BNL, Upton, New York, USA
JLab, Newport News, Virginia, USA
Douglas Consulting, York, Virginia, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Xelera Research LLC, Ithaca, New York, USA
The Electron-Ion Collider will achieve a luminosity of 1034 cm-2 s−1 by incorporating strong hadron cooling to counteract hadron Intra-Beam Scattering, using a coherent electron cooling scheme. An accelerator will deliver the beams with key parameters, such as 1 nC bunch charge, and 1e-4 energy spread. The paper presents the design and beam dynamics simulation results. Methods to minimize beam noise, the challenges of the accelerator design, and the R&D topics being pursued are discussed.
JLab, Newport News, Virginia, USA
Fermilab, Batavia, Illinois, USA
BNL, Upton, New York, USA
The central detector in the present EIC design includes a 4 m long solenoid with an integrated strength of up to 12 Tm. The electron beam passes on-axis through the solenoid, but the hadron beam has an angle of 25 mrad. Thus the solenoid couples horizontal and vertical betatron motion in both electron and hadron storage rings, and causes a vertical closed orbit excursion in the hadron ring. The solenoid also couples the transverse and longitudinal motions of both beams, when crab cavities are also considered. In this paper, we present schemes for closed orbit correction and coupling compensation at the IP, including crabbing.
BNL, Upton, New York, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
JLab, Newport News, Virginia, USA
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.
BNL, Upton, New York, USA
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.
BNL, Upton, New York, USA
The EIC will make use of the existing RHIC storage rings with their superconducting (SC) magnet arcs. A stainless-steel beam screen with co-laminated copper and a thin amorphous carbon (aC) film on the inner surface will be installed in the beam pipe of the SC magnets. The copper will reduce the beam-induced resistive-wall (RW) heating from operation with the higher intensity EIC beams, that if not addressed would make the magnets quench. Limiting the RW heating is also important to achieve an adequately low vacuum level. The aC coating will reduce secondary electron yield which could also cause heating and limit intensity. Among all the RHIC SC magnets, the arc dipoles present the biggest challenge to the design and installation of beam screens. The arc dipoles, which make up for 78% (2.5 km) length of all SC magnets in RHIC, expect the largest RW heating due to their smallest aperture. These magnets are also the longest (9.45 m each), thus experiencing the largest temperature rise over their length, and have a large sagitta (48.5 mm) that increases the difficulty to install the beam screen in place. This paper presents a detailed thermal analysis of the magnet-screen system.
BNL, Upton, New York, USA
JLab, Newport News, USA
SLAC, Menlo Park, California, USA
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.
* An Assessment of U.S.-Based Electron-Ion Collider Science. (2018). Washington, D.C.: National Academies Press. https://doi.org/10.17226/25171
BNL, Upton, New York, USA
JLab, Newport News, Virginia, USA
SLAC, Menlo Park, California, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Fermilab, Batavia, Illinois, USA
ODU, Norfolk, Virginia, USA
FRIB, East Lansing, Michigan, USA
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.
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
BNL, Upton, New York, USA
KEK, Ibaraki, Japan
BNL, Upton, New York, USA
FRIB, East Lansing, Michigan, USA
ODU, Norfolk, Virginia, USA
JLab, Newport News, Virginia, USA
LBNL, Berkeley, California, USA
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.
BNL, Upton, New York, USA
FRIB, East Lansing, Michigan, USA
ODU, Norfolk, Virginia, USA
JLab, Newport News, Virginia, USA
LBNL, Berkeley, California, USA
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.