Helmholtz Zentrum Berlin


BESSY • The ideal microscope for space and time

business as (un)usual

authored a year ago:

Accelerator tourism Part 8: Swiss Light Source & Swiss FEL

The last annual meeting of the „ESLS-RF“ (which stands for “European Synchrotron Light Source-Radio Frequency”) experts in November 2016 was hosted by the Paul Scherrer Institute, PSI, near Villigen. Softly settled in the middle of a smooth Switzerland landscape on both sides of the Aare river, it´s a huge center for research in the fields of matter, material, energy, health and environment.


Besides of getting to know what the workshop folks would report from their last year´s activities at their different synchrotrons all around Europe, my main interest was focussed on the tour through the Swiss Light Source, with its sophisticated architecture.


Looking down on it from a nearby hill, SLS lookes like an over-sized doughnut with a thatched roof.


With an energy of 2.4 GeV, the 288 m circumference storage ring started its program in summer 2001. The accelerating machine is formed by 36 dipole bending magnets, -designed in 3 groups by 12 magnets each-, 177 focussing quadrupole and 120 sextupole magnets, correcting focussing errors. Additional 24 skew quadrupole magnets became installed to correct beam torsion and vertical emittance. Skew magnets are very complicated to understand and I asked my colleague Paul here after having returned back here: "What exactly does a skew magnet do?" I learned to use the so-called "right-hand-rule", using your right hand fingers to determine 1) the particle direction, 2) the magnetic field lines and 3) the force.


Unlike BESSY, the office and control room at SLS are not located outside of the tunnel and machine. Offices are located in the middle of the doughnut, within the machine ring.


PSI also hosts the brandnew free-electron X-ray laser Swiss FEL, which has been built and assembled during the last 5 years. Inauguration took place in December 2016. At the time of our visit, we caught a glimpse on the straight geometry by having a tour through the RF-infrastructure.


Facilities like FEL´s are rather squeamish when it comes to vibrations and tremors. Hence Swiss FEL is located in a quiet forest in close proximinity to the PSI site and it needed a lovely walk to getting there. For me, seeing the workshop group of scientists and engineers, usually rather working with HighTech machines, wandering through a Swiss forest, aiming for something very interesting to see-at-the-whereever-end, for a moment backflashed me to my "former life", when doing geology.

Funny to see that from time to time... it goes together.