Legacy information

In the last months of 2012 and the first months of 2013 CRYRING was moved to Darmstadt in Germany, as described on the History page. The information on this page has been kept for historical reasons, and reflects the situation in 2010.

The heart of the CRYRING facility is an ion synchrotron and storage ring with 51.6 m circumference. It has twelve straight sections and six superperiods. Six of the straight sections have focusing magnets (quadrupoles and sextupoles) and correction dipoles in them, the other six are used for injection, acceleration, diagnostics, electron cooling, a gas-jet target, and the last one for other experimental equipment. The lattice functions are shown in the figure.

lattice functions The injection is made electrostatically, using four pairs of deflection plates creating a local closed-orbit bump on the injection straight section only. The injection takes place over 10 turns, filling up the horizontal acceptance of 200 pi mm mrad. The vertical acceptance is 100 pi mm mrad.

The ions are accelerated by a driven drift tube - a 2.7 m long drift tube which is connected to a broad-band amplifier. The maximum voltage on the drift tube is 7 kV at frequencies between 40 kHz and 1.5 MHz. The magnet power supplies can be run in two modes, fast or slow. In the fast mode, the acceleration to full energy takes 150 ms, while in the slow mode, ramping to full energy is made in 1 s or more. The maximum energy, set by the 1.44 Tm rigidity of the ring, is 96 (q/A)2 MeV/u.

Diagnostics, scattered all over the ring, consist of Faraday cups for finding the beam at injection; electrostatic pickups for measurements of beam intensities, closed-orbit distortions, Q values, etc.; a Schottky pickup; a horizontal and a vertical residual-gas beam-profile monitor; an AC and a DC current transformer for absolute measurements of beam currents; and particle detectors detecting charge-changed ions.

The electron cooler cools the stored ion beam, i.e., it reduces its velocity spread both transversally and longitudinally. It also acts as an electron target for studies of recombination between the stored ions and electrons.

Ultra-high vacuum is important for operation of the ring. The true hydrogen pressure is approximately 1x10-11 torr (which means that the nitrogen-equivalent pressure is less than 7.5x10-12 torr). Pumping is done mainly through NEG (Non-Evapourable Getter) pumps, and also ion pumps, turbo-molecular pumps and cryopumps.

A good vacuum is essential for long beam lifetimes. These range from milliseconds to weeks and more, depending on the type of ion, its energy and its charge state. The diversity of ions that have been stored and in most cases also accelerated in the ring can be appreciated from this list.

The operation of the CRYRING facility for physics experiments was ended in December 2009. It will be taken out of use in the spring of 2010, after some concluding tests related to the planned transfer of the ring to FAIR in Darmstadt.