Principal characteristics of the facility and of the support offered to users:
The Forschungszentrum Julich is a German national laboratory which carries out research in different fields. The accelerator COSY of the center is used for medium energy hadron physics studies. This cooler synchrotron provides beams of protons with energies of up to 2.6 GeV with electron and stochastic phase space cooling. Presently unpolarized beams are used for the experimental studies, the acceleration of polarized protons is under development. Experiments are performed with thin targets inside the accelerator ring and with extracted beam. High beam quality is achieved through phase space cooling (electron cooling at present, stochastic cooling under commissioning). Beam intensities amount of 1011 protons per spill. As a fully computer controlled device COSY is very flexible with respect to beam handling and the selection of beam energies. Measurements of energy dependent observables during acceleration and the investigation of processes very close to threshold are possible. Four installations for research with intemal targets and three external target positions are available and are presently used for the investigations of meson production of proton-proton elastic scattering and of the modification of elementary processes in-medium. The research is carried out by internal and external users in international collaborations including theoretical experts. COSY will under the proposed EU contract be given full access to the experimental facilities of the reserach center, e.g. beam time at the accelerators, computing facilities, data acquisition systems, electronics, technical assistance from the local staff, of fice space, help to arrange housing. Proposed experiments will be evaluated by the program advisory committee.
Quantity of access being offered and number of users who may benefit: This proposal seeks to extend the beamtime by 20 % in order to satisfy the growing interest of scientdsts from EU on research at COSY. New researchers can use the existing major equipment (in pardcular a large time-of-flight spectrometer for muldparticle events, a magnetic spectrograph with detectors for large angle acceptance and, on internal targets, a scindlladon-counter detector-system, a setup for investigadng fission of hypernuclei and two magnetic spectrometers) or can install their own experimental equipment. About 30 new users are expected to benefit from this extension of the available beamtime.