JLab, Newport News, Virginia, USA
Northern Illinois University, DeKalb, Illinois, USA
DESY, Hamburg, Germany
SLAC, Menlo Park, California, USA
ODU, Norfolk, Virginia, USA
JINR, Dubna, Russia
Texas A&M University, College Station, Texas, USA
Old Dominion University, Norfolk, Virginia, USA
Science and Technique Laboratory Zaryad, Novosibirsk, Russia
ANL, Argonne, Illinois, USA
The Medium-energy Electron Ion Collider (MEIC) at JLab is designed to provide high luminosity and high polarization needed to reach new frontiers in the exploration of nuclear structure. The luminosity, exceeding 1033 cm-2s−1 in a broad range of the center-of-mass (CM) energy and maximum luminosity above 1034 cm-2s−1, is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, 3He) can be easily preserved and manipulated due to the unique figure-8 shape of the collider rings. A fully consistent set of parameters have been developed considering the balance of machine performance, required technical development and cost. This paper reports recent progress on the MEIC accelerator design including electron and ion complexes, integrated interaction region design, figure-8-ring-based electron and ion polarization schemes, RF/SRF systems and ERL-based high-energy electron cooling. Luminosity performance is also presented for the MEIC baseline design.
JLab, Newport News, Virginia, USA
ODU, Norfolk, Virginia, USA
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
Numerous proposals invoke recirculation and/or energy recovery for cost-performance optimization. These often encounter challenges with the beam-quality-degrading effects of incoherent and coherent synchrotron radiation (ISR and CSR). We describe a means of controlling of this degradation. The approach utilizes results by diMitri et al. *, and invokes behavior observed during simulations of the recirculation process. The method is based on the use of periodically isochronous 2nd-order achromats; this not only insures that the conditions for the suppression of CSR-driven emittance growth are met*, it also suppresses micro-bunching gain over a broad range of parameter space **. Details of specific designs will be presented, and a reference to an analysis of micro-bunching effects ** provided. A planned test of the CSR suppression mechanism in CEBAF will be described.
*S. diMitri et al., Phys. Rev. Lett. 110, 014801, 2 January 2013.
**C.Y. Tsai et al., these proceedings.
JLab, Newport News, Virginia, USA
Experimental Hall D, with flagship experiment GlueX, was constructed as part of the 12 GeV CEBAF upgrade. A new magnetically extracted electron beam line was installed to support this hall. Bremsstrahlung photons from retractable radiators, are delivered to the experiment through a series of collimators following a long drift to allow for beam convergence. Coherent Bremsstrahlung generated by interaction with a diamond radiator will achieve a nominal 40% linear polarization and photon energies between 8.5 and 9 GeV from 12.1 GeV electrons, which are then tagged or diverted to a medium power 60kW electron dump. The expected photon flux is 107-108 Hz. This paper discusses the experimental line design, commissioning experience gained since first beam in spring 2014, and the present results of beam commissioning by the experiment.
JLab, Newport News, Virginia, USA