1,009 Matching Results

Search Results

Advanced search parameters have been applied.

The SLAC Damped Detuned Structure: Concept and design

Description: The SLAC Damped Detuned Structure (DDS) is an accelerator structure designed to suppress the long range transverse wakefields which limit the performance of high current multibunch accelerators. We discuss the conceptual considerations which have led to its development and discuss the steps involved in arriving at a design.
Date: May 1, 1997
Creator: Kroll, N.M.
Partner: UNT Libraries Government Documents Department

Opportunistic or event-driven maintenance at the Stanford Linear Accelerator Center

Description: The Stanford Linear Accelerator Center (SLAC) uses a maintenance management philosophy that is best described as opportunistic or event-driven. Opportunistic maintenance can be defined as a systematic method of collecting, investigating, pre-planning, and publishing a set of proposed maintenance tasks and acting on them when there is an unscheduled failure or repair ``opportunity``. Opportunistic maintenance can be thought of as a modification of the run-to-fail maintenance management philosophy. This maintenance plan was adopted and developed to improve the overall availability of SLAC`s linear accelerator, beam delivery systems, and associated controls, power systems, and utilities. In the late 1980`s, as the technical complexity of the accelerator facility increased, variations on a conventional maintenance plan were used with mixed results. These variations typically included some type of regular periodic interruption to operations. The periodic shutdowns and unscheduled failures were additive and resulted in unsatisfactory availability. Maintenance issues are evaluated in a daily meeting that includes the accelerator managers, maintenance supervisors and managers, safety office personnel, program managers, and accelerator operators. Lists of pending maintenance tasks are made available to the general SLAC population by a World Wide Web site on a local internet. A conventional information system which pre-dates the WWW site is still being used to provide paper copies to groups that are not yet integrated into the WWW system. The local internet provides real time maintenance information, allowing people throughout the facility to track progress on tasks with essentially real-time status updates. With the introduction of opportunistic maintenance, the accelerator`s availability has been measurably better. This paper will discuss processes, rolls and responsibilities of key maintenance groups, and management tools developed to support opportunistic maintenance.
Date: March 1, 1997
Creator: Allen, C.W.; Anderson, S.; Erickson, R.; Linebarger, W.; Sheppard, J.C. & Stanek, M.
Partner: UNT Libraries Government Documents Department

Report of Snowmass 2001 working group E2: Electron - positron colliders from the phi to the Z

Description: We report on the status and plans of experiments now running or proposed for electron-positron colliders at energies between the {phi} and the Z. The e{sup +}e{sup -}B and charm factories we considered were PEP-II/BABAR, KEKB/Belle, superKEK, SuperBABAR, and CESR-c/CLEO-c. We reviewed the programs at the {phi} factory at Frascati and the proposed PEP-N facility at Stanford Linear Accelerator Center. We studied the prospects for B physics with a dedicated linear collider Z factory, associated with the TESLA high energy linear collider. In all cases, we compared the physics reach of these facilities with that of alternative experiments at hadron colliders or fixed target facilities.
Date: December 23, 2002
Creator: al., Zhen-guo Zhao et
Partner: UNT Libraries Government Documents Department

Preparation of GaAs photocathodes at low temperature

Description: The preparation of an atomically clean surface is a necessary step in the formation of negative electron affinity (NEA) GaAs. Traditional methods to this end include cleaving, heat cleaning and epitaxial growth. Cleaving has the advantage of yielding a fresh surface after each cleave, but is limited to small areas and is not suitable for specialized structures. Heat cleaning is both simple and highly successful, so it is used as a preparation method in virtually all laboratories employing a NEA source on a regular basis. Due to its high cost and complexity, epitaxial growth of GaAs with subsequent in vacuo transfer is not a practical solution for most end users of GaAs as a NEA electron source. While simple, the heating cleaning process has a number of disadvantages. Here, a variety of cleaning techniques related to preparation of an atomically clean GaAs surface without heating to 600 C are discussed and evaluated.
Date: October 1, 1996
Creator: Mulhollan, G.; Clendenin, J. & Tang, H.
Partner: UNT Libraries Government Documents Department

The development of seismic guidelines for the Stanford Linear Accelerator Center

Description: This paper describes the development of Seismic Guidelines for the Stanford Linear Accelerator Center (SLAC). Although structures have always been built conservatively, SLAC management decided to review and update their seismic guidelines. SLAC is about mid-way between the epicenters of the 8.3 Richter magnitude 1906 San Francisco and the 7.2 Loma Prieta Earthquakes. The west end of the two mile long electron/positron particle accelerator lies a half mile from the large San Andreas Fault. Suggestions for seismic planning processes were solicited from local computer manufacturing firms, universities, and federal laboratories. A Committee of the various stakeholders in SLAC`s seismic planning retained an internationally known Seismic Planning Consultant and reviewed relevant standards and drafted Guidelines. A panel of seismic experts was convened to help define the hazard, site response spectra, probabilistic analysis of shaking, and near field effects. The Facility`s structures were assigned to seismic classes of importance, and an initial assessment of a sample of a dozen buildings conducted. This assessment resulted in emergency repairs to one structure, and provided a {open_quotes}reality basis{close_quotes} for establishing the final Guidelines and Administrative Procedures, and a program to evaluate remaining buildings, shielding walls, tunnels, and other special structures.
Date: August 1, 1996
Creator: Huggins, R.
Partner: UNT Libraries Government Documents Department

Beam-based optical tuning of the final focus test beam

Description: In order to reduce the SLAC 46.6 GeV beam to submicron sizes, the Final Focus Test Beam (FFTB) must meet tight tolerances on many aberrations. These aberrations include: mismatch and coupling of the incoming beam; dispersion; chromaticity; lattice errors in the chromatic correction sections; lattice coupling; and residual sextupole content in the quadrupoles. In order to address these aberrations, the authors have developed a procedure which combines trajectory analysis, use of intermediate wire scanners, and a pair of novel beam size monitors at the IP. This procedure allows the FFTB IP spot to be reduced to sizes under 100 nanometers.
Date: May 1, 1995
Creator: Tenenbaum, P.; Burke, D.; Hartman, S.; Helm, R.; Irwin, J.; Iverson, R. et al.
Partner: UNT Libraries Government Documents Department

Spectral function calculation of angle wakes, wake moments, and misalignment wakes for the SLAC Damped Detuned Structures (DDS)

Description: Transverse wake functions so far reported for the SLAC DDS have been limited to those caused by uniform offset of the drive beam in a straight perfectly aligned structure. The complete description of the betatron oscillations of wake coupled bunches requires an array of wake functions, referred to as moments. Modifications of these arrays induced by structure misalignments are also of interest. In this paper we express the array elements in terms of a spectral function array. Examples are given based upon DDS1.
Date: May 1, 1997
Creator: Jones, R.M.; Miller, R.H. & Kroll, N.M.
Partner: UNT Libraries Government Documents Department

Dipole magnets for the SLAC 50 GeV A-Line upgrade

Description: The SLAC A-Line is a transport system originally designed to deliver electron beams of up to 25 GeV to fixed target experiments in End Station A. To raise the beam energy capability of the A-Line to 52 GeV, the eight original bending magnets, plus four more of the same type, have been modified by reducing their gaps and adding trim windings to compensate for energy loss due to synchrotron radiation. In this paper the authors describe the modifications that have been completed, and they compare test and measurement results with predicted performance.
Date: May 1, 1995
Creator: Erickson, R.; DeBarger, S.; Spencer, C.M. & Wolf, Z.
Partner: UNT Libraries Government Documents Department

Advanced damped detuned structure (DDS) development at SLAC

Description: The first damped detuned accelerator structure, DDS 1, has been built, tested in the ASSET experiment, and installed in the NLCTA. The planning and construction of a series of further structures, incorporating some modifications, is under way. DDS 2, 3, and 4 all incorporate the same basic design as DDS 1. The manifold design for the last 5 % of the downstream end of the structure has been modified to accommodate improvements in the manifold loads. Calculations based on the spectral function method indicate, on average, a factor two or better reduction in the long range wake. Modest modifications in the distribution of geometrical detuning parameters along the structure which, according to calculations based on spectral function theory, significantly improve the short range wake will be incorporated in DDS 3 and 4. The basic cell configuration will be redesigned in DDS 5 with the intention of improving shunt impedance as well as incorporating further improvements in the wake.
Date: May 1, 1997
Creator: Jones, R. M.; Kroll, N. M.; Miller, R. H.; Ruth, R. D. & Wang, J. W.
Partner: UNT Libraries Government Documents Department

Final Report: BaBar Detector and Experimental at SLAC, September 30, 1998 - September 29, 1999

Description: The Prairie View A&M University High Energy Physics Group with its contingent of three undergraduates physics majors, joined the BaBar Collaboration at SLAC in September 1994. BaBar is the experiment and detector running in the PEP-II ring at SLAC as part of the Asymmetric B Factory project there to study CP violation and heavy flavor physics. The focus of our effort before this year was with the Muon/Neutral Hadron Detector/Instrumented Flux Return (IFD) subgroup within the BaBar collaboration, and particularly with the GEANT simulation of the IFR. With the GEANT3 simulation essentially frozen, and the GEANT4 full simulation of the IFR done, we have decided to redirect our efforts toward other areas.
Date: January 20, 2000
Creator: Judd, Dennis J.
Partner: UNT Libraries Government Documents Department

Analysis of Laser Tracker and Total Station Surveys

Description: The SMX 4500 laser tracker has proven itself to be a beneficial addition to SLAC's set of alignment tools. Through actual field surveys and laboratory testing, a question regarding some unknown scale factor appearing after adjusting the combined tracker and total station results arose. Through a simple line survey and instrument analysis and then progressing through more and more rigorous network adjustments, the authors deduced that the apparent scale problem was in fact more likely attributed to wrong offset values introduced into the adjustment by mixing TC2002 total station data with the laser tracker measurements. A recalibration procedure of all of SLAC's total station prisms was designed and analyzed.
Date: July 12, 2000
Creator: LeCocq, Catherine M
Partner: UNT Libraries Government Documents Department

Wakefield and Beam Centering Measurements of a Damped and Detuned X-Band Accelerator Structure

Description: In the Next Linear Collider (NLC) design, X-Band (11.4 GHz) accelerator structures are used to accelerate multibunch beams to several hundred GeV. Although these structures allow for high gradient operation, their strong deflecting modes impose a number of operational constraints. In particular, the long-range transverse wakefields generated by the bunches need to be reduced by about two orders of magnitude to prevent significant beam breakup. During the past five years, a reduction scheme that employs both detuning and damping of the structure dipole modes has been developed to meet this requirement. Several prototype Damped and Detuned Structures (DDS) have been built to test and refine this scheme. The wakefield of the latest version, DDS3, has recently been measured in the Accelerator Structure Setup (ASSET) facility at SLAC. In this paper, we present these results together with predictions based on an equivalent circuit model of the structure. We also present ASSET studies in which the beam-induced dipole signals that are coupled out for damping purposes are used to center the beam in the structure.
Date: September 14, 1999
Creator: Adolphsen, Chris
Partner: UNT Libraries Government Documents Department

Chiral Boson Theory on the Light-Front

Description: The framework for describing the quantized theory of chiral boson is discussed. It avoids the conflict with the requirement of the principle of microcausality as is found in the conventional treatment. The discussion of the Floreanini-Jackiw model and its modified version for describing the chiral boson becomes very transparent on the light-front.
Date: September 16, 1999
Creator: Srivastava, Prem P.
Partner: UNT Libraries Government Documents Department

Recent physics results from CDF and D0

Description: Recent physics results from CDF and D0 on heavy flavor physics, electroweak precision measurements, top physics, QCD and searches for new physics are discussed. The results are based on approximately 140 pb{sup -1} of data collected at {radical}s = 1.96 TeV between 2002 and 2003.
Date: February 25, 2004
Creator: Thomson, Evelyn
Partner: UNT Libraries Government Documents Department

Progress of the PEP-II-B-factory

Description: PEP-II is an e{sup +}e{sup -} B-Factory Collider located at SLAC operating at the Upsilon 4S resonance. PEP-II has delivered, over the past five years, an integrated luminosity to the BaBar detector of over 139 fb{sup -1} and has reached a luminosity of 6.58 x 10{sup 36}/cm{sup 2}/s. Steady progress is being made in reaching higher luminosity. The goal over the next several years is to reach a luminosity of at least 2 x 10{sup 34}/cm{sup 2}/s. The accelerator physics issues being addressed in PEP-II to reach this goal include the electron cloud instability, beam-beam effects, parasitic beam-beam effects, high RF beam loading, shorter bunches, lower beta y*, interaction region operation, and coupling control. A view of the PEP-II tunnel is shown in Figure 1. The present parameters of the PEP-II B-Factory are shown in Table 1 compared to the design. The present peak luminosity is 219% of design and the best integrated luminosity per month is 7.4 fb{sup -1} that is 225% of design. The best luminosity per month is shown in Figure 2. The integrated luminosity over a month is shown in Figure 3 and the total integrated luminosity in shown in Figure 4. The progress in luminosity has come from correcting the orbits, adding specific orbit bumps to correct coupling and dispersion issues, lowering the beta y* in the LER, and moving the fractional horizontal tunes in both rings to just above the half integer (<0.52).
Date: June 1, 2003
Creator: Seeman, J.; Browne, M.; Cai, Y.; Colocho, W.; Decker, F.-J.; Donald, M. et al.
Partner: UNT Libraries Government Documents Department

The role of supersymmetry phenomenology in particle physics

Description: Supersymmetry phenomenology is an important component of particle physics today. I provide a definition of supersymmetry phenomenology, outline the scope of its activity, and argue its legitimacy. This essay derives from a presentation given at the 2000 SLAC Summer Institute.
Date: December 14, 2000
Creator: Wells, James D.
Partner: UNT Libraries Government Documents Department

Network management and performance monitoring at SLAC

Description: The physical network plant and everything attached to it, including the software running on ``computers`` and other peripheral devices is the {bold system}. Subjectively, the ultimate measurers of {bold system} performance are the users and their perceptions of the performance of their networked applications. The performance of a {bold system} is affected by the physical network plant (routers, bridges, hubs, etc.) as well as by every ``computer`` and peripheral device that is attached to it, and the software running on the computers and devices. Performance monitoring of a network must therefore include computer systems and services monitoring as well as monitoring of the physical network plant. This paper will describe how this challenge has been tackled at SLAC, and how, via the World Wide Web, this information is made available for quick perusal by concerned personnel and users.
Date: August 1, 1995
Creator: Logg, C.A. & Cottrell, R.L.A.
Partner: UNT Libraries Government Documents Department

Multiphysics Applications of ACE3P

Description: The TEM3P module of ACE3P, a parallel finite-element electromagnetic code suite from SLAC, focuses on the multiphysics simulation capabilities, including thermal and mechanical analysis for accelerator applications. In this pa- per, thermal analysis of coupler feedthroughs to supercon- ducting rf (SRF) cavities will be presented. For the realistic simulation, internal boundary condition is implemented to capture RF heating effects on the surface shared by a di- electric and a conductor. The multiphysics simulation with TEM3P matched the measurement within 0.4%.
Date: July 1, 2012
Creator: Lee, Ki H.; Ko, Kwok; Li, Zenghai; Ng, Cho-Kuen; Xiao, Liling; Cheng, G. et al.
Partner: UNT Libraries Government Documents Department

LCLS Undulator Fiducialization Plan

Description: This note presents the LCLS undulator fiducialization plan. The undulators will be fiducialized in the Magnetic Measurement Facility at SLAC. The note begins by summarizing the requirements for the fiducialization. A brief discussion of the measurement equipment is presented, followed by the methods used to perform the fiducialization and check the results. This is followed by the detailed fiducialization plan in which each step is enumerated. Finally, the measurement results and data storage format are presented.
Date: November 24, 2010
Creator: Wolf, Zachary
Partner: UNT Libraries Government Documents Department

LCLS Undulator Test Plan

Description: This note presents the test plan for the LCLS undulators. The undulators will be measured and tuned in the Magnetic Measurement Facility at SLAC. The requirements for tuning are well established and are summarized. A brief discussion of the measurement equipment is presented. This is followed by the detailed test plan in which each step is enumerated. Finally, the measurement results and storage format are presented. The LCLS consists of 33 undulator segments, hereafter referred to as undulators, plus 6 spares and one reference undulator. The undulators must be tuned to meet strict requirements. They must also be fiducialized to allow alignment with other components. This note details the plan for tuning and fiducializing the LCLS undulators. The note begins with the list of tuning and fiducialization requirements. The laboratory in which the work will be performed and the relevant equipment is then briefly described. This is followed by a detailed test plan in which all the steps of tuning and fiducialization are enumerated.
Date: November 24, 2010
Creator: Wolf, Zachary
Partner: UNT Libraries Government Documents Department

The Role of INSPIRE in HEP Data Preservation Efforts

Description: INSPIRE is a new community resource for HEP literature and associated information. It is based on the combination of SPIRES content and features and the powerful Invenio software developed at CERN. The INSPIRE service will come online in fall of 2009, and be run by CERN, DESY, Fermilab and SLAC. Data preservation, to be successful, must not only preserve the data, but must also organize it and allow it to be found by those who would make use of it, and resources such as INSPIRE are ideally positioned and ready to provide this organization and context. In addition, INSPIRE will soon be ready to provide storage of smaller datasets, such as high-level analysis objects, as stand-alone objects placed in the repository or as objects associated with an analysis paper. This small project could pave the way towards the context and organization which is one piece of the infrastructure needed for all levels of data preservation.
Date: June 11, 2010
Creator: Brooks, Travis C.; /SLAC & ,
Partner: UNT Libraries Government Documents Department

Fermilab research Program 1976

Description: This collection of one-page summaries of Fermilab proposals is intended to serve as a way station between the experiment number with its short title and the full proposal. It is not intended to be a review of the Fermilab experimental program. Just as an abstract of a journal article embodies the main points of the article, so these one-page summaries are intended to convey the major points of a proposal. These should include its physics justification, a brief description of the apparatus and the demands that the experiment will make on the Laboratory. Of course these summaries are not intended to take the place of the proposal itself which is the primary document available in the Fermilab library and at SLAC, BNL and CERN. Individual copies should be obtained from the spokesman of the experiment whose name is underlined in these summaries. Summaries for all experiments and pending proposals are included. These comprise approved, unconsidered and deferred proposals. Rejected, withdrawn and inactive proposals are not included. It is the experimenters themselves who are best able to write the summary and in most cases that is what was done. For the early proposals and those cases where repeated cajoling could not produce one from the experimenters, the summary was prepared by a Fermilab staff member and then sent to the spokesman for comment. All proposals submitted before the May 7, 1976 deadline for consideration at the extended summer meeting of our Program Advisory Committee are included. It is not intended that this volume be updated annually but perhaps only reissued when the previous ones becomes hopelessly obsolete.
Date: January 1, 1976
Creator: Lach, J.
Partner: UNT Libraries Government Documents Department