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News from May Cosmics GC

Jacques & Yasmine16 mai 2008

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Plan for the discussion

« It’s all about timing »   Yasmine has a plane to take @ 18h50 :-)

• 1Zone by zone analysis needs brainstorming

• 2Efficiency of the selection We have an explanation

• 3High multiplicity events Irina suggests in her mail a way of understanding this.

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data

• Run 22476 from GC May 08.• We started to worry because:• We noticed that the rms of the asymmetry Was worse then what we had in the

previous run (10/04/08).We made the same plots as usual ref: mail

from Jacques Jeudi 8 mai only we seperate them for each zone of the ECAL and the HCAL see slide 3-12.

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HCALCurrent/Next Outer

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HCALCurrent/Prev Outer

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HCALCurrent/Next Inner

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HCALCurrent/Prev Inner

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Up to now the HCAL

• HCAL:

• The behaviour of the HCAL seems fine:1We have roughly the same

number of events in the Current/Next or Current/Prev.

2 the difference of the statistics between the Outer and the inner zone is consistent with the geometry of both regions.

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ECALCurrent/Next Outer

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ECALCurrent/Prev Outer

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ECALCurrent/Next Middle

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ECALCurrent/Prev Middle

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ECALCurrent/Next Inner

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ECALCurrent/Prev Inner

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Up to now ECAL ouch!

• The middle ECAL seems fine.

• The outer ECAL is strange we see only 25 Current/Next events for 600 events in the Current/Prev!

• The amount of selected events in the inner ECAL is really small 8 Current/Next events and 0 Current/Prev events!!!

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Conclusion for Part 1

From looking at the same distributions for different regions of the XCAL we learn a lot!

ex: the number of events in Current/Prev and Current/Next is really different!!

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Old remaining pbs!

• We go back to the run of march A side 20876

• We start with 13686 and we end up with 663 for the coincidence the efficiency

of the whole selection is 4.8 % while from the trigger side we know that we should have 95% good cosmics.

Question: Where do we loose them?

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What we do in detail

For each cell: ADC(P)+ADC(C) > 150 or

ADC(C)+ADC(N) > 150 for the ECAL (resp 20 HCAL)

For each Event : Condition2: Hits >1 Condition3: |R|<0.8 We always have two sets of events, events which

appear in the Current/Next or Current/Prev.Note: In the following the conditions 1,2,3 will be Refered as C1, C2,C3.

Condition 1

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Selection in detailRun 14 Mars

• ECAL – Current/Prev

• After C1: 4524• After C2: 3796• After C3: 968

– Current/Next:• After C1: 7286• After C2: 6420• After C3: 27

• HCAL– Current/Prev:

– After C1 : 5965– After C2: 5084– After C3: 3259

– Current/Next:– After C1: 6828– After C2: 5105– After C3: 148

Note: Within in ECAL events 32 are not usuable #  of hits>60.

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So

• For the Current/Prev Events we loose a lot !This is explained by the fact that in this run we had a +7 ns offset computed from the fit.

• For the Current/Next Event we loose almost everything because of the extra L0DU delay that we had in this run! In the analysis we looked at Prev1/Current/Next1 but really the cosmics were in Prev2/Prev1/Current!

• To validate these hypothesis, we should look at the selection efficiency for a run where the offsets in the TTCRx were corrected and where we have no pb with the

L0DUNext slide

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10 April Run C side But the offsetin the TTCRx

were corrected• ECAL

– Current/Next • After C1:5752• After C2: 4921• After C3:2955

• Current/Prev• After C1: 4985• After C2: 4467• After C3: 2888

• HCAL– Current/Prev

• After C1: 5808• After C2:5097• After C3:3375

– Current/Next• After C1 : 4636• After C2: 3911• After C3: 2918

Conclusion for part 2:We Start with 10893 Events out of which 2907 were used for the coincidence studyWe have 28% of efficiency which sounds reasonable!

22 Event 588 Run 22476

Either a super nova? but most probably something that we need to understand!

We saw this previously in March.

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Summary of events with mutiplicity > 60

• 9 events in total. • 8 are always in the same Y region

according to Irina these events might be actually LED Events.

• 1 Event doesn’t belong to this region see event display in the following

slide.

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Event 21408

Bremsstralhung??

Prs Ecal Hcal

From Olivier

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Back up slides

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To understand the strange behaviour of the inner ecal:

ECALCurrent/Next InnerEvent display

And we use the « eye» pattern recognition !

27Event 2043 Run 22476

Cosmic

28Event 2528 Run 22476

Cosmic

Cosmic

The direction In the ecal and The hcal does not make any sense!!!!

Yasmine’s Culpa !!!!Thanks Olivier for the cross check!

29Event 2528 Run 22476

Cosmic

30Event 2643 Run 22476

Cosmic

Cosmic

Noise??

31Event 1313 Run 22476

Cosmic

Cosmic??Why not!