Data/Monte Carlo disagreement for Rustem’s Signal Fluctuation

variable in the Far Detector(Working Title)

Part 2

Philip RodriguesOxford MINOS Group Meeting

5 Feb 08

2

Low/High variable

• Rationale: muon tracks small variation between planes, non-muon tracks larger variation

• Construction:1. Exclude first 30% of track planes (to veto shower)2. Find window around reco’d track: ±4 strips, ±40ns3. Take all strips in this window (track and non-track)4. Sort these strips by PH5. Find mean PH of lower half, mean PH of upper half6. Low/High = mean of lower half / mean of upper half

3

Outline

• ND Low/High problem fairly well studied• FD still uncertain

– Various ad hoc cuts help– Crosstalk looks promising

• This week:– Is it track modelling or detector modelling?

4

Crosstalk

• Fixes up low/high distribution• Doesn’t fix up everything else

• Not conclusive:– model is more

complicated than the one param I changed!

5

A suggestive distribution

• Additional small hits are at ±1-2 strips from track

• Diagonal xtalk can jump 1 strip• But so can physics

6

A mini mystery

• Excess of tiny (<0.6 pe) hits in data

• Looks like crosstalk

7

(De)Muxing

Tubes 0,2 Tube 1

8

Crosstalk vs Physics

• Muxing pattern helps:• Simplistic way: P(hit on pixel i | hit on

pixel j )• Data/MC:

9

Crosstalk vs Physics 2

• Less simplistic: P(small hit on pixel i | track hit on pixel j)

• 9/6 pair goes opposite way on different tubes!• Not very significant (see backup slides)

10

More stats!• Cosmics could improve significance, but

angular dist, etc• ND PMTs, electronics different, but physics

should still show…

No ±1 strip excess!NN xtalk/afterpulsing

(Normalized to #events)

11

Tentative conclusion

• Extra hits at ±1 strip consistent with crosstalk– But low stats crosstalk map seems to disagree

• ND shows no extra hits at ±1 strip– Not physics

• Believe the ND over my ad hoc crosstalk map:– Effect is not physics

12

Backup

• Pull plots for small given track

13

Backup 2

• Pull plots for any given any