Beam Cooling

Beam cooling systems are complex installations in circular accelerators. Their task is to improve and control the ion beam properties. They are indispensable for the accumulation of beams (increase of intensity for experiments) and for the preparation of secondary beams (rare isotopes, antiprotons) for further use in the accelerator or in the experimental facility. Furthermore, they enable a wide spectrum of efficient beam manipulations as well as high-precision experiments in synchrotrons and storage rings.

The GSI expert department focusses on the two main and „universal“ beam cooling methods
(with respect to the ion species):

(a) electron cooling – invented by G. Budker in Novosibirsk; the Budker Institute for Nuclear Physics (BINP) was named after him; (b) die stochastische Kühlung, erfunden von S. van der Meer am CERN, Nobelpreis der Physik in 1986.


Compared to other laboratories world-wide, GSI and FAIR run the largest number of beam cooling systems. All of them serve different machine cycles and technical requirements:

3 electron coolers at SIS18, ESR (in operation), CRYRING(under commissioning)

1 stochastic cooling at ESR (in operation)

1 stochastic cooling at CR (work package - GSI in-kind for FAIR)

1 stochastic cooling at HESR (work package for FAIR at Forschungszentrum Jülich)

possibly 1 electron cooler at HESR (Forschungszentrum Jülich)


Technologically, beam cooling devices are sophisticated mechanical constructions requiring ultra-high vacuum technology, cooling water and cryogenic equipment, as well as dedicated RF technology in particular in the microwave region (> 1GHz), electrical engineering practice (e.g. high voltages up to 500 kV), measurement and control techniques.

The department is responsible for

  1. the operation, maintenance and development of the 4 existing cooling systems in close contact with experiments and technical departments. This task is strongly connected to the operation of the circular accelerators and the responsibility for safety-related aspects of the systems. The beam cooling experts adjust the devices with beam and optimize the settings according to the users’ needs.
  2.  the realization of the stochastic cooling system in the future Collector Ring (CR) of the FAIR facility (GSI in-kind work package – PSP 2.5.10, Council Decision 2012): design, development, procurement, test, integration, commissioning. The main tasks are long-lasting (more than 10 years), people-intensive developments in house. Many necessary components are not available commercially. Next to specifications and procurements the department runs production laboratories and testing sites and tests components in the existing accelerator facility.
  3. the operation and maintenance of all future FAIR beam cooling systems.
  4. gaining and preserving the highly specialized know-how of these systems.