1. Roundup of Week at ATF
Mikey Davis
19 April 2013
1/26

2. Introduction
I will give an overview of what happened on the shifts this week and the implications this has
Will also give a roundup of the results from yesterday
I’m going to try and cover everything so won’t go into anything (including the BPM waveforms etc) in great detail
I’m also presenting what I think has happened, I’m not sure everyone will agree
Mikey Davis
19 April 2013
2/26

3. What Happened Started off the shift with tests using an oscilloscope
Found that the BPMs are also noisy with the scope
Signals were taken with the output of the second stage split
One input to the FONT V board
The other input to the scope
Mikey Davis
19 April 2013
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4. Scope Test
Mikey Davis
19 April 2013
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5. Scope Test
Mikey Davis
19 April 2013
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6. Scope Test
Mikey Davis
19 April 2013
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7. What Happened
We then setup to take data using both the FONT board and the SIS digitiser
Decided as we only had 2 channels on the SIS digitiser we should undo BPM signal split and connect both BPMs
We then continued with the normal program
We decided to centre the beam at IPA due to the ripples at IPB
I noticed that the orbit wasn’t flat through the IP so tried to correct this
Mikey Davis
19 April 2013
7/26

8. What Happened
The method for flattening the orbit involves QD0FF and QF7FF
First centre beam in the BPM where the waist is using QD0FF
Then use QF7FF to rotate the beam around the IP
Whilst doing this I noticed that the beam moved a lot at IPA but not at all in IPB (in the Honda system)
I then realised the jitter was also much larger at IPA then at IPB (in the Honda system)
Mikey Davis
19 April 2013
8/26

9. What Happened
We then looked at direct comparison with the EPICs system and Honda system
In the EPICs system the beam waist was clearly at IPA, QD0FF magnet strength was also 145A
The Honda system however seemed to give the opposite impression
We took an access and checked everything was setup correctly in the tunnel and out of it
It was, which suggests that what the cable we think gives us IPA is in fact IPB
Mikey Davis
19 April 2013
9/26

10. Summary
In EPICs as we record it, and on the control system IPA and IPB are the correct way round
In our system, certainly this trip and I think in March IPA and IPB have been back to front
Neven and I have evidence to suggest that they were correct in January
Our system is setup as we think, and was setup as we thought in March
The BPM labels must be back to front
Mikey Davis
19 April 2013
10/26

11. Implications
We have now spent considerable time measuring the jitter at the “waist” BPM and getting a number of 4 microns or higher
We’ve then put this down to resolution
Last night showed us that the real jitter at the non waist BPM is 4 microns
We have been measuring the true jitter at that BPM
This trip only using one BPM has not helped this
This helps make sense of some erroneous results
EPICs and Honda no longer have a 60 micron offset
Mikey Davis
19 April 2013
11/26

12. March IPB Waist Scan
Mikey Davis
19 April 2013
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13. March IPB Waist Scan
Mikey Davis
19 April 2013
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14. IPB Waist Scan Last Night
Mikey Davis
19 April 2013
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15. Summary of Jitters Attenuation Setting (dB) IPA Jitter (μm)
IPB Jitter (μm) 20 4
1.1 10
3.8
0.4
Calibration not done
0.25
Mikey Davis
19 April 2013
15/26

16. Two Bunch Mode
We decided to capitalise on the BPMs working and switch to two bunch mode
Wanted to see if the results were the same
Also wanted to look at the correlations
Mikey Davis
19 April 2013
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17. Summary of Correlations
Bunch to Bunch Correlations
Attenuation Setting (dB)
P2 b2b Correlation (%)
P3 b2b Correlation (%)
IPA b2b Correlation (%)
IPB b2b Correlation (%) 10 94 92 45 95
Calibration not done 79
Upstream Downstream First Bunch Correlations
Attenuation Setting (dB)
P2 IPA Correlation (%)
P3 IPA Correlation (%)
P2 IPB Correlation (%)
P3 IPB Correlation (%) 10 68 57 4 5
Calibration not done 25 24
For this run you get the same even if you’re looking at first bunch to second bunch correlations
Mikey Davis
19 April 2013
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18. Feedback Runs We see a good improvement at IPA, nothing at IPB
3 runs done at 10 dB, 1 run done at 0 dB
Mikey Davis
19 April 2013
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19. FB Run 1 – 10 dB
Mikey Davis
19 April 2013
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20. FB Run 2 – 10 dB
Mikey Davis
19 April 2013
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21. FB Run 3 – 10 dB
Mikey Davis
19 April 2013
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22. FB Run 4 – 0 dB
Mikey Davis
19 April 2013
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23. Feedforward Runs IPK appears to be working fine
Only one valid run, others we were just kicking 4000 counts in one direction every time
We make it worse for this run
Still kicking the beam a long way away from zero
We guessed at the calibration constants
At 0 dB so expect nothing from IPA
Mikey Davis
19 April 2013
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24. IPK Scan
Mikey Davis
19 April 2013
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25. FF Run 3 – 0 dB
Mikey Davis
19 April 2013
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26. FF Run 1 – 0 dB
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19 April 2013
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