SPS Beam Loss System The SPS Beam-Loss System Hardware: Gianfranco Ferioli Software: Lars K. Jensen CERN SL/BI SL/OP Linkman: Antoine Ferrari

SPS Beam Loss System What is it used for ?? Machine protection –Ring, Injection/Extraction, Transfer lines Diagnostics –Identify hot-spots etc Loss Survey –store integrated data for each monitor in SPS measurement/logging databases every hour

SPS Beam Loss System System Description Low-level system (VME crate): CPUCPU TG8TG8 ADCADC ADCADC ADCADC ADCADC ADCADC DMPDMP ADC modules –Each module has 8 channels (multiplexed) –Total of 40 channels per crate (last 4 special)

SPS Beam Loss System Installations and interlock #1 BA2 BA1 BA6 BA3 BA4 BA5 TT20 TT60 (TT40) LSS1 LSS2 (LSS4) LSS6 Beam Dump

SPS Beam Loss System Installations and interlock #2 SPS Ring (one interlock cable for 6 crates) –Ionization chambers are placed next to each main quadrupole –The beam-loss interlock is handled in software (latency = 20msec): – 1) If( monitor(n) (n = 1;36) is enabled) and if(Loss(n) > threshold(n)) => Count += 1 2) If(Count > N (user settable) ) => request dump BLD System (3 individual cables) –Injection (LSS1), Extraction (LSS2, LSS6, (LSS4)) –Max. 16 channels –Interlock handled in hardware (latency ~1 usec) (DACs + comparators)

SPS Beam Loss System Emergency beam dump Presently the emergency beam dump channel for BLRING is shared with Beam Current Interlock -> problem as we are unable to disable only one We will need one more channel for LSS4 for CNGS and LHC extraction

SPS Beam Loss System Active Cycles Presently a maximum of 10 possible elementary cycles can be handled in the low-level system (3 are presently used: P1 (FT), P2 (MD), ambient radiation) We have our own events for each elementary cycle: –0x2156+CT+CN: warning (T msec) –0x2157+CT+CN: start (T msec) (acquisition of offsets) –0x2158+CT+CN: stop (T0 + ???) (max acq = 2000) We calculate an integer index to settings and acquisitions from: CT+CN The number of acquisitions follows automatically the beam-in time (stop - start) Improvement: CT+CN follows beam-type (FT, ions..)

SPS Beam Loss System Alarm/injection inhibit handling An alarm survey is done on P1 (FT) and P2 (MD) cycles -> alarm screen in PCR The acquisition of alarm states is synchronised using an SSM beam-out event: (0x2189+T+N) The alarm surveillance process will inhibit injection of beam into the SPS, if a beam dump was requested for 3 consecutive cycles - else automatic reset by emergency system