COSY

The acclerator in Jülich

The COoler SYnchrtron COSY at the Institute for Nuclear Physics at Reserach Center Jülich provides polarized and unpolarized proton beams in the energy range between 45 and 2700 MeV for basics science experiments. Alternatively, it can provide deuteron beams between 90 and 2100 MeV. The particle beam can be cooled if required to improve beam quality.

To provide protons in COSY H^-- Ions are produced at an ion source first and extracted from the plasma by an volatage of about 4000V. They are hen injected into the Cyclotron JULIC whee they are acclerated from 4 keV to 45 MeV and transported to COSY. At the injection point the ions pass through a thin carbon foil where they get stripped of their electrons and hencforth circulate as protons in COSY. One lap around COSY takes about 2 µs. Within 1-2 seconds the particles are then acclerated to the experimenatlly required energy. Depending on the required beam properties this process is followed by a period for beam cooling after which the protons are available for data collection at the experiment. Typical timespans for data collection are between a few micro seconds to one hour. Finally all magnet currents are set back to injection beam energy to start a new cycle. These cycles are repeated for one day to a few weeks. Afterwards the accerlator can be prepared for the next experiment.

Experiments can be conducted internally (traget and detector are part of the COSY ring) and externally (beam is extracted and target and beam are outside the ring).

Proposals are directed to the COSY Beamtime Advisory Committee (CBAC), which ranks the experiments and allocates beam time at COSY.