Bahrdt, J.; Frentrup, W.; Gaupp, A.; Schäfers, F.; Scheer, M.; Wüstefeld, G.;: Mini-Beta Sections in the Storage Ring BESSY II. In: Proceedings IPAC 10. First International Particle Accelerator Conference, Kyoto, Japan, 23 - 28 May, 2010, 2010. - ISBN 978-92-9083-352-9, p. 3108-3110
http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/wepd011.pdf
Abstract:
At BESSY II photon energies above 2keV can be produced only with a permanent magnet wiggler, with superconducting wavelength shifters and with a superconducting wiggler. The wiggler brilliance suffers from the depth of field effect and the wavelength shifters produce the X-rays only from a single pole. For the generation of brilliant radiation above 2keV a small period cryogenic undulator has to be used. This paper discusses the machine requirements for the operation of small gap cryogenic devices at BESSY II. A scheme with two adjacent vertical low-beta sections inside of one of the long straight sections is suggested. The straight is divided into two parts by a quadrupole triplet in the center. An optic with an increased vertical beta tune by 0.5 is presently studied. The optics outside of the low-beta section and the horizontal tune are kept unchanged.