BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, Illinois, USA
FRIB, East Lansing, Michigan, USA
The Electron-Ion Collider (EIC) is being envisioned as the next facility to be constructed by the DOE Nuclear Physics program. Brookhaven National Laboratory is proposing eRHIC, a facility based on the existing RHIC complex as a cost effective realization of the EIC project with a peak luminosity of 1034 cm-2 sec-1. An electron storage ring with an energy range from 5 to 18 GeV will be added in the existing RHIC tunnel. A spin-transparent rapid-cycling synchrotron (RCS) will serve as a full-energy polarized electron injector. Recent design improvements include reduction of the IR magnet strengths to avoid the necessity for Nb3Sn magnets, and a novel hadron injection scheme to maximize the integrated luminosity. We will provide an overview of this proposed project and present the current design status.
BNL, Upton, Long Island, New York, USA
The sPHENIX experiment is a proposal for a new detector at the Relativistic Heavy Ion Collider (RHIC), that plans to expand on discoveries made by RHIC’s existing STAR and PHENIX research groups. To minimize the luminosity outside the 20 cm vertex detector and keeping the radiation to other detector components as low as possible, a 56 MHz SRF system is added to the existing RHIC RF systems to compress the bunches with less beam loss. The existing 56 MHz SRF cavity was commissioned in previous RHIC runs, and contributed to the luminosity at a voltage of 300kV with thermal limitations from the Higher Order Mode coupler at high field, and at 1MV while using its fundamental damper for HOM damping. In this paper, we will analyze and compare the effect of different RF systems at various scenarios, and discuss possible solutions to the Higher Order Mode (HOM) damping scheme to bring the cavity to 2 MV.
BNL, Upton, Long Island, New York, USA
The electron-ion collider eRHIC proposed by Brookhaven National Laboratory includes a crabbing system to reestablish head-on collisions for a maximum geometric overlap of the colliding bunches. Since the last cavity design, the crossing angle has increased from 22 to 25 mrad to relax the field strength requirement in one of the IR magnets - increasing the deflecting kick required to collider the bunches head on - and one of the considered options is to have both proton and electron crab cavities work at 200 MHz. The present paper discusses the RF design of the 200 MHz crab cavities for the electron and hadron beams of eRHIC.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
Lancaster University, Lancaster, United Kingdom
CERN, Meyrin, Switzerland
JLab, Newport News, Virginia, USA
SLAC, Menlo Park, California, USA
Crab cavities are one of the several components included in the luminosity upgrade of the Large Hadron Collider (HL-LHC). The cavities have to provide a nominal deflecting kick of 3.4 MV per cavity while the cryogenic load per cavity stays below 5 W. Cold RF tests confirmed the required performances in bare cavities, with several cavities exceeding the required voltage by more than 50%. However, the first tests of a Double-Quarter Wave (DQW) cavity with one out of three HOM filters did not reach the required voltage. The present paper describes the studies and tests conducted on a DQW cavity with HOM filter to understand the limiting factor. The recipe to meet the performance specification and exceed the voltage requirement by more than 35% is discussed.
BNL, Upton, Long Island, New York, USA
PVI, Oxnard, California, USA
A unique apparatus for measuring RF resistivity of tubes and coated tubes at cryogenic temperatures is operational at BNL, which to our knowledge is the first of its kind. A folded quarter wave resonator structure of 300 mm length accesses a wide range of frequencies. The structure is cooled in liquid He bath at 4 K. All internal resonator components (except for test samples) were fabricated out of superconducting materials. Consequently, when the resonator is cooled, the bulk of the losses are due to the copper coating. The RF resistivity is determined from Q measurements, since for a fixed geometry the quality factor of a resonant cavity is proportional to the square root of the conductivity. The RF input loop and the output signal antenna are adjustable when cold via bellows to control matching to each cavity mode. The Q values of 10 resonant modes between 180 and 2500 MHz are deduced from the bandwidth of the S21 response Network Analyzer measurements. CST MicroWave Studio is used to extract the resistivity of the samples from the Q measurements. Resistivity results of solid Cu tube, 2, 5, & 10 μm Cu coated 316LN stainless steel RHIC beam tubes will be presented.