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Using transfer maps to simulate charged particle motion in accelerators is advantageous since it is much faster than tracking step-by-step. One challenge to using transfer maps is to properly include radiation effects. The effect of radiation can be divided into deterministic and stochastic parts. While computation of the deterministic effect has been previously reported, handling of the stochastic part has not. In this paper, an algorithm for including the stochastic effect is presented including taking into account the finite opening angle of the emitted photons. A comparison demonstrates the utility of this approach. Generating maps which include radiation has been implemented in the PTC software library which is interfaced to the Bmad toolkit., Proceedings of the 5th North American Particle Accelerator Conference, NAPAC2022, Albuquerque, NM, USA

Routinely, particle tracking in accelerators is done either by tracking element-by-element which is slow, or by using a transfer map that does not take into account radiation effects. However, there is a fairly straight forward way for constructing Taylor maps that do have radiation effects included. This paper shows how, by partial map inversion, non-symplectic effects due to the finite truncation of the Taylor series can be eliminated. This enables tracking simulations to use maps of lower order than what would otherwise be necessary leading to a speedup of the simulation., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Bmad/Tao software toolkit has been extended to estimate the rate of radiative spin depolarization in e⁺/e⁻ storage rings. First estimates are made using the SLIM algorithm of linearized spin-orbit motion. The extension implements the effects on s-o motion of stochastic photon emission using a Monte-Carlo tracking algorithm. Spins are tracked in 3-D along particle trajectories with the aid of Taylor expansions of quaternions provided by PTC*. The efficiency of long-term tracking is guarantied by the use of a sectioning technique that was exploited in previous-generation software**. Sectioning is the construction of the deterministic s-o maps for sections between the dipoles during the initialization phase. Maps can be reused during the tracking. In a simulation for a realistic storage ring, the computational cost of initial map construction is amortized by the multi-turn tracking computational cost. The use of 1st-order terms in the quaternion expansions to construct the s-o coupling matrices in the matrices of the SLIM algorithm. These matrices are then available for an extension of the optimization facilities in Bmad to minimize depolarizing effects by spin matching., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

To steer the closed orbit in a storage ring through the center of its quadrupoles, it is important to accurately know the quadrupole centers relative to nearby beam position monitors. Usually this is achieved by beam-based alignment (BBA). Assuming the quadrupole strength can be changed individually, one finds the BPM reading where changing a quadrupole’s strength does not alter the closed orbit. Since most quadrupoles are powered in series, they can only be varied independently if costly power supplies are added. For the EIC electron storage ring (ESR), we investigate whether sextupole BBA can be used instead. Individually powered sextupole BBA techniques already exist, but most sextupoles are powered in families and cannot be individually changed. We therefore developed a method where a localized bump changes the beam excursion in a single sextupole of a family, turning off all families that also have sextupoles in the bump. The bump amplitude at which the sextupole does not cause a closed orbit kick determines the sextupole’s alignment. This study was made to investigate the precision to which this method can be utilized., Proceedings of the 5th North American Particle Accelerator Conference, NAPAC2022, Albuquerque, NM, USA

Variations in strength of a sextupole magnet in a storage ring result in changes to the closed orbit, phase functions and tunes which depend on the position of the beam relative to the center of the sextupole and on the beam size. Such measurements have been carried out with 6 GeV positrons at the Cornell Electron Storage Ring. The initial analysis presented at IPAC21 has been extended to both transverse coordinates, introducing additional tune shifts and coupling kicks caused by skew quadrupole terms arising from the vertical position of the positron beam relative to the center of the sextupole. Variations of strength in each of the 76 sextupoles provide measurements of difference orbits, phase and coupling functions. An optimization procedure applied to these difference measurements determines the horizontal and vertical orbit kicks and the normal and skew quadrupole kicks corresponding to the the strength changes. Continuously monitored tune shifts during the sextupole strength scans provide a redundant, independent determination of the two quadrupole terms. Following the recognition that the calculated beam size is highly correlated with the calibration of the sextupole, a campaign was undertaken to obtain precise calibrations of the sextupoles and to measure their offsets relative to the reference orbit, which is defined by the quadrupole centers. We present the measured distributions of calibration correction factors and sextupole offsets together with the accuracy in their determination., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Accurate spin tracking is essential for the simulation and propagation of polarized beams, in which a majority of the particles’ spin point in the same direction. Bmad, an open-sourced library for the simulation of charged particle dynamics, traditionally tracks spin via integrating through each element of a lattice. While exceptionally accurate, this method has the drawback of being slow; at best, the runtime is proportional to the length of the element. By solving the spin transport equation for simple magnet elements, Bmad can reduce this algorithm to constant runtime while maintaining high accuracy. This method, known as "Sprint," enables quicker spin matching and prototyping of lattice designs via Bmad., Proceedings of the 5th North American Particle Accelerator Conference, NAPAC2022, Albuquerque, NM, USA

The Electron Ion Collider aims to produce luminosities of 10³⁴ cm⁻²s⁻¹ . The machine will operate over a broad range of collision energies with highly polarized beams. The coexistence of highly radiative electrons and nonradiative ions produce a host of unique effects. Strong hadron cooling will be employed for the final factor of 3 luminosity boost., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Electron-Ion Collider (EIC) is being designed for construction at Brookhaven National Laboratory. Activities have been focused on beam-beam simulations, polarization studies, and beam dynamics, as well as on maturing the layout and lattice design of the constituent accelerators and the interaction region. The latest design advances will be presented., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

We present an implementation of charged particle tracking with the cathode space charge effect included which is now openly available in the Bmad toolkit for charged particle simulations. Adaptive step size control is incorporated to improve the computational efficiency. We demonstrate its capability with a simulation of a DC gun and compare it with the well-established space charge code Impact-T., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Electron-Ion Collider (EIC) will collide electrons with hadrons at center-of-mass energies up to 140 GeV (in the case of electron-proton collisions). A 3.8-kilometer electron storage ring is being designed, which will store electrons with a range of energies up to 18 GeV for collisions at one or two interaction points. At energies up to 10 GeV the arcs will be tuned to provide 60 degree phase advance per cell in both planes, whereas at top energy of 18 GeV a 90 degree phase advance per cell will be used, which largely compensates for the horizontal emittance increase with energy. The optics must be matched at three separate energies, and the different phase-advance requirements in both the arc cells and the straight sections make this challenging. Moreover, the spin rotators must fulfill requirements for polarization and spin matching at widely different energies while satisfying technical constraints. In this paper these challenges and proposed solutions are presented and discussed., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The quadratic dependence of sextupole fields on position results in a beam-size-dependent kick on a beam traversing a sextupole magnet. A change in sextupole strength changes the closed orbit and the tune of the beam in a storage ring. Measuring both therefore allows conclusions about the beam size in the sextupole. Here we derive the pertinent formula and discuss the applicability to storage rings. In particular we investigate the measurement accuracy that can be achieved at the Cornell High Energy Synchrotron Source. The Cornell Electron-positron Storage Ring underwent a major upgrade in 2018 with the goal of reducing the emittance by a factor of four. A variety of beam size measurement methods have been developed to monitor the positron beam size, including visible synchrotron light and interferometry. We investigate the sensitivity of the sextupole method and compare to other measurement techniques. The design horizontal emittance of the 6-GeV positron beam is about 30 nm-rad with typical beam sizes of about 1 mm, setting the scale for the required accuracy in the beam-size measurement., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

SLAC is developing the Lightsource Unified Modeling Environment (LUME) for efficient modeling of X-ray free electron laser (XFEL) performance. This project takes a holistic approach starting with the simulation of the electron beams, to the production of the photon pulses, to their transport through the optical components of the beamline, to their interaction with the samples and the simulation of the detectors, and finally followed by the analysis of simulated data. LUME leverages existing, well-established simulation codes, and provides standard interfaces to these codes via open-source Python packages. Data are exchanged in standard formats based on openPMD and its extensions. The platform is built with an open, well-documented architecture so that science groups around the world can contribute specific experimental designs and software modules, advancing both their scientific interests and a broader knowledge of the opportunities provided by the exceptional capabilities of X-ray FELs., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The Cornell-BNL ERL Test Accelerator (CBETA) developed several energy-saving measures: multi-turn energy recovery, low-loss superconducting radiofrequency (SRF) cavities, and permanent magnets. With green technology becoming imperative for new high-power accelerators, the lessons learned will be important for projects like the FCC-ee or new light sources, where spinoffs and lessons learned from CBETA are already considered for modern designs., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

Polarization lifetime for He3 using two and six snakes are studied using the T-BMT Spin Resonance Tracker code. This code integrates a reduced spinor form of the T-BMT equation including only several spin resonances and the kinematics of synchrotron motion. It was previously benchmarked against RHIC polarization lifetime under the two snake system *., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The design of the Electron-Ion Collider Rapid Cycling Synchrotron (RCS) to be constructed at Brookhaven National Laboratory is advancing to meet the injection requirements for the Electron Storage Ring (ESR). Over the past year activities are focused on developing the approach to inject two 28 nC bunches every second, up from the original design of one 10nC bunch every second. The solution requires several key changes concerning the injection and extraction kickers, charge accumulation via bunch merging and a carefully calibrated RF acceleration profile to match the longitudinal emittance required by the ESR., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The Cornell-Brookhaven CBETA machine is a four pass Energy Recovery Linac (ERL) with a Non-scaling Fixed-Field Alternating gradient (NS-FFA) arc. For online modeling of single particle dynamics in CBETA, a customized version of the Tao program, which is based upon the Bmad toolkit, has been developed. This online program, called CBETA-V, is interfaced to CBETA’s EPICS control system. This paper describes the online modeling system and initial experience during machine running., Proceedings of the 13th Int. Computational Accelerator Physics Conf., ICAP2018, Key West, FL, USA

CBETA, the Cornell-BNL ERL Test Accelerator, is an SRF multi-turn ERL which has been commissioned in the one-turn configuration from March to July 2019. During this time, the project has demonstrated an energy acceptance of 1.5 in the FFA arc, high-transmission energy recovery performance, and increased the CBETA energy-recovered maximum average current., Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA

We are successfully commissioning a unique Cornell University and Brookhaven National Laboratory Electron Recovery Linac (ERL) Test Accelerator ’CBETA’ [1]. The ERL has four accelerating passes through the supercon-ducting linac with a single Fixed Field Alternating Linear Gradient (FFA-LG) return beam line built of the Halbach type permanent magnets. CBETA ERL accelerates elec-trons from 42 MeV to 150 MeV, with the 6 MeV injec-tor. The novelties are that four electron beams, with ener-gies of 42, 78, 114, and 150 MeV, are merged by spreader beam lines into a single arc FFA-LG beam line. The elec-tron beams from the Main Linac Cryomodule (MLC) pass through the FFA-LG arc and are adiabatically merged into a single straight line. From the straight section the beams are brought back to the MLC the same way. This is the first 4 pass superconducting ERL and the first single permanent magnet return line., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

CBETA, the Cornell BNL ERL Test Accelerator, will be the first multi-turn Energy Recovery Linac (ERL) with SRF accelerating cavities and Fixed Field Alternating gradient (FFA) beamline. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving varying phase advances are being investigated., Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA

CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return beamline accepting all energies from 42 to 150 MeV. While CBETA gives promise to deliver unprecedentedly high beam current with simultaneously small emittance, Coherent Synchrotron Radiation (CSR) can pose detrimental effect on the beam at high bunch charges and short bunch lengths. To investigate the CSR effects on CBETA, we used the established simulation code Bmad to track a bunch with different parameters. We found that CSR causes phase space dilution, and the effect becomes more significant as the bunch charge and recirculation pass increase. Potential ways to mitigate the effect involving vacuum chamber shielding and increasing bunch length are being investigated., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

A collaboration between Cornell University and Brookhaven National Laboratory has designed and is constructing CBETA, the Cornell-BNL ERL Test Accelerator on the Cornell campus. The ERL technology that has been prototyped at Cornell for many years is being used for this new accelerator, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed multi-turn ERLs for several purpose, dominantly for the electron beam of eRHIC, its Electron Ion Collider (EIC) project and for the associated fast electron cooling system. Also in JLEIC, the EIC designed at JLAB, an ERL is envisioned to be used for electron cooling. The number of transport lines in an ERL is minimized by using return arcs that are comprised of a Fixed Field Alternating-gradient (FFA) design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150~MeV and up to 40~mA will have applications beyond accelerator research, in industry, in nuclear physics, and in X-ray science. Low current electron beam has already been sent through the most relevant parts of CBETA, from the DC gun through both cryomodules, through one of the 8 similar separator lines, and through one of the 27 similar FFA structures. Further construction is envisioned to lead to a commissioning start for the full system early in 2019., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Stroboscopic averaging can be used to calculate the invariant spin field \bfn for particles with a finite oscillation amplitude in phase space. The standard technique starts with making a guess for \bfn(\bfr), which is a function of the phase space position \bfr. By tracking a particle's orbital position forward in time and then projecting the guessed \bfn backwards to the starting phase space point, the average of the backward projected spins will converge to the invariant spin direction linearly as 1/N where N is the number of turns tracked. The convergence can be accelerated by an iterative method that uses an approximate invariant spin field constructed by averaging the calculated spin field over points that are close in orbital phase space. This superconvergent algorithm has been built into a new program based upon the Bmad toolkit for charged particle and X-ray simulations., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

In order to maintain beam quality during transport through a storage ring, sextupole magnets are used to make chromatic corrections, but necessarily introduce deleterious effects such as nonlinear resonances and reduced dynamic aperture. Implementing intricate sextupole distributions to mitigate these effects will rely on precision beam-based measurement of the applied sextupole distribution. In this work, we generalize previous sextupole mapping techniques by using resonant phase-locked excitation of the beam at the Cornell Electron Storage Ring (CESR), which accounts for variations in the normal mode tunes on a turn by turn basis. The methods presented here are applied to simulation and actual turn by turn data in CESR for both simplified and realistic sextupole distributions., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

We present a parallel fast Fourier transform based 3D space charge software library based on integrated Green functions. The library is open-source, and has been structured to easily be used by existing beam dynamics codes. We demonstrate this by incorporating it with the Bmad toolkit for charged particle simulation, and compare with analytical formulas and well-established space charge codes., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 MeV to 150 MeV. We simulate a 6-dimensional particle distribution from the injector through the end of the dump line. Space charge forces are taken into account at the low energy stages. We compare results using field maps to those using simpler magnet models. We introduce random and systematic magnet errors to the lattice, apply an orbit correction algorithm, and study the impact on the beam distribution., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Cornell-Brookhaven Energy-recovery Linac Test Accelerator is a four-pass, 150-MeV electron accelerator with a six-cell 1.3 GHz superconducting-RF linear accelerator and a fixed-field alternating-gradient (FFAG) return loop made up of Halbach-style quadrupole magnets. The optics matching between the linear accelerator and the return loop is achieved with a conventional magnet system comprised of 50 dipole magnets and 64 quadrupole magnets in four beamlines at each end of the linac. The 42-, 78-, 114- and 150-MeV electron beams are separated into independent vacuum chambers in order to allow for the path-length adjustment required by energy recovery. We report on the first beam tests of the initial installation of the splitter/combiner section at the exit of the linac. The vacuum system of the 42-MeV S1 line was installed during the first week of April. Nine dipole and four quadrupole magnets were installed and surveyed into position the following week, and the water cooling system was commissioned. A 6-MeV beam passed through the line on April~11 with no need for adjusting pre-set magnet excitation currents. One week later, time-of-flight measurements were used to calibrate and phase the individual superconducting RF cavities. The S1 magnet settings were then scaled up to achieve 5-cavity, 42-MeV operation through the first nine FFAG permanent-magnet quadrupoles. This initial Fractional Arc Test will conclude on May 18, when the installation of the remaining seven splitter/combiner lines and the return loop will begin. CBETA operations are scheduled to begin in early 2019., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Cornell-Brookhaven Energy Recovery Linac Test Accelerator now under construction will accelerate electrons from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 to 150 MeV. We describe the optical design of the machine, with emphasis on recent updates. We explain how we choose parameters for the wide energy acceptance return arc, taking into account 3D field maps generated from magnet designs. We give the final machine parameters resulting from iterations between desired lattice properties and magnet design. We modified the optics to improve the periodicity of the return arc near its ends and to create adequate space for vacuum hardware. The return arc is connected to the linac with splitter lines that serve to match the optics for each beam energy. We describe how matching conditions were chosen for the splitter lines and how we use them to control longitudinal motion. We simulate the injection and low energy extraction systems including space charge effects, matching the beam properties to the optical parameters of the rest of the machine., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Coherent synchrotron radiation (CSR) potentially limits operation accelerators with high bunch charges and/or short bunch lengths by increasing energy spread, and by Except at the lowest beam energies, the one dimensional treatment of coherent synchrotron radiation (CSR) originally developed by Saldin is an efficient and reasonably accurate way to simulate the effects of CSR on a particle beam. A possible problem with standard implementations of the 1D CSR formalism is that these implementations assume that the beam centroid is close to the reference trajectory that defines the lattice. In this paper, the one dimensional treatment is extended to take into account beams whose centroid is far from the reference trajectory and an example using the Cornell-BNL Fixed Field Alternating Gradient (FFAG) accelerator CBETA is given., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Cornell's Lab of Accelerator-based Sciences and Education (CLASSE) and the Collider Accelerator Department (BNL-CAD) are developing the first SRF multi-turn energy recovery linac with Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) racetrack. The existing injector and superconducting linac at Cornell University are installed together with a single NS-FFAG arcs and straight section at the opposite side of the the linac to form an Electron Energy Recovery (ERL) system. Electron beam from the 6 MeV injector is injected into the 36 MeV superconducting linac, and accelerated by four successive passes: from 42 MeV up to 150 MeV using the same NS-FFAG structure made of permanent magnets. After the maximum energy of 150 MeV is reached, the electron beam is brought back to the linac with opposite Radio Frequency (RF) phase. Energy is recovered and reduced to the initial value of 6 MeV with 4 additional passes. There are many novelties: a single NS-FFAG structure, made of permanent magnets, brings electrons with four different energies back to the linac. A new adiabatic NS-FFAG arc-to-straight section merges 4 separated orbits into a single orbit in the straight section., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

In previous work it was shown that at high proton-beam energies, synchrotron radiation is an important source of beam-screen heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can contribute to electron cloud formation. We have used the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we studied the effect of the sawtooth chamber. In this paper specific results of the Synrad3D simulations are compared with simulations in Synrad+, developed at CERN; and later on compared with experimental data for actual LHC vacuum-chamber samples., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

We propose a novel use of Fixed Field Altrenating Gradient beam line (FFAG) to replace multiple beam lines in existing ERL’s (4-pass at Novosibirsk, ERL of CEBAF, ERL at KEK, etc.) with a single FFAG beam line connected with spreaders and combiners to the linac. We present two designs for the Electron Ion Colliders one at CERN LHeC and one at Brookhaven National Laboratory to be placed in the tunnel of the existing Relativistic Heavy Ion Collider (RHIC) called eRHIC. The proof of principle electron accelerator with the FFAG arc is to be built at Cornell University Wilson Hall where there are already available injector, superconducting linac accelerator and the dump. There are very new developments in the FFAG design never accomplished before: arc-to straight adiabatic matching with merged multiple orbits into one, permanent magnet design for the arc and straights with ability of four times in energy, etc., Proceedings of the 21st Int. Conf. on Cyclotrons and their Applications, Cyclotrons2016, Zurich, Switzerland

In a major upgrade of the Cornell Electron Storage Ring (CESR) one sextant of ring will be replaced with double bend achromats (DBAs) and undulator straights for x-ray users. The resistive wall impedance from the narrow gap (4.5 mm) undulator chambers (5 m per straight) may limit total beam. Here we report recent results of modelling and calculation of multibunch instabilities due to the impedance of chamber walls and transition tapers. The short range wakefields and resistive wall impedance are modelled and incorporated in a tracking simulation. The coupled-bunch growth rate found with the tracking study is in good agreement with the analytic approximation. We find that the resistive wall instability can be readily damped by our existing bunch-by-bunch feedback system., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. We use the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we study the effect of the "sawtooth" chamber, for the HL-LHC the consequences of the ATS optics with large beta beating in the arcs, and for the FCC-hh the effect of a novel beam-screen design, with a long slit surrounded by a "folded" ante-chamber., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

To improve collaborative studies on beam dynamics for SuperKEKB between several labs, efforts have been made to translate the SAD lattices of SuperKEKB rings to the versions for other codes: AT, Bmad, MAD-X, and PTC. It turns out that lattice translations between these codes are not straightforward because of the complexity of the SuperKEKB lattices. In this paper, we describe our experiences of lattice translations, and present some results of benchmarks for the case of SuperKEKB., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

A storage ring provides an attractive option for directly measuring the electric dipole moment~(EDM) of charged particles. To reach a sensitivity of 10^-29 e x cm, it is critical to mitigate the systematic errors from all sources. This daunting task is pushing the precision frontier of accelerator science and technology beyond its current state of the art. Here, we present a unique idea of a magnetic dipole moment~(MDM) spin transparent quadrupole that can significantly reduce the systematic errors due to the transverse electric and magnetic fields that particle encounters., Comment: 10 pages

We report on modeling results for synchrotron radiation absorption in the SuperKEKB positron storage ring vacuum chamber including the effects of photon scattering on the interior walls. A detailed model of the geometry of the inner vacuum chamber profile has been developed and used as input to a photon tracking code. Particular emphasis is placed on the photon absorption rates in the electron-positron interaction region., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Short-range wake fields have been incorporated into a Bmad-based particle tracking code in order to assess their contribution to current-dependent emittance growth, tune shift, and single bunch instabilities. The wakes are computed for CESR vacuum components using the T3P modeling software. Simulation results are compared with measurements of bunch length, vertical beam size, and coherent tune shift. Additionally, we use insertable scrapers to vary the transverse wake and measure the effect on the beam. We show that a vertical emittance increase at high current may be due to a transverse monopole wake, originating in the lump pump slots throughout CESR., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Recent reports from CesrTA have shown measurement and calculation of beam size versus current in CesrTA beams at 2.1 GeV. Here, the effect of changing the energy of IBS-dominated beams is reported. IBS growth rates have roughly a γ⁻³ dependence. Measurements at 1.8, 2.1, 2.3, and 2.5 GeV are shown and compared with predictions from IBS theory., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

We are developing techniques for measuring and correcting emittance diluting optical and alignment errors in the CesrTA storage ring. Our principle measurement method is to resonantly excite the beam at all three normal mode frequencies and then to extract the amplitude and phase of each mode at all 100 beam position monitors. We reconstruct beta-functions, betatron phase advance, coupling parameters, dispersion, and BPM tilts from the data. A complete characterization including data collection and analysis can be done in a few minutes. To measure the emittance, an x-ray beam size monitor capable of measuring the size of a single bunch on a turn by turn basis provides a real time measure with a resolution on the order of a few microns. This resolution corresponds to a few pm emittance. Our ability to identify alignment and optical errors is limited by systematic measurement errors. We report on the status of our efforts to understand and eliminate systematic errors, the accuracy of our characterization of the machine optics, and our success at reducing sources of emittance dilution., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent tune shifts for a variety of electron and positron beam energies, bunch current levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low-energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters such as the synchrotron radiation flux, its interaction with the vacuum chamber wall, the beam emittance and lattice optics, as well as to those of the various contributions to the electron secondary yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modelling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan