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1997 Annual Site Environmental Report (ASER)

Description: The SLAC program centers around experimental and theoretical research in elementary particle physics using accelerated electron beams and a broad program of research in atoms and solid-state physics, chemistry, and biology using synchrotron radiation from accelerated electron beams. There is also an active program in the development of accelerators, detectors, and new sources and instrumentation for synchrotron radiation research. The main instrument of research is the 3.2-km linear accelerator (linac) that generates high intensity beams of electrons and positrons up to 50 GeV, which are among the highest energy electron and positron beams available in the world. The linac is also used for injecting electrons and positrons into colliding-beam storage rings for particle physics research. The Positron-Electron Project (PEP) storage ring is about 800 meters in diameter. The PEP program was completed several years ago. PEP is now being upgraded to serve as an Asymmetric B Factory (or PEP-II) that will study the B meson. PEP-II will make use of much of PEP's existing equipment and infrastructure, and is scheduled for completion in 1998. A smaller storage ring, the Stanford Positron-Electron Asymmetric Ring (SPEAR) has its own smaller linac and a booster ring for injecting accelerated beams of electrons. SPEAR is fully dedicated to synchrotron radiation research. The synchrotron light generated by the SPEAR storage ring is used by the Stanford Synchrotron Radiation Laboratory (SSRL) to perform experiments. Scientists from all parts of the United States and from throughout the world participate in the experimental programs at SLAC.
Date: October 1, 1998
Creator: Holden, Gene
Partner: UNT Libraries Government Documents Department

The VISA FEL undulator

Description: The Visible-Infrared SASE Amplifier (VISA) FEL is an experimental device designed to show Self Amplified Spontaneous Emission (SASE) to saturation in the visible light energy range. It will generate a resonant wavelength output from 800--600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is the first SASE FEL designed to reach saturation, and its diagnostics will provide important checks of theory. This paper includes a description of the VISA undulator, the magnet measuring and shimming system, and the alignment strategy. VISA will have a 4 m pure permanent magnet undulator comprising four 99 cm segments, each with 55 periods of 18 mm length. The undulator has distributed focusing built into it, to reduce the average beta function of the 70--85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walkoff, or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, the authors expect to be able to control trajectory walkoff to less than {+-}50 {micro}m per field gain length.
Date: August 1998
Creator: Carr, R.; Cornacchia, M. & Emma, P.
Partner: UNT Libraries Government Documents Department

Light-Front Quantized Chiral Model and its Vacuum Structure

Description: The bosonized Chiral Schwinger model (CSM) is quantized on the light-front (LF). The physical Hilbert space of CSM is obtained directly once the constraints on the LF phase space are eliminated. The discussion of the degenerate vacua and the absence in the CSM of the theta-vacua, as found in the Schwinger model (SM), becomes straightforward. The differences in the structures of the mass excitations and the vacua in these gauge theories are displayed transparently. The procedure followed is the one used successfully in the previous works for describing the spontaneous symmetry breaking (SSB) and the SM on the LF. The physical contents following from the LF quantized theory agree with those known in the conventional treatment. The LF hyperplane is argued to be equally appropriate as the conventional equal-time one for the canonical quantization. Some comments on the irrelevance, in quantized field theory, of the fact that the hyperplanes x{sup {+-}} = 0 constitute characteristic surfaces of hyperbolic partial differential equation are also made.
Date: November 30, 1998
Creator: Srivastava, Prem P.
Partner: UNT Libraries Government Documents Department

Third-Order Transport with MAD Input: A Computer Program for Designing Charged Particle Beam Transport Systems

Description: TRANSPORT has been in existence in various evolutionary versions since 1963. The present version of TRANSPORT is a first-, second-, and third-order matrix multiplication computer program intended for the design of static-magnetic beam transport systems.
Date: October 28, 1998
Creator: Brown, Karl
Partner: UNT Libraries Government Documents Department

High-Speed, High-Resolution Analog Waveform Sampling in VLSI Technology

Description: Switched-capacitor analog memories are well-suited to a number of applications where a continuous digitization of analog signals is not needed. In data acquisition systems based on the use of an analog memory, the input waveforms are sampled and stored at a high rate for a limited period of time, and the analog samples are then retrieved at a lower rate and digitized with a slow ADC before new waveforms are acquired. The advantages of using an analog memory are lower overall power dissipation and cost, higher density and reliability, and potentially superior performance. The analog memory essentially exploits the fact that the sampling and storage of samples in a bank of analog memory cells can be accomplished at a higher rate and with a greater precision than direct digital conversion. This dissertation examines the important components of an analog memory in detail and investigates their use in a number of architectures. The research has led to the design of an analog memory that can acquire analog waveforms at sampling rates of several hundred MHz with a dynamic range and linearity of more than 12 bits, without the need for elaborate calibration and correction procedures. This is accomplished by means of a new memory architecture that results in memory cell pedestals and sampling times that are independent of the signal level, as well as cell gains that are insensitive to component sizes. The write address control for this memory has been realized with an inverter delay chain that provides substantially higher performance with respect to sampling rate and timing accuracy than other published approaches. Based upon the concepts developed in this work, an experimental analog memory was designed and integrated in a 2-{mu}m CMOS process. Extensive measurements of this prototype at sampling rates up to 700MHz are presented and demonstrate a ...
Date: October 13, 1998
Creator: Haller, Gunther
Partner: UNT Libraries Government Documents Department

Linac Coherent Light Source (LCLS) Design Study Report

Description: The Stanford Linear Accelerator Center, in collaboration with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of California at Los Angeles, is proposing to build a Free-Electron-Laser (FEL) R and D facility operating in the wavelength range 1.5-15 {angstrom}. This FEL, called the ''Linac Coherent Light Source'' (LCLS), utilizes the SLAC linac and produces sub-picosecond pulses of short wavelength x-rays with very high peak brightness and full transverse coherence. Starting in FY 1998, the first two-thirds of the SLAC linac will be used for injection into the B factory. This leaves the last one-third free for acceleration to 15 GeV. The LCLS takes advantage of this opportunity, opening the way for the next generation of synchrotron light sources with largely proven technology and cost effective methods. This proposal is consistent with the recommendations of the Report of the Basic Energy Sciences Advisory Committee (Synchrotron Radiation Light Source Working Group, October 18-19, 1997). The report recognizes that ''fourth-generation x-ray sources...will in all likelihood be based on the free electron laser concepts. If successful, this technology could yield improvements in brightness by many orders of magnitude.'' This Design Study, the authors believe, confirms the feasibility of constructing an x-ray FEL based on the SLAC linac. Although this design is based on a consistent and feasible set of parameters, some components require more research and development to guarantee the performance. Given appropriate funding, this R and D phase can be completed in 2 years.
Date: December 4, 1998
Creator: Cornacchia, Massimo
Partner: UNT Libraries Government Documents Department

BaBar Physics Book

Description: This book presents the results of a year-long workshop devoted to a review of the physics opportunities of the BABAR experiment at the PEP-II B Factory, at the Stanford Linear Accelerator Center laboratory. The workshop brought together a number of theorists with experimentalists from the BABAR Collaboration. Each chapter represents the contribution of a working group and presents both a theoretical summary of the relevant topics and the results of related simulation studies. The working group convenors, listed below, were teams that included both theorists and experimentalists. The book represents the status of work around the beginning of 1998. Both the state of the theory and of the experiment's simulation and analysis tools continue to advance. The results presented here are thus not a final view of what the experiment can achieve, but represent an interim study. The studies are more detailed and comprehensive than those made at the time of the Technical Design Report, but still lack many features that will be needed for the real data analysis. The book is intended as a guide to the work that still needs to be done, and as a detailed introduction which will assist new members, joining the Collaboration, and, we hope, other researchers in the field.
Date: November 4, 1998
Creator: Quinn, Helen
Partner: UNT Libraries Government Documents Department

Characterization of Low-Energy (6-30 keV) Response of Polish TLDs (MTS-N, MCP-N) with Synchrotron Radiation and Determination of Some Fundamental TLD Quantities

Description: Relative to <sup>137</sup>Cs gamma rays, the response of MTS-N (<sup>Nat</sup>LiF:Mg,Ti-0.04 cm thick) increased from 0.4 to 1.4 between x-ray energies of 6 and 30 keV and that of MCP-N (<sup>Nat</sup>Lif:Mg, Cu, P-0.04 cm thick) increased from 0.02 to 1.2 between 6 and 26 keV. A mathematical model for TLD response was used with measured responses to determine overall TLD efficiency C(k) and efficiency relative to <sup>137</sup>Cs. The effective energy attenuation coefficient {mu}(k) and light attenuation coefficient f were also determined experimentally. The relative efficiency of MTS-N increased from 0.66 to 1.30 between 6 and 30 keV and that of MCP-N increased from 0.37 to 0.99 between 6 and 26 keV.
Date: November 17, 1998
Creator: Ipe, Nisy E.
Partner: UNT Libraries Government Documents Department