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Requirements and limitations on beam quality in synchrotron radiation sources

Description: The requirements and limitations of the third generation of synchrotron radiation facilities are reviewed. These machines are designed to emit radiation of very high intensity, extreme brightness, very short pulses, and laserlike coherence. These performance goals put severe requirements on the quality of the electron or positron beams. Phenomena affecting the injection process and the beam lifetime are discussed. Gas desorption by synchrotron radiation, collective effects (coupled bunch oscillations) and ion trapping (for an electron beam) play an important role. Low emittance lattices are more sensitive to quadrupole movements and at the same time, in order not to lose the benefits of high brilliance, require tighter tolerances on the allowed movement of the photon beam source. 22 refs., 9 figs.
Date: July 1, 1989
Creator: Cornacchia, M.
Partner: UNT Libraries Government Documents Department

The Advanced Light Source at Lawrence Berkeley Laboratory

Description: The Advanced Light Source is a national user facility for the production of high brightness and partially coherent X-ray and ultraviolet synchrotron radiation, which is now under construction at Lawrence Berkeley Laboratory. The facility is based on a low emittance electron storage ring, photon beamlines and user support facilities. The lattice optics is optimized for undulator operation and can accommodate up to 11 insertion devices in the straight sections and up to 48 ports in the bending magnets. The nominal electron energy is 1.5 GeV, the horizontal emittance 10/sup -8/ m rad, the circulating current 400 mA in the multibunch mode of operation. The parameters are chosen to cover the photon spectrum from about 5 eV to 1 keV with undulators and up to 10 keV with wigglers. The choice of energy is dictated by the need to cover the above photon energy range with an undulator gap not smaller than 1.4 cm. The facility is now in its second year of construction and is planned to be completed in late 1992 at a total cost of $98.7 million. 4 refs., 8 figs., 1 tab.
Date: August 1, 1988
Creator: Cornacchia, M.
Partner: UNT Libraries Government Documents Department

The LBL (Lawrence Berkeley Laboratory) 1-2 GeV synchrotron radiation source

Description: A description is presented of the conceptual design of the 1 to 2 GeV Synchrotron Radiation Source proposed for construction at Lawrence Berkeley Laboratory. This facility is designed to produce ultraviolet and soft x-ray radiation. The accelerator complex consists of an injection system (linac plus booster synchrotron) and a low-emittance storage ring optimized for insertion devices. Eleven straight sections are available for undulators and wigglers, and up to 48 photon beam lines may ultimately emanate from bending magnets. Design features of the radiation source are the high brightness of the photon beams, the very short pulses (tens of picoseconds), and the tunability of the radiation.
Date: March 1, 1987
Creator: Cornacchia, M.
Partner: UNT Libraries Government Documents Department

Study on the conditions required for the transverse stability of a coasting beam in proton storage rings

Description: A general theory of the transverse instability of coasting beams in circular accelerators produced by the interaction of the beam charge and current with its electromagnetic environment is presented. The theory allows to numerically calculate the threshold current for an arbitrary frequency versus momentum curve. The numerical solution is used to study the stability of a coasting beam in a high energy proton storage ring like ISABELLE during the stacking process and for a full intensity beam.
Date: February 1, 1982
Creator: Cornacchia, M. & Pellegrini, C.
Partner: UNT Libraries Government Documents Department

Observations and computations of higher energy collective effects in the Fermilab Booster

Description: The aim of the experiments reported was to shed some light on the observed horizontal beam size growth in the Booster. A computational study of the effect of the impedance of the radio-frequency accelerating cavities has been carried out, and the results are compared with the experimental observations. Finally, possible cures for the instabilities are discussed.
Date: March 1, 1987
Creator: Cornacchia, M.
Partner: UNT Libraries Government Documents Department

Report on some beam-beam functional dependencies in SPEAR

Description: A considerable amount of experimental results on beam-beam effects in SPEAR is available. We have analyzed the results which give the functional dependences of some important machine parameters. The data have been taken from machine physics experiments carried out during the period December 1977 to October 1978, and from records of the operation runs. 10 refs., 13 figs., 3 tabs.
Date: November 1, 1978
Creator: Cornacchia, M.
Partner: UNT Libraries Government Documents Department

Beam-beam effects in curvilinear interaction regions in ISABELLE

Description: The presence of experimental apparatus in the interaction regions of an intersecting beam accelerator changes the configuration of the crossing beams. This changes the space-charge forces with respect to the standard, magnet-free crossing. There is strong interest in instrumenting one of the intersections at ISABELLE with a major spectrometer facility, which involves a large aperture dipole magnet located at the intersection of the beams. Various configurations of the dipole spectrometer have been proposed, and they are analyzed in this paper from the point of view of the perturbation introduced to the beam-beam interaction.
Date: October 1, 1979
Creator: Cornacchia, M & Parzen, G
Partner: UNT Libraries Government Documents Department

Pulsed rf operation analysis

Description: The need for a very low final amplifier output impedance, always associated with class A operation, requires a very large power waste in the final tube. The recently suggested pulsed rf operation, while saving a large amount of power, increases the inherent final amplifier non linearity. A method is presented for avoiding the large signal non linear analysis and it is shown how each component of the beam induced voltage depends upon all the beam harmonics via some coupling coefficients which are evaluated.
Date: January 1, 1981
Creator: Puglisi, M. & Cornacchia, M.
Partner: UNT Libraries Government Documents Department

Effects of magnetic non-linearities on a stored proton beam and their implications for superconducting storage rings

Description: In this report we describe an experiment which was conducted at the SPS to observe the combined effects of a single isolated high-order nonlinear resonance, nonlinear detuning, and tune modulation. The nonlinear resonance, as well as the nonlinear detuning, was driven by a nonlinear lens, which had been previously used at the SPS for the study of the beam-beam interactions. The nonlinear motion of a particle in the field of the lens is discussed.
Date: October 7, 1982
Creator: Cornacchia, M. & Evans, L.
Partner: UNT Libraries Government Documents Department

Effects of magnetic non-linearities on a stored proton beam and their implications for superconducting storage rings

Description: A nonlinear lens may be used to study the effect of high-order multipolar field imperfections on a stored proton beam. Such a nonlinear lens is particulary suitable to simulate field imperfections of the types encountered in coil dominated superconducting magnets. We have studied experimentally at the SPS the effect of high order (5th and 8th) single isolated resonances driven by the nonlinear lens. The width of these resonances is of the order one expects to be caused by field errors in superconducting magnets of the SSC type. The experiment shows that, in absence of tune modulation, these resonances are harmless. Slow crossings of the resonance, on the other hand, have destructive effects on the beam, much more so than fast crossings caused by synchrotron oscillations. In the design of future storage rings, sources of low-frequency tune modulation should be avoided as a way to reduce the harmful effects of high order multipolar field imperfection.
Date: June 1, 1985
Creator: Cornacchia, M. & Evans, L.
Partner: UNT Libraries Government Documents Department

Chromatic properties and tracking studies of a 20 TeV pp collider

Description: The chromatic properties of a lattice for the 20 TeV pp collider described in an accompanying paper have been investigated. Since this machine has a low ..beta..-function value at the interaction points (..beta../sub x,y/ = 2 m), the large value in the nearby quadrupoles is a major source of perturbations for off-momentum particles. Preliminary tracking studies have been performed in an attempt to determine the dynamic aperture. The model includes the effects of chromaticity sextupoles, octupoles to straighten the working line, random multipoles simulating magnet construction errors and closed orbit distortions.
Date: August 1, 1983
Creator: Garren, A.; Cornacchia, M. & Dell, F.
Partner: UNT Libraries Government Documents Department

Fundamentals of relativistic particle beam optics

Description: This lecture introduces the nonaccelerator-specialist to the motion of charged particles in a Storage Ring. The topics of discussion are restricted to the linear and nonlinear dynamics of a single particle in the transverse plane, i.e., the plane perpendicular to the direction of motion. The major omissions for a complete review of accelerator theory, for which a considerable literature exists, are the energy and phase oscillations (1). Other important accelerator physics aspects not treated here are the collective instabilities (2), the role of synchrotron radiation in electron storage rings (3), scattering processes (4), and beam-beam effects in colliding beam facilities (5). Much of the discussion that follows applies equally well to relativistic electron, proton, or ion synchrotrons. In this narrative, we refer to the particle as electron. After a broad overview, the magnetic forces acting on the electrons and the associated differential equations of motion are discussed. Solutions of the equations are given without derivation; the method of solution is outlined. and references for deeper studies are given. In this paper, the word electron is used to signify electron or positron. The dynamics of a single particle are not affected by the sign of its charge when the magnetic field direction is changed accordingly.
Date: December 1, 1995
Creator: Cornacchia, M.
Partner: UNT Libraries Government Documents Department

Theoretical treatment of transverse feedback systems with memory

Description: The differential equation of the dipole moment of coherent oscillations in the presence of a feedback system is derived. The analysis, which starts in the time domain, is extended to the frequency domain; this allows a straightforward derivation of the damping rate for both coasting and bunched beams. The damping rate is expressed in terms of the transfer function of the feedback system and in a general form which takes into account the ..beta..-function and betatron phase modulation along the beam trajectory, the effect of memory arising from the finiteness of the system bandwidth, the effect of the time delay and of the betatron phase advance between detector and kicker. Some examples of the dependence of the damping rate on the feedback parameters are given.
Date: January 1, 1981
Creator: Cornacchia, M. & Wang, J.M.
Partner: UNT Libraries Government Documents Department

Longitudinal feedback system for PEP

Description: Whether the wide bandwidth longitudinal feedback system described in this paper is made to act on the individual modes in frequency domain or on the individual bunches in time domain, it represents a clean and efficient way of damping the longitudinal oscillations without influencing other beam parameters such as bunch shape or synchrotron frequency distribution. The frequency domain feedback presents the advantage of providing information on which modes are unstable and on their risetimes, which may be helpful in locating dangerous resonators in the ring.
Date: February 1, 1979
Creator: Allen, M.A.; Cornacchia, M. & Millich, A.
Partner: UNT Libraries Government Documents Department

Performance and design concepts of a free electron laser operating in the x-ray region

Description: We report on the Design Study of a Free-Electron-Laser experiment designed to produce coherent radiation at the wavelength of 1.5 {Angstrom} and longer. The proposed experiment utilizes 1/3 of the SLAC linac to accelerate electrons to 15 GeV. The high brightness electron beam interacts with the magnetic field of a long undulator and generates coherent radiation by self-amplified spontaneous emission (SASE). The projected output peak power is about, 10 GW. The project presents several challenges in the realization of a high brightness electron beam, in the construction and tolerances of the undulator and in the transport, of the x-ray radiation. The technical solutions adopted for the design are discussed. Numerical simulations are used to show the performance as a function of system parameters.
Date: March 1, 1997
Creator: Cornacchia, M.
Partner: UNT Libraries Government Documents Department

Colliding-beam-accelerator lattice

Description: We describe the lattice of the Colliding Beam Accelerator, a 400 x 400 GeV pp facility proposed for construction at Brookhaven National Laboratory. The structure adopted is very versatile, in part in consequence of its desirable behavior as function of momentum deviation and as function of the betatron tunes. Each of the six insertions can be arranged to meet specific requirements at the crossing points as illustrated by a discussion of the tuneable low-beta insertions. The luminosity in these low-beta insertions (2 x 10/sup 33/ cm/sup -2/ sec/sup -1/) would be an order of magnitude larger than the standard insertions.
Date: January 1, 1983
Creator: Claus, J.; Cornacchia, M.; Courant, E.D. & Parzen, G.
Partner: UNT Libraries Government Documents Department

Status of ISABELLE lattice

Description: ISABELLE, a facility for colliding protons with center of mass energies between 60 and 800 GeV, is presently under construction at Brookhaven National Laboratory. The device consists of two identical rings for the accumulation, acceleration and storage of proton beams, shaped and interlaced in the horizontal plane to intersect in six so-called crossing points where the beams that rotate in opposite directions in the two rings are exposed to each other. The overall dimensions of the facility are kept relatively small because advantage is taken of the large fields and gradients that are possible in superconducting magnets; the associated saturation effects in the magnet iron make a separated function lattice practically inevitable. The rings are to be filled from the AGS, using synchronous beam transfer; this forces their circumference to an integer multiple of the rf wavelength in the AGS (=67.26 m). The integer chosen is 57, about the lowest value possible, thus the circumference of each ring is 3833.85 m. The charge in each ring is expected to be about 6.4 x 10/sup 14/ protons, which requires about 250 AGS charges of 2.75 x 10/sup 12/ protons per pulse if the injection efficiency is 100%.The actual efficiency is unlikely to be better than 50%, so that in excess of 500 AGS pulses may be needed per ring. The beam is to be accumulated in synchrotron phase space by means of an injection and stacking procedure similar to one developed for the ISR at CERN; this leaves the betatron emittance of the circulating beams independent of its intensity and equal to that in the AGS just before extraction while its momentum spread increases with intensity.
Date: January 1, 1979
Creator: Claus, J.; Cornacchia, M.; Courant, E.D. & Parzen, G.
Partner: UNT Libraries Government Documents Department

Accelerator physics experiments at Aladdin

Description: The Aladdin accelerator is a 1 GeV synchrotron light source located at the University of Wisconsin. The results of experimental studies of the Aladdin accelerator are described. The primary purpose of the experiments reported was to investigate reported anomalies in the behavior of the linear lattice, particularly in the vertical plane. A second goal was to estimate the ring broadband impedance. Experimental observations and interpretation of the linear properties of the Aladdin ring are described, including the beta function and dispersion measurements. Two experiments are described to measure the ring impedance, the first a measurement of the parasitic mode loss, and the second a measurement of the beam transfer function. Measurements of the longitudinal and transverse emittance at 100 and 200 MeV are described and compared with predictions. 10 refs., 24 figs., 2 tabs. (LEW)
Date: July 1, 1985
Creator: Chattopadhyay, S.; Cornacchia, M.; Jackson, A. & Zisman, M.S.
Partner: UNT Libraries Government Documents Department

Proposed orbit and vertical dispersion correction system for PEP

Description: The scheme for minimization of the rms orbit errors in ISR and SPEAR will be used to correct the closed orbit errors in PEP. The effectiveness of this scheme has been studied for some alignment and field errors in the PEP magnets and position monitors. It has been found for orbit correction system in PEP consisting of 48 correctors and 96 monitors, both horizontal and vertical orbits can be kept below 0.5 mm rms values even allowing for a position monitor alignment error of 0.5 mm rms. This method of correction has also been found to be usable to reduce the rms value of the vertical dispersion without appreciably affecting the corrected orbits. The result of this study is presented.
Date: February 1, 1979
Creator: Close, E.; Cornacchia, M.; King, A. & Lee, M.J.
Partner: UNT Libraries Government Documents Department

Effect of a spectrometer magnet on the beam-beam interaction

Description: The presence of experimental apparatus in the interaction regions of an intersecting beam accelerator changes the configuration of the crossing beams. This changes the space-charge forces with respect to the standard, magnet-free crossing. The question is: what is the maximum allowable perturbation caused by the spectrometer magnet that can be tolerated from the point of view of the beam dynamics. This paper is limited to the perturbations that the curved trajectories cause the beam-beam space charge nonlinearities. The question has arisen of how one defines the strength of the perturbation. The only solution is to compute the strength of the most important nonlinear resources. In what follows, the computational method used in calculating these resonances is described, and compared with those induced by random orbit errors.
Date: January 1, 1981
Creator: Cornacchia, M & Parzen, G
Partner: UNT Libraries Government Documents Department

ISABELLE accelerator software, control system, and beam diagnostic philosophy

Description: The ISABELLE Project combines two large proton accelerators with two storage rings in the same facility using superconducting magnet technology. This combination leads to severe constraints on beam loss in magnets and involves complex treatment of magnetic field imperfections and correction elements. The consequent demands placed upon beam diagnostics, accelerator model programs, and the computer oriented control system are discussed in terms of an illustrative operation scenario.
Date: January 1, 1981
Creator: Cornacchia, M.; Humphrey, J.W.; Niederer, J. & Poole, J.H.
Partner: UNT Libraries Government Documents Department

A proposed orbit and vertical dispersion correction system for PEP

Description: The proposed arrangement of position monitors and dipole magnets for the closed orbit correction system in PEP is described. The computer code ALIGN, which simulates and corrects closed orbit displacements, has been used to study the most effective layout of monitors and correctors. The vertical dispersion function has been computed before and after closed orbit correction. The results indicate that the residual vertical dispersion after the orbit is corrected could exceed the tolerable values. A correction procedure for the vertical dispersion has been studied with the compute code CO-OP and this scheme of correction has been verified experimentally in SPEAR. 9 refs., 8 figs., 2 tabs.
Date: July 1, 1978
Creator: Close, E.; Cornacchia, M.; King, A.S. & Lee, M.J.
Partner: UNT Libraries Government Documents Department

Running fermi with one-stage compressor: advantages, layout,performance

Description: CBP-Tech Note-345 (July 2005), devoted to a study of microbunching instability in FERMI@ELETTRA linac quotes '...the above analysis shows that the most of the gain in microbunching instability occurs after BC2, i.e. after transformation of the energy modulation to the spatial modulation that takes place in BC2. It is possible to avoid that if we use only BC1 for all our needs for bunch compression. There are also additional advantages for a mitigation of the microbunching instability related to that. First, we would need to increase R56 in BC1 (for given energy chirp in the electron beam). Second, a relative energy spread is significantly larger at BC1 than at BC2. Both these factors would contribute to instability suppression due to increased Landau damping effect.' One additional argument was however missed in that report. Instability smearing due to finite emittance is stronger in BC1 simply because the geometrical emittance is larger than in BC2. In spite of the considerations in favor of a lattice with one-stage compressor, it was thought at the time that the two bunch compressors configuration was still preferable as it appeared difficult to obtain a flat-flat distribution at the end of the linac with only one bunch compressor. A flat-flat distribution has constant medium energy and a constant peak current along the electron bunch. Now, two years later and more studies behind, this problem is solvable. It has been demonstrated1 that shaping the intensity of the electron bunch at the injector using intensity modulation of the photocathode laser allows to use the linac structural wake fields to advantage to obtain a flat-flat distribution at the end of the linac in a two-stage compressor. This report shows that, using the back-tracking technique, it is possible to obtain a flat-flat distribution also in a single-stage compressor. Preliminary results of ...
Date: May 25, 2007
Creator: Cornacchia, M.; Craievich, P.; Di Mitri, S.; Penco, G.; Venturini, M. & Zholents, A.
Partner: UNT Libraries Government Documents Department

Non Linear Beam Dynamics Studies at SPEAR

Description: The frequency map analysis of a Hamiltonian system recently introduced to accelerators physics in combination with turn-by-turn phase space measurements opens new experimental opportunities for studying non linear dynamic in storage rings. In this paper we report on the experimental program at SPEAR having the goal of measuring the frequency map of the machine. In this paper we discuss the accuracy of the instantaneous tune extraction from experimental data and demonstrate the possibility of the frequency map measurement. The instantaneous tune extraction technique can be applied to experimental tracking data with reasonable accuracy. Frequency map can be experimentally determined using the existing turn-by-turn phase space measurement techniques and NAFF instantaneous tune extraction.
Date: September 12, 2011
Creator: Terebilo, A.; Pellegrini, C.; /UCLA; Cornacchia, M.; Corbett, J.; Martin, D. et al.
Partner: UNT Libraries Government Documents Department