1. Do you believe in Operation Statistics
Do you believe in Operation Statistics? Presented at the Accelerator Reliability Workshop 2011
Paul Scherrer Institut
Andreas Lüdeke

2. Paul Scherrer Institute (PSI), Switzerland
PSI: Swiss national research center
1300 employees
Proton facility: 1 MW cw beam
Spallation neutron source
Proscan SC cyclotron
Cancer therapy
Swiss Light Source (SLS)
e- storage ring
400mA, 2.4 GeV
PSI West:
Large Research Facilities
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 1

3. Swiss Light Source Operation
Swiss Light Source is
In operation since 2001
A user facility with 19 beam-lines in operation
Providing ~ 5000 hours beam to users per year
Users need to apply for beam time
Just 30% of the proposals are accepted
Accepted users need to wait about 6 month for beam time
One important metric to judge machine quality
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 2

4. 3rd Generation Synchrotron Light Sources: Availability
Year
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 3 3

5. Availability: "Concours des Alpes"
Year
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 4 4

6. Availability: "Concours des Alpes"
Year
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 5 5

7. Metrics of the Swiss Light Source (SLS)
Availability definition:
“Delivered_Beam_Time” = “Beam_for_Users” during “User_Time”
“User_Time" = “Scheduled_User_Time" + "User_Reserve_Time”
Example for 2005:
Uncompensated Availability
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 6

8. Elettra Metrics for Availability
Thunderstorms are excluded from failure statistics at Elettra
Example from 2005:
Availability including outages from thunderstorms:
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 7 7

9. Availability: "Concours des Alpes” corrected
Bare Availability [%]
Year
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 8 8

10. Special Events: ESRF 2005 and the Crotch Absorber
In March 2005
A water-to-vacuum leak
Five days of user operation lost
120 hours downtime
ESRF statistics 2005
Availability 97.6%,
Total User Operation 5496 hours
131 hours downtime
How can that be?
All users of 5 days re-scheduled
Not counted as downtime
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 9 9

11. What can we learn from this?
Availability statistics not proportional to system reliability
But large effort spend to compile downtime statistics
Accurate failure data exists, but kept internal. Why?
If that would be public, what could it be used for?
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 10 10

12. RF arcing at the Swiss Light Source
Background
SLS has 60 to 100 beam outages per year
About 20 outages were caused by RF arcs
Inquiry
Asking around at the EPAC’08: “What is your experience with arc detectors?”
Answer: arc detectors are often unreliable!
Action
We are replacing detectors with arc-coincidence detectors
Result
No arc interlock from any upgraded detector!
Single diodes still show arcs, but do not cause interlocks
Conclusion
We had in 10 years 200 unnecessary beam losses!
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 11

13. What can we do? What we do now What we should do How to do that?
We do your own mistakes
Sometimes we share selected insights during workshops
What we should do
Learn from the failures of others
Create a database of all outages of many facilities!
How to do that?
Define a simple document format
Provide a web-platform to publish downtime event data
I’ll start, will you join?
Participate in the Friday morning discussion! .
Andreas Lüdeke, Paul Scherrer Institute at the ARW11 in Cape town, 11-Apr Slide 12