P. Spiller

Electric energy consumption of an accelerator facility

The changes of the German electricity system approaching a high share of renewable electricity production (80% by 2050) leads to a cost increase of electrical energy. This alters the basic conditions for big industrial consumers of electric energy. Fundamental research facilities, especially accelerator facilities (here GSI) have to develop innovative concepts for a more efficient use of electric energy in order to reduce running costs. A major part of the running costs is caused by the electric energy consumption. One of the main aspects of this development is the breakdown of electric energy consumption into consumer groups. To start this process we analyze the load curves of the last three years and identify periodic patterns, employee consumption, base load and energy consumption of different operational modes of the accelerator facility. First results point out a high base load, which is equal to about 40% of consumed energy and a high amount of peak load over a short time period, both could possibly be reduced in the future. The research, analysis and interpretation breaks down the large energy consumption, which averages to about 55GWh per year.

Beam Loss and Longitudinal Emittance Growth in SIS

Beam losses of several percent occur regularly in SIS. The onset occurs during the RF capture of the beam. Previous studies have revealed that the losses can come from the RF bucket at the start of acceleration being over filled due to the longitudinal bucket acceptance being too small, or due to the mismatch between the mean energy from the UNILAC and synchronous energy of the SIS. The beam losses as measured by a DC beam transformer however show in addition to the sharp initial drop, for the above reasons, a much slower decay in the beam intensity. The speculated cause comes from the incoherent transverse tune shift of the bunched beam, which forces particles into transverse resonant conditions. The longitudinal emittance growth is also another important issue for SIS. Past measurements from Schottky‐noise pick‐ups have shown a factor of 3–5 increase in the longitudinal emittance depending on the extraction energy; a large factor when compared against expectations from theory. These factors were calcula...

SIS100 Beam Dynamics Challenges Related to the Magnet System

The SIS100 synchrotron [1] is the central accelerator of the upcoming FAIR project [2] at GSI, Darmstadt, Germany. The major challenges of the future operation are related to high-intensity, low beam loss operation for a wide range of ion species and charge states, for different operational cycles and extraction schemes. The magnet system [3] consists of 108 dipole, 166 quadrupole and additional correction magnets. The magnets are presently under production and testing, with detailed measurements of the magnetic field imperfections. This results will eventually construct the complete database for the SIS100 magnet system. The delivery of the series dipole magnets to GSI is presently in progress [4]. In this paper, we analyze the magnetic filed data for the four series dipole magnets. The implications of the magnetic field imperfections for the singleparticle stability are studied.

Laser Cooling of Relativistic Highly Charged Ions at FAIR

FAIR∗ D. Winters1†, O. Boine-Frankenheim1,4‡, L. Eidam1,4, Th. Kühl1,2, P. Spiller1, Th. Stöhlker1,2,3 T. Beck4, G. Birkl4,‡, D. Kiefer4, Th. Walther4,‡, M. Bussmann5, M. Löser5,6, U. Schramm5,6,‡, M. Siebold5, X. Ma7§, W. Wen7, D. Winzen8, V. Hannen8, 1GSI Helmholtzzentrum, Darmstadt, Germany, 2Helmholtz-Institute Jena, Germany, 3Jena University, Germany, 4Technical University Darmstadt, Germany, 5Helmholtz-Zentrum Dresden-Rossendorf, Germany, 6Technical University Dresden, Germany 7Institute of Modern Physics, Lanzhou, China, 8Münster University, Germany

SIS100 status report 2014

SIS100 is the main accelerator of the FAIR project. It is a worldwide unique heavy ion synchrotron dedicated to accelerate highest intensities of intermediate charge sta t heavy ion and proton beams up to 100 Tm. From the technical point of view, most challenging issues are the fast ramped superconducting magnets and the acceleration of intense, intermediate charge state heavy ions beams. The latter required a unique lattice design (charge separator lattice) in combination with an ultra-high vacuum system based on distributed cryopumping with actively cooled magnet chambers, adsorption pumps and dedicated cryocatchers for local suppression of gas desorption.

The SIS100 laser cooling facility

High-quality, stored ion beams can be obtained by means of electron cooling and/or stochastic cooling. At intermed iate kinetic energies ( γ≈1), these methods work very well. But at very high kinetic energies ( γ>5), they become less effective. For instance, to reach electron cooling at γ=12, a very sophisticated (voltage up to 6 MV) and thus expensive electron cooling system is required. Therefore, another method was considered for the FAIR heavy-ion synchrotron SIS100: Laser cooling of bunched ion beams. Based on successful experiments with stored, relativistic heavy-ion beams at the ESR [1], it was (2013) decided to set up a laser cooling facility at the SIS100. Within the 3rd term of the Programme Oriented Funding (POFIII) of the Helmholtz Society, we wrote a proposal for this facility as part of accelerator research and development (ARD) within ”Matter and Technologies” [2]. Early 2014, the proposal was approved and received the highest marks (‘highlight’). Within FAIR@GSI primary beams, a special project group ‘SIS100 laser cooling’ (PSP-code 2.8.10) was formed, which tasks are to specify, design, order, construc t, setup, and test the SIS100 laser cooling facility. ( Note: The planned laser cooling facility can serve both the SIS100 and the future SIS300.) The project group consists of scientists from SPARC ‘laser cooling’ [3], which come from GSI and the collaborating partner universities and researc h centers in Dresden-Rossendorf, Darmstadt, Jena, Münster , and Lanzhou (China). For laser cooling at the SIS100, the setup must be similar to that used at the ESR, and at least contain a laser system with a beamline (incl. optics and diagnostics), a set of scrapers, a buncher (exciter), and a dedicated fluorescence detection system. The facility will be located 20 m underground (see Fig.1). The laser light will be transported from the laser lab in the (inner) service tunnel to the (outer) accelerator tunnel, passing through concrete walls and a thic k layer of soil between the two tunnels. This laser beamline (length 25 m, diameter 20 cm) should be made out of stainless steel vacuum tubes. Vacuum conditions are required to transport the laser light, which covers a very broad spectrum ranging from the IR ( λ∼μm) down to the XUV range (λ∼nm). The laser lab (180 m ) will contain a special cleanroom (50 m ) to operate the laser systems. There will also be a detector cave (45 m ) in which special ∗Work supported by HGF POFIII ARD-ST2. † d.winters@gsi.de ‡ Work supported by BMBF. § Work supported by BMBF-WTZ. ¶Work supported by DAAD. detector systems for x-ray measurements can be installed (SIS300). Detectors for the IRto the XUV-range are still compact enough to fit into the SIS100 tunnel. To couple the laser light in and out of the accelerator, special vacuum chambers with optics and diagnostics will be used. Spatial overlap (about 25 m) between laser and ion beam needs to be adjusted using scrapers and reference points. First tests of the facility will use Li-like ions and laser ystems provided by the groups in Darmstadt and Dresden. Once the facility has passed all the tests, and first laser coo ling has been demonstrated, other ion species and/or laser systems could be used as well. We emphasize that also laser spectroscopy experiments can be performed! Once the cooling transition is found, it can also precisely be mea sured. Ultracold beams are also of great interest by themselves. Last, but not least, it will be attempted to extract the laser-cooled ions from the SIS100 and uniquely deliver very cold and very short ultra-relativistic ion bunches to experiments.