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S.Ivanov, O.Lebedev (Institute for High Energy Physics, Moscow, Russia) Beam Tests of a Stochastic Slow Extraction System Prototype in the U70

The paper reports on development of a stochastic slow extraction system prototype beam-tested during the 2004-6 MD runs of the 70 GeV proton synchrotron of IHEP-Protvino. Flat-topped 2-3 sec long and smooth (r.m.s. AC-to-DC ratio < 0.3) spills were obtained. The scheme imple- mented has a few inventive features. Protons are forced into the 3-rd order horizontal resonance with a supplementary 200 MHz RF system driven by sum of a non-random RF carrier and an additive base-band low-pass phase noise. Waiting beam stack is kept coasting in a close outer vicinity of 200 MHz buckets, in the longitudinal phase half-plane opposite to that housing mo- mentum image of extraction resonance. RF buckets are kept repopulated by inward diffusion from the outer stack. Shape of noise power spectrum is invariable (no conventional frequency sweeping is applied), magnitude of noise being controlled via a proportional DC-coupled feed- back loop acquiring data from a beam loss monitor. Terminal travel to resonance is carried out via a fast trapped cyclic motion inside buckets. It drastically improves immunity of extraction to ripples in power supplies of beam optics. No mains harmonics are observed in spills.

Dr. Sergey Vladislavovitch Ivanov: Sergey.Ivanov@ihep.ru

V.Yakimenko, I.Pogorelsky (Brookhaven National Laboratory, USA)

Nonlinear Compton scattering and its application to polarized positron source for ILC

We propose a novel gamma-source suitable for generating a polarized positron beam for the next generation of electron-positron colliders, such as the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). This 40-MeV polarized gamma-source is based on Compton scattering inside a picosecond CO2 laser cavity from electron bunches produced by a 4-GeV li- nac. We identified and experimentally verified the optimum conditions for generating at least one gamma photon per every electron. After multiplication at several consecutive interaction points, the gamma-rays so produced will be stopped on a target, thereby creating a copious num- bers of circularly polarized positrons. We address the practical feasibility of having an intra- cavity Compton polarized positron source as the injector for these new colliders.

Dr. Vitaly Yakimenko: yakimenko@bnl.gov

Plenary session: Accelerators for industrial applications

R.Salimov (Budker Institute of Nuclear Physics, Novosibirsk, Russia)

Status of ELV-type electron accelerators Prof. Rustam Salimov: veis@inp.nsk.su


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