Thoughts on EEMC calibration from "KIVA" meeting 6/8/11

This is a summary of some of the discussion on EEMC calibration from the day.  Comments and corrections are welcome:

Action items identified for possible future study are in bold

EEMC Overview: Scott

Some questions related to possible projects related to calibration

• How "MIP-like" is a MIP? (slide 6)?  Don't know the momentum spectrum of MIPs in the endcap so how does changing dE/dx vs momentum influence calibration?
• How well do we know the sampling fraction (slide 24)?  MIP calibration provides no information here so must determine independently.  Some study from Ilya already, but probably room for improvement.
• Any new ideas?

Question about whether gain changes related to the HV change at the end of Run 7 were propogated correctly to the DB.  Using HV tables on eemc-sc and gains in DB this wouldn't be hard to check.

Eta and Pi0 mass comparisons:  Nick

• Comparison of Run 6 and Run 9 mass peaks indicates a ~7-8% gain shift between the two runs.
• Is there a time dependence in Run 9?
• There was a field flip in Run 9 (RFF through day 146 and FF day 147 and after), does it have any effect?

Electron analysis:  Justin

• Similar gain shift between Run 6 and Run 9 as pion analysis
• Some discussion of improvements in background estimation with 2D fit (in dE/dx and E/p), and most likely electron enhancement cuts could be tuned up better.
• If to be used for absolute scale calibration in the future need to understand background and shower leakage well

MIP analysis:  John

• Looking forward to comparison of Run 6 and Run 9 with the same code for apples to apples comparison
• Hopefully more clues on mechanism from other layers
• Some things to possibly consider from Scott's presentation above for determining calibration values
• Difference in MB trigger brought up again (Run 6 is BBC MB and Run 9 is ZDC MB), maybe could do some study of BBC MB data in Run 9 from st_physics stream if desired?
• Reminder of Alice's MIP analysis from Run 8, which indicated that gain drop wasn't until after Run 8.
• Data for Run 11 is available for analysis once Run 6 and 9 comparisons make good progress, good check if this is a "one time change" or persistent drop in gain.

Jet analysis: Brian

• Better data/MC comparison in the endcap region with simulation gains changed by 10% as indicated by analyses above

Other thoughts:

1) Possible sources for gain change discussed to be investigated:

• Integration gate changed somehow (could have crate dependence?)
• HV all relative to some base value which could have changed
• Different MB trigger used in Run 6 and Run 9 MIP analysis mentioned above
• Is there a time dependence or field dependence which may provide other clues?
• Others I missed?

2) How does ETOW calibration fit into upcoming simulation requests?

• Best case scenario is calibration is final before any Run 9 simulation production begins
• How do incorrect gains effect simulations that could otherwise begin today (eg. inclusive jet embedding)?
• If some simulations begin before calibration is final, are simulations still useful for the endcap analysis (ie. can afterburner be applied to correct ADCs post-production)? 

3) What will be used for final Run 9 calibration?

• One overall scale factor (probably too naive)
• Eta dependent correction
• Tower by tower calibration from MIP analysis
• Some additional information from pions or electrons?
• The answer probably depends on how results from the MIP analysis turn out