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Hit rate at high luminosity logical channels - ghosts – efficiency

Hit rate at high luminosity logical channels - ghosts – efficiency. T oy Monte Carlo : # I have assumed a uniform particle distribution inside the TS # I have assumed a fraction of BC/ orbit = 0.7 # Given a particle rate/cm 2

geraldine-salinas
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Hit rate at high luminosity logical channels - ghosts – efficiency

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  1. Hit rate at high luminositylogicalchannels - ghosts – efficiency • Toy Monte Carlo : • # I haveassumed a uniformparticledistribution inside the TS • # I haveassumed a fraction of BC/orbit = 0.7 • # Given a particle rate/cm2 • # Given the geometry of the Trigger Sectors(in M2 and M2R1) • Number of logicalpads hit in the TS (per BC) • Inefficiency due to CARIOCA dead time • Number of logicalpadsreconstructed (X & Y crossing) • Accidental ‘’triggers’’ Thanks to Alessia and Roberta for usefuldiscussions

  2. INPUT: ratesreported by Giacomo asparticle rate. I evaluated the ghost rate starting from this. Thisassumptionisreasonableif the extrapolationdone by Giacomo starts from low rate data. PROCEDURE: A = Trigger Sector area. Averagenumber of hits/BC on TS = N = RxA/(0.7x40) with R= rate/cm2 (in MHz) # Poissondistribution with average N isused to find the averagenumber of X Y crossings. Ratesat 2x1033 with shielding (kHz/cm2) X Y strips are sent to the TRIGGER and DAQ to reconstructlogicalchannels (XY crossings) Strips are composed by onlyone (as in M2M3R1) or more physicalchannelsOred.

  3. To calculate the rates on the FE channels and inefficiencies, I assumed the percentage of correlated and uncorrelatedhitsmeasured in the pastat 2.76 TeV and used by Giacomo Weshouldcarefullycheckwhoreally are the ‘’uncorrelated’’ hits # Understand the apparentdisagreement with Monte Carlo. Noticethatthere are 2 differentdefinitions: In Data the AND of projectivelyalignedpadsisrequired to havecorrelatedhits In MC the fraction of trackscrossingall the 4 gaps isshown

  4. dead time inefficiencyisnotyetconsidered. M2R1 Trigger Sector: 48 logicalpadsobtained by crossing 6x8 X and Y channels Area=95 cm2 NUMBER OF LOGICAL PADS RECONSTRUCTED FROM X Y CROSSINGS Max chamb Min chamb GHOSTS Average LOGICAL PAD HITS/BC In TRIGGER SECTOR (‘’PARTICLES’’) N hitson the TS Rate/cm2 kHz Averagerates/cm2 for the chambers with minimal, average, maximalpopulation. The rates on Trigger Sectors are spread from ~ 100 to 800 kHz/cm2. The ghostnumber on the chambersisunderevaluated due to non linear effects.

  5. Now the effect of inefficiency due to CARIOCA dead time M2R1 Inefficiency due to dead time isapplied to each FE physicalchannel(1) Carioca dead time =75ns isassumed for bothwires and cathodes. The two bi-gap layers are Ored. The AND of XY isrequired FortunatelyGhostsdon’tcontribute to dead time. The effect of inefficiencyincreasesdramaticallyat a relatively high rate. important to reduce the rate # improve the shielding # feedeach FE with onlyone gap GHOSTS PARTICLES Particle HITS notin dead time N hitson the TS Rate/cm2 (kHz) (1) Efficiency = (1 - δeffR/0.7) WhereR is the rate (in GHz) measured on the FE channelsδeff= δcar -12.5 ns

  6. Most of the hits are uncorrelated Feedingthe FE by only 1 gap, the ratescan be reduced by ‘’almost’’ a factor 2 (redlines blue lines) If the inefficiencyisstilltoo high we must reduce the padsize PRESENT DETECTOR Particles X Y OR PAD DETECTOR Pad=logicalpad X Y AND Twocurves ~ superimposed: no inefficiency N hitson the TS The inefficiencycould be recoveredif in the region M2R1 the OR of wires and cathodesisacceptedbut the rate of accidentalcombinationwouldenormouslyincrease(seenext)

  7. M2R1 Accidentalassociations/Triggers opening a random FOI (1Y, 5 X) Requiring the OR of X and Y strips. (The FOI isallcontained in the TS) Notconsideringinefficiency • Accidentalprobabilityistoo high •  MUID should work with AND. • Checkhow the evaluation of MisIDispresentlyperformed Consideringinefficiency The probability of accidentals in M2 isrelevant for trigger/filter on muonPt. Given a lowPtmuondetected in M3-M4-M5, itwillresultaccidentally a high Ptmuon with thisprobability. probability Rate/cm2 (kHz)

  8. M2R1 Accidentalassociations/Triggers opening a random FOI (1Y, 5 X) Requiring the AND of X and Y strips Present strip detector If the accidental trigger probabilityistoo high also with the AND (to be studied), to reduce accidentalswe can only reduce the rate # feed the Front End with 1 gap only # improve the shielding probability Rate/cm2 (kHz)

  9. Accidentalassociations/Triggers opening a random FOI (1Y, 5 X) M2R1 For a pad detector For comparison the case of the pad detector with pads = logicalpadsisreported. Almost no difference in the accidental ‘’trigger’’ probability To reduce the accidentalprobabilityonlydrasticactionsare possible: # Onecould reduce the Y padsize by a factor 2 (Y padislargerthanMult. Scatt.) and eventuallyrequire in M3 M2 a coincidence in Y/2 pads)  a factor 2 reduction # Onecouldbuilt a detector with 4 independent gaps with theirfront end (1 AND 2) OR (3 AND 4)  very strong reduction Inefficiencyrecovered Accidentalsstill high probability Rate/cm2 (kHz)

  10. Trigger Sector: 48 logicalpads X Y = 6 x 8 Area=110 cm2 M3R1 The effect of inefficiencyseemsmuchlessdramaticthan for M2R1 (I willfurthercomment on it) ‘’EFFICIENCY’’ INEFFICIENCY NOT INCLUDED INEFFICIENCY EFFECT particles ghosts hitsnot in dead time N hitson the TS particles Rate/cm2 (kHz)

  11. Accidentalassociations/Triggers opening a random FOI (1Y, 5 X) Requiring the AND of X and Y strips M3R1 The probability of accidentalassociationsis > 2 timessmaller w.r.t. the M2R1 case probability Rate/cm2 (kHz)

  12. Apparentlywedon’thavesignificantinefficiency from CARIOCA. In M2R2, logicalpads are obtainedcrossingwires with a cathodepadbeing the OR of 4 pyisicalchannelshaving an area 4 timessmaller (~ 4 timessmaller dead time) Trigger Sector: 48 logicalpads 12 x 4 X Y Area=380 cm2 M2R2 NO INEFFICIENCY INEFFICIENCY EFFECT ghosts N hitson the TS hitsnot in dead time N particles on the TS particles Rate/cm2 (kHz)

  13. The Trigger Sectors of M2R2can be reduced (presently 12 x 4 logicalpads are obtainedcrossingwirestrips with a cathodepadobtained by the OR of 2x2 phys. chann.) thispadhas Y = Y of the logicalpad, but X = 2X of the logicalpad) The verticalsize of the TS isfixed, butit can be divided in two TS of 24 logicalpads 6 x 4.  The efficiencydoesnotchange. The number of ghostsisstronglyreduced. ghosts N hitson the TS particles

  14. M3R1 M2R1 Apparentdisagreement with inefficienciesreported by Giacomo Inefficienciesreported by Giacomo M2R2

  15. WHAT TO DO # Investigate how to reduce the size of trigger sectors in M2 R2,R3,R4 (IB – ODE … I would benefit from information/discussionabout) # Investigate the problem (the nature) of ‘’uncorreleted’’ hits, understanding the apparentdiscrepancybetween MC and measurement. (assoonaswe can, make a new measurement with onlyonelayer, twolayers in OR – AND and switching off one of the two gaps of the FE) # I wouldlike to betterunderstand the MuID and MisIDalgorithms in use # Investigate the apparentdisagreement with the inefficienciesreported by Giacomo # I thinkthatto cope with the large CARIOCA dead time, atleast in M2 R1 we haveto design a new Pad detector (a workinggroup..)

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