Extraction from the CERN SPS

The experimental programme requires three different modes of extraction from the SPS : fast extraction (burst duration from 3 ??s to 23 ??s), slow resonant extraction (spill duration 0.5 s to 2 s) and fast resonant extraction (spill duration shorter than 3 ms). All three modes have been successfully tested and brought into operation. Fast extraction of the full beam is 100% efficient. By fast beam shaving, fractions as low as 1% of the circulating beam can be extracted in a fairly stable way. Third-integer extraction is used to produce slow spills of 700 ms or more. The efficiency of resonant extraction is currently some 97%. The spill duty factor at present amounts to about 40%. Fast resonant spills of less than 2 ms were achieved with both integer and half-integer extraction. The different modes of extraction are consecutively performed during each accelerator cycle. At present, a 1 s third-integer spill at 200 GeV/c is followed by a fast shaving extraction at 210 GeV/c and by a fast or fast resonant extraction of the remaining protons at 400 GeV/c.