• C. Yao
  
• A. H. Lumpkin
  ANL, Argonne, Illinois
• D. W. Rule
  NSWC, West Bethesda, Maryland

Interest in nonintercepting (NI) beam size monitoring for top-up operations at the Advanced Photon Source (APS) motivated our investigations of optical diffraction radiation (ODR) techniques. We have reported our experiment results earlier. In particular, we wanted to monitor the beam size in the booster-to-storage ring (BTS) transport line using near-field ODR. An analytical model was numerically evaluated for the APS BTS beam size cases. In addition, the simulations show that near-field ODR profiles have sensitivity to beam size in the 20- to 50-μm region, which are relevant to X-ray FELs and the international linear collider (ILC). The simulation indicates that the orthogonal polarization component is close to a Gaussian distribution and more sensitive to beam size variations, and therefore is more suitable for beam size measurement. Under some circumstances the parallel polarization component shows a non-Gaussian distribution that is also beam size dependent. This report describes the simulation method, the results, and the comparison with experiment results.

• B. Sayyar-Rodsari
  
• W. J. Corbett, M. J. Lee, P. Lui, J. M. Paterson
  SLAC, Menlo Park, California
• E. Hartman, C. A. Schweiger
  Pavilion Technologies, Inc, Austin, Texas

Synchrotron light is used for a wide variety of scientific disciplines ranging from physical chemistry to molecular biology and industrial applications. As the electron beam circulates, random single-particle collisional processes lead to decay of the beam current in time. We report a simulation study in which a combined neural network (NN) and first-principles (FP) model is used to capture the decay in beam current due to Touschek, Bremsstralung, and Coulomb effects. The FP block in the combined model is a parametric description of the beam current decay where model parameters vary as a function of beam operating conditions (e.g. vertical scraper position, RF voltage, number of the bunches, and total beam current). The NN block provides the parameters of the FP model and is trained (through constrained nonlinear optimization) to capture the variation in model parameters as operating condition of the beam changes. Simulation results will be presented to demonstrate that the proposed combined framework accurately models beam decay as well as variation to model parameters without direct access to parameter values in the model.

• R. Miyamoto
  
• A. Jansson, M. J. Syphers
  Fermilab, Batavia, Illinois
• S. E. Kopp
  The University of Texas at Austin, Austin, Texas

• R. Miyamoto
  
• A. Jansson, M. J. Syphers
  Fermilab, Batavia, Illinois
• S. E. Kopp
  The University of Texas at Austin, Austin, Texas

• Y. Alexahin
  

To avoid multiple head-on collisions the proton and antiproton beams in the Tevatron move along separate helical orbits created by 7 horizontal and 8 vertical electrostatic separators. Still the residual long-range beam-beam interactions can adversely affect particle motion at all stages from injection to collision. With increased intensity of the beams it became necessary to modify the orbits in order to mitigate the beam-beam effect on both antiprotons and protons. This report summarizes the work done on optimization of the Tevatron helical orbits, outlines the applied criteria and presents the achieved results.

• J.-P. Carneiro
  
• V. Kamerdzhiev, A. Semenov, R. C. Webber
  Fermilab, Batavia, Illinois

• A. Jansson
  
• K. Bowie, T. Fitzpatrick, R. Kwarciany, C. Lundberg, D. Slimmer, L. Valerio, J. R. Zagel
  Fermilab, Batavia, Illinois

Two Ionization Profile Monitors (IPMs) were installed in the Tevatron in 2006. The detectors are capable of resolving single bunches turn-by-turn, using a combination of gas injection to boost the ionization signal and very fast and sensitive electronics to detect it. This paper presents recent improvements to the system hardware and its use for beam monitoring. In particular, the correction of beam size oscillations observed at injection is discussed.

• P. Snopok
  
• M. Berz
  MSU, East Lansing, Michigan
• C. Johnstone
  Fermilab, Batavia, Illinois

• K. Y. Ng
  

• J. Ruan
  
• H. Edwards, V. E. Scarpine, C.-Y. Tan, R. Thurman-Keup
  Fermilab, Batavia, Illinois
• YL. Li, J. G. Power
  ANL, Argonne, Illinois
• T. J. Maxwell
  Northern Illinois University, DeKalb, Illinois

The free space electro-optical (EO) sampling technique is a powerful tool for analyzing the longitudinal charge density of an ultrashort e-beam. In this paper, we present

1. experimental results for a laser-based mock-up of the EO experiment* and
2. a design for a beam-based, single-shot, EO sampling experiment using the e-beam from the Argonne Wakefield Accelerator (AWA) RF photoinjector.

* Yuelin Li, Appl. Phys. Lett. 88, 251108, 2006

• C.-Y. Tan
  

In the classical chromaticity measurement technique, chromaticity is measured by measuring the change in betatron tune as the the RF frequency is varied. This paper will describe a 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 both the SPS and Tevatron and we will show the results here.

• C.-Y. Tan
  
• V. H. Ranjbar
  Tech-X, Boulder, Colorado

In the classical head-tail chromaticity measurement technique, a single large kick is applied transversely to the beam. The resulting phase difference between the head and the tail is measured and the chromaticity extracted. In the continuous head-tail kicking technique, a very small transverse kick is applied to the beam and the asymptotic phase difference between the head and the tail is found to be a function of chromaticity. The advantage of this method is that since the tune tracker PLL already supplies the small transverse kicks, no extra modulation is required.

• A. Valishev
  
• G. Annala, V. A. Lebedev, R. S. Moore
  Fermilab, Batavia, Illinois

• M.-J. Yang
  
• J. L. Crisp, P. S. Prieto
  Fermilab, Batavia, Illinois

• M.-J. Yang
  

• F. M. Bieniosek
  
• M. Leitner
  LBNL, Berkeley, California

We describe a high resolution (a few x 10-4) 90-degree cylindrical electrostatic energy analyzer for 1-MeV (singly ionized) heavy ions for experiments in the Heavy Ion Fusion Science Virtual National Laboratory. By adding a stripping cell, the energy reach of the analyzer is extended to 2 MeV. This analyzer has high dispersion in a first-order focus with bipolar deflection-plate voltages in the range of ±50 kV. We will present 2- and 3-D calculations of vacuum-field beam trajectories, space-charge effects, field errors, and a multipole corrector. The corrector consists of 12 rods arranged in a circle around the beam. Such a corrector has excellent properties as an electrostatic quadrupole, sextupole, or linear combination. The improved energy diagnostic allows measurements of beam charge state and energy spread, such as caused by charge exchange or temperature anisotropy, and better understanding of experimental results in longitudinal beam studies.

• S. De Santis
  
• J. M. Byrd
  LBNL, Berkeley, California
• M. T.F. Pivi
  SLAC, Menlo Park, California

We present the results of measurements of the electron cloud intensity in the PEP-II low energy ring (LER) by propagating a TE wave into the beam pipe. Connecting a pulse generator to a beam position monitor button we can excite a signal above the vacuum chamber cut-off and measure its propagation with a spectrum analyzer connected to another button a few meters away. The measurement can be performed with different beam conditions and also at different settings of the solenoids used to reduce the build up of electrons. The presence of a modulation in the TE wave transmission, synchronous with the beam revolution frequency and only measurable with the solenoids off, would be directly correlated to the intensity of the electron cloud phenomenon in the relative region of the ring. In this paper we present and discuss our measurements taken near Interaction Region 12 on the LER, during 2006 and early 2007.

• S. De Santis
  
• J. M. Byrd, R. B. Wilcox
  LBNL, Berkeley, California
• Y. Yin
  Y. Y. Labs, Inc., Fremont, California

We present the results of an experimental study of a beam timing monitor based on a technique demonstrated by Loehl*. This technique uses the electrical signal from a beam position monitor to amplitude-modulate a train of laser pulses, converting timing jitter into an amplitude jitter. This modulation is then measured with a photodetector and sampled by a fast ADC. This approach has already demonstrated sub-100 fsec resolution and promises even better results. Our study focuses on the use of this technique for precision timing for storage rings. We show results of measurements using signals from the Advanced Light Source.

* F. Loehl, et al., Proc. of the 2006 EPAC., p. 2781.

• G. Huang
  
• J. M. Byrd, J. Feng, J. Qiang, W. Wan
  LBNL, Berkeley, California

• J. Qiang
  
• J. M. Byrd, J. Feng, G. Huang
  LBNL, Berkeley, California

Streak camera is an important diagnostic device in the studies of laser plasma interaction, the detailed structure of photo reaction from material science to biochemistry, and in the measurement of the longitudinal distribution of a beam in accelerators. In this paper, we report on a new method which can potentially improve the temporal resolution of a streak camera down to femtoseconds. This method uses a time-dependent acceleration field to defocus the photo electrons longitudinally. This not only reduces the time dispersion distortion caused by initial energy spread but also mitigates the effects from the space-charge forces. An illustration of the method shows significant improvement of the modulation transfer function (MFT) compared with the conventional design.

• J. Qiang
  
• W. Fischer
  BNL, Upton, Long Island, New York
• T. Sen
  Fermilab, Batavia, Illinois

Long-range beam-beam interactions can cause significant degrade of beam quality and lifetime in high energy ring colliders. At RHIC, a series of experiments were carried out to study these effects. In this paper, we report on numerical simulation of the long-range beam-beam interactions at RHIC using a parallel strong-strong particle-in-cell code, BeamBeam3D. The simulation includes nonlinearities from both the beam-beam interactions and the arc sextupoles. We observed significant emittance growth for beam separation below 4 σs under nominal tunes. A scan study in tune space shows strong emittance growth around 7th order resonance. Including the tune modulation due to chromaticity and synchrotron motion shows larger emittance growth than the case without the tune modulation.

• K. G. Sonnad
  
• C. M. Celata, M. A. Furman, D. P. Grote, J.-L. Vay, M. Venturini
  LBNL, Berkeley, California

The Fermilab main injector (MI) is being considered for an upgrade as part of the high intensity neutrino source (HINS) effort. This upgrade will involve a significant increasing of the bunch intensity relative to its present value. Such an increase will place the MI in a regime in which electron-cloud effects are expected to become important. We have used the electrostatic particle-in-cell code WARP, recently augmented with new modeling capabilities and simulation techniques, to study the dynamics of beam-electron cloud interaction. This study involves a systematic assesment of beam instabilities due to the presence of electron clouds.

• J. M. Weber
  
• M. J. Chin, CA. Timossi, E. C. Williams
  LBNL, Berkeley, California

The ALS booster magnet upgrade for top off operation requires new instrumentation to meet increased magnet ramping requirements. To address these requirements, the ALS Instrumentation and Controls groups collaborated to design a new control system module called the Mini IOC. The Mini IOC hardware is based on a commercial evaluation board containing an FPGA with embedded processor and built-in interfaces for 128MB of DDR SDRAM and Ethernet. A custom module is used for analog controls and monitors. The PowerPC embedded processor runs an EPICS database built on the VxWorks operating system allowing remote access via Ethernet. This paper includes an overview of the Mini IOC design and operational results.

• V. H. Ranjbar
  
• D. T. Abell, K. Paul
  Tech-X, Boulder, Colorado
• I. Ben-Zvi, J. Kewisch
  BNL, Upton, Long Island, New York
• J. Qiang, R. D. Ryne
  LBNL, Berkeley, California

Plans for the RHIC luminosity upgrade call for an electron cooling system that will place substantial demands on the energy, current, brightness, and beam quality of the electron beam. In particular, the requirements demand a new level of fidelity in beam dynamics simulations. New developments in MaryLie/IMPACT have improved the space-charge computations for beams with large aspect ratios and the beam dynamic computations for rf cavities. We present the results of beam dynamics simulations that include the effects of space charge and nonlinearities, and aim to assess the tolerance for errors and nonlinearities on current designs for a super-conducting ERL.

• R. B. Fiorito
  
• B. L. Beaudoin, S. J. Casey, D. W. Feldman, P. G. O'Shea, B. Quinn, A. G. Shkvarunets
  UMD, College Park, Maryland

We present strong evidence of the observation of optical transition radiation (OTR) from aluminized silicon targets intercepting the UMER 10 keV, 100 ns pulsed electron beam, using fast (300ps and 1ns rise time) photomultiplier tubes. An intensified gated (3ns-1ms) CCD camera is used to image the beam using OTR and to study its time evolution throughout the beam pulse. A comparison of wave forms and time resolved OTR images is presented along with time integrated images obtained with phosphor screens for different initial conditions, i.e. beam currents and gun bias voltages.

correspondance email: rfiorito@umd.edu

• A. G. Shkvarunets
  
• M. E. Conde, W. Gai, J. G. Power
  ANL, Argonne, Illinois
• R. B. Fiorito, P. G. O'Shea
  UMD, College Park, Maryland

We have developed a new optical diffraction radiation (ODR) - dielectric foil radiation interferometer to measure the divergence of the low energy (8 - 14 MeV) ANL - Advanced Wakefield Accelerator electron beam. The interferometer employs an electro-formed micromesh first foil, which overcomes the inherent scattering limitation in the solid first foil of a conventional OTR interferometer, and an optically transparent second foil. The interference of forward directed ODR from the mesh and optical radiation from the dielectric foil is observed in transmission. This geometry allows a small gap between the foils (1 - 2 mm), which is required to observe fringes from two foils at low beam energies. Our measurements indicate that a single Gaussian distribution is sufficient to fit the data.

correspondance email: shkvar@umd.edu

• T. J. Maxwell
  
• C. L. Bohn, D. Mihalcea, P. Piot
  Northern Illinois University, DeKalb, Illinois

Electrons impinging on a thin metallic foil are seen to deliver small bursts of transition radiation (TR) as they cross the boundary from one medium to the next. A popular diagnostic application is found for compact electron bunches. In this case they will emit radiation more or less coherently with an N-squared enhancement of the intensity on wavelengths comparable to the bunch size, generating coherent transition radiation (CTR). Several detailed analytical descriptions have been proposed for describing the resulting spectral distribution, often making different simplifying assumptions. Given that bunches tenths of millimeters long can generate measurable spectra into the millimeter range, concern may arise as to weak diffraction effects produced by optical interference devices containing elements with dimensions in the centimeter range. The work presented here is a report on an upcoming graduate thesis exploring these effects as they apply to the Fermilab/NICADD photoinjector laboratory using a minimal C++ code that implements the methods of virtual quanta and vector diffraction theory.

• C. L. Bohn
  
• E. W. Nissen
  Northern Illinois University, DeKalb, Illinois

We undertake a study of particle dynamics in a model fixed-field alternating-gradient (FFAG) synchrotron in which space-charge plays a central role. The space-charge force corresponds to a Gaussian charge distribution in both transverse dimensions. The betatron-tune is linearly ramped through resonance. This ramping alone can cause particles to enter orbits that have chaotic motion.. We found that space-charge can lead to spreading of the available tunes which can either increase or decrease the effects of resonance. By applying recently developed techniques to measure complexity in the orbital dynamics, we also determine whether chaoticity can arise in particle trajectories and subsequently influence resonance crossings. Furthermore, we can see that the chaoticity changes drastically in the area around a resonance crossing.

• M. M. Rihaoui
  
• C. L. Bohn, P. Piot
  Northern Illinois University, DeKalb, Illinois
• J. G. Power
  ANL, Argonne, Illinois

• Y. Kim
  
• J. Li, Y. K. Wu
  FEL/Duke University, Durham, North Carolina

• J. Li
  
• P. Wang, Y. K. Wu
  FEL/Duke University, Durham, North Carolina

The beam position monitor system of the Duke storage ring has been in operation since 1998. Recently, by injecting at higher energy with a booster synchrotron, the single bunch current threshold is much more increased. This makes the BPM system do not work properly and rises the risk to damaged the BPM signal processing modules. To get reliable orbit data and protect the BPM modules, we carefully studied the BPM signal, and then found a way to overcome this problem. This paper will report the study results and the solution method.

• S. Huang, S. Huang
  PKU/IHIP, Beijing
• J. Li, Y. K. Wu
  FEL/Duke University, Durham, North Carolina

One of critical beam parameters for the storage ring based light sources is the energy spread of the electron beam. An accurate measurement of the energy spread remains a challenge. It is well known that the electrons with different energies can degrade the spontaneous emission spectrum of a two-wiggler system in an optical-klystron configuration. The reduced modulation in the spectrum can be used to determine the energy spread of the beam. This paper describes our newly developed energy spread measurement system employing a scanning spectrometer and a fast CCD. A fast CCD with a burst mode of operation is used so that dynamical changes of the energy spread from tens of microseconds to tens of milliseconds can be measured. This system will be used in the beam instability research and free-electron laser research. Together with compact wigglers, such a system can be developed as a dedicated beam diagnostic for storage rings and linacs.

• V. Popov
  
• M. D. Busch, S. M. Hartman, J. Li, S. F. Mikhailov, P. W. Wallace, P. Wang, Y. K. Wu
  FEL/Duke University, Durham, North Carolina
• G. Y. Kurkin
  BINP SB RAS, Novosibirsk

First operational experience has been gained with the linac and booster diagnostic system during the commissioning of the booster synchrotron at Duke University. Beam charge measurements are provided by Faraday cups, Integrated Current Transformers (ICT) and Modular Parametric Current Transformer (MPCT). Beam position monitoring is based on BPM system delivered from Bergoz company. Betatron tune measurements use synchrotron radiation (SR) and are different for two modes of operation: stored beam and energy ramping. Transverse profile and temporal beam structure monitoring employ insertable screens, CCD cameras, striplines and dissector. The diagnostics provided good understanding of electron beam behavior and allowed to adjust important beam parameters within design specifications. An overview of the diagnostic instrumentation of the Duke linac and booster synchrotron is given along with measurement examples and discussion of operational experience.

• C. Sun
  
• Y. K. Wu
  FEL/Duke University, Durham, North Carolina

• Y. K. Wu
  
• J. Li, S. F. Mikhailov, V. Popov, P. Wang
  FEL/Duke University, Durham, North Carolina

The betatron tune measurement system is one of the most important diagnostics for any circular accelerator. During the commissioning of a booster synchrotron newly developed for top-off injection into the Duke storage ring, a versatile tune measurement system employing a photomultiplier tube (PMT) and a space filter has been developed to provide reliable measurements for low current operation at a few micro-amperes of beam-current. Using the turn-by-turn technique, this tune measurement system is being used as a live tune monitor during the booster energy ramping. This system has also be used to measure chromaticity and other important beam parameters. In this paper, we describe the tune measurement system in detail and report our most recent experimental results using this system.

• A. E. Dabrowski
  
• H.-H. Braun, R. Corsini, S. Doebert, T. Lefevre, F. Tecker, P. Urschutz
  CERN, Geneva
• M. Velasco
  NU, Evanston

A non-destructive bunch length detector has been installed in the CLIC Test Facility (CTF3). Using a series of down-converting mixing stages and filters, the detector analyzes the power spectrum of the electromagnetic field picked-up by a single waveguide. This detector evolved from an earlier system which was regularly used for bunch length measurements in CTF2. Major improvements are increase of frequency reach from 90 GHz to 170 GHz, allowing for sub-pico second sensitivity, and single shot measurement capability using FFT analysis from large bandwidth waveform digitisers. The results of the commissioning of the detector in 2006 are presented.

• Y. Yin
  
• X. Che
  Y. Y. Labs, Inc., Fremont, California
• J. H. Wang, K. Zheng
  USTC/NSRL, Hefei, Anhui

• M. A. Palmer
  
• B. Cerio, R. Holtzapple, J. S. Kern
  Alfred University, Alfred, New York
• J. Dobbins, D. L. Hartill, C. R. Strohman
  CLASSE, Ithaca
• E. Tanke
  CESR-LEPP, Ithaca, New York
• M. E. Watkins
  CMU, Pittsburgh, Pennsylvania

A fast vertical beam profile monitor has been implemented at the Cornell Electron Storage Ring (CESR). Readout is based on the Hamamatsu H7260K multianode photomultiplier. This device has a 32 channel linear anode array with 1 mm channel pitch and sub-nanosecond rise time. It provides the ability to probe individual electron and position bunches which are separated by 14 ns within the trains in CESR. A custom 72 MHz digitizer unit allows synchronous multibunch and turn-by-turn data acquisition. An on-board digital signal processor provides local data processing capability. This system provides the capability to probe a range of single bunch and multibunch beam dynamics issues as well as machine stability issues. In this paper we describe the profile monitor hardware, data acquisition system, calibration of the profile monitor, and data analysis software.

• V. Tang
  
• C. G. Brown, T. L. Houck
  LLNL, Livermore, California

Traditionally, thin metal foils are employed for optical transition radiation (OTR) beam diagnostics but the possibility of plating or shorting accelerator insulating surfaces precludes their routine use on high-demand machines. The successful utilization of dielectric foils in place of metal ones would alleviate this issue but necessitates more modeling and understanding of the OTR data for inferring desired beam parameters because of the dielectric's finite permittivity. Additionally, the temperature dependence of the relevant foil parameters must be accounted for due to instantaneous beam heating. Here, we analyze quartz and kapton foil OTR data from the Flash X-Ray (FXR) induction linear accelerator using a model that includes these effects and discuss the resultant FXR beam profiles.

• S. Walston
  
• S. T. Boogert
  Royal Holloway, University of London, Surrey
• C. C. Chung, P. Fitsos, J. Gronberg
  LLNL, Livermore, California
• J. C. Frisch, S. Hinton, J. May, D. J. McCormick, S. Smith, T. J. Smith, G. R. White
  SLAC, Menlo Park, California
• H. Hayano, Y. Honda, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• Yu. G. Kolomensky, T. Orimoto
  UCB, Berkeley, California
• P. Loscutoff
  LBNL, Berkeley, California
• A. Lyapin, S. Malton, D. J. Miller
  UCL, London
• R. Meller
  Cornell University, Department of Physics, Ithaca, New York
• M. C. Ross
  Fermilab, Batavia, Illinois
• M. Slater, M. Thomson, D. R. Ward
  University of Cambridge, Cambridge
• V. Vogel
  DESY, Hamburg

• B. Blind
  
• J. D. Gilpatrick
  LANL, Los Alamos, New Mexico

In order to characterize the beam-centroid jitter in transverse phase space, sets of position data of the 100-MeV H⁺ beam and 800-MeV H^- beam were taken in the transport lines of the Los Alamos Neutron Science Center (LANSCE) accelerator complex. Subsequent data evaluation produced initially puzzling inconsistencies in the phase-space plots from different pairs of beam-position monitors. It is shown that very small random measurement errors will produce systematic differences between plots that should nominally be identical. The actual beam-centroid jitter and the amount of random error in the measurements can be extracted from the data by performing simulations and determining the parameters for which the resulting plots are consistent with the results from the data. Examples will be shown.

• J. D. Gilpatrick
  
• B. Blind, M. J. Borden, J. L. Erickson, M. S. Gulley, S. S. Kurennoy, R. C. McCrady, J. F. O'Hara, M. A. Oothoudt, C. Pillai, J. F. Power, L. Rybarcyk, F. E. Shelley
  LANL, Los Alamos, New Mexico

Presently, the Los Alamos National Laboratory is in the process of planning a refurbishment of various sub-systems within its Los Alamos Neutron Science Center accelerator facility. A part of this LANSCE facility refurbishment will include some replacement of and improvement to existing older beam diagnostics instrumentation. While plans are still being discussed, some instrumentation that is under improvement or replacement consideration are beam phase and position measurements within the 805-MHz side-coupled cavity linac, slower wire profile measurements, typically known as wire scanners, and possibly additional installation of fast ionization-chamber loss monitors. This paper will briefly describe the requirements for these beam measurements, what we have done thus far to answer these requirements, and some of the technical issues related to the implementation of these instrumentation.

• J. D. Gilpatrick
  
• B. Blind, M. S. Gulley, C. Pillai, J. F. Power
  LANL, Los Alamos, New Mexico

During the CY2005 and CY2006 Los Alamos Neutron Science Center (LANSCE) beam runs, six beam-development shifts were performed in order to acquire and analyze beam-current and beam-position jitter data for both the LANSCE H⁺ and H^- beams. These data were acquired using three beam position monitors (BPMs) from the 100-MeV Isotope Production Facility (IPF) beam line and three BPMs from the Switchyard transport line at the end of the LANSCE 800-MeV linac. The two types of data acquired, intermacropulse and intramacropulse, were analyzed for statistical and frequency characteristics as well as various other correlations including comparing their phase-space characteristics in a coordinate system of transverse angle versus transverse position. This paper will briefly describe the measurements required to acquire these data, the analysis of these jitter data, and some interesting implications to beam operation.

• S. S. Kurennoy
  

* J. D. Gilpatrick et al. These proceedings.** S. S. Kurennoy and R. E. Shafer, EPAC 2000 (Vienna, Austria, 2000), 1768.

• J. F. O'Hara
  
• M. J. Borden, A. A. Browman, N. A. Gillespie, D. Martinez, K. G. McKeown, F. R. Olivas
  LANL, Los Alamos, New Mexico
• J. E. Ledford, R. J. Macek
  TechSource, Santa Fe, New Mexico

In order to better understand the two stream e-p instability issue in the LANSCE Proton Storage Ring, a new diagnostic instrument has been developed to measure the electron cloud formation and trapping in a quadrupole magnet at the LANSCE, PSR. The device called the Electron Cloud Detector (ECD) was fabricated and has successfully been installed in the PSR. Along with the Electron Cloud Detector, an additional device was developed to manipulate electrons ejected from the quadrupole and allow additional information to be obtained from ECD measurements. This paper will discuss the mechanical design and fabrication issues encountered during the course of developing both devices.

• J. F. O'Hara
  
• M. J. Borden, D. C. Bruhn, J. L. Erickson, J. D. Gilpatrick, S. S. Kurennoy
  LANL, Los Alamos, New Mexico

A prototype Beam Position and Phase Monitor (BPPM) beam line device is being designed to go in the LANSCE 805-MHz linac. The concept is to install two beam line devices in locations where their measurements can be compared with older existing Delta-T loop and wire scanner measurements. The plan is to install two devices so that transverse position, angular trajectory, as well as central beam phase and energy will be measured. The mechanical design will combine features from previous LANL designs that were done for the LANSCE Isotope Production Facility, LANSCE Switchyard project, and those done for the SNS linac. This paper will discuss the mechanical design and fabrication issues encountered during the course of developing the BPPM.

• X. P. Ding
  
• M. Babzien, K. Kusche, V. Yakimenko
  BNL, Upton, Long Island, New York
• D. B. Cline
  UCLA, Los Angeles, California
• W. D. Kimura
  STI, Washington
• F. Zhou
  SLAC, Menlo Park, California

Two compressed electron beam bunches from a single 60-MeV bunch have been generated in a reproducible manner during compression in the magnetic chicane - "dog leg" arrangement at ATF. Measurements indicate they have comparable bunch lengths (~100-200 fs) and are separated in energy by ~1.8 MeV with the higher-energy bunch preceding the lower-energy bunch by 0.5-1 ps. Some simulation results for analyzing the double-bunch formation process are also presented.

• R. J. England
  
• D. Alesini
  INFN/LNF, Frascati (Roma)
• B. D. O'Shea, J. B. Rosenzweig, G. Travish
  UCLA, Los Angeles, California

A 9-cell standing wave deflecting cavity has recently been constructed and installed at the UCLA Neptune Laboratory for use as a temporal diagnostic for the 13 MeV, 300 to 700 pC electron bunches generated by the Neptune photoinjector beamline. The cavity is a center-fed Glid-Cop structure operating in at TM110-like deflecting mode at 9.59616 GHz with a pi phase advance per cell. At the maximum deflecting voltage of 500 kV, the theoretical resolution limit of the device is 50 fs, although with current beam parameters and a spot size of 460 microns RMS the effective resolution is approximately 400 fs. We discuss the operation and testing of the cavity as well as its intended application: measuring the temporal current profile of ramped electron bunches generated using the Neptune dogleg compressor, and we present the first measurements of the electron beam current profile obtained using the deflecting cavity.

• K. L.F. Bane
  
• S. A. Heifets, Z. Li, C.-K. Ng, A. Novokhatski, G. V. Stupakov, R. L. Warnock
  SLAC, Menlo Park, California
• M. Venturini
  LBNL, Berkeley, California

One of the action items for the damping rings of the International Linear Collider (ILC) is to compute the broad-band impedance and, from it, the threshold to the microwave instability. For the ILC it is essential that the operating current be below threshold. Operating above threshold would mean that the longitudinal emittance of the beam would be increased. More seriously, above threshold there is the possibility of time dependent variation in beam properties (e.g. the "sawtooth" effect) that can greatly degrade collider performance. In this report, we present the status of our study including calculations of: an impedance budget, a pseudo-Green's function suitable for Haissinski equation and instability calculations, and instability calculations themselves.

• W. D. Zacherl
  
• I. Blumenfeld, M. J. Hogan, R. Ischebeck
  SLAC, Menlo Park, California
• C. E. Clayton, P. Muggli, M. Zhou
  UCLA, Los Angeles, California

A typical diagnostic used to determine the bunch length of ultra-short electron bunches is the autocorrelation of coherent transition radiation. This technique can produce artificially short bunch length results due to the attenuation of low frequency radiation if corrections for the material properties of the Michelson interferometer and detector response are not made. Measurements were taken using FTIR spectroscopy to determine the absorption spectrum of various materials and the response of a Molectron P1-45 pyroelectric detector. The material absorption data will be presented and limitations on the detector calibration discussed.

• W. J. Corbett
  
• X. Huang, M. J. Lee, P. Lui
  SLAC, Menlo Park, California
• B. Sayyar-Rodsari
  Pavilion Technologies, Inc, Austin, Texas

The primary contributing factors to electron beam lifetime in a storage ring are elastic and inelastic gas scattering, and intrabeam scattering. In order to further quantify the relative contributions of each mechanism, a series of measurements using vertical scraper position and rf-voltage sweeps were performed in SPEAR3 with fill patterns featuring different single-bunch and total beam currents. In parallel, an analytic beam-lifetime simulator was developed taking scattering cross-sections, rf-bucket height and bunch lengthening effects into account. In this paper, we compare measured results with the simulated results in an effort to develop a comprehensive model for electron beam lifetime under a variety of operating conditions.

• W. J. Corbett
  
• A. S. Fisher, X. Huang, J. A. Safranek, J. J. Sebek
  SLAC, Menlo Park, California
• A. H. Lumpkin
  ANL, Argonne, Illinois
• W. Y. Mok
  Life Imaging Technology, Palo Alto, California

In the nominal SPEAR3 storage ring optics, the natural radiation pulse length is 40ps fwhm per bunch. Due to the double-bend achromat lattice configuration, it is relatively straightforward to reduce the momentum compaction factor (α) and hence reduce the bunch length by modest values. In this paper we present streak camera measurements of the bunch length in the nominal optics, and with ~α/20 and α/50 optics as a function of single-bunch current. The results demonstrate <10ps fwhm radiation pulses with up 5x10⁸ particles/bunch (~100μ amp). Radiation pulse power, bunch length scaling and broadband impedance estimates are discussed.

• A. S. Fisher
  
• S. Ecklund, R. C. Field, S. M. Gierman, P. Grossberg, K. E. Krauter, E. S. Miller, M. Petree, N. Spencer, M. K. Sullivan, K. K. Underwood, U. Wienands
  SLAC, Menlo Park, California
• K. G. Sonnad
  LBNL, Berkeley, California

To maximize luminosity, a feedback system adjusts the relative transverse (x,y) position and vertical angle (y') of the electron and positron beams at the interaction point (IP) of PEP-II. The original system sequentially moved ("dithered") the electrons in four steps per coordinate. Communication with DC corrector magnets and field penetration through copper vacuum chambers led to a full-cycle time of 10 s. Machine tuning can move the beams at the IP and so had to be slowed to wait for the feedback. A new system installed in 2006 simultaneously applies a small sinusoidal dither to all three coordinates at 73, 87 and 103 Hz. Air-core coils around stainless-steel chambers give rapid field penetration. A lock-in amplifier at each frequency detects the magnitude and phase of the luminosity's response. Then corrections for all coordinates are determined using Newton's method, based on convergence from prior steps, and are applied by the same DC correctors used previously but with only one adjustment per cycle for an expected ten-fold increase in speed. We report on the commissioning of this system and on its performance in maintaining peak luminosity and aiding machine tuning.

• R. Ischebeck
  
• M. K. Berry, I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
  SLAC, Menlo Park, California
• C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
  UCLA, Los Angeles, California
• T. C. Katsouleas, P. Muggli, E. Oz
  USC, Los Angeles, California

Particles are leaving the meter-long plasma wakefield accelerator with a large energy spread. To determine the spectrum of these particles, four diagnostics have been set up. These were used to determine energies of the particles that gain energy in the plasma, those that lose energy by driving the wake and the self-injected particles that are accelerated from rest.

• R. M. Jones
  
• G. Burt
  Cockcroft Institute, Lancaster University, Lancaster
• N. Chanlek, B. Spencer
  UMAN, Manchester
• P. Goudket
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

• N. A. Kirby
  
• M. K. Berry, I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. Ischebeck, R. H. Iverson, R. Siemann, D. R. Walz
  SLAC, Menlo Park, California
• C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
  UCLA, Los Angeles, California
• T. C. Katsouleas, P. Muggli, E. Oz
  USC, Los Angeles, California

Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC showed trapping of plasma electrons. These trapped electrons appeared on an energy spectrometer with smaller transverse size than the beam driving the wake. A connection is made between transverse size and emittance; due to the spectrometer?s resolution, this connection allows for placing an upper limit on the trapped electron emittance. The upper limit for the lowest normalized emittance measured in the experiment is 1 mm∙mrad.

• H. Loos
  
• T. Borden, P. Emma, J. C. Frisch, J. Wu
  SLAC, Menlo Park, California

The ultra-short bunches of the electron beam for LCLS are generated in two 4-dipole bunch compressors located at energies of 250 MeV and 4.3 GeV. Although an absolute measurement of the bunch length can be done by using a transverse deflecting cavity in an interceptive mode, a non-interceptive single shot method is needed as a relative measurement of the bunch length used in the continuous feedback for beam energy and peak current. We report on the design and implementation of two monitors measuring the integrated power of coherent edge radiation from the last dipole in each chicane. The first monitor is installed in early 2007 and we compare its performance with the transverse cavity measurement and other techniques.

• C. Mcguinness
  
• R. L. Byer, T. Plettner
  Stanford University, Stanford, Califormia
• E. R. Colby, R. Ischebeck, R. J. Noble, C. M.S. Sears, R. Siemann, J. E. Spencer, D. R. Walz
  SLAC, Menlo Park, California

The laser acceleration experiments conducted for the E163 project at the NLC Test Accelerator facility at SLAC have stringent requirements on the temporal properties of the electron and laser beams. A system has been implemented to measure the relative phase stability between the RF sent to the gun, the RF sent to the accelerator, and the laser used to generate the electrons. This system shows rms timing stability better than 1 psec. Temporal synchronicity between the 0.5 psec electron bunch, and the 0.5 psec laser pulse is also of great importance. Cherenkov radiation is used to measure the arrival time of the electron bunch with respect to the laser pulse, and the path length of the laser transport is adjusted to optimize temporal overlap. A linear stage mounted onto a voice coil is used to make shot-by-shot fine timing adjustments to the laser path. The final verification of the desired time stability and control is demonstrated by observing the peak of the laser-electron interaction signal over the course of several minutes.

• S. Molloy
  
• V. Blackmore
  OXFORDphysics, Oxford, Oxon
• P. Emma, J. C. Frisch, R. H. Iverson, D. J. McCormick, M. Woods
  SLAC, Menlo Park, California
• M. C. Ross
  Fermilab, Batavia, Illinois
• S. Walston
  LLNL, Livermore, California

We report on measurements of picosecond bunch lengths and the energy-z correlation of the bunch with a high energy electron test beam to the A-line and End Station A (ESA) facilities at SLAC. The bunch length and the energy-z correlation of the bunch are measured at the end of the linac using a synchrotron light monitor diagnostic at a high dispersion point in the A-line and a transverse RF deflecting cavity at the end of the linac. Measurements of the bunch length in ESA were made using high frequency diodes (up to 100 GHz) and pyroelectric detectors at a ceramic gap in the beamline. Modelling of the beam's longitudinal phase space through the linac and A-line to ESA is done using the 2-dimensional tracking program LiTrack, and LiTrack simulation results are compared with data. High frequency diode and pyroelectric detectors are planned to be used as part of a bunch length feedback system for the LCLS FEL at SLAC. The LCLS also plans precise bunch length and energy-z correlation measurements using transverse RF deflecting cavities.

• S. Molloy
  
• C. D. Beard, J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• A. Bungau
  UMAN, Manchester
• S. Seletskiy, M. Woods
  SLAC, Menlo Park, California
• J. D.A. Smith
  Cockcroft Institute, Warrington, Cheshire
• A. Sopczak
  Lancaster University, Lancaster
• N. K. Watson
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon

We report on measurements of the transverse wakefields induced by collimators of differing characteristics. An apparatus allowing the insertion of different collimator jaws into the path of a beam was installed in End Station A (ESA) in SLAC. Eight comparable collimator geometries were designed, including one that would allow easy comparison with previous results, and were installed in this apparatus. Measurements of the beam kick due to the collimator wakefields were made with a beam energy of 28.5 GeV, and beam dimensions of ~100 microns vertically and a range of 0.5 to 1.5 mm longitudinally. The trajectory of the beam upstream and downstream of the collimator test apparatus was determined from the outputs of ten BPMs (four upstream and six downstream), thus allowing a measurement of the angular kick imparted to the beam by the collimator under test. The transverse wakefield was inferred from the measured kick. The different aperture designs, data collection and analysis, and initial comparison to theoretical and analytic predictions are presented here.

* "An Apparatus for the Direct Measurement of Collimator Transverse Wakefields", P. Tenenbaum, PAC '99** "Direct Measurement of the Resistive Wakefield in Tapered Collimators", P Tenenbaum, PAC '04

• A. Novokhatski
  
• J. Seeman, M. K. Sullivan
  SLAC, Menlo Park, California

The PEP-II B-factory at SLAC has recently experienced unexpected aborts due to anomalously high radiation levels at the BaBar detector. Before the problem was finally traced we performed the wake field analysis of the Q-2 bellows, which is situated at a distance of 2.2 m from the interaction point. Analysis showed that electric field in a small gap between a ceramic tile and metal flange can be high enough to produce sparks or even breakdowns. Later the traces of sparks were found in this bellows.

• A. Novokhatski
  
• S. DeBarger, S. Ecklund, N. Kurita, J. Seeman, M. K. Sullivan, S. P. Weathersby, U. Wienands
  SLAC, Menlo Park, California

A new Q2-bellows absorber will damp only transverse wake fields and will not produce additional beam losses due to Cherenkov radiation. The design is based on the results of the HOM analysis. Geometry of the slots and absorbing tiles was optimized to get maximum absorbing effect.

• A. Novokhatski
  
• S. A. Heifets, D. Teytelman
  SLAC, Menlo Park, California

Wake fields defining beam stability affect also the beam optics and beam properties in high current machines. We present observations and analysis of the optical effects in the PEP-II SLAC B-factory, which has the record in achievement of high electron and positron currents. We study the synchronous phase and the bunch length variation along the train of bunches, overall bunch lengthening and effects of the wakes on the tune and on the Twiss parameters. This analysis is being used in upgrades of PEP II and may be applied to future B-factories and damping rings for Linear Colliders.

• A. Novokhatski
  

Based on numerical solution of the Fokker-Plank Equation we study the effect of longitudinal damping on the modulation of the bunch length in a storage ring with high RF voltage and momentum compaction

• L. Wang
  
• K. L.F. Bane, C. Chen, T. M. Himel, M. Munro, M. T.F. Pivi, T. O. Raubenheimer, G. V. Stupakov
  SLAC, Menlo Park, California

The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit machine performance. The suppression of electrons in a magnet is a challenge for the positron damping ring of the International Linear Collider (ILC) as well as the Large Hadron Collider. Simulation show that grooved surfaces can significantly reduce the electron yield in a magnet. Some of the secondary electrons emitted from the grooved surface return to the surface within a few gyrations, resulting in a low effective secondary electron yield (SEY) of below 1.0 A triangular surface is an effective, technologically attractive mitigation with a low SEY and a weak dependence on the scale of the corrugations and the external magnetic field. A chamber with triangular grooved surface is proposed for the dipole and wiggler sections of the ILC and will be tested in PEP-II in 2007. The strategy of electron cloud control in ILC and the optimization of the grooved chamber such as the SEY, impedance as well as the manufacturing of the chamber, are also discussed.

SLAC-PUB-11933 & NIMA in publication

• L. Wang
  
• Y. Cai, T. O. Raubenheimer
  SLAC, Menlo Park, California

Ion induced beam instability is one critical issue for the electron damping ring of the International Linear Collider (ILC) due to its ultra small emittance of 2pm. Bunch train filling pattern is proposed to mitigate the instability and bunch-by-bunch feedback is applied to suppress it. Multi-bunch train fill pattern is introduced in the electron beam to reduce the number of trapped ions. Our study shows that the ion effects can be significantly mitigated by using multiple gaps. However, the beam can still suffer from the beam-ion instability driven by the accumulated ions that cannot escape from the beam during the gaps. The effects of beam fill pattern, emittance, vacuum and various damping mechanism are studied using self-consistent program, which includes the optics of the ring.

• L. Wang
  
• A. Chao
  SLAC, Menlo Park, California
• J. Wei
  BNL, Upton, Long Island, New York

• L. Wang
  
• Z. Li, A. Seryi
  SLAC, Menlo Park, California

The effects of the round edge beam hole on the frequency and wake field are studied using variational method, which allows for rounded iris disk hole without any approximation in shape treatment. The frequency and wake field of accelerating mode and dipole mode are studied for different edge radius cases, including the flat edge shape that is often used to approximately represent the actual structure geometry. The edge hole shape has weak effect on the frequency, but much effect on the wake field. Our study shows that the amounts of wake fields are not precise enough with the assumption of the flat edge beam hole instead of round edge.

• R. L. Warnock
  

Realistic modeling of coherent synchrotron radiation (CSR) and the space charge force in single-pass systems and rings usually requires at least a two-dimensional (2-D) description of the charge/current density of the bunch. Since that leads to costly computations, one often resorts to a 1-D model of the bunch for first explorations. This paper provides several improvements to previous 1-D theories, eliminating unnecessary approximations and physical restrictions.

• W. Wittmer
  
• A. S. Fisher, D. J. Martin, J. J. Sebek
  SLAC, Menlo Park, California

During the last PEP-II run a major goal was to bring the Low-Energy Ring optics as close as possible to the design. Sudden artificial jumps of the orbit, which were regularly observed by a large number of BPMs during routine operation, were interfering with this effort. The source of the majority of these jumps had been traced to the filter-isolator boxes (FIBs) near the BPM buttons. A systematic approach to find and repair the failing units had been developed and implemented. Despite this effort, the instrumental orbit jumps never completely disappeared. To trace the source of this behavior a test setup, using a spare Bergoz MX-BPM processor (kindly provided by SPEAR III at SSRL) was connected in parallel to various PEP-II BPM processors. In the course of these measurements a slow instrumental orbit drift was found which was clearly not induced by a moving positron beam. Based on the size of the system and the limited time before the end of PEP II an accelerator improvement project was initiated to install BERGOZ BPM-MX processors close to all sextupoles.

• J. Wu
  
• A. Chao
  SLAC, Menlo Park, California
• J. R. Delayen
  Jefferson Lab, Newport News, Virginia

For accelerator projects with ultra short electron beam, beam dynamics study has to invoke the short-range wakefield. In this paper, we first obtain the short-range dipole mode resistive wall wakefield. Analytical approach is then developed to study the single bunch transverse beam dynamics due to this short-range resistive wall wake. The results are applied to the LCLS undulator and some other proposed accelerators.

• J. R. Delayen
  
• J. Wu
  SLAC, Menlo Park, California

In this paper, we study the single bunch transverse beam dynamics in the presence of random displacements of resistive wall segments and focusing elements. Analytical formulas are obtained for long-range resistive wall wake, together with numerical results for short-range resistive wall wake. Tolerances on this random displacement are studied regarding to emittance growth and phase slippage in an undulator. The results are applied to the LCLS project and some other proposed accelerators.

• F. Wang
  
• W. A. Franklin, C. Tschalaer, D. Wang, J. van der Laan
  MIT, Middleton, Massachusetts

• R. C. Davidson
  
• H. Qin, E. Startsev
  PPPL, Princeton, New Jersey

This paper makes use of a one-dimensional kinetic model based on the Vlasov-Maxwell equations to describe nonlinear wave and soliton excitations in coasting charged particle beams. The kinetic description makes use of the recently-developed g-factor model [1] that incorporates self-consistently the effects of transverse density profile shape at moderate beam intensities. The nonlinear evolution of wave and soliton excitations is examined for disturbances both moving faster and moving slower than the sound speed, incorporating the important effects of wave dispersion [2]. Analytical solutions are obtained for nonlinear traveling wave pulses with and without trapped particles, and the results of nonlinear perturabtive particle-in-cell simulations are presented that describe the stability properties and long-time evolution.

[1] R. C. Davidson and E. A. Startsev, Phys. Rev. ST Accel. Beams 7, 024401 (2004).[2] R. C. Davidson, Phys. Rev. ST Accel. Beams 7, 054402 (2004).

• E. Startsev
  
• R. C. Davidson, H. Qin
  PPPL, Princeton, New Jersey

A numerical scheme for the electromagnetic particle simulation of high-intensity charged-particle beams has been developed which is a modification of the Darwin model. The Darwin model neglects the transverse induction current in Ampere?s law and therefore eliminates fast electromagnetic (light) waves from the simulations. The model has been incorporated into the nonlinear delta-f Beam Equilibrium Stability and Transport(BEST) code. As a benchmark, we have applied the model to simulate the transverse electromagnetic Weibel-type instability in a single-species charged-particle beam with large temperature anisotropy. Results are compared with previous theoretical and numerical studies using the eighenmode code bEASt. The nonlinear stage of the Weibel instability is also studied using BEST code, and the mechanism for nonlinear saturation is identified.

• A. Kanareykin
  
• W. Gai, J. G. Power
  ANL, Argonne, Illinois
• C.-J. Jing, A. L. Kustov, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio

We report on the experimental and numerical investigation of beam breakup (BBU) effects in dielectric structures resulting from parasitic wakefields. The experimental program focuses on measurements of BBU in a number of wakefield devices: (a) a 26 GHz power extraction structure; (b) a high gradient dielectric wakefield accelerator; (c) a wakefield structure driven by a high current ramped bunch train for multibunch BBU studies. New beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable at the AWA facility. The numerical part of this research is based on a particle-Green's function based beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the accurate numerical results obtained from the new BBU code with the results of the detailed experimental measurements. An external focusing system for the control of the beam in the presence of strong transverse wakefields is considered.

• J. Beebe-Wang
  

The beam-beam interaction has a significant impact on the beam emittance growth and the luminosity lifetime in RHIC. A simulation study of the emittance growth was performed using the Lifetrac code. The operational conditions of RHIC 2006 100GeV polarized proton run were used in the study. In this paper, the result of this study is presented and compared to the experimental measurements.

• J. Beebe-Wang
  
• A. K. Jain
  BNL, Upton, Long Island, New York

The existence of multipolar components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. So, a realistic non-linear model is crucial for understanding the beam behavior and to achieve the ultimate performance in RHIC. A procedure is developed to build a non-linear model using the available multipolar component data obtained from measurements of RHIC magnets. We first discuss the measurements performed at different stages of manufacturing of the magnets in relation to their current state in RHIC. We then describe the procedure to implement these measurement data into tracking models, including the implementation of the multipole feed down effect due to the beam orbit offset from the magnet center. Finally, the field quality analysis in the RHIC interaction regions is presented.

• J. Bengtsson
  

In earlier work related to the NSLS-II project we have outlined a control theory approach for the dynamic aperture problem. In particular, an algorithm for the joint optimization of the Lie generator and the working point for the Poincare map. This time we report on how the Lie generator provides guidelines on acceptable magnitudes for e.g. the intrinsic nonlinear effects from insertion devices, and the nonlinear pseudo-invariant can be used to optimize the dynamic aperture. We also show how a polymorphic beam line class can be used to study the parameter dependance and rank conditions for control of optics and dynamic aperture.

bengtsson@bnl.gov

• A. Blednykh
  
• S. Krinsky
  BNL, Upton, Long Island, New York

• A. Blednykh
  
• S. Krinsky, J. Rose
  BNL, Upton, Long Island, New York

• A. Blednykh
  
• S. Krinsky
  BNL, Upton, Long Island, New York

• Y. Luo
  
• M. Bai, J. Bengtsson, R. Calaga, W. Fischer, N. Malitsky, F. C. Pilat, T. Satogata
  BNL, Upton, Long Island, New York

To further improve the polarized proton (pp) run collision luminosity in the Relativistic Heavy Ion Collider, correction of the horizontal two-third resonance is desirable to increase the available tune space. The third resonance driving term (RTD) is measured with the turn-by-turn (TBT) beam position monitor (BPM) data with AC dipole excitation. A first order RTD response matrix based on the optics model is used to on-line compensate the third resonance driving term h30000 while keeping other first order RTDs and first order chromaticities unchanged. The results of beam experiment and simulation correction are presented and discussed.

• Y. Luo
  
• W. Fischer, N. Malitsky, S. Tepikian, D. Trbojevic
  BNL, Upton, Long Island, New York

With 8 arc sextupole families in each RHIC ring, the nonlinear chromaticities can be corrected on-line by matching the off-momentum tunes onto the wanted off-momentum tunes with linear chromaticity only. The Newton method with singular value decomposition (SVD) technique is used for this multi-dimensional nonlinear optimization, where the off-momentum tune response matrix with respect to sextupole strength changes is adopted to simplify and fasten the on-line optimization process. The off-momentum tune response matrix can be calculated with the on-line accelerator optics model or directly measured with the real beam. This correction method will be verified and used in the coming RHIC run'07.

• Y. Luo
  
• M. Bai, J. Beebe-Wang, W. Fischer, A. K. Jain, C. Montag, T. Roser, S. Tepikian, D. Trbojevic
  BNL, Upton, Long Island, New York

To further improve the the polarized proton (pp) luminosity in the Relativistic Heavy Ion Collider, the beta functions at the two interaction points (IPs) will be reduced from 1.0 m to 0.9m in 2007. In addition, it is planned to increase the bunch intensity from 1.5*10¹¹ to 2.0*10¹¹. To accommodate these changes, the nonlinear chromaticities and the third resonance driving term should be corrected. In 2007, the number of the arc sextupole power supplies will be doubled from 12 to 24, which allows nonlinear chromaticity correction. With the updated field errors in the interaction regions (IRs), detailed dynamic aperture studies are carried out to optimize the nonlinear correction schemes, and increase the available tune space in collision.

• Y. Makdisi
  
• I. G. Alekseev, D. Svirida
  ITEP, Moscow
• A. Bravar, G. Bunce, R. L. Gill, H. Huang, A. Khodinov, A. Kponou, Z. Li, W. Meng, A. N. Nass, S. Rescia, A. Zelenski
  BNL, Upton, Long Island, New York
• M. Chapman, W. Haeberli, T. Wise
  UW-Madison/PD, Madison, Wisconsin
• S. Dhawan
  Yale University, Physics Department, New Haven, CT
• O. Eyser
  UCR, Riverside, California
• O. Jinnouchi, I. Nakagawa
  RBRC, Upton, Long Island, New York
• H. Okada, N. Saito
  Kyoto University, Kyoto
• E. J. Stephenson
  IUCF, Bloomington, Indiana

The spin physics program at the Relativistic Heavy Ion Collider (RHIC) requires knowledge of the proton beam polarization to better than 5%. To achieve this goal, a polarized hydrogen jet target was installed in RHIC where it intersects both beams. The premise is to utilize the precise knowledge of the jet proton polarization to measure the analyzing power in the proton - proton elastic scattering process in the Coulomb Nuclear Interference (CNI) region at the prescribed RHIC proton beam energy, then use the reverse reaction to measure the degree of the beam polarization, and finally confront the results with simultaneous measurements by the fast high statistics polarimeter that measure the p-Carbon elastic scattering process in the CNI region to calibrate the latter. In this presentation, the polarized jet target mechanics, operation, detector systems and the p-Carbon polarimeter are described. The statistical accuracy attained as well as the systematic uncertainties will be discussed. Such techniques may well become the standard for high energy polarized proton beams planned elsewhere in Russia and Japan.

• C. Montag
  
• J. Bengtsson, B. Nash
  BNL, Upton, Long Island, New York

The beam lifetime in most medium-energy synchrotron radiation sources is limited by the Touschek effect, which describes the momentum transfer from the transverse into the longitudinal direction due to binary collisions between electrons. While an analytical formula exists to calculate the resulting lifetime, the actual momentum acceptance necessary to perform this calculation can only be determined by tracking. This is especially the case in the presence of small vertical apertures at insertion devices. In this case, nonlinear betatron coupling leads to beam losses at these vertical aperture restrictions. In addition, a realistic model of the storage ring is necessary for calculation of the equilibrium beam sizes (particularly in the vertical direction) which are important for a self-consistent lifetime calculation.

• E. Pozdeyev
  
• I. Ben-Zvi, P. Cameron, K. A. Drees, D. M. Gassner, D. Kayran, V. Litvinenko, G. J. Mahler, T. Rao
  BNL, Upton, Long Island, New York

The ERL Prototype project is currently under development at the Brookhaven National Laboratory. The ERL is expected to demonstrate energy recovery of high-intensity beams with a current of up to a few hundred milliamps, while preserving the emittance of bunches with a charge of a few nanocoulombs produced by a high-current SRF gun. To successfully accomplish this task the machine will include beam diagnostics that will be used for accurate characterization of the three dimensional beam phase space at the injection and recirculation energies, transverse and longitudinal beam matching, orbit alignment, beam current measurement, and machine protection. This paper outlines requirements on the ERL diagnostics and describes its setup and modes of operation.