used to probe the x-ray reflectivity properties of the multilayers as they underwent change of state during the heating pulse. A fluorescer-fiber optic-streak camera system was used to monitor the changes in x-ray reflectivity as a function of time and irradiance. Preliminary results are presented for a W/C multilayer. Work in progress to model the experiment is discussed. 13 refs., 4 figs.
Date: January 1, 1985
Creator: Hockaday, M.P.; Blake, R.L.; Grosso, J.S.; Selph, M.M.; Klein, M.M.; Matuska, W. Jr. et al.
Partner: UNT Libraries Government Documents Department

Secondary Electron Yield Measurements of Fermilab?s Main Injector Vacuum Vessel

Description: We discuss the progress made on a new installation in Fermilab's Main Injector that will help investigate the electron cloud phenomenon by making direct measurements of the secondary electron yield (SEY) of samples irradiated in the accelerator. In the Project X upgrade the Main Injector will have its beam intensity increased by a factor of three compared to current operations. This may result in the beam being subject to instabilities from the electron cloud. Measured SEY values can be used to further constrain simulations and aid our extrapolation to Project X intensities. The SEY test-stand, developed in conjunction with Cornell and SLAC, is capable of measuring the SEY from samples using an incident electron beam when the samples are biased at different voltages. We present the design and manufacture of the test-stand and the results of initial laboratory tests on samples prior to installation.
Date: May 1, 2012
Creator: Scott, D.J.; Capista, D.; Duel, K.L.; Zwaska, R.M.; /Fermilab; Greenwald, S. et al.
Partner: UNT Libraries Government Documents Department

Application of Coherent Tune Shift Measurements to the Characterization of Electron Cloud Growth

Description: Measurements of coherent tune shifts at the Cornell Electron Storage Ring Test Accelerator (CesrTA) have been made for electron and positron beams under a wide variety of beam energies, bunch charge, and bunch train configurations. Comparing the observed tunes with the predictions of several electron cloud simulation programs allows the evaluation of important parameters in these models. These simulations will be used to predict the behavior of the electron cloud in damping rings for future linear colliders. We outline recent improvements to the analysis techniques that should improve the fidelity of the modeling.
Date: March 28, 2011
Creator: Kreinick, D.L.; Crittenden, J.A.; Dugan, G.; Holtzapple, R.L.; Randazzo, M.; Furman, M.A. et al.
Partner: UNT Libraries Government Documents Department

CesrTA Retarding Field Analyzer Modeling Results

Description: Retarding field analyzers (RFAs) provide an effective measure of the local electron cloud density and energy distribution. Proper interpretation of RFA data can yield information about the behavior of the cloud, as well as the surface properties of the instrumented vacuum chamber. However, due to the complex interaction of the cloud with the RFA itself, understanding these measurements can be nontrivial. This paper examines different methods for interpreting RFA data via cloud simulation programs. Techniques include postprocessing the output of a simulation code to predict the RFA response; and incorporating an RFA model into the cloud modeling program itself.
Date: May 23, 2010
Creator: Calvey, J.R.; Celata, C.M.; Crittenden, J.A.; Dugan, G.F.; Greenwald, S.; Leong, Z. et al.
Partner: UNT Libraries Government Documents Department

Simulations of Electron-Cloud Current Density Measurements in Dipoles, Drifts And Wigglers at CesrTA

Description: A core component of the CesrTA research program at Cornell is to fully understand the electron cloud effect through the use of simulation programs that have been developed to predict the growth of the cloud and its interaction with the beam. As a local probe of the electron cloud, several segmented retarding field analyzers (RFAs) have been installed in CesrTA in dipole, drift and wiggler regions. Using these RFAs, the energy spectrum of the time-average electron cloud current density striking the walls has been measured for a variety of bunch train patterns, with different bunch currents, beam energies, emittances, and bunch lengths, and for both positron and electron beams. This paper will compare these measurements with the predictions of simulation programs.
Date: May 4, 2009
Creator: Calvey, J.; Crittenden, J. A.; Dugan, G.; Greenwald, S.; Livezey, J. A.; Palmer, M. A. et al.
Partner: UNT Libraries Government Documents Department

CesrTA Retarding Field Analyzer Measurements in Drifts, Dipoles, Quadrupoles and Wigglers

Description: Over the course of the CesrTA program, the Cornell Electron Storage Ring (CESR) has been instrumented with several retarding field analyzers (RFAs), which measure the local density and energy distribution of the electron cloud. These RFAs have been installed in drifts, dipoles, quadrupoles, and wigglers; and data have been taken in a variety of beam conditions and bunch configurations. This paper will provide an overview of these results, and give a preliminary evaluation of the efficacy of cloud mitigation techniques implemented in the instrumented vacuum chambers.
Date: June 15, 2010
Creator: Calvey, J. R.; Li, Y.; Livezey, J. A.; Makita, J.; Meller, R. E.; Palmer, M. A. et al.
Partner: UNT Libraries Government Documents Department

Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA

Description: The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced lowenergy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photoelectrons on the vacuum chamberwall, the beam emittance, lattice optics,and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.
Date: May 23, 2010
Creator: Crittenden, J.A.; Calvey, J.R.; Dugan, G.F.; Kreinick, D.L.; Leong, Z.; Livezey, J.A. et al.
Partner: UNT Libraries Government Documents Department