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TPAT091 | IBS for Ion Distribution Under Electron Cooling | 4263 |
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Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-98CH10886. Standard models of the intra-beam scattering (IBS) are based on the growth of the rms beam parameters for a Gaussian beam distribution. As a result of electron cooling, the core of beam distribution is cooled much faster than the tails, producing a denser core. Formation of such a core is an important feature since it plays dominant role in the luminosity increase. A simple use of standard rms-based IBS approach may significantly underestimate IBS for the beam core. A detailed treatment of IBS, which depends on individual particle amplitudes, was recently proposed by Burov,* with an analytic formulation done for a Gaussian distribution. However, during the cooling process the beam distribution quickly deviates from a Gaussian profile. To understand the extent of the dense core formation in the ion distribution, the "core-tail" model for IBS, based on the diffusion coefficients for bi-Gaussian distributions, was employed in cooling studies for RHIC. In addition, the standard IBS theory was recently reformulated for rms parameters growth of a bi-Gaussian distribution by Parzen.** In this paper, we compare various approaches to IBS treatment for such distribution. Its impact on the luminosity is also discussed. *A. Burov, FERMILAB-TM-2213 (2003). **G. Parzen, Tech Note C-AD/AP/150 (2004). |
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TPAP043 | Electron Cooling of RHIC | 2741 |
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We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.
Under contract with the U.S. Department of Energy, Contract Number DE-AC02-98CH10886. |