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News from May Cosmics GC

Jacques & Yasmine16 mai 2008

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Selection of Yasmin transparencies

• For the full story consult• http://indico.cern.ch/conferenceDisplay.py?confId=34031

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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 .

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HCALCurrent/Next Outer

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HCALCurrent/Prev Inner

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Up to now the HCAL

• 2 noisy cells in HCAL =>worsen timing => to be removed

• 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/Next Middle

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ECALCurrent/Next 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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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 offset

in the TTCRxwere 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!

17 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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Conclusion of Friday

• Difference between outer middle inner ECAL could be crate timing problem? Or tell1 problem? Look at -2 events (when Yasmin back)

• The big flare event could be unvolontary LED (some pin diode signal) but why not all cells (16/LED). How can all LED triggers when LEDTSB cycles by groups of LED

• Efficiency when timed is OK => program for other users