Upgrade BESSY II - The variable pulse-length storage ring proposed by Helmholtz-Zentrum Berlin (BESSY VSR)

BESSY VSR is a novel approach to create in the Storage Ring BESSY II long and short photon pulses simultaneously for all beam lines through a pair of superconducting bunch compression cavities. Pulse-picking schemes will allow each individual user to freely switch between high average flux for X-ray spectroscopy, microscopy and scattering and picosecond pulses up to 500 MHz repetition rate for dynamic studies. Thus BESSY VSR preserves the present average brilliance of BESSY II and adds the new capability of user accessible picosecond pulses at high repetition rate.

The investigations with X-rays from BESSY VSR are highly complementary and compatible to dynamic studies conducted by users with optical lasers at their home universities and laboratories. BESSY VSR represents also a missing link between the extreme average brilliance of ultimate storage rings like PETRA III and Free Electron Lasers. Technologically, the employed superconducting bunch compression cavities in BESSY VSR are a direct synergy to the CW superconducting cavities developed for BERLinPro.