BNL, Upton, Long Island, New York, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Two normal conducting cavities operating at 704 MHz and 2.1 GHz will be used for the Low Energy RHIC electron Cooling (LEReC) under development at BNL to improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon. The single cell 704 MHz cavity and the 3-cell 2.1 GHz third harmonic cavity will be used in LEReC to correct the energy spread introduced in the SRF cavity. The successful operation of normal RF cavities has to satisfy both RF and mechanical requirements. 3-D coupled RF-thermal-structural analysis has been performed on the cavities to confirm the structural stability and to minimize the frequency shift resulting from thermal and structural expansion. In this paper, we will present an overview of the mechanical design, results from the RF-thermal-mechanical analysis, progress on the fabrication and schedule for the normal conducting RF cavities for LEReC.
BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, Illinois, USA
Stony Brook University, Stony Brook, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under development at BNL. The Linac of LEReC is designed to deliver 2 MV to 5 MV electron beam, with rms dp/p less than 5·10-4. The HOM in this Linac is carefully studied to ensure this specification.
BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, Illinois, USA
Stony Brook University, Stony Brook, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energy RHIC electron Cooler (LEReC) is currently under development at BNL. Two normal conducting cavities, a single cell 704 MHz cavity and a 3 cell 2.1 GHz third harmonic cavity, will be used in LEReC for energy spread correction. Currently these two cavities are under fabrication. In this paper we report the RF design of these two cavities.
BNL, Upton, Long Island, New York, USA
Providing Au-Au collisions in the Relativistic Heavy Ion Collider (RHIC) at energies equal or lower than 10 GeV/nucleon is of particular interest to study the location of a critical point in the QCD phase diagram. To mitigate luminosity limitations arising from intra-beam scattering at such low energies, an electron cooling system is being developed. To achieve cooling, the relative velocities of the electrons and protons need to be small with maximized transverse overlap. Recombination rates of ions with electrons in the electron cooler can provide signals that can be used to tune the energies and transverse overlap to the required conditions. In this paper we take a close look at various detection methods for recombination processes that may be used to approach cooling.
BNL, Upton, Long Island, New York, USA
FZJ, Jülich, Germany
ESRF, Grenoble, France
The Relativistic Heavy Ion Collider (RHIC) has two main operating modes with heavy ions and polarized protons respectively. In addition to a continuous increase in the bunch intensity in all modes, two major new systems were completed recently mitigating the main luminosity limit and leading to significant performance improvements. For heavy ion operation stochastic cooling mitigates the effects of intrabeam scattering, and for polarized proton operation head-on beam-beam compensation mitigated the beam-beam effect. We present the performance increases with these upgrades for heavy ions and polarized protons, as well as an overview of all operating modes past and planned.
BNL, Upton, Long Island, New York, USA
Lower risk ring-ring alternatives to the BNL linac-ling~[linacring] eRHIC electron ion collider (EIC) are discussed. The baseline from the Ring-Ring Working Group~[ringring] has a peak proton-electron luminosity of ≈§I{1.2e33}{cm-2.s-1}. An option has final focus quadrupoles starting immediately after the detector at 4.5~m, instead of at 32~m in the baseline. This allows the use of lower β*s. It also uses more, 720, lower intensity, bunches, giving reduced IBS emittance growth and requiring only low energy pre-cooling. It has a peak luminosity of ≈§I{7e33}{cm-2.s-1}. An upgrade of this option, requiring magnetic, or coherent, electron cooling, has 1440 bunches and peak luminosity of ≈§I{15e33}{cm-2.s-1}.
BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, Illinois, USA
Recent developments of the ERL-based design of future high luminosity electron-hadron collider eRHIC focused on balancing technological risks present in the design versus the design cost. As a result a lower risk design has been adopted at moderate cost increase. The modifications include a change of the main linac RF frequency, reduced number of SRF cavity types and modified electron spin transport using a spin rotator. A luminosity-staged approach is being explored with a Nominal design (L ~ 1033 cm-2 s-1) that employs reduced electron current and could possibly be based on classical electron cooling, and then with the Ultimate design (L > 1034 cm-2 s-1) that uses higher electron current and an innovative cooling technique (CeC). The paper describes the recent design modifications, and presents the full status of the eRHIC ERL-based design.
BNL, Upton, Long Island, New York, USA
To reduce the technical risk of the future electron-ion collider eRHIC currently under study at BNL, the ring-ring scheme has been revisited over the summer of 2015. The goal of this study was a design that covers the full center-of-mass energy range from 32 to 141 GeV with an initial luminosity around 1033 cm-2 sec-1, upgradeable to 1034 cm-2 sec-1 later on. In this presentation the baseline design will be presented, and future upgrades will be discussed.