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in creator/contributor: "Raubenheimer, T O"

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A formalism and computer program for coupled lattices

In this paper, a formalism to calculate the lattice functions and emittances of a coupled electron/positron storage ring is presented. The lattice functions are calculated directly from the modal matrix of the betatron transport matrix for the ring. The emittances and damping rates are then calculated from the invariants found in the diagonalized representation. In addition, a computer program is described which uses the formalism to calculate the coupled lattice functions, emittances and dampi… more

Date: April 1, 1989

Creator: Raubenheimer, T.O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron beam acceleration and compression for short wavelength FELs

No Description Available.

Date: November 1, 1994

Creator: Raubenheimer, T. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Analytic estimates of coupling in damping rings

In this paper we present analytic formulas to estimate the vertical emittance in weakly coupled electron/positron storage rings. We consider contributions from both the vertical dispersion and linear coupling of the betatron motions. In addition to simple expressions for random misalignments and rotations of the magnets, formulas are presented to calculate the vertical emittance blowup due to orbit distortions. The orbit distortions are assumed to be caused by random misalignments, but because … more

Date: March 1, 1989

Creator: Raubenheimer, T. O. & Ruth, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The generation and acceleration of low emittance flat beams for future linear colliders

Many future linear collider designs call for electron and positron beams with normalized rms horizontal and vertical emittances of {gamma}{epsilon}{sub x} = 3{times}10{sup {minus}6} m-rad and {gamma}{epsilon}{sub y} = 3{times}10{sup {minus}8} m-rad; these are a factor of 10 to 100 below those observed in the Stanford Linear Collider. In this dissertation, we examine the feasibility of achieving beams with these very small vertical emittances. We examine the limitations encountered during both t… more

Date: November 1, 1991

Creator: Raubenheimer, T.O.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The generation and acceleration of low emittance flat beams for future linear colliders

Date: November 1, 1991

Creator: Raubenheimer, T. O.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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The preservation of low emittance flat beams

Many future linear collider designs require beams with very small transverse emittances and large emittance ratios {epsilon}{sub x} {much_gt} {epsilon}{sub y}. In this paper, we will discuss issues associated with the preservation of these small emittances during the acceleration of the beams. The primary sources of transverse emittance dilution in a high energy linear accelerator are the transverse wakefields, the dispersive errors, RF deflections, and betatron coupling. We will discuss the es… more

Date: April 1, 1993

Creator: Raubenheimer, T. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Zeroth-order design report for the next linear collider. Volume 2

This Zeroth-Order Design Report (ZDR) for the Next Linear Collider (NLC) has been completed as a feasibility study for a TeV-scale linear collider that incorporates a room-temperature accelerator powered by rf microwaves at 11.424 GHz--similar to that presently used in the SLC, but at four times the rf frequency. The purpose of this study is to examine the complete systems of such a collider, to understand how the parts fit together, and to make certain that every required piece has been includ… more

Date: May 1, 1996

Creator: Raubenheimer, T.O.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Zeroth-order design report for the next linear collider. Volume 1

This Zeroth Order Design Report (ZDR) for the Next Linear Collider (NLC) has been completed as a feasibility study for a TeV-scale linear collider that incorporates a room-temperature accelerator powered by rf microwaves at 11.424 GHz--similar to that presently used in the SLC, but at four times the rf frequency. The purpose of this study is to examine the complete systems of such a collider, to understand how the parts fit together, and to make certain that every required piece has been includ… more

Date: May 1, 1996

Creator: Raubenheimer, T.O.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ion effects in future circular and linear accelerators

In this paper, the author discusses ion effects relevant to future storage rings and linear colliders. The author first reviews the conventional ion effects observed in present storage rings and then discusses how these effects will differ in the next generation of rings and linacs. These future accelerators operate in a new regime because of the high current long bunch trains and the very small transverse beam emittances. Usually, storage rings are designed with ion clearing gaps to prevent io… more

Date: May 1, 1995

Creator: Raubenheimer, T.O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ions in the linacs of future linear colliders

Ions have been identified as a potential limitation in high current storage rings, but they are not usually thought to be a problem in electron linear accelerators. In this paper, we consider the effects of ions in the linacs of future linear colliders. Future linear collider designs call for long trains of closely spaced bunches and/or very dense bunches. Thus, significant ion densities can be generated through the collisional ionization process and ``trapping`` in a long train of bunches or t… more

Date: July 1, 1992

Creator: Raubenheimer, T. O. & Chen, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Luminosity Optimization With Offset, Crossing Angle, and Distortion

In a linear collider, sources of beam jitter due to kicker noise, quadrupole vibration and long-range transverse wakefields will lead to beam offsets and tilts at the Intersection Point (IP). In addition, sources of emittance dilution such as short-range transverse wakefields or dispersive errors will lead to internal beam distortions. When the IP disruption parameter is large, these beam imperfections will be amplified by a single bunch kink instability which will lead to luminosity loss. In t… more

Date: June 15, 2005

Creator: Wu, Juhao & Raubenheimer, T. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Compensation of longitudinal nonlinearities in the NLC bunch compressor

The X-Band linac of the Next Linear Collider (NLC) will accelerate bunches of about 100 {mu}m rms length to energies of 250-750 GeV. The task of the NLC bunch compressor is to reduce the initial bunch length of 4-5 mm, at extraction from the damping ring, by a factor of 40, to the desired value. This task is accomplished in two separate stages. The first stage at 2 GeV consists of an rf section and a wiggler. The second stage at 10 GeV is formed by an arc, an rf section, and a chicane. The syst… more

Date: October 1, 1995

Creator: Zimmermann, F. & Raubenheimer, T. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A beam-based alignment technique for correction of accelerator structure misalignments

This paper describes a method of reducing the transverse emittance dilution in linear colliders due to transverse wakefields arising-from misaligned accelerator structures. The technique is a generalization of the Wake-Free correction algorithm. The structure alignment errors are measured locally by varying the bunch charge and/or bunch length and measuring the change in the beam trajectory. The misalignments can then be corrected by varying the beam trajectory or moving structures. The results… more

Date: August 1, 1994

Creator: Kubo, K. & Raubenheimer, T. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ions in the linacs of future linear colliders

Ions have been identified as a potential limitation in high current storage rings, but they are not usually thought to be a problem in electron linear accelerators. In this paper, we consider the effects of ions in the linacs of future linear colliders. Future linear collider designs call for long trains of closely spaced bunches and/or very dense bunches. Thus, significant ion densities can be generated through the collisional ionization process and trapping'' in a long train of bunches or thr… more

Date: July 1, 1992

Creator: Raubenheimer, T. O. & Chen, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Damping ring designs for a TeV Linear Collider

In this paper we present a damping ring design for the TLC (TeV Linear Collider). The ring operates at 1.8 GeV. It has normalized emittances of elepsilon/sub x/ = 2.8 mrad and elepsilon/sub y/ = 25.4 nmrad. The damping times are /tau//sub x/ = 2.5 ms and /tau//sub y/ = 4.0 ms. To achieve these extremely low emittances and fast damping times, the ring contains 22 m of wigglers. 30 refs., 7 figs., 7 tabs.

Date: December 1, 1988

Creator: Raubenheimer, T. O.; Rivkin, L. Z. & Ruth, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Centrifugal space-charge force for bunched beams

In 1990, E. Lee showed for a DC beam that the effect of the centrifugal space-charge force (CSCF) on an electron`s transverse motion in a end is cancelled to lowest order by the effect of the potential depression of the beam. However, this cancellation does not in general occur when the beam is bunched. We solve for the harmonic scalar and vector potentials and explicitly find the energy-independent transverse and longitudinal space-charge forces. We make estimates of the emittance growth as a … more

Date: August 1, 1994

Creator: Carlsten, B. E. & Raubenheimer, T. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Computer studies of a combined-function bend magnet for a proposed redesign of the SLAC SLC damping rings

A proposed redesign of the SLAC SLC Damping Ring requires a combined-function bending magnet. The magnet will operate with a main field of 1.8338 T, and quadrupole and sextupole gradients dB{sub y}/dx, d{sup 2}B{sub y}/dx{sup 2} of {minus}14.1 T/m and {minus}477 T/m{sup 2}, respectively. Because the orbit sagitta in the magnet is in excess of 2 cm, the pole will be curved with a 2 m radius of curvature. Furthermore, since the current must be variable over a range of {plus_minus}2 percent, we ha… more

Date: April 1, 1993

Creator: Early, R. A. & Raubenheimer, T. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A new method of correcting the trajectory in linacs

This paper describes a new method of reducing the transverse emittance dilution in linear colliders due to both transverse wakefields and dispersive errors. The technique is a generalization of the Dispersion-Free correction algorithm; the dilutions are corrected locally by varying the beam trajectory. This technique complements BNS damping which primarily corrects the dilutions resulting from coherent betatron oscillations. Finally, the results of simulations are presented demonstrating the vi… more

Date: May 1, 1991

Creator: Raubenheimer, T. O. & Ruth, R. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Simulation of Wakefield Effect in ILC IR Chamber

To achieve super high luminosity, high current beams with very short bunch length are needed, which carry high intensity EM fields. For ILC, two bunch trains with bunch length of 300 {micro}m and bunch charge of 3.2nC are needed to collide at the IR to achieve the ILC luminosity goals. When the 300 {micro}m bunches pass through the IR chamber, wakefields will be excited, which will cause HOM power flowing through the IR chamber beam pipe to the final doublets due to the high frequency character… more

Date: June 26, 2008

Creator: Pei, S; Seryi, A. & Raubenheimer, T.O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Distortion of Crabbed Bunch Due to Electron Cloud and Global Crabbing

Crab cavities may be used improve the luminosity in colliding beam colliders with crab crossing. In a global crab crossing correction, only one crab cavity is installed in each ring and the crab cavities generate a horizontally titled bunch oscillating around the ring. The electron cloud in positively charged rings may distort the crabbed bunch and cause the luminosity drop. This paper briefly estimates the distortion of positron bunch due to the electron cloud with global crab and estimates th… more

Date: August 1, 2008

Creator: Wang, L.; Raubenheimer, T.O. & Cai, Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Suppression of Secondary Emission in a Magnetic Field Using a Sawtooth and Isosceles Triangle Surface

The effect of surface roughness on the secondary electron emission from a sawtooth and isosceles triangle surface in a magnetic field under electron bombardment is investigated using a Monte-Carlo method. Some of the secondary electrons emitted from the surface return to the surface within their first few gyrations, resulting in a low effective secondary electron yield. Both sawtooth and isosceles triangle surface in magnetic field can significantly reduce the secondary emission yield below the… more

Date: September 26, 2006

Creator: Wang, L.; Raubenheimer, T.O. & Stupakov, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Chicane and wiggler based bunch compressors for future linear colliders

In this paper, we discuss bunch compressors for future linear colliders. In the past, the bunch compression optics has been based upon achromatic cells using strong sextupoles to correct the dispersive and betatron chromaticity. To preserve the very small emittances required in most future collider designs, these schemes tend to have very tight alignment tolerances. Here, we describe bunch compressors based upon magnetic chicanes or wigglers which do need sextupoles to correct the chromatic emi… more

Date: May 1, 1993

Creator: Raubenheimer, T. O.; Emma, P. & Kheifets, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Multi-Stage Bunch Compressors for the International Linear Collider

We present bunch compressor designs for the International Linear Collider (ILC) which achieve a reduction in RMS bunch length from 6 mm to 0.3 mm via multiple stages of compression, with stages of acceleration inserted between the stages of compression. The key advantage of multi-stage compression is that the maximum RMS energy spread is reduced to approximately 1%, compared to over 3% for a single-stage design. Analytic and simulation studies of the multi-stage bunch compressors are presented,… more

Date: May 27, 2005

Creator: Tenenbaum, P.; Raubenheimer, T. O. & Wolski, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A fast beam-ion instability

Mutually driven transverse oscillations of an electron beam and residual gas ions may result in a fast transverse instability. This effect arises either during a single pass of a train of electron bunches or it is caused by ionization electrons oscillating within a single positron bunch. In both cases, the beam oscillations grow exponentially with an exponent proportional to the square root of time. In this report, instability rise times are calculated analytically and compared with computer si… more

Date: June 1, 1995

Creator: Zimmermann, F.; Raubenheimer, T.O. & Stupakov, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department