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HK: Hadronen und Kerne

HK 3: Instrumentation I, Ion Sources, Targets

HK 3.9: Talk

Monday, March 16, 1998, 16:15–16:30, A

Pulsed Cs Beam Development for the COSY-J"ulich Polarized Ion Source — •M. Eggert¹, S. Lemaitre¹, R. Reckenfelderb"aumer¹, P. v. Rossen², A. Z"ollich¹, and H. Paetz gen. Schieck¹ — ¹Institut f"ur Kernphysik, Universit"at zu K"oln — ²Institut f"ur Kernphysik, Forschungszentrum J"ulich

At the Cooler Synchrotron COSY (Forschungszentrum J"ulich) a polarized ion source based on the colliding-beams principle (CBS) is being operated. For the production of a negative nuclear-polarized H beam the charge-exchange reaction

is used. While the H⁰ beam is already being pulsed the Cs ion source is still operated in DC mode. To increase the reliability of the CBS, the possibilities to develop a pulsing mechanism adapted to the requirements of the COSY injection scheme have been investigated. The Cs⁺ beam is produced by surface ionization on a hot (1300 K) porous tungsten surface, accelerated to up to 60 keV and then neutralized in Cs vapor. The injection time of COSY is between 10 and 20 ms with a duty factor of less than 0.5 %. A mechanical pulsing mechanism using a specially designed fast valve and various electrical pulsing schemes have been investigated. The experimental results will be presented and compared with theoretical models.