Bochum 1998 – wissenschaftliches Programm

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HK: Hadronen und Kerne

HK 25: Instrumentation III, Accelerators

HK 25.1: Gruppenbericht

Dienstag, 17. März 1998, 14:00–14:30, A

Status and Perspectives of ELSA — •C. Steier, H. Bongartz, W. v. Drachenfels, F. Frommberger, M. Gentner, M. Hoffmann, D. Husmann, J. Keil, S. Nakamura, C. Nietzel, and K. Raecke — Physikalisches Institut, Universität Bonn, Nußallee 12, D-53115 Bonn

The stretcher ring ELSA at Bonn University provides external electron beams with high duty factor in the energy range between 0.5 and 3.5 GeV. Furthermore it is operated as a partly dedicated synchrotron radiation source. The main emphasis of the current activities of the group is put on the upgrade of the facility for the acceleration of polarized electrons which are necessary for new double polarization experiments at Bonn.

The polarized electrons are produced in a dedicated source using the photo effect with circular polarized laser light on a GaAs superlattice crystal. Recently polarized electrons have been accelerated up to 2.0 GeV crossing several depolarizing resonances. The achieved polarization degree is sufficient for the planned experiments (eg. to measure the GDH-sumrule [1]). This is the first time depolarizing resonances have been crossed without significant depolarization in an electron storage ring. The actual performance of the accelerator facilities at Bonn is outlined and details of the measurements concerning depolarizing resonances are given.

[1] G. Anton on behalf of the GDH collaboration, Prog. Part. Nucl. Phys. 34, 173 (1995)