Calo preparation for 2015
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Transcript of Calo preparation for 2015
Calo preparation for 2015
Goals:-Trigger stability-Good calibration for HLT2 processing-Improved calibration ( timing, e/gamma response) for all calo sub-detectors-Improved monitoring
Calibration workshop 8/10/2013• The hardware changes :
– Damaged Ecal LED fibers will be changed -> improved gain monitoring (Iouri)– Exposed PMT will be replaced ( hundreds)
• The current calibration scheme for ECAL/PRS– Initial calibration from pi0 fine calibration (D.Savrina) using FMDST available ~ 4 weeks of data taking
• Minimum biais events . Low energy in PS • ~ 80M events needed• Iterative procedure • The more precise method
– Ageing effect corrected from e/p of tagged conversions 55 sets in 2013 (MNM) – Calibration from electron provide also calibration constant also for pre-shower. (O. Steinakin)
available only after reconstruction. • Analytic solution
• The current calibration scheme for Hcal – Ageing monitoring through LED response (2012)– PMT change when deviation above certain threshold – Controlled by Cs source run ( every TS)– Fine Hcal calibration on reconstructed data :100-200M events needed to get a cell/cell calibration.
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LED system: HCAL 2012
sum/sumref, 56 central cells
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LED-based HV corrections (17) Cs calibrations (3)
results of Cs calibrations at TS is used as a starting point, then LED-based correctionstotal of 4 Cs calibrations and 17 LED-based corrections
Precision of LED corrections is limited by: annealing during TS (and faster ageing afterwards) - PMT rate effect – variation within fill (can be optimized by regrouping PMTs, to be done @ LS1)uncertainty in the “plastic ageing” prediction – non linearity, annealing
(the attempts to take the plastic ageing into account are visible)
Occupancy Method & dependence• For each cell calculate the occupancy ratio :
- Threshold to be determined – Precision to be reached 1-2%Irina Machkhilyan LHCb-INT-2013-050Calo meeting presentations from Irina in each calo meeting since July 2012.http://indico.cern.ch/contributionDisplay.py?contribId=9&confId=217410http://indico.cern.ch/contributionDisplay.py?contribId=8&confId=235526http://indico.cern.ch/contributionDisplay.py?contribId=7&confId=244405http://indico.cern.ch/contributionDisplay.py?contribId=5&confId=252503http://indico.cern.ch/contributionDisplay.py?contribId=6&confId=260472
Occupancy ratio #fill dependence
MagDown Magup
- Depends upon the fill m Stable period in m to be used
-Depends of the trigger type -> Minimum biais 85 Hz for 8 hours fill enough to reach a 1% precision
- Magup/Magdown reference
Can be extended to HcalHcal / LED response
Ecal/LED correlated to HV change
PRS case
Determination of the integration range complicated By the scale change of the adc spectrum .
Checked on data as well.
Method’s checks on 2012 data
* Several run used to calculate the correction from occupancy . Bothpolarity
Reference are in italic
Ecal
• E/p fit
Hcal
Removing the Hcal HV change effect calculated from LED
On raw Hcal fluctuation at 2% level .More investigation on PMTs affecting the triggerThe accuracy of the method can be compared to the LED
PS
Ecal corrected
Ecal +PS corrected
E/p for electrons
-Ecal occupancy correction applied -Ecal & PS occupancy correction applied
-Overcorrection when both are applied:
-To be understood
-Impact on L0 to be investigated but is expected to be small.
For 2015 • 85 Hz minimum biais needed ~ 300K /hour
– 1 :1.5 % precision all over the calorimeter (10 hours)– 2 consecutive fill can be used– Choose stable m period– Raw information should be available for end of fill processing
• Built tools able to determine runs with stable mu • 2 options
– Correction table / cell – HV change – preferred will solve the trigger instability
• Cannot be reversed• PMT HV curves used
• With new LED system the ageing amplitude can be monitored and used to cross check occupancy changes.
• Initial calibration needs other methods – P0 (Ecal)– Electrons (Ecal +PS)
Is it possible ?• Need 85Hz of minimum biais event to calculate occupancy cell by cell
( occupancy farm ?)• Analyse events only in mu stable condition • Reference depends upon the magnetic field• The PMT HV can be updated when the deviation > 2-sigma of its resolution• Possible to check the agreement with LED measurement (Ecal & Hcal)
• This method had been used in November 2012 to update Ecal HV• It will remove the ageing dependance from trigger• Is it possible to fit with the new HLT1/HLT2 scheme• It has to be completed by fine calibration
• To be checked in event replaying mode . ( 1st 2014 half)
Data quality controls• Improved data quality to point wrong behavior:
– On line (in investigation) :• The possibility to use the 85 Hz mimimum biais event to check the pi0 mass
reconstruction as done in the fine calibration: with or without iterative procedure– e/p per zone for conversion to become standard plots– Pi0 Mass /zone will also become standard DQ plots– e/p on hadronic charged tracks
• Current developement ( available in 2014)– Retuning of all corrections for electrons and pions– Clustering (2x2 investigate for the upgrade )
• Initial precise calibration will come from pi0 , electrons , hadrons: FMDST scheme still needed.
spares
2012 procedure• Reference calibration from reconstructed p0
– Processing using the current calibration– Extract correction coefficient (Dasha)
• Need FMDST to be available • Processing 2 weeks
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Reference used
Ageing trend general
Lumi (pb-1)
The correction are dominated by the higher flux in each zone.They correspond to higher ageing.
HV change end of august~1% /100pb-1
HV change: occupancy methodEnd of November .Back to initial calibration.~0.4%/100pb-1
Annealing effect : Christmas stop4% annealing in average
Frac
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gain
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E/p for electron (O.Steniakin)
Fine calibration applied on already calibrated data
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HCAL E/p calibration: track selectionFor all tracks from Rec/Track/Best : find associated cells in HCAL, ECAL, PS laying at the track extrapolation; calculate E(HCAL), E(ECAL), E(PS)
using the CaloEnergyForTrack tool (Vanya) (AddNeighbors=1) keep only tracks with E(HCAL)>0 require isolation in HCAL (no HCAL cells associated with given track is shared with any other track); keep only long tracks, -200<z<400mm reject muons (tight and loose) reject protons (by RICH): the HCAL responses to and differ, which distorts calibration require E(ECAL) < 800 MeV && 0< E(PRS) < 20, to reject showers started much before HCALThe track position in HCAL is defined as the position of a cell with max energy deposition. further refinement:
cut on ptrack: 7 GeV for all cells, somewhat higher for the innermost ones (safety) cut on E(HCAL): 2.5 GeV for all cells, somewhat higher for the innermost ones
p p
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HCAL response to hadrons, data
More uniform than response to muons: ~4% RMS for both inner and outer (borders excluded).