• W. Meng, Y. Hao, A.K. Jain, V. Litvinenko, G.J. Mahler, J.E. Tuozzolo
  BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

eRHIC, a future high luminosity electron-ion collider at BNL, will add polarized electrons to the list of colliding species in RHIC. A 10-to-30 GeV electron energy recovery linac will require up to six passes around the RHIC 3.8 km circumference. We are developing and testing small (3-to-5 mm gap) dipole and quadrupole magnets and vacuum chambers for cost-effective eRHIC passes. We are also studying the sensitivity of eRHIC pass optics to magnet and alignment errors in such a small-magnet structure. We present the magnetic and mechanical designs of the small gap eRHIC components and prototyping test results.

• A. Burrill, I. Ben-Zvi, R. Calaga, T. D'Ottavio, L.R. Dalesio, D.M. Gassner, H. Hahn, L.T. Hoff, A. Kayran, J. Kewisch, R.F. Lambiase, D.L. Lederle, V. Litvinenko, G.J. Mahler, G.T. McIntyre, B. Oerter, C. Pai, D. Pate, D. Phillips, E. Pozdeyev, C. Schultheiss, L. Smart, K. Smith, T.N. Tallerico, J.E. Tuozzolo, D. Weiss, A. Zaltsman
  BNL, Upton, Long Island, New York

This paper will present the preliminary results of the testing of the 703 MHz SRF cryomodule designed for use in the ampere class ERL under construction at Brookhaven National Laboratory. The preliminary VTA cavity testing, carried out at Jefferson Laboratory, demonstrated cavity performance of 20 MV/m with a Qo of 1x10¹⁰, results we expect to reproduce in the horizontal configuration. This test of the entire string assembly will allow us to evaluate all of the additional cryomodule components not previously tested in the VTA and will prepare us for our next milestone test which will be delivery of electrons from our injector through the cryomodule to the beam dump. This will also be the first demonstration of an accelerating cavity designed for use in an ampere class ERL, a key development which holds great promise for future machines.

• V. Ptitsyn, J. Beebe-Wang, I. Ben-Zvi, A. Burrill, R. Calaga, X. Chang, A.V. Fedotov, H. Hahn, L.R. Hammons, Y. Hao, A. Kayran, V. Litvinenko, G.J. Mahler, C. Montag, B. Parker, A. Pendzick, S.R. Plate, E. Pozdeyev, T. Roser, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang
  BNL, Upton, Long Island, New York
• E. Tsentalovich
  MIT, Middleton, Massachusetts

Funding: Work performed under US DOE contract DE-AC02-98CH1-886

Design of a medium energy electron-ion collider (MEeIC) is under development at Collider-Accelerator Department, BNL. The design envisions a construction of 4 GeV electron accelerator in a local area inside the RHIC tunnel. The electrons will be produced by a polarized electron source and accelerated in the energy recovery linac. Collisions of the electron beam with 100 GeV/u heavy ions or with 250 GeV polarized protons will be arranged in the existing IP2 interaction region of RHIC. The luminosity of electron-proton collisions at 10³² cm^-2 s^-1 level will be achieved with 40 mA CW electron current with presently available parameters of the proton beam. Efficient cooling of proton beam at the collision energy may bring the luminosity to 10³³ cm^-2 s^-1 level. The important feature of the MEeIC is that it would serve as first stage of eRHIC, a future electron-ion collider at BNL with both higher luminosity and energy reach. The majority of the MEeIC accelerator components will be used for eRHIC.

• A. Zelenski, G. Atoian, A. Bazilevsky, G. Bunce, R. Connolly, D.M. Gassner, R.L. Gill, H. Huang, G.J. Mahler, Y. Makdisi, B. Morozov, S. Nemesure, T. Russo, M. Sivertz, D. Steski, S. Tepikian, R.J. Todd, K. Yip
  BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

The proton polarization measurements in AGS and RHIC are based on proton-carbon and proton-proton elastic scattering in the Coulomb Nuclear Interference region. Polarimeter operation in the scanning mode gives polarization profiles and beam intensity profile measurements. This polarimeter is an ideal wire-scanner due to: extremely good signal/noise ratio and high counting rate, which allows accurate bunch by bunch emittance measurements during 100 ms time of the beam crossing. The measurements of the beam emittance in both vertical and horizontal planes will be possible after polarimeter upgrade for the 2009 polarized run. Two new vacuum chambers and two target motion mechanisms and detectors assembly will be installed in each ring. One polarimeter can be used for the vertical polarization and intensity profile measurements and the second can be used for the horizontal profile measurements. The absolute accuracy limitations and cross-calibration of different techniques will be also discussed.