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A high-energy, multiple-pass energy recovery (ER) experiment proposal, using CEBAF, is in preparation by a JLab-BNL collaboration. The experiment will be proposed in support of the electron-ion collider project (EIC) R&D going on at BNL. This new experiment extends the 2003, 1-pass, 1 GeV CEBAF-ER demonstration into a range of energy and recirculation passes commensurate with BNL's anticipated linac-ring EIC parameters. The experiment will study ER and recirculating beam dynamics in the presence of synchrotron radiation, provide opportunity to develop and test multiple-beam diagnostic instrumentation, and can also probe BBU limitations. This paper gives an overview of the ER@CEBAF project, its context and preparations., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The Hadron Storage Ring (HSR) of the Electron-Ion Collider (EIC) will accelerate protons and heavy ions up to a proton energy of 275 GeV and an Au⁺⁷⁹ 110 GeV/u to collide with electrons of energies up to 18 GeV. To accomplish the acceleration process, the hadrons are pre-accelerated in the Alternating Gradient Synchrotron (AGS), extracted, and transferred to HSR for injection. The planned area for injection is the current Relativistic Heavy Ion Collider (RHIC) 4 o’clock straight section. To inject hadrons, a series of modifications must be made to the existing RHIC 4 o’clock straight section to accommodate for the 20 new ~18 ns injection kickers and a new injection septum, while providing sufficient space and proper beam conditions for polarimetry equipment. These modifications will be discussed in this paper., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Electron-Ion Collider (EIC) Hadron Storage Ring (HSR) will be composed of the current Relativistic Heavy Ion Collider (RHIC) yellow ring sextants with the exception of the 1 o’clock and the 11 o’clock arc. These two arcs use the existing blue ring inner (1 o’clock) and outer (11 o’clock) magnetic lattice for 275 GeV proton operation. The inner yellow 11 o’clock arc is used for 41 GeV energy operation. A switching magnet must be used to guide the hadron beam from the low and high energy arc respectively into the shared arc. This report provides the necessary lattice configuration, magnetic fields, and optics for the 10 o’clock utility straight section (USS) switchyard for both high and low energy configuration while providing the necessary space allocations and beam specifications for accelerator systems such as an additional radiofrequency cavity and beam dump., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Electron Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosity up to 10³⁴ cm⁻² s⁻¹ in the center mass energy range of 20 to 140 GeV. Due to the detector solenoid in the interaction region, the design horizontal crabbing angle will be coupled to the vertical plane if uncompensated. In this article, we estimate the tolerance of crab dispersion at the interaction point in the EIC Hadron Storage Ring (HSR). Both strong-strong and weak-strong simulations are used. We found that there is a tight tolerance of vertical crabbing angle at the interaction point in the HSR., Proceedings of the 5th North American Particle Accelerator Conference, NAPAC2022, Albuquerque, NM, USA

The Electron-Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collider polarized high energy electron beams with hadron beams with luminosity up to 1×10³⁴cm⁻²s⁻¹ in the center mass energy range of 20-140 GeV. We simulated the planned electron-proton collision of flat beams with Particle-In-Cell (PIC) based Poisson solver in strong-strong beam-beam simulation. We observed a much larger proton emittance growth rate than that from weak-strong simulation. To better understand the emittance growth rate from the strong-strong simulation, we compare the beam-beam kicks between the PIC method and the analytical calculation and calculate the RMS variation in beam-beam kicks among 1000 sets of random Gaussian particle distributions. The impacts of macro-particle number, grid number, and bunch flatness are also studied., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Two helical full snakes are used in both Blue and Yellow rings of RHIC collider, in order to preserve beam polarization during acceleration to collision energy and polarization lifetime at store. A snake in RHIC is comprised of four 2.4m long modules, powered by pair. During the startup of RHIC Run 22 in December 2021, two successive power dips have caused the 9 o’clock RHIC BlBrookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.ue ring snake to loose two of its four modules. In spite of this regrettable loss, it has been possible to maintain near 180deg snake precession, by proper powering of the remaining two modules, as well as, by re-tuning the 3 o’clock sister snake, vertical spin precession axis around the ring and spin tune 1/2. Determining these new settings, in order to salvage polarization with the handicapped Blue snake pair, has required series of numerical simulations, a brief overview is given here., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The electron ion collider (EIC) presently under construction at Brookhaven National Laboratory will collider polarized high energy electron beams with hadron beams with luminosities up to 10³⁴ cm⁻²s⁻¹ in the center mass energy range of 20-140 GeV. In this article, we evaluate the dynamic aperture of the Hadron Storage Ring (HSR) with symplectic element-by-element tracking. Crab cavities, nonlinear magnetic field errors, and weak-strong beam-beam interaction are included. We compared the dynamic aperture from head-on collision to crossing-angle collision and found the reason for the dynamic aperture drop. We also studied the field error tolerances for IR magnets and for some particular magnets., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

In addition to the day-one primary Interaction Region (IR), the design of the Electron Ion Collider (EIC) must support operation of a 2nd IR potentially added later. The 2nd IR is envisioned in an existing experimental hall at RHIC IP8, compatible with the same beam energy combinations as the 1st IR over the full center of mass energy range of ~20 GeV to ~140 GeV. The 2nd IR is designed to be complementary to the 1st IR. In particular, a secondary focus is added in the forward ion direction of the 2nd IR hadron beamline to optimize its capability in detecting particles with magnetic rigidities close to those of the ion beam. We provide the current design status of the 2nd IR in terms of parameters, magnet layout and beam dynamics., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Electron Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with luminosity up to 10³⁴ cm⁻² s⁻¹ in the center mass energy range of 20 to 140 GeV. Crab cavities are used to compensate the geometric luminosity due to a large crossing angle in the EIC. However, it was found that the phase noise in crab cavities will generate a significant emittance growth for hadron beams and its tolerance from analytical calculation is very small for the Hadron Storage Ring (HSR) of the EIC. In this paper, we report on 6-D symplectic particle tracking to estimate the proton emittance growth rate, especially in the vertical plane, for the HSR with weak-strong beam-beam and other machine or lattice errors., Proceedings of the 5th North American Particle Accelerator Conference, NAPAC2022, Albuquerque, NM, USA

The Electron-Ion Collider (EIC) will be built in the existing Relativistic Heavy Ion Collider (RHIC) tunnel with the addition of electron acceleration and storage rings. The two RHIC rings will be reconfigured as a single Hadron Storage Ring (HSR) for accelerating and storing ion beams. The proton beam energy will be raised from 255 to 275 GeV to achieve the desired center-of-mass energy range: 20’140 GeV. It is also mandatory to operate the HSR with a constant revolution frequency over a large energy range (41’275 GeV for protons) to synchronize with the Electron Storage Ring (ESR). These and other requirements/challenges dictate modifications to RHIC accelerators. This report gives an overview of the modifications to the RHIC straight sections together with their individual challenges., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Electron-Ion Collider (EIC) project* has been approved by the Department of Energy to be built at the site of Brookhaven National Laboratory (BNL). The goal of the project is the collision of energetic (of many GeV/amu) ion species with electron bunches of energies up to 18 GeV. The EIC includes two electron rings, the Rapid Cycling Synchrotron (RCS) which accelerates the electron beam up to 18 GeV, and the Electron Storage Ring (ESR) which stores the electron beam for collisions with hadron beam, both to be installed in the same tunnel as the Hadron Storage Ring (HSR). This paper discusses the layout and the beam optics of the injection/extraction beam lines the electron rings and the beam optics of the transfer line from the RCS to the ESR ring., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The electron Ion Collider (eIC) project* has been approved by the Department of Energy to be built at the site of Brookhaven National Laboratory (BNL). Part of the eIC accelerator complex and more specifically the Rapid Cycling Syncrotron (RCS) which accelerates the electron beam up to 18 GeV and the electron Storage Ring (eSR) which stores the electron beam bunces for collisions with the hadrons, will be built inside the tunnel of the Relativistic Heavy Ion Collider (RHIC)**. This paper provides information on the electromagnetic design of the septa magnets which will be employed to inject and extract the beam to and from the two synchrotrons used for the acceleration and storage of the electron beam bunches. The type of the septum is of induction type made o laminated iron and it is similar to the one described in ref.[3] The electromagnetic study is performed by the use of the transient module of the OPERA computer code***., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Insertion Region 2 (IR2) of the Relativistic Heavy Ion Collider will be modified to accommodate a Strong Hadron Cooling facility in the Hadron Storage Ring (HSR) of the Electron-Ion Collider (EIC). This paper describes the current proof-of-principle design of HSR-IR2 - layout, optical performance, design methodology, and engineering requirements. It also describes the challenges and opportunities in the future development of the HSR-IR2 design, in order to further optimize Strong Hadron Cooling performance., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Electron-Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams with design luminosities up to 1×10³⁴cm⁻²s⁻¹ in the center mass energy range of 20-140 GeV. We simulated the planned electron-proton collision of flat beams with Particle-In-Cell (PIC) based Poisson solver in strong-strong beam-beam simulation. We observed a much larger proton emittance growth rate than that from weak-strong simulation. To understand the numerical noises further, we calculate the beam size growth rate of macro-particles as function of their initial longitudinal and transverse actions. This method is applied to both strong-strong and weak-strong simulations. The purpose of this study is to identify which group of macro-particles contributes most of the artificial emittance growth in strong-strong beam-beam simulation., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

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 in BNL will collide polarized electrons with polarized protons or polarized 3He ions. Spin rotators will be used to create the longitudinal beam polarization at a location of the EIC experimental detector. Helical spin rotators utilized for polarized proton operation in present RHIC will be reused in the EIC Hadron Storage Ring. However, due to a significant difference of EIC and RHIC interaction region layouts, the EIC spin rotator arrangement has several challenges. Turning on the EIC spin rotators may lead to a significant spin tune shift. To prevent beam depolarization during the spin rotator turn-on, Siberian Snakes have to be tuned simultaneously with rotators. The EIC spin rotators must be able to operate in a wide energy range for polarized protons and polarized 3He ions. The paper presents the challenges of spin rotator usage in the EIC and remedies assuring the successful operation with the rotators., 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

The Electron-Ion Collider (EIC) presently under construction at Brookhaven National Laboratory will collide polarized high energy electron beams with hadron beams, reaching luminosities up to 1×10³⁴cm⁻²s⁻¹ in center mass energy range of 20-140 GeV. We studied the planned electron-proton collisions using a Particle-In-Cell (PIC) based Poisson solver in strong-strong beam-beam simulation. We observed a much larger proton emittance growth rate than in weak-strong simulation. To understand the numerical noise and its impact on strong-strong simulation results, we carried out extensive studies to identify all possible causes for artificial emittance growth and quantify their contributions. In this article, we summarize our study activities and findings. This work will help us better understand the simulated emittance growth and the limits of the PIC based strong-strong beam-beam simulation., 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 possibility of two interaction regions (IRs) is a design requirement for Electron-Ion Collider (EIC). There is also a significant interest from the nuclear physics community to have a 2nd IR with measurement capabilities complementary to those of the 1st IR. While the 2nd IR will be in operation over the entire energy range of ~20GeV to ~140GeV center of mass (CM). The 2nd IR can also provide an acceptance coverage complementary to that of the 1st. In this paper, we present a brief overview and the current progress of the 2nd IR design in terms of the parameters, magnet layout, and beam dynamics., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The design of the electron-ion collider EIC to be constructed at Brookhaven National Laboratory has been continuously evolving towards a realistic and robust design that meets all the requirements set forth by the nuclear physics community in the White Paper. Over the past year activities have been focused on maturing the design, and on developing alternatives to mitigate risk. These include improvements of the interaction region design as well as modifications of the hadron ring vacuum system to accommodate the high average and peak beam currents. Beam dynamics studies have been performed to determine and optimize the dynamic aperture in the two collider rings and the beam-beam performance. We will present the EIC design with a focus on recent developments., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The Electon Ion Collider (EIC) hadron ring will use the existing Relativistic Heavy Ion Collider storage rings, including the superconducting magnet arcs. The vacuum chambers in the superconducting magnets and the cold mass interconnects were not designed for EIC beams and so must be updated to reduce its resistive-wall heating and to suppress electron clouds. To do so without compromising the EIC luminosity goal, a stainless steel beam screen with co-laminated copper and a thin layer of amorphous carbon will be installed. This paper describes the main requirements that our solution for the hadron ring vacuum chamber needs to satisfy, including impedance, aperture limitations, vacuum, thermal and structural stability, mechanical design, installation and operation. The conceptual design of the beam screen currently under development is introduced., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The physics program in the EIC calls for polarized neutron beam at high energies. The best neutron carriers are 3He nuclei and deuterons. Both neutron carries are expected to be used by spin physics program in the EIC. Due to the small magnetic moment anomaly of deuteron particles, much higher magnetic fields are required for spin rotation, so full Siberian snake is not feasible. However, the resonance strength is in general weak and the number of resonances is also small. It is possible to deal with individual resonances with conventional methods, such as betatron tune jump for intrinsic depolarizing resonances; and a weak partial snakes for imperfection resonances. The study shows that accelerating polarized deuteron beyond 100GeV/n is possible in the EIC., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

This paper presents an overview of the Interaction Region (IR) design for the planned Electron-Ion Collider (EIC) at Brookhaven National Laboratory. The IR is designed to meet the requirements of the nuclear physics community *. The IR design features a ±4.5 m free space for the detector; a forward spectrometer magnet is used for the detection of hadrons scattered under small angles. The hadrons are separated from the neutrons allowing detection of neutrons up to ±4 mrad. On the rear side, the electrons are separated from photons using a weak dipole magnet for the luminosity monitor and to detect scattered electrons (e-tagger). To avoid synchrotron radiation backgrounds in the detector no strong electron bending magnet is placed within 40 m upstream of the IP. The magnet apertures on the rear side are large enough to allow synchrotron radiation to pass through the magnets. The beam pipe has been optimized to reduce the impedance; the total power loss in the central vacuum chamber is expected to be less than 90 W. To reduce risk and cost the IR is designed to employ standard NbTi superconducting magnets, which are described in a separate paper., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

A new high-luminosity Electron Ion Collider (EIC) is being developed at Brookhaven National Laboratory (BNL). The conceptual design [1] has recently been completed. The EIC will be realized in the existing RHIC facility. In addition to improving the existing hadron storage ring instrumentation, new electron accelerators that include a 350 keV gun, 400 MeV Linac, a rapid-cycling synchrotron, an electron storage ring, and a strong hadron cooling facility will all have new instrumentation systems. An overview of the conceptual design of the beam instrumentation will be presented., Proceedings of the 10th International Beam Instrumentation Conference, IBIC2021, Pohang, Rep. of Korea

The Electron-Ion Collider (EIC) is aiming at a design luminosity of 1e34 cm⁻²s⁻¹. To maintain such a high luminosity, both beams in the EIC need an acceptable beam lifetime in the presence of the beam-beam interaction. For this purpose, we carried out weak-strong element-by-element particle tracking to evaluate the long-term dynamic aperture for the hadron ring lattice design. We improved our simulation code SimTrack to treat some new lattice design features, such as radially offset on-momentum orbits, coordinate transformations in the interaction region, etc. In this article, we will present the preliminary dynamic aperture calculation results with β^{*}- function scan, radial orbit shift, crossing angle collision, and magnetic field errors., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

In order to minimize the systematic errors for the Relativistic Heavy Ion Collider (RHIC) spin physics experiments, flipping the spin of each bunch of protons during the stores is needed. Experiments done with single RF magnet at energies less than 2 GeV have demonstrated a spin-flip efficiency over 99%. At high energy colliders with Siberian snakes, a single magnet spin flipper does not work because of the large spin tune spread and the generation of multiple, overlapping resonances. Over past decade, RHIC spin flipper design has evolved and a sophisticated spin flipper, constructed of nine-dipole magnets, was developed to flip the spin in RHIC. A special optics choice was also used to make the spin tune spread very small. In recent experiment, 97% spin-flip efficiency was measured at both 24 and 255 GeV for the first time. The results show that efficient spin flipping can be achieved at high energies., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The Electron Ion Collider will collide hadrons in the Hadron Storage Ring (HSR) with ultra-relativistic electrons in the Electron Storage Ring. The HSR design trajectory includes a large radial shift over a large fraction of its circumference, in order to adjust the hadron path length to synchronize collisions over a broad range of hadron energies. The design trajectory goes on-axis through the magnets, crab cavities and other components in the six HSR Insertion Regions. This paper discusses the issues involved and reports on past and future beam experiments in the Relativistic Heavy Ion Collider, which will be upgraded to become the HSR., 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 luminosity goal for the Electron-Ion Collider (EIC) is 1e34 cm⁻²s⁻¹. To achieve such a high luminosity, the EIC design adopts high bunch intensities, flat beams at the interaction point (IP) with a small vertical β^{*}-function, and a high collision frequency, together with crab cavities to compensate the geometrical luminosity loss due to the large crossing angle of 25mrad. In this article, we present our strategies and approaches to obtain the design luminosity by optimizing some key beam-beam related design parameters. Through our extensive strong-strong and weak-strong beam-beam simulations, we found that beam flatness, electron and proton beam size matching at the IP, electron and proton working points, and synchro-betatron resonances arising from the crossing angle collision play a crucial role in proton beam size growth and luminosity degradation. After optimizing those parameters, we found a set of beam-beam related design parameters to reach the design luminosity with an acceptable beam-beam performance., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The electron-ion luminosity in EIC has a number of limits, including the ion intensity available from the injectors, the total ion beam current, the electron bunch intensity, the total electron current, the synchrotron radiation power, the beam-beam effect, the achievable beta functions at the interaction points (IPs), the maximum angular spreads at the IP, the ion emittances reachable with stochastic or strong cooling, the ratio of horizontal to vertical emittance, and space charge effects. We map the e-A luminosity over the center-of-mass energy range for some ions ranging from deuterons to uranium ions. For e-Au collisions the present design provides for electron-nucleon (e-Au) peak luminosities of 1.7x1033 cm⁻²s⁻¹ with stochastic cooling, and 4.7x1033 cm⁻²s⁻¹ with strong hadron cooling., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

Spin flipper experiments during RHIC Run 17 have demonstrated the 97% effectiveness of polarization sign reversal during stores. Zgoubi numerical simulations were setup to reproduce the experimental conditions. A very good agreement between the experimental measurements and simulation results was achieved at 23.8GeV, thus the simulations are being used to help optimize the various Spin Flipper parameters. The ultimate goal for these simulations is to serve as guidance towards a perfect flip at high energies to allow a routine Spin Flipper use during physics runs., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The design effort for the electron-ion collider eRHIC has concentrated on electron-proton collisions at the highest luminosities over the widest possible energy range. The present design also provides for electron-nucleon peak luminosities of up to 4.7·10³³ cm⁻²s^{−1} with strong hadron cooling, and up to 1.7·10³³ cm⁻²s^{−1} with stochastic cooling. Here we discuss the performance limitations and design choices for electron-ion collisions that are different from the electron-proton collisions. These include the ion bunch preparation in the injector chain, acceleration and intrabeam scattering in the hadron ring, path length adjustment and synchronization with the electron ring, stochastic cooling upgrades, machine protection upgrades, and operation with polarized electron beams colliding with either unpolarized ion beams or polarized He-3., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

This presentation summarizes the physics requirements as they translate into accelerator requirements at the machine-detector interface. Unique aspects of the Interaction Region and detector acceptance – unique to an Electron Ion Collider – are summarized. Designs of both site-specific concepts are outlined., Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA

Closed orbit calculations of the AGS synchrotron were performed and the beam parameters at the extraction point of the AGS [1] were calculated using the RAYTRACE computer code [2] which was modified to generate 3D fields from the experimentally measured field maps on the median plane of the AGS combined function magnets. The algorithm which generates 3D fields from field maps on a plane is described in reference [3] which discusses the details of the mathematical foundation of this approach. In this presentation we will discuss results from studies [1,4] that are based on the 3D fields generated from the known field components on a rectangular grid of a plane. A brief overview of the algorithm used will be given, and two methods of calculating the required field derivatives on the plane will be presented. The calculated 3D fields of a modified Halbach magnet [5] of inner radius of 4.4 cm will be calculated using the two different methods of calculating the field derivatives on the plane and the calculated fields will be compared against the ’ideal’ fields as calculated by the OPERA computer code [6]. [1] N. Tsoupas et. al. ’Closed orbit calculations at AGS and Extraction Beam Parameters at H13 AD/RHIC/RD-75 Oct. 1994 [2] S.B. Kowalski and H.A. Enge ’The Ion-Optical Program Raytrace’ NIM A258 (1987) 407 [3] K. Makino, M. Berz, C. Johnstone, Int. Journal of Modern Physics A 26 (2011) 1807-1821 [4] N. Tsoupas et. al. ’Effects of Dipole Magnet Inhomogeneity on the Beam Ellipsoid’ NIM A258 (1987) 421-425 [5] ’The CBETA project: arXiv.org > physics > arXiv:1706.04245’’ [6] Vector Fields Inc. https://operafea.com/, Proceedings of the 13th Int. Computational Accelerator Physics Conf., ICAP2018, Key West, FL, USA

For the proposed electron-ion collider eRHIC, an electron storage ring will be installed in the existing RHIC tunnel. To reach the high luminosity of up to 10³⁴ cm⁻² sec⁻¹, beam currents up to 2.5A have to be stored. Besides high luminosity the physics program requires spin polarization levels of 70 percent, with both spin "up" and spin "down" orientations present in the fill. This is only feasible by using a full-energy spin polarized injector that replaces bunches faster than the depolarization rate. To limit the repetition rate of that injector to about one hertz, the polarization lifetime in the storage ring has to be maximized by proper spin matching and countermeasures for the machine misalignments. We will give an overview of the electron storage ring design., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

In the eRHIC, to compensate the geometric luminosity loss due to the crossing angle, crab cavities are to be installed on both sides of the interaction point. When the proton bunch length is comparable to the wavelength of its crab cavities, protons will not be perfectly tilted in the x-z plane. In the article, we employ weak-strong beam-beam interaction model to calculate the proton beam size growth rates and luminosity degradation rate with various machine and time parameters. The goal of these studies is to optimize the the beam-beam related machine and beam parameters of eRHIC., Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA

The brand-new state of the art electron accelerator, LEReC, was built and commissioned at BNL. LEReC accelerator includes a photocathode DC gun, a laser system, a photocathode delivery system, magnets, beam diagnostics, a SRF booster cavity, and a set of Normal Conducting RF cavities to provide sufficient flexibility to tune the beam in the longitudinal phase space. Electron beam quality suitable for cooling in the Relativistic Heavy Ion Collider (RHIC) was achieved [1], which lead to the first demonstration of bunched beam electron cooling of hadron beams [2]. This presentation will discuss commissioning results, achieved beam parameters and performance of the LEReC systems., Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA

Future operations of the electron-ion collider eRHIC call for beams circulating off of the magnetic center of all arc elements. In order to ensure that both stable beam conditions and the desired circumference change can be achieved, dedicated experiments were conducted during RHIC Run18, which included the first off-momentum linear optics correction. This article reviews the experimental setup as well as the dedicated algorithm for optics correction, and presents the measured radial excursion and residual off-momentum beta-beat., Proceedings of the North American Particle Accelerator Conference, NAPAC2019, Lansing, MI, USA