13,163 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Beam"

open access

Beam expansion with specified final distributions

The formation of nearly uniformly distributed beams has been accomplished by the use of multipole magnets. Multipole fields, however, are an inappropriate basis for creating precise distributions, particularly since substantial departures from uniformity are produced with a finite number of multipole elements. A more appropriate formalism that allows precise formation of a desired distribution is presented. Design of nonlinear magnets for uniform-beam production and the optics of an accompanyin… more

Date: May 9, 1997

Creator: Jason, A.J.; Blind, B. & Halbach, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Simulations of the LEDA RFQ 6.7-MeV accelerator

The codes PARMTEQM and RFQTRAK simulate the beam transport through the radio-frequency-quadrupole (RFQ) accelerator for the low-energy-demonstration accelerator (LEDA). They predict 95% transmission for a matched 110-mA proton beam with a normalized-rms emittance of 0.02 mm mrad. RFQTRAK simulates the effects of arbitrary vane-tip misalignments. This RFQ includes some new features in its design. It consists of four resonantly coupled 2-m-long segments that make up its 8-m length. It has higher … more

Date: October 1997

Creator: Young, L. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Status of the APS diagnostics undulator beamline

We report the status of the diagnostics undulator beamline for the Advanced Photon Source (APS) storage ring. The beamline was designed for the characterization of the 7-GeV, low-emittance positron beam at high resolution. The special diagnostics undulator has been manufactured by STI Optronics. The device exhibits very low magnetic field errors at closed gap of 10.5 mm: first field integral less than 15 gauss{center_dot}cm, and optical phase error less than 1.5{degrees}. The front end of the b… more

Date: June 1, 1997

Creator: Yang, B. X.; Lumpkin, A. H. & Goeppner, G. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

US-LHC IR magnet error analysis and compensation

This paper studies the impact of the insertion-region (IR) magnet field errors on LHC collision performance. Compensation schemes including magnet orientation optimization, body-end compensation, tuning shims, and local nonlinear correction are shown to be highly effective.

Date: August 1, 1998

Creator: Wei, J.; Ptitsin, V.; Pilat, F.; Tepikian, S.; Gelfand, N.; Wan, W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Simulations of transition crossing in the main injector

The design goal for the Fermilab Main Injector (FMI) is to accelerate a minimum of 6{times}10{sup 10} protons per bunch through the transition. We present here the results from simulation studies of the transition crossing in the FMI using the particle tracking code ESME.

Date: May 1, 1995

Creator: Bhat, C.M. & MacLachlan, J.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Progress towards top-up mode operations at the Advanced Photon Source

The Advanced Photon Source (APS) is a 7-GeV, third-generation synchrotron radiation source. To provide a more stable beam for users, in September 1998 the authors began commissioning a new operating mode called top-up. In this mode, the beam current does not decay but is maintained at a high level using frequent injection, while photon shutters are open and photon beams are delivered to users. The exhaustive analysis for top-up safety will be reviewed as well as the hardware and software requir… more

Date: October 26, 1999

Creator: Emery, L. & Borland, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The calculation, simulation, and measurement of longitudinal beam dynamics in electron injectors

Polarized electrons are a valuable commodity for nuclear physics research and every effort must be made to preserve them during transport Measurements of the beam emitted from the polarized source at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) have shown a considerable bunch lengthening with increasing beam current. This lengthening leads to unacceptable loss as the beam passes through the injector chopping system. We present an application of the longitudinal envelope eq… more

Date: June 1, 1997

Creator: Dunham, B.; Liu, H. & Kazimi, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Summary of Beam Beam Observations During Stores in Rhic.

During stores, the beam-beam interaction has a significant impact on the beam and luminosity lifetimes in RHIC. This was observed in heavy ion, and even more pronounced in proton collisions. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. In addition, RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. Co… more

Date: May 19, 2003

Creator: Fischer, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Low emittance growth funneling line: preliminary design and beam dynamics study

A theoretical design study has resulted in a conceptual funneling-line design that has a transverse emittance growth limited to only 15% based on beam-dynamics calculations. Two 2-MeV, 100-mA proton beams are funneled from a two-channel, 212.5-MHz radio-frequency quadrupole (RFQ) to a single beam suitable for injection into a 425-MHz linac. The design uses permanent-magnet quadrupoles, dipoles, and combined-function elements. The low emittance growth is obtained by arranging the focusing streng… more

Date: January 1, 1985

Creator: Guy, F.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Experimental Study of the Main Ring Transition Crossing

A number of different experiments were proposed as part of the Fermilab III Instabilities Workshop in order to study the transition crossing in the Main Ring. Due to time limitations and operational restrictions only one of the experiments was actually performed. The results and analysis presented here are preliminary. We used an injection mismatch to deliberately blow up the longitudinal emittance in the MR 29 cycles, and measured the increase in bunch emittance and the particle loss through t… more

Date: October 1990

Creator: Kourbanis, Ioanis; Meisner, Keith & Ng, King-Yuen

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Reducing bunch disruption in transition crossing by modification of the rf waveform

We investigate the utility of accelerating during the nonadiabatic period surrounding the time of transition with an rf waveform modified by a second or third harmonic component to eliminate rf focusing. Simulation study shows this scheme not only to control momentum spread but also to have apparent advantage with respect to microwave instability. An experimental test has been initiated in the Fermilab Main Ring using a cavity at the third harmonic of the rf.

Date: July 1, 1992

Creator: MacLachlan, J.; Griffin, J.; Crawford, C.; Wildman, D.; Bhat, C. & Martens, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Advanced Light Source instrumentation overview

The accelerator instrumentation played a vital role in commissioning the ALS injector accelerator. It helped us to see whether electron dynamics agreed with our theoretical predictions and important beam parameters met the design specifications. It helped us to see where beam losses occurred and why. In this paper we will start with a brief description of the ALS accelerator complex and the expected performance of it. Then we will describe each diagnostics instrument by its construction, operat… more

Date: October 1, 1992

Creator: Kim, C. H. & Hinkson, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The development of the Next Linear Collider at SLAC

At SLAC, we are pursuing the design of a Next Linear Collider (NLC) which would begin with a center-of-mass energy of 0.5 TeV and be upgradable to at least 1.0 TeV, and possibly 1.5 TeV. The luminosity is designed to be 10{sup 33} cm{sup {minus}2}s{sup {minus}1} at the lower energy and 10{sup 34} cm{sup {minus}2}s{sup {minus}1} at the top energy. In this paper, we discuss the accelerator physics issues which are important in our approach, and also the present state of the technology development… more

Date: February 1, 1992

Creator: Ruth, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Instrumentation in medical systems

The demand for clinical use of accelerated heavy charged-particle (proton and light-ion) beams for cancer treatment is now burgeoning worldwide. Clinical trials are underway at more than a dozen accelerators. Several hospital-based accelerator facilities dedicated to radiation treatment of human cancer have been constructed, and their number is growing. Many instruments in medical systems have been developed for modifying extracted particle beams for clinical application, monitoring the deliver… more

Date: May 1995

Creator: Chu, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The performance of the Tevatron collider at Fermilab

This paper will describe the actual operating performance of the Tevatron, operating as a collider, and will indicate the planned upgrades which will enhance, the physics results coming from the experiments being performed at Fermilab.

Date: October 1, 1991

Creator: Gelfand, N. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Debugging real accelerators

Particle losses and emittance growth in the injection process can result form mismatched injected beams arising from quadrupole errors in the ring and injection line. We describe a method, based on carefully analyzing the BPM-corrector response matrix, which allows the accurate determination of quadrupole errors and, at the same time, determines BPM and corrector calibration errors as well as the BPM resolution. Results from SPEAR, NSLS, ALS, and CELSIUS will be briefly described.

Date: December 1, 1996

Creator: Corbett, W.J.; Robin, D.; Safranek, J. & Ziemann, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Light source job list and plan: Part 1

This note is intended to describe our current thinking and to show interconnections of various subtasks. The discussed topics are: (1) Storage Ring Group - A. Refinement of lattices to include: photons from bending magnets, dynamic aperture studies, refinement of accelerator physics straight section, B. Non-standard lattice, C. Touschek lifetime, D. Gas scattering lifetime, E. BBI (bunched beam instabilities), F. Magnet error considerations, G. tracking of particles, H. Orthogonal adjustments o… more

Date: October 29, 1984

Creator: Cho, Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Polarization correlations in the SLC final focus

At the SLC, the electron beam polarization (P) is measured by a Compton polarimeter downstream of the Interaction Point. This measurement averages over the entire beam distribution and must be corrected for various correlations to calculate the luminosity (L) weighted polarization. Because the spin rotation in the ARC is energy dependent, off energy particles have lower polarization. These particles may also be poorly focused and contribute less luminosity due to the higher order chromatic opti… more

Date: May 1, 1995

Creator: Decker, F.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design of the SLC damping ring to linac transport lines

The first and second order optics for the damping ring to linac transport line are designed to preserve the damped transverse emittance while simultaneously compressing the bunch length of the beam to that length required for reinjection into the linac. This design, including provisions for future control of beam polarization, is described.

Date: July 1, 1983

Creator: Fieguth, T. H. & Murray, J. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Measurement of wakefields generated in accelerator test structures using the SLC

Research is underway at SLAC to develop accelerator structures for the next generation linear collider. An important feature of the design is a detuning of the dipole modes of the cells to suppress the long-range transverse wakefield by two orders of magnitude. This paper describes a facility, called ASSET, that will be incorporated into the SLAC Linear Collider (SLC) to test the long-range wakefield suppression and also to measure the other components of the wakefields generated in accelerator… more

Date: October 1, 1992

Creator: Adolphsen, C.; Bane, K.; Loew, G.; Ruth, R.; Thompson, K. & Wang, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Intense beams at the micron level for the Next Linear Collider

High brightness beams with sub-micron dimensions are needed to produce a high luminosity for electron-positron collisions in the Next Linear Collider (NLC). To generate these small beam sizes, a large number of issues dealing with intense beams have to be resolved. Over the past few years many have been successfully addressed but most need experimental verification. Some of these issues are beam dynamics, emittance control, instrumentation, collimation, and beam-beam interactions. Recently, the… more

Date: August 1, 1991

Creator: Seeman, J. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effect of wakefields on first order transport in the SLC linac

The limitation in increasing the beam current in the SLC linac comes from the emittance growth caused by wakefields. Simulations of the beam transport that model the wakefield dynamics are being done to study methods to control this growth. To verify the theoretical estimates of the wakefield strengths assumed in these simulations, data were taken which are sensitive to their effect on the first order linac transport. Specifically, the dependence of single beam loading and betatron motion on be… more

Date: June 1, 1991

Creator: Adolphsen, C.; Bane, K. L. F. & Seeman, J. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Progress on next generation linear colliders

In this paper, I focus on reviewing the issues and progress on a next generation linear collider with the general parameters of energy, luminosity, length, power, technology. The energy range is dictated by physics with a mass reach well beyond LEP, although somewhat short of SSC. The luminosity is that required to obtain 10/sup 3/ /minus/ 10/sup 4/ units of R/sub 0/ per year. The length is consistent with a site on Stanford land with collisions occurring on the SLAC site. The power was determi… more

Date: January 1, 1989

Creator: Ruth, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

An ``NLC-style`` short bunch length compressor in the SLAC linac

Experimental tests of a ``second bunch length compressor`` in a linac is important for the next generation of linear colliders and for other future accelerators. These future accelerators need bunches with lengths of order 0.06 {minus} 0.2 mm. At these lengths, new accelerator dynamics will be encountered. We have studied the possibility of constructing a second compressor with the present SLAC linac and have found a reasonable design. The core of this project is to reconfigure an old beamline … more

Date: June 1, 1993

Creator: Seeman, J. T. & Holtzapple, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department