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Common Mode Rejection of Stack Tail Kicker Hybrids

Description: The betatron heating of the core is commonly agreed to be due to a undesired difference mode in the kickers. This could be due to tolerances and mistakes in the kickers or in the hydrids which ideally drive the kickers in the sum mode. The purpose of this note is to estimate the effect of the latter. The hydrids, by the nature of their construction, have systematic errors. These errors appear to be larger than the errors which come from construction tolerances.
Date: November 22, 1985
Creator: Marriner, J.
Partner: UNT Libraries Government Documents Department

Difference between BPM reading one bunch and the average of multi-bunch in Booster

Description: Differences caused by BPM reading one bunch and multi-bunch average need to be well understood before the beam parameters, such as the synchrotron tune, betatron tune, and chromaticity, are extracted from those BPM data. It is easy to perform such a study using numerical simulation other than modifying the BPM electronics.
Date: August 18, 2004
Creator: Yang, Xi
Partner: UNT Libraries Government Documents Department

Beam diagnostics via model independent analysis of the turn-by-turn BPM data

Description: Model independent analysis (MIA) can be used to obtain all the eigen modes included in the turn-by-turn BPM data. Not only the synchrotron tune and betatron tune can be obtained from the fast Fourier transforms (FFT) of the temporal eigen vector of the corresponding mode, but also the error mode, which could be caused by the different gain of a BPM, can be observed in both the temporal and spatial eigen vectors of the error mode. It can be applied as a diagnostic tool for Booster.
Date: August 11, 2004
Creator: Yang, Xi
Partner: UNT Libraries Government Documents Department

REAL TIME BETATRON TUNE CONTROL IN RHIC.

Description: Precise control of the betatron tunes is necessary to preserve proton polarization during the RHIC ramp. In addition, control of the tunes during beam deceleration is necessary due to hysteresis in the superconducting magnets. A real-time feedback system to control the betatron tunes during ramping has been developed for use in RHIC. This paper describes this system and presents the results from commissioning the system during the polarized proton run.
Date: June 2, 2002
Creator: SCHULTHEISS,C.; CAMERON,P.; MARUSIC,A. & VAN ZEIJTS,J.
Partner: UNT Libraries Government Documents Department

Measurement of coupling resonance driving terms with the AC dipole

Description: Resonance driving terms for linear coupled betatron motion in a synchrotron ring can be determined from corresponding spectral lines of an excited coherent beam motion. An AC dipole is one of instruments to excite such a motion. When a coherent motion is excited with an AC dipole, measured Courant-Snyder parameters and betatron phase advance have apparent modulations, as if there is an additional quadrupole field at the location of the AC dipole. Hence, measurements of these parameters using the AC dipole require a proper interpretation of observed quantities. The situation is similar in measurements of resonance driving terms using the AC dipole. In this note, we derive an expression of coupled betatron motion excited with two AC dipoles in presence of skew quadrupole fields, discuss an impact of this quadrupole like effect of the AC dipole on a measurement of coupling resonance driving terms, and present an analytical method to determine the coupling resonance driving terms from quantities observed using the AC dipole.
Date: October 1, 2010
Creator: Miyamoto, R.
Partner: UNT Libraries Government Documents Department

Emittance Growth in TESLA

Description: The results of collective simulation of a typical TeV Energy Superconducting Linear Accelerator (TESLA) are reported. Because of accelerating gradient is low and the accelerator is long compared to other TeV colliders, betatron phase mixing must be suppressed along with the usual sources of emittance growth. Including single bunch effects, alignment tolerances consistent with reasonable emittance growth are given. When such tolerances are achieved, multibunch effects do not cause excessive effective emittance growth. In addition, longitudinal multibunch effects are discussed.
Date: May 1, 1991
Creator: Krafft, Geoffrey & Bisognano, Joseph
Partner: UNT Libraries Government Documents Department

Beta* and beta-waist measurement and control at RHIC

Description: During the course of last RHIC runs the beta-functions at the collision points ({beta}*) have been reduced gradually to 0.7m. In order to maximize the collision luminosity and ensure the agreement of the actual machine optics with the design one, more precise measurements and control of {beta}* value and {beta}-waist location became necessary. The paper presents the results of the implementation of the technique applied in last two RHIC runs. The technique is based on well-known relation between the tune shift and the beta function and involves precise betatron tune measurements using BBQ system as well as specially developed knobs for {beta}-waist location control.
Date: May 4, 2009
Creator: Ptitsyn,V.; Della Penna, A.; Litvinenko, V.N.; Malitsky, N. & Satogata, T.
Partner: UNT Libraries Government Documents Department

ORBIT DYNAMICS IN THE SPIRAL-RIDGED CYCLOTRON

Description: Formulas are derived for the equilibrium orbit, isochronous condition, vertical and horizontal betatron frequencies, and for the effects of the 3/3 radial resonance in a three-fold geometry. The magnetic field is represented by a Fourier series in azimuth with amplitudes expanded in a Taylor series about the reference radius. The form is such that the various parameters may be deduced from an arbitrary set of field measurements in the median plane and the results obtained by direct substitution in algebraic formulas.
Date: January 12, 1959
Creator: Smith, Lloyd & Garren, Alper A.
Partner: UNT Libraries Government Documents Department

A Study of the Effects of Betatron Coupling the Accumulator Using a Tracking Program

Description: This report will summarize some tracking simulations I performed to demonstrate that in a strongly coupled machine all or most of the transverse energy associated with betatron motion can at times reside in a single dimension. In this case the maximum excursion from the closed orbit is larger than what is expected from the known emittances, and can cause beam loss when it otherwise is not expected.
Date: February 7, 1992
Creator: Halling, Mike
Partner: UNT Libraries Government Documents Department

Common Mode Rejection Calculations on the Debuncher Upgrade

Description: The 4-8 GHz Transverse Debuncher Cooling Systems are power limited. Misalignments and imperfections in the transverse pickup arrays will generate a longitudinal signal in addition to the betatron signal. This longitudinal signal can use up a significant fraction of the precious TWT power if the imperfections are large enough. This note will summarize calculations of the contributions to the longitudinal signal observed in the transverse systems of the 4-8 GHz Debuncher slow-wave pickup arrays due to various misalignments and imperfections.
Date: February 2, 2001
Creator: McGinnis, Dave
Partner: UNT Libraries Government Documents Department

Preliminary Studies of a Phase Modulation Technique for Measuring Chromaticity

Description: The classical method for measuring chromaticity is to slowly modulate the RF frequency and then measuring the betatron tune excursion. The technique that is discussed in this paper modulates instead the phase of the RF and then the chromaticity is obtained by phase demodulating the betatron tune. However, this technique requires knowledge of the betatron frequency in real time in order for the phase to be demodulated. Fortunately, the Tevatron has a tune tracker based on the phase locked loop principle which fits this requirement. A preliminary study with this technique has showed that it is a promising method for doing continuous chromaticity measurement and raises the possibility of doing successful chromaticity feedback with it.
Date: April 1, 2006
Creator: Tan, Cheng-Yang
Partner: UNT Libraries Government Documents Department

Chromaticity tracking using a phase modulation technique

Description: In the classical chromaticity measurement technique, chromaticity is measured by measuring the change in betatron tune as the RF frequency is varied. This paper will describe a novel way of measuring chromaticity: we will phase modulate the RF with a known sine wave and then phase demodulate the betatron frequency. The result is a line in Fourier space which corresponds to the frequency of our sine wave modulation. The peak of this sine wave is proportional to chromaticity. For this technique to work, a tune tracker PLL system is required because it supplies the betatron carrier frequency. This method has been tested in the Tevatron and we will show the results here.
Date: June 1, 2007
Creator: Tan, C.Y.
Partner: UNT Libraries Government Documents Department

Chromaticity tracking with a phase modulation/demodulation technique in the Tevatron

Description: The Tevatron chromaticity tracker (CT) has been successfully commissioned and is now operational. The basic idea behind the CT is that when the phase of the Tevatron RF is slowly modulated, the beam momentum is also modulated. This momentum modulation is coupled transversely via chromaticity to manifest as a phase modulation on the betatron tune. And so by phase demodulating the betatron tune, the chromaticity can be recovered. However, for the phase demodulation to be successful, it is critical that the betatron tune be a coherent signal that can be easily picked up by a phase detector. This is easily done because the Tevatron has a phase locked loop based tune tracker which coherently excites the beam at the betatron tune.
Date: January 1, 2009
Creator: Tan, C.Y.
Partner: UNT Libraries Government Documents Department

The Tevatron Chromaticity tracker

Description: The Tevatron chromaticity tracker (CT) has been successfully commissioned and is now operational. The basic idea behind the CT is that when the phase of the Tevatron RF is slowly modulated, the beam momentum is also modulated. This momentum modulation is coupled transversely via chromaticity to manifest as a phase modulation on the betatron tune. Thus by phase demodulating the betatron tune, the chromaticity can be recovered. However, for the phase demodulation to be successful, it is critical that the betatron tune be a coherent signal that can be easily picked up by a phase detector. This is easily done because the Tevatron has a phase locked loop (PLL) based tune tracker which coherently excites the beam at the betatron tune.
Date: December 1, 2008
Creator: Tan, Cheng-Yang
Partner: UNT Libraries Government Documents Department

Methods of orbit correction system optimization

Description: Extracting optimal performance out of an orbit correction system is an important component of accelerator design and evaluation. The question of effectiveness vs. economy, however, is not always easily tractable. This is especially true in cases where betatron function magnitude and phase advance do not have smooth or periodic dependencies on the physical distance. In this report a program is presented using linear algebraic techniques to address this problem. A systematic recipe is given, supported with quantitative criteria, for arriving at an orbit correction system design with the optimal balance between performance and economy. The orbit referred to in this context can be generalized to include angle, path length, orbit effects on the optical transfer matrix, and simultaneous effects on multiple pass orbits.
Date: August 1, 1997
Creator: Chao, Yu-Chiu
Partner: UNT Libraries Government Documents Department

Betatron tune shifts and Laslett image coefficients

Description: The complicated expressions of betatron tune shifts in terms of Laslett image coefficients are explained. The expressions of image coefficients for a centered or off-centered beam inside an elliptical or rectangular vacuum chamber are gathered. Typos in earlier literature are corrected.
Date: July 20, 2001
Creator: Ng, K. Y.
Partner: UNT Libraries Government Documents Department

SINGLE BUNCH BEAM BREAKUP - A GENERAL SOLUTION.

Description: Caporaso, Barletta and Neil (CBN) found in a solution to the problem of the single-bunch beam breakup in a linac[1]. However, their method applies only to the case of a beam traveling in a strongly betatron-focused linac under the influence of the resistive wall impedance. We suggest in this paper a method for dealing with the same problem. Our methods is more general; it applies to the same problem under any impedance, and it applies to a linac with or without external betatron focusing.
Date: June 26, 2000
Creator: Wang, J. M.; Mane, S. R. & Towne, N.
Partner: UNT Libraries Government Documents Department

Chromaticity measurement via the fourier spectrum of transverse oscillations

Description: Turn-by-turn data from a single BPM includes information on the chromaticity in sidebands displaced above and below the betatron frequency by an amount of the synchrotron frequency. It may be necessary to induce small amplitude synchrotron oscillation by giving the beam a small kick. Power spectrum of the BPM data gives clear chromatic sidebands, and they can be applied to the chromaticity measurement in the Fermilab Booster.
Date: August 13, 2004
Creator: Yang, Xi
Partner: UNT Libraries Government Documents Department

Betatron motion with coupling of horizontal and vertical degrees of freedom

Description: The Courant-Snyder parameterization of one-dimensional linear betatron motion is generalized to two-dimensional coupled linear motion. To represent the 4 x 4 symplectic transfer matrix the following ten parameters were chosen: four beta-functions, four alpha-functions and two betatron phase advances which have a meaning similar to the Courant-Snyder parameterization. Such a parameterization works equally well for weak and strong coupling and can be useful for analysis of coupled betatron motion in circular accelerators as well as in transfer lines. Similarly, the transfer matrix, the bilinear form describing the phase space ellipsoid and the second order moments are related to the eigen-vectors. Corresponding equations can be useful in interpreting tracking results and experimental data.
Date: November 21, 2002
Creator: Bogacz, S. A. & Lebedev, V. A.
Partner: UNT Libraries Government Documents Department

Coupled-bunch instabilities of the Tevatron at Run II

Description: The longitudinal and transverse coupled-bunch instabilities of the Tevatron at Run II are addressed in two scenarios. The first scenario corresponds to the present Run II condition: 36 proton bunches on 36 antiprotons. Each proton bunch contains 1.7 x 10{sup 11} particles with a rms bunch length 60 cm. The second scenario is for the future upgrade when there are 108 proton bunches colliding with 108 antiproton bunches. Each proton bunch contains 2.7 x 10{sup 11} particles with a rms bunch length 50 cm. The analysis shows that the growth rates of transverse coupled-bunch instabilities are slow and will be damped by a small betatron tune spread. On the other hand, growth rates of longitudinal coupled-bunch instabilities will be fast especially for the 108-by-108 scenario.
Date: March 6, 2003
Creator: Ng, K. Y.
Partner: UNT Libraries Government Documents Department

Epicyclic Twin-Helix Ionization Cooling Simulations

Description: Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a highluminosity muon collider. For the implementation of PIC, we earlier developed an epicyclic twin-helix channel with correlated behavior of the horizontal and vertical betatron motions and dispersion. We now insert absorber plates with short energy-recovering units located next to them at the appropriate locations in the twin-helix channel. We first demonstrate conventional ionization cooling in such a system with the optics uncorrelated. We then adjust the correlated optics state and induce a parametric resonance to study ionization cooling under the resonant condition.
Date: April 1, 2011
Creator: Vasiliy Morozov, Yaroslav Derbenev, A. Afanaciev, R.P. Johnson
Partner: UNT Libraries Government Documents Department

Solenoid Fringe Field Effects for the Neutrino Factory Linac - MAD-X Investigation

Description: International Design Study for the Neutrino Factory (IDS-NF) assumes the first stage of muon acceleration (up to 900 MeV) to be implemented with a solenoid based Linac. The Linac consists of three styles of cryo-modules, containing focusing solenoids and varying number of SRF cavities for acceleration. Fringe fields of the solenoids and the focusing effects in the SRF cavities have significant impact on the transverse beam dynamics. Using an analytical formula, the effects of fringe fields are studied in MAD-X. The resulting betatron functions are compared with the results of beam dynamics simulations using OptiM code.
Date: May 1, 2010
Creator: M. Aslaninejad,C. Bontoiu,J. Pasternak,J. Pozimski,Alex Bogacz
Partner: UNT Libraries Government Documents Department

Searching for the Optimal Working Point of the MEIC at JLab Using an Evolutionary Algorithm

Description: The Medium-energy Electron Ion Collider (MEIC), a proposed medium-energy ring-ring electron-ion collider based on CEBAF at Jefferson Lab. The collider luminosity and stability are sensitive to the choice of a working point - the betatron and synchrotron tunes of the two colliding beams. Therefore, a careful selection of the working point is essential for stable operation of the collider, as well as for achieving high luminosity. Here we describe a novel approach for locating an optimal working point based on evolutionary algorithm techniques.
Date: March 1, 2011
Creator: Terzic, Balsa; KRamer, Matthew & Jarvis, Colin
Partner: UNT Libraries Government Documents Department