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Critical Beam Dumps Here a list of all uncontrolled / critical beam dumps is kept main.html

Categories of uncontrolled beam dump events

  • 1 - Distributed loss of upto 50 mA
  • 2 - Distributed loss of upto 400 mA
  • 3 - Localized loss of upto 50 mA
  • 4 - Localized loss of upto 400 mA
  • 5 - Shutdown required
Category Amount detected
1 1
2 11
3 0
4 4
5 0
Total 16

16 - Mon 08-Dec-25 09:02

15 - Sun 12-Oct-25 12:41

14 - Mon 06-Oct-25 18:36

  • BDC Triggered by LLRF for Storage Ring Cavity 3 at 402 mA
  • Root cause: Classical ion instability due to bad vacuum in X02SA with U15 gap closed
  • Issue: Uncontrolled loss of 400 mA at thin septum and collimators
  • Category: 2
  • Filling gap of 50 buckets and vacuum interlock at 1e-7 mbar
  • Vacuum interlock is triggered but far too late with 200 ms delay
  • https://elog-gfa.psi.ch/SLS/62668
  • https://elog-gfa.psi.ch/SLS+RF/2135

13 - Sat 04-Oct-25 17:09

  • BDC Triggered by LLRF for Storage Ring Cavity 2 at 402 mA
  • Root cause: unknown
  • Issue: Libera data indicates uncontrolled beam loss
  • Category: 2
  • RadFET indicates controlled beam loss
  • https://elog-gfa.psi.ch/SLS/62639

12 - Tue 30-Sep-25 13:55

11 - Mon 29-Sep-25 17:18

  • BDC Triggered by Vakuum at 385 mA
  • Root cause: Misfiring of 4 kicker bump K1 and K2 during accumulation
  • Issue: Uncontrolled loss of 385 mA at thin septum
  • Category: 4
  • VCS: ARS01 VPIC 0010 :PUMP1-PRESSURE
  • https://elog-gfa.psi.ch/SLS/62552

10 - Sun 28-Sep-25 11:10

  • Root cause: Vacuum in injection straight
  • Issue: Uncontrolled loss of 400 mA at thin septum
  • Category: 2
  • VCS: ARS01 VPIC 0010 :PUMP1-PRESSURE
  • Beam lost over ~500 ms
  • not clear since RadFET indicates good dump and while Libera loss data does not agree
  • steep drop of lifetime before beam loss also indicates uncontrolled beam loss since usually faster than vacuum interlock
  • https://elog-gfa.psi.ch/SLS/62525

9 - Fri 26-Sep-25 03:37

  • Root cause: Classical ion instability due to bad vacuum in X02SA with U15 gap closed
  • Issue: Uncontrolled loss of 400 mA at thin septum and collimators
  • Category: 2
  • Filling gap of 50 buckets and vacuum interlock at 1e-7 mbar
  • Vacuum interlock is triggered but far too late with 230 ms delay
  • https://elog-gfa.psi.ch/SLS/62668

8 - Thu 25-Sep-25 22:58

  • Root cause: Classical ion instability due to bad vacuum in X02SA with U15 gap closed
  • Issue: Uncontrolled loss of 400 mA at thin septum and collimators
  • Category: 2
  • Filling gap of 30 buckets and vacuum interlock at 4e-7 mbar
  • From now on:
    • Vacuum Interlock threshold now reduced to 1e-7 mbar
    • Filling pattern gap increased from 30 to 50 buckets
  • https://elog-gfa.psi.ch/SLS/62484

7 - Thu 25-Sep-25 18:04

  • Root cause: Classical ion instability due to bad vacuum in X02SA with U15 gap closed
  • Issue: Uncontrolled loss of 400 mA at thin septum and collimators
  • Category: 2
  • Beam dump seems to be caused by an initially slow-rising vacuum spike inside the X02SA U15 undulator
  • Lifetime went down from 8 hours to <2 hours slowly in the last 5 minutes before the beam dump simultaneously with the pressure going up
  • The observed vacuum spike could be a classical ion instability
  • Vacuum Interlock unfortunately was not triggered
  • ID gap is stuck at minimum value and cannot be opened which would improve the vacuum
  • https://elog-gfa.psi.ch/SLS/62480
  • https://elog-gfa.psi.ch/SLS/62482

6 - Tue 23-Sep-25 15:56

  • Root cause: FOFB writes bad values to correctors
  • Issue: Uncontrolled loss of 388 mA
  • Category: 2
  • Happened during BPM Sector reboot, i.e., overall reliability issue with BPM/FOFB system
  • Beam dump controller only triggered by RF stations
  • Post mortem data clearly shows that beam was lost before dump kicker was fired
  • Communication issue between machine experts concerning disabling the orbit deviation beam dump seems irrelevant
  • It would be good if the disabling and reenabling of the orbit deviation beam dump for sector reboots could be automized in a safe way
  • https://elog-gfa.psi.ch/SLS/62451
  • https://elog-gfa.psi.ch/SLS+RF/2121

5 - Thu 07-Aug-25 20:31

  • Root cause: misfiring of one individual beam dump kicker stage
  • Issue: Uncontrolled loss of 400 mA
  • Category: 4
  • it seems one stage of the beam dump kicker misfired, partially killing the beam and triggering an RF interlock which requested a beam dump which led to a intended firing of the beam dump kicker that failed for the only just misfired stage
  • https://elog-gfa.psi.ch/SLS/61987
  • https://elog-gfa.psi.ch/SLS/62030

4 - Tue 29-Jul-25 16:43

  • Root cause: Fast change of quadrupole setpoints (MD shift)
  • Issue: Uncontrolled loss of 200 mA
  • Category: 2
  • Fast orbit detection might prevent this in future but not if tune moved to 0.5
  • https://elog-gfa.psi.ch/SLS/61837

3 - Tue 29-Jul-25 15:51

  • Root cause: Fast change of quadrupole setpoints (MD shift)
  • Issue: Uncontrolled loss of 140 mA
  • Category: 2
  • Fast orbit detection might prevent this in future but not if tune moved to 0.5
  • https://elog-gfa.psi.ch/SLS/61836

2 - Wed 23-Jul-25 16:32

  • Root cause: FOFB wrote NAN to corrector magnets
  • Issue: Uncontrolled loss of 400 mA
  • Category: 2
  • Automated testing clearly shows the bug of the EPICS ringbuffer record in EPICS 7.0.8 leading to the regular appearance of huge numbers about every 5 seconds when writing a new value to the ringbuffer with 10 Hz. The bug is not observed at all for EPICS 7.0.9
  • https://elog-gfa.psi.ch/SLS/61782
  • https://elog-gfa.psi.ch/SLS/61768

1 - Tue 13-May-25 09:36

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