1. Pedestal Correction in action (but still during shutdown) Philippe Laurens Michigan State University 16-Oct-2007

2. Active Control of Trigger Tower Zero Energy Response L1Cal TCC can now automatically track and correct the Zero Energy Response for the Transverse Energy of each Trigger Tower, at the output from the ADF cards, i.e. the input to the TAB Cards, to remain at the design value of 8 counts = 0 GeV. –For each Trigger Tower, the Zero Energy Response Drift is measured from the average of 1000 samples of Live Crossing Energy. –If the measured drift is below a programmed threshold (0.5 counts) TCC immediately applies 50% of the correction needed to correct the measured drift. –If the measured drift is above the threshold, TCC does not make any correction and waits until the next sample to decide if this is a spike or a step change. At the next snapshot, and if this was a spike, do nothing and return to the 50% correction mode for future correction cycles. If this is a step, do the full correction instantly and return to the 50% method for future corrections. –These decisions are taken on a tower by tower basis.

3. Comparison of pedestal stability with/without active correction Examine a few of the quiet, and some of the noisiest Trigger Towers and compare: –Store 5435 (17&18-May-2007) –No beam period 5438 to 5443 (19-May-2007) –Active correction during shutdown 09-Oct-2007 –Active correction during shutdown 10-Oct-2007

4. Averages of all Trigger Towers Physics Running Between Stores (Old) (Current)  StdDev of Averages of all TTs is ~0 (with spikes)  and Average of Abs(Drift) is ~0 Physics Running Between Stores

5. Individual Towers: EM_TT(- 2, 5) (Current) Physics Store Between Stores (Old) (Current)

6. EM_TT(- 2, 5) Corresponding Control Values

7. EM_TT(+ 8,26)

9. HD_TT(- 2, 5)

11. HD_TT(- 6,26)

13. HD_TT(- 8, 9)

15. Looking back at oversampled data 2006 studies for HD_TT(- 8, 9)  ADF captures 4 sampling points per tick 1:159  Each point in the graph is the average (or StdDev) of 1000 samples

16. HD_TT(- 8,26)

18. HD_TT(- 8,26) oversampled data

19. ….

20. EM_TT(- 7,12)

22. EM_TT(- 8, 9)

24. EM_TT(+ 1, 1)

26. EM_TT(+ 7,27)

28. HD_TT(+ 1, 1)

30. HD_TT(- 7,12)

32. HD_TT(- 7,26)

34. HD_TT(+ 6,26)

36. HD_TT(+ 7,27)

38. HD_TT(+10,16)