BNL, Upton, Long Island, New York, USA
CERN, Geneva, Switzerland
Stony Brook University, Stony Brook, USA
SLAC, Menlo Park, California, USA
LBNL, Berkeley, California, USA
The LHC high luminosity project envisages the use of the crabbing technique for increasing and levelling the LHC luminosity. Double-Quarter Wave (DQW) resonators are compact cavities especially designed to meet the technical and performance requirements for LHC beam crabbing. A couple of DQW crab cavities are under preparation and will be tested with beam in the Super Proton Synchrotron (SPS) of CERN by 2017. This paper describes the design and prototyping of DQW crab cavities for the SPS test.
Tech-X, Boulder, Colorado, USA
BNL, Upton, Long Island, New York, USA
We developed modeling capabilities, within the Vorpal particle-in-cell code, for three-dimensional (3D) simulations of surface effects and electron emission from semiconductor photocathodes. They include calculation of emission probabilities using general, piece-wise continuous, space-time dependent surface potentials, effective mass and band bending field effects. We applied these models, in combination with previously implemented capabilities for modeling charge generation and transport in diamond, to investigate the emission dependence on applied electric field in the range from approximately 2 to 17 MV/m along the [100] direction. The simulation results were compared to experimental data when using different emission models, band bending effects, and surface-dependent electron affinity. Simulations using surface patches with different levels of hydrogenation lead to the closest agreement with the experimental data.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
Stony Brook University, Stony Brook, USA
BNL, Upton, Long Island, New York, USA
The first RF commissioning of 112 MHz QWR superconducting electron gun was done in late 2014. The coaxial Fundamental Power Coupler (FPC) and Cathode Stalk (stalk) were install and tested for the first time. During this experiment, we observed several multipacting barriers at varied gun voltage levels. The simulation work was done within the same range. The comparison between the experimental observation and the simulation results are presented in this paper. The observations during the test are consisted with the simulation predictions. We were able to overcome most of the multipacting barriers and reach 1.7 MV gun voltage under pulsed mode after several round of conditioning processes.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
The 704 MHz superconducting RF gun successfully generated the first photoemission beam on Nov. 17 2014. This paper will report the latest results of SRF beam commissioning, including the SRF cavity performance, cathode QE measurements, and beam parameter measurements. The beam commissioning setup is described in the paper as well.
Stony Brook University, Stony Brook, USA
Transfer Engineering and Manufacturing, Inc, Fremont, California, USA
BNL, Upton, Long Island, New York, USA
Stangenes Industries, Palo Alto, California, USA
Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place at Stangenes Industries in Palo Alto, CA, where the cathodes were placed in radially opposite locations inside the high voltage shroud. No significant cross talking between the cathodes were found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.
BNL, Upton, Long Island, New York, USA
Transfer Engineering and Manufacturing, Inc, Fremont, California, USA
Stangenes Industries, Palo Alto, California, USA
Stony Brook University, Stony Brook, USA
A prototype of a high average current polarized electron funneling gun as an eRHIC injector has been built at BNL. The gun was assembled and tested at Stangenes Incorporated. Two beams were generated from GaAs photocathodes and combined by a switched combiner field. We observed the combined beams on a YAG crystal and measured the photocurrent by a Faraday cup. The gun has been shipped to Stony Brook University and is being tested there. In this paper we will describe the major components of the gun and recent beam test results. High voltage conditioning is discussed as well.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
The Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment at BNL includes a short electron linac. During Phase I a 112 MHz superconducting RF photoemission gun and two 500 MHz normal conducting bunching cavities were installed and commissioned. The paper describes the Phase I linac layout and presents commissioning results for the cavities and associated RF, cryogenic and other sub-systems.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
The Low Energy RHIC electron Cooling (LEReC) is under development at BNL to improve RHIC luminosity at low energies. It will consist of a short electron linac and two cooling sections, one for blue and one for yellow beams. For the first stage of the project, LEReC-1, we will to install a 704 MHz superconducting RF cavity and two normal conducting cavities operating at 704 MHz and 2.1 GHz. The SRF cavity will boost the electron beam energy up to 2 MeV. The warm cavities will be used to correct the energy spread introduced in the SRF cavity. The paper describes layouts of the SRF and RF systems, their parameters and status.
BNL, Upton, Long Island, New York, USA
ANL, Argonne, Illinois, USA
Niowave, Inc., Lansing, Michigan, USA
Fermilab, Batavia, Illinois, USA
A 5-cell SRF cavity operating at 704 MHz will be used for the Coherent Electron Cooling Proof of Principle (CeC PoP) system currently under development for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The CeC PoP experiment will demonstrate the ability of relativistic electrons to cool a single bunch of heavy ions in RHIC. The cavity will accelerate 2 MeV electrons from a 112 MHz SRF gun up to 22 MeV. Novel mechanical designs, including the helium vessel, vacuum vessel, tuner mechanism, and FPC are presented. This paper provides an overview of the design, the project status and schedule of the 704 MHz 5-cell SRF for the CeC PoP experiment.
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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, Geneva, Switzerland
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
A double quarter wave crab cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multi-physics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.
BNL, Upton, Long Island, New York, USA
CERN, Geneva, Switzerland
Stony Brook University, Stony Brook, USA
SLAC, Menlo Park, California, USA
A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109. We report the test results of this design.
BNL, Upton, Long Island, New York, 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 Energey 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 bunch stretching and energy spread correction. In this paper we report the design of these two cavities.
BNL, Upton, Long Island, New York, USA
A 56 MHz superconducting RF cavity has been designed, fabricated and installed in the Relativistic Heavy Ion Collider (RHIC). The cavity operated at 4.4 K with a “quiet helium source” to isolate the cavity from environmental acoustic noise. The cavity is a beam driven quarter wave resonator. It is detuned and damped during injection and acceleration cycles and is brought to operation only at store energy. For a first test operation, the cavity voltage was stabilized at 300 kV with full beam current. Within both Au + Au and asymmetrical Au + He3 collisions, luminosity improvement was detected from direct measurement, and the hourglass effect was reduced. One higher order mode (HOM) coupler was installed on the cavity. We report in this paper on our measurement of a broadband HOM spectrum excited by the Au beam.