TA1-Transnational Access to COSY

Two cooling systems for phase space cooling of the beam, an electron cooler and a stochastic cooling system are in operation. At internal experiments with the stochastic cooling a momentum resolution of dp/p = 2.10-4 (FWHM) is achieved at a beam intensity of about 5.1010 stored protons at the maximum momentum. Via resonance extraction the beam can be extracted to the external target stations. Routinely the extraction with stochastic feeding of the resonance (ultraslow extraction) is used which allows long spills with a nearly constant extraction current. The extraction efficiency is above 80 % allowing extraction currents of up to 1010 protons per second. For special applications a fast kicker extraction can be used where the full COSY beam is extracted in one bunch of about 200 ns with up to 109 particles. The accelerator is fully computer-controlled. All machine parameters can be stored and reloaded allowing a rapid change of momentum setting and beam optics. With this concept also very special operation modes can be performed like measuring during ramping or switching between different momentum settings from spill to spill. The whole machine is designed for high precision beams resulting in a very stable operation. Another important feature of COSY is the precise handling of polarized beams. COSY is equipped with tools for spin manipulations like RF solenoid and RF dipole, a Sibirian snake and polarimeters, which allow to manipulate and measure the beam polarization with an extremely high precision and stability. The available targets include solid state and liquid hydrogen or deuterium at the external target stations and cluster jet, pellet and polarized atomic beam with storage cell for internal experiments.
COSY delivers particle beams with a high brilliance and very stable conditions. Such a beam is required for precise data in the field of hadron physics and even more important for precision experiments like the activities towards EDM studies. In order to investigate the precision limits of storage ring experiments a precise and stable operating machine is essential. COSY is the only cooler ring worldwide in the medium energy regime. Especially in view of the realization ofthe European FAIR facility the availability of access to an accelerator in the few GeV/c energy range is very important for accelerator equipment and detector tests. The other field for which COSY is a unique machine is precision physics.The challenge of precision physics at accelerators like the measurements of electric dipole moments requires extreme precision of the machine operation. COSY is indispensable for exploring the limits for these kind of studies as it is the only hadron machine worldwide for detailed spin physics studies.
Services currently offered by the infrastructure: At COSY the experiments are performed within international collaborations of typically 20 - 50 scientists. A new user may either join an existing collaboration or make a new proposal. The installation of new equipment at internal or external target places is possible and the development of new components can be supported due to the large infrastructure departments at the FZJ. The widespread interest from usersin other countries is demonstrated by the number of institutions which are involved in the COSY experiments. In the last years about 460 scientists and students from 72 different institutions worked at the COSY experiments. The user Community is composed of about 150 German users from 16 different institutions, about 150 users from 10 different European and associated countries and about 160 users out of 8 countries outside of Europe.