1. DCH calibrations 2013
Gordon Lim, UCI

2. DCH calibrations Wire & pad time offsets Effective wire lengths
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
DCH calibrations
Wire & pad time offsets
Effective wire lengths
Wire & pad gain corrections
Foil bowing corrections
TIC-DCH time offset

3. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
DCH calibrations
Input: Reconstructed Michel tracks from 800 unbiassed runs ( )
Starting point: All calibration constants = 0
Acronyms used in this presentation:
UA (DA) = upstream (downstream) anode
UH (DH) = upstream (downstream) hood
UC (DC) = upstream (downstream) cathode DH UH UA DA DC UC

4. Wire time offsets Goal: Alignment of all anode waveforms Procedure:
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Wire time offsets
Goal: Alignment of all anode waveforms
Procedure:
Use hits on reconstructed Michel tracks to determine the time offset of the (hit time – track time) distribution of each wire-end. Time offsets are calculated via 3rd order polynomial fits to the corresponding “reverse-cumulative” distributions, e.g.:
Reprocess raw data with new time offsets.
Repeat steps 1-2 for a number of iterations (typically 5). ΔT0 between successive iterations should converge.
Administer persisting time offsets among two ends of the same wire symmetrically across the two ends.
time offset
hit time – track time [ns]
hit time – track time [ns]

5. Wire time offsets 1st iteration:
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Wire time offsets
1st iteration:

6. Wire time offsets 6th iteration:
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Wire time offsets
6th iteration:
outliers due to bad fits – corrected by hand
outliers due to bad fits – corrected by hand

7. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Pad time offsets
Goal: Alignment of pad and anode waveforms Waveform alignment is done by taking into account the upstream-downstream time difference of hits on each pad (UH-DH and UC-DC) and the time differences of hits on each upstream/downstream wire-pad pair (UA-UH, UA-UC, DA-DH and DA-DC) e.g.:

8. Hood time offsets (UH-DH)
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Hood time offsets (UH-DH)
before calib
after calib
outliers due to bad fits – corrected by hand

9. Hood time offsets (UA-UH)
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Hood time offsets (UA-UH)
before calib
after calib
outliers due to bad fits – corrected by hand

10. Hood time offsets (DA-DH)
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Hood time offsets (DA-DH)
before calib
after calib
outliers due to bad fits – corrected by hand

11. Cathode time offsets (UC-DC)
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Cathode time offsets (UC-DC)
before calib
after calib
outliers due to bad fits – corrected by hand

12. Cathode time offsets (UA-UC)
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Cathode time offsets (UA-UC)
before calib
after calib
outliers due to bad fits – corrected by hand

13. Cathode time offsets (DA-DC)
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Cathode time offsets (DA-DC)
before calib
after calib
outliers due to bad fits – corrected by hand

14. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Comparison between the anode time offsets from this time calibration and the preliminary CRC time calibration (DCHCellT0 ID #50)
this calib
CRC calib
time
difference

15. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Comparison between the hood time offsets from this time calibration and the preliminary CRC time calibration (DCHCellT0 ID #50)
this calib
CRC calib
time
difference

16. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Comparison between the cathode time offsets from this time calibration and the preliminary CRC time calibration (DCHCellT0 ID #50)
this calib
CRC calib
time
difference

17. Effective wire lengths, wire & pad gain corrections
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Effective wire lengths, wire & pad gain corrections
Goal: Improve z-coordinate determination
Plot pad charge asymmetry vs. z-anode, and fit the profile with the following function:
where
It can be shown that:
l effective wire length
d anode gain ratio
h pad gain ratio
Pad gain calibration (h) can be improved
by doing the above exercise using z-track

18. outliers due to bad fits – corrected by hand
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Effective wire length
before calib
after calib
outliers due to bad fits – corrected by hand

19. outliers due to bad fits – corrected by hand
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Wire gain corrections
before calib
after calib
outliers due to bad fits – corrected by hand

20. outliers due to bad fits – corrected by hand
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Hood gain corrections
before calib
after calib
outliers due to bad fits – corrected by hand

21. Cathode gain corrections
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Cathode gain corrections
before calib
after calib
outliers due to bad fits – corrected by hand

22. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Foil bowing effect
Goal: Correct bowing of hood foils due to pressure difference with surroundings
Procedure:
Plot the pad charge ratio as a function of z for each cell and fit with 3rd order polynomial
Calculate correction factor for hood charge of each cell according to fit results
Plot the pad charge asymmetry amplitude ratio as a function of the pad total charge ratio for all cells and values of z, and fit with 1st order polynomial
before calib
/ after calib

23. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
TIC-DCH time offset
The relative time difference between the TIC and DCH is determined by using tracks that have a matching TIC cluster:

24. Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
DCH status 2013
20 cells with a dead wire: , 29, 98, 107, 124, 125, 152, , 196, , 218, 254
9 cells with a dead pad: 44, 67, 68, 160, 175, 221, 272, 274, 278
20 cells with a “semi-dead” pad: 88, 120, 131, (DC14)
4 cells with a weak pad: 97, 117, 216, 229
new in 2013

25. Conclusions Database: To do:
Introduction Wire timing Pad timing Wire lengths Wire gains Pad gains Foil bowing TIC-DCH time Conclusions
Conclusions
Database:
The DCHConfig table for 2013 data (ID #24) has been updated with the following IDs:
Wire & pad time offsets: DCHCellT0 ID #51
Eff. wire lengths & dead channels: DCHCellParam ID #31
Wire & pad gain corrections: DCHCellGain ID #37
Foil bowing corrections: DCHHoodAsymRescale ID #8
TIC-DCH time offset: MEGTimeDifference ID #42
Wire positions: DCHWirePosition ID #91
To do:
Reprocess a larger data sample and check the DCH performance
optical survey 2013