SPEAR3 Short-Pulse, Low-α Operation

The SPEAR3 storage ring at SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, is delivering beam in a short-pulse, low-α operational mode. In order to deliver short photon pulses, the stored current in SPEAR3 must be reduced. In low-α mode, we presently deliver 100 mA total current with bunch lengths of 15 psec FWHM, compared to our standard operations with 500 mA and 46 psec FWHM bunch lengths. It is possible to deliver still shorter pulses at lower current. The low-α beam is stored in four bunch trains, interleaved with up to four “camshaft” timing bunches for pump-probe experiments. This simultaneously provides short pulses for timing experiments while ensuring 100 mA for experiments at other beamlines.