effects of beam-beam interactions on luminosity decay rates at the lhc in 2012 anton esmail-yakas,...
TRANSCRIPT
![Page 1: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/1.jpg)
Effects of beam-beam interactions on luminosity
decay rates at the LHC in 2012Anton Esmail-Yakas, 2015
For completion of the 3rd year of the Physics with a Year in Europe Msci at Imperial College London in relation with École
Polytechnique Fédérale de Lausanne as part of the Swiss European Mobility Program.
![Page 2: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/2.jpg)
Special thanks to Xavier Buffat for help with the analysis and Danilo Banfi for help with the initial Python codes
used
Main supervisor: Tatiana PieloniSupervisor from Imperial College London: Gavin Davies
Supervisor from EPFL: Leonid Rivkin
![Page 3: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/3.jpg)
Aims
• Analyse different available models for luminosity decay
• Analyse the dependency of decay rates on BBIs
• Analyse the time dependency of decay rates
![Page 4: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/4.jpg)
Different fitting methods
• Simple exponential model• C = 0, variable C
• Tevatron model (“Fitting the luminosity decay in the Tevatron, E. McCrory et al., 2005)
•Brightness model (Xavier Buffat)
![Page 5: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/5.jpg)
Simple exponential model
• (C = 0)
• + C (C variable)
Constant decay rate
![Page 6: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/6.jpg)
Tevatron model
Theory attempts to account for IBS, beam burn-up due to luminosity, and beam-beam interactions.
Time varying decay rate
![Page 7: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/7.jpg)
Brightness model
Assumes 2 different processes of decay – slow process () (e.g. IBS)Fast process () that is present for brightness larger than (e.g. incoherent growth due to a resonance)
Two decay rates – C varying in initial hoursC = 0 in later hours
![Page 8: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/8.jpg)
C = 0 fit
![Page 9: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/9.jpg)
C varying fit
![Page 10: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/10.jpg)
Brightness fit
![Page 11: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/11.jpg)
Tevatron fit
![Page 12: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/12.jpg)
Residual analysis – Whole FillC = 0 fit qualitatively worse.
3 other fits produce similar results.
![Page 13: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/13.jpg)
Residual analysis – 1st Hour
Whole fill does not model 1st hour accurately – need to fit 1st hour separately
Little difference between Variable C fit and other models when fitting first hour.
![Page 14: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/14.jpg)
Filling scheme 2710
- First half 2012
![Page 15: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/15.jpg)
Decay rates pop out for bunches missing IP2s and IP8s
Luminosity and Specific luminosity decay rates follow the same pattern
![Page 16: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/16.jpg)
Strong and varying correlations with the LRs
![Page 17: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/17.jpg)
Bunches seem to also follow HOs – only noticeable when they are missing
![Page 18: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/18.jpg)
Very different pattern over whole fill compared to 1st hour
Some shifts at bunches with different HOs/LRs
Related to drop in HOs?
![Page 19: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/19.jpg)
Negative correlation with LRs?Or a different effect? IBS?
![Page 20: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/20.jpg)
Specific luminosity decays show some relation to HOs
Whole fill decay shows stronger relation to HOsrather than LRs?Likely due to stronger effect of HOs persisting throughout fill
![Page 21: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/21.jpg)
Filling scheme 2998
- Second half2012
![Page 22: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/22.jpg)
Decay rates pop out for bunches missing IP8s
Luminosity and Specific luminosity decay rates follow the similar pattern
Very different patterncompared to fill 2710
![Page 23: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/23.jpg)
Strong and varying correlations with the LRs
Also for spec. lumi.
![Page 24: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/24.jpg)
Very different pattern over whole fill compared to 1st hour
Drops in decay rates for bunches with fewer total LRs
![Page 25: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/25.jpg)
But no bunch by bunch correlation with LRs
![Page 26: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/26.jpg)
Large change in pattern after 1st hour
Expanding time window
![Page 27: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/27.jpg)
Similar change in pattern
![Page 28: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/28.jpg)
Equivalent analysis using 1hr sliding window – results are very different and not consistent enough to produce results for each hour
Modelling sections by single hours is not effective outside of the first hour
![Page 29: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/29.jpg)
However, the expanding window is not necessarily better, as it only shows a different pattern for the first hour, and misses it in the following hours – e.g. hours 1-2, as seen below…
![Page 30: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/30.jpg)
Decay rate vs time analysisDecay rate is calculated by an expanding window as for the bunch-bunch analysis, though expanding in 5 minute steps.
Sharp drop after first hoursThough somewhat unreliable due to expanding window
![Page 31: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/31.jpg)
More examples…
![Page 32: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/32.jpg)
• Importance of model used to fit luminosity – simple exponential (C=0) is not suitable. Models based around varying decay regimes are much better• Importance of the time period that is looked at – currently no model can
fit to the whole fill and still accurately model behaviour contained within the first hour. Need to find a better model for consistent time analysis• Effects in the first hours are VERY different to effects over the whole fill –
Strong BBI dependencies – not yet obvious the nuances within this• Studies on a larger number of fills and relating to injection intensities of
fills would be useful
Closing ideas…
![Page 33: Effects of beam-beam interactions on luminosity decay rates at the LHC in 2012 Anton Esmail-Yakas, 2015 For completion of the 3 rd year of the Physics](https://reader036.vdocuments.site/reader036/viewer/2022070413/5697bfbe1a28abf838ca2a0b/html5/thumbnails/33.jpg)
Thank you!
Questions?