BNL, Upton, Long Island, New York, USA
Coherent electron cooling (CeC) relies on Debye shielding to imprint information of the ion beam to an electron beam [1]. Apart from the density modulation, Debye shielding also modulates the energy of electrons, which provides additional seeding for the free electron laser (FEL) amplifier. In this work, we show that the energy modulation of a longitudinal slice of the electrons, induced by dynamic Debye shielding of a moving ion in anisotropic electron plasma with κ-2 velocity distribution, can be expressed into a 1D integral. The results are then applied to the 1D FEL model to investigate the effects of energy modulation to the correcting force in the kicker.
[1] V.N. Litvinenko, Y.S. Derbenev, Coherent Electron Cooling, Physical Review Letters, 102 (2009) 114801. http://link.aps.org/abstract/PRL/v102/e114801
Tech-X, Boulder, Colorado, USA
CIPS, Boulder, Colorado, USA
BNL, Upton, Long Island, New York, USA
PSI, Villigen PSI, Switzerland
Advances in nuclear physics depend on experiments that employ relativistic hadron accelerators with dramatically increased luminosity. Current methods of increasing hadron beam luminosity include stochastic cooling and electron cooling; however, these approaches face serious difficulties at the high intensities and high energies proposed for eRHIC *. Coherent electron cooling promises to cool hadron beams at a much faster rate**. A single pass of an ion through a coherent electron cooler involves the ion's modulating the charge density of a copropagating electron beam, amplification of the modulated electron beam in a free-electron laser, and energy correction of the ion in the kicker section. Numerical simulations of these three components are underway, using the parallel Vorpal framework and Genesis 1.3, with careful coupling between the two codes. Here we present validations of two components of the simulations: Adding bunching to an electron beam at the start of an FEL, and the time-dependent charge density modulation in the kicker.
* http://www.bnl.gov/cad/eRHIC/
** V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
BNL, Upton, Long Island, New York, USA
As the world’s only high energy polarized proton collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been providing collisions of polarized proton beams at beam energy from 100~GeV to 255~GeV for the past decade to explore the proton spin structure as well as other spin dependent measurements. With the help of two Siberian Snakes per accelerator plus outstanding beam control, beam polarization is preserved up to 100~GeV. About 10% polarization loss has been observed during the acceleration between 100~GeV and 255~GeV due to several strong depolarizing resonances. Moderate polarization loss was also observed during a typical 8 hour physics store. This presentation will overview the achieved performance of RHIC, both polarization as well as luminosity. The plan for providing high energy polarized He-3 collisions at RHIC will also be covered.
This work is on behalf of RHIC team.
BNL, Upton, Long Island, New York, USA
Tech-X, Boulder, Colorado, USA
Niowave, Inc., Lansing, Michigan, USA
BINP SB RAS, Novosibirsk, Russia
JLAB, Newport News, Virginia, USA
BNL, Upton, Long Island, New York, USA
In the 2012 RHIC heavy ion run, we collided 96.4~GeV U-U ions and 100~GeV Cu-Au ions for the first time in RHIC. The new pre-injector with the electron-beam ion source (EBIS) was used to provide ions for RHIC ion collisions for the first time. By adding the horizontal cooling, the powerful 3-D stochastic cooling largely enhanced the luminosity. With the double bunch merging in the Booster and AGS, the bunch intensities of Cu and Au ions in RHIC surpassed their projections. Both PHENIX and STAR detectors reached their integrated luminosity goals for the U-U and Cu-Au collisions. In this article we review the machine improvement and performance in this run.
BNL, Upton, Long Island, New York, USA
UCR, Riverside, California, USA
The 2013 operation of the Relativistic Heavy Ion Collider (RHIC) marks the second year of running under the RHIC II era. Additionally this year saw the implementation of several important upgrades designed to push the intensity frontier. Two new E-lenses have been installed, along with a new lattice designed for the E-lens operation. A new polarized proton source which generates about factor of 2 more intensity was commissioned as well as a host of RF upgrades from a new longitudinal damper, Landau cavity in RHIC to a new low level RF and new harmonic structure for the AGS. We present an overview of the challenges and results from this years run.
BNL, Upton, Long Island, New York, USA
Electron cooling has the potential to compensate the emittance growth of the circulating ion beam due to intra-beam scattering at low energy. A test of electron cooling for RHIC low energy operations has been planned at IP2. Apart from the wakefield from the environment, the coherent interaction between the electron beam and ion beam could also play a role for the instability threshold. This work presents studies of ion beam stabilities in presence of coherent electron-ion interactions for the planned low energy RHIC electron-cooling test using the simulation code TRANFT.