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173 lines
7.8 KiB
Markdown
173 lines
7.8 KiB
Markdown
---
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title: Critical Beam Dumps
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description: Here a list of all uncontrolled / critical beam dumps is kept
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template: main.html
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---
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<!-- Template for entry
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## xx - Fri 26-Sep-25 03:37
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* BDC Triggered by **xxx** at **xxx mA**
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* **Root cause:** xxxx
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* **Issue:** xxxx
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* more comments
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* [https://elog-gfa.psi.ch/SLS/xxxx](https://elog-gfa.psi.ch/SLS/xxxx)
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-->
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**Categories of uncontrolled beam dump events**
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* 1 - Distributed loss of upto 50 mA
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* 2 - Distributed loss of upto 400 mA
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* 3 - Localized loss of upto 50 mA
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* 4 - Localized loss of upto 400 mA
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* 5 - Shutdown required
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| **Category** | **Amount detected** |
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| :- | :- |
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| 1 | 1 |
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| 2 | 11 |
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| 3 | 0 |
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| 4 | 4 |
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| 5 | 0 |
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| Total | 16 |
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## 16 - Mon 08-Dec-25 09:02
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* BDC Triggered by **LLRF for Storage Ring Cavity 4** at **403 mA**
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* **Root cause:** Misfiring of injection kicker bump during top up
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* **Issue:** Uncontrolled loss of 403 mA downstream of X01
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* **Category:** 4
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* [https://elog-gfa.psi.ch/SLS/62799](https://elog-gfa.psi.ch/SLS/63420)
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* [https://elog-gfa.psi.ch/SLS+RF/2140](https://elog-gfa.psi.ch/SLS+RF/2178)
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## 15 - Sun 12-Oct-25 12:41
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* BDC Triggered by **LLRF for Storage Ring Cavity 2** at **400 mA**
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* **Root cause:** unknown
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* **Issue:** Uncontrolled loss of 400 mA at unknown location
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* **Category:** 2
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* Beam lost over ~700 ms
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* [https://elog-gfa.psi.ch/SLS/62799](https://elog-gfa.psi.ch/SLS/62799)
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* [https://elog-gfa.psi.ch/SLS+RF/2140](https://elog-gfa.psi.ch/SLS+RF/2140)
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## 14 - Mon 06-Oct-25 18:36
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* BDC Triggered by **LLRF for Storage Ring Cavity 3** at **402 mA**
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* **Root cause:** Classical ion instability due to bad vacuum in X02SA with U15 gap closed
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* **Issue:** Uncontrolled loss of 400 mA at thin septum and collimators
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* **Category:** 2
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* Filling gap of 50 buckets and vacuum interlock at 1e-7 mbar
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* Vacuum interlock is triggered but far too late with 200 ms delay
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* [https://elog-gfa.psi.ch/SLS/62668](https://elog-gfa.psi.ch/SLS/62668)
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* [https://elog-gfa.psi.ch/SLS+RF/2135](https://elog-gfa.psi.ch/SLS+RF/2135)
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## 13 - Sat 04-Oct-25 17:09
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* BDC Triggered by **LLRF for Storage Ring Cavity 2** at **402 mA**
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* **Root cause:** unknown
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* **Issue:** Libera data indicates uncontrolled beam loss
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* **Category:** 2
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* RadFET indicates controlled beam loss
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* [https://elog-gfa.psi.ch/SLS/62639](https://elog-gfa.psi.ch/SLS/62639)
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## 12 - Tue 30-Sep-25 13:55
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* BDC Triggered by **Orbit Deviation** at **53 mA**
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* **Root cause:** unknown
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* **Issue:** Uncontrolled beam loss at thin septum
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* **Category:** 1
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* happened during MD [kw40](https://sls.psi.ch/schedule/#2025-kw40)
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* [https://elog-gfa.psi.ch/SLS/62568](https://elog-gfa.psi.ch/SLS/62568)
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## 11 - Mon 29-Sep-25 17:18
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* BDC Triggered by **Vakuum** at **385 mA**
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* **Root cause:** Misfiring of 4 kicker bump K1 and K2 during accumulation
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* **Issue:** Uncontrolled loss of 385 mA at thin septum
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* **Category:** 4
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* VCS: ARS01 VPIC 0010 :PUMP1-PRESSURE
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* [https://elog-gfa.psi.ch/SLS/62552](https://elog-gfa.psi.ch/SLS/62552)
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## 10 - Sun 28-Sep-25 11:10
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* **Root cause:** Vacuum in injection straight
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* **Issue:** Uncontrolled loss of 400 mA at thin septum
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* **Category:** 2
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* VCS: ARS01 VPIC 0010 :PUMP1-PRESSURE
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* Beam lost over ~500 ms
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* not clear since RadFET indicates good dump and while Libera loss data does not agree
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* steep drop of lifetime before beam loss also indicates uncontrolled beam loss since usually faster than vacuum interlock
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* [https://elog-gfa.psi.ch/SLS/62525](https://elog-gfa.psi.ch/SLS/62525)
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## 9 - Fri 26-Sep-25 03:37
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* **Root cause:** Classical ion instability due to bad vacuum in X02SA with U15 gap closed
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* **Issue:** Uncontrolled loss of 400 mA at thin septum and collimators
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* **Category:** 2
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* Filling gap of 50 buckets and vacuum interlock at 1e-7 mbar
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* Vacuum interlock is triggered but far too late with 230 ms delay
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* [https://elog-gfa.psi.ch/SLS/62668](https://elog-gfa.psi.ch/SLS/62492)
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## 8 - Thu 25-Sep-25 22:58
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* **Root cause:** Classical ion instability due to bad vacuum in X02SA with U15 gap closed
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* **Issue:** Uncontrolled loss of 400 mA at thin septum and collimators
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* **Category:** 2
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* Filling gap of 30 buckets and vacuum interlock at 4e-7 mbar
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* From now on:
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* Vacuum Interlock threshold now reduced to 1e-7 mbar
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* Filling pattern gap increased from 30 to 50 buckets
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* [https://elog-gfa.psi.ch/SLS/62484](https://elog-gfa.psi.ch/SLS/62484)
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## 7 - Thu 25-Sep-25 18:04
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* **Root cause:** Classical ion instability due to bad vacuum in X02SA with U15 gap closed
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* **Issue:** Uncontrolled loss of 400 mA at thin septum and collimators
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* **Category:** 2
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* Beam dump seems to be caused by an initially slow-rising vacuum spike inside the X02SA U15 undulator
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* 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
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* The observed vacuum spike could be a classical ion instability
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* Vacuum Interlock unfortunately was not triggered
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* ID gap is stuck at minimum value and cannot be opened which would improve the vacuum
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* [https://elog-gfa.psi.ch/SLS/62480](https://elog-gfa.psi.ch/SLS/62480)
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* [https://elog-gfa.psi.ch/SLS/62482](https://elog-gfa.psi.ch/SLS/62482)
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## 6 - Tue 23-Sep-25 15:56
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* **Root cause:** FOFB writes bad values to correctors
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* **Issue:** Uncontrolled loss of 388 mA
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* **Category:** 2
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* Happened during BPM Sector reboot, i.e., overall reliability issue with BPM/FOFB system
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* Beam dump controller only triggered by RF stations
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* Post mortem data clearly shows that beam was lost before dump kicker was fired
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* Communication issue between machine experts concerning disabling the orbit deviation beam dump seems irrelevant
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* 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
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* [https://elog-gfa.psi.ch/SLS/62451](https://elog-gfa.psi.ch/SLS/62451)
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* [https://elog-gfa.psi.ch/SLS+RF/2121](https://elog-gfa.psi.ch/SLS+RF/2121)
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## 5 - Thu 07-Aug-25 20:31
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* **Root cause:** misfiring of one individual beam dump kicker stage
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* **Issue:** Uncontrolled loss of 400 mA
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* **Category:** 4
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* 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
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* [https://elog-gfa.psi.ch/SLS/61987](https://elog-gfa.psi.ch/SLS/61987)
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* [https://elog-gfa.psi.ch/SLS/62030](https://elog-gfa.psi.ch/SLS/62030)
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## 4 - Tue 29-Jul-25 16:43
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* **Root cause:** Fast change of quadrupole setpoints (MD shift)
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* **Issue:** Uncontrolled loss of 200 mA
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* **Category:** 2
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* Fast orbit detection might prevent this in future but not if tune moved to 0.5
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* [https://elog-gfa.psi.ch/SLS/61837](https://elog-gfa.psi.ch/SLS/61837)
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## 3 - Tue 29-Jul-25 15:51
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* **Root cause:** Fast change of quadrupole setpoints (MD shift)
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* **Issue:** Uncontrolled loss of 140 mA
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* **Category:** 2
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* Fast orbit detection might prevent this in future but not if tune moved to 0.5
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* [https://elog-gfa.psi.ch/SLS/61836](https://elog-gfa.psi.ch/SLS/61836)
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## 2 - Wed 23-Jul-25 16:32
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* **Root cause:** FOFB wrote NAN to corrector magnets
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* **Issue:** Uncontrolled loss of 400 mA
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* **Category:** 2
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* 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
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ringbuffer with 10 Hz. The bug is not observed at all for EPICS 7.0.9
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* [https://elog-gfa.psi.ch/SLS/61782](https://elog-gfa.psi.ch/SLS/61782)
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* [https://elog-gfa.psi.ch/SLS/61768](https://elog-gfa.psi.ch/SLS/61768)
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## 1 - Tue 13-May-25 09:36
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* **Root cause:** Misfiring of individual kicker during turning off 4 Kicker Bump at 400 mA
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* **Issue:** Uncontrolled loss of 400 mA
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* **Category:** 4
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* EPICS procedure to prevent this is implemented
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* [https://elog-gfa.psi.ch/SLS/60877](https://elog-gfa.psi.ch/SLS/60877)
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* [https://elog-gfa.psi.ch/SLS/60878](https://elog-gfa.psi.ch/SLS/60878) |