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Alessia, Roberta. M2-M5 Absolute Efficiency. R.Santacesaria, February 3, 2010- Muon [email protected] Efficiency calculation. Method: - MuonTrackRec standalone reconstruction using 4 stations, - Look for Clusters in the 5 th station within large tolerances

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Alessia roberta

Alessia, Roberta

M2-M5 Absolute Efficiency

R.Santacesaria, February 3, 2010- Muon [email protected]


Efficiency calculation

  • Method:

  • - MuonTrackRec standalone reconstruction using 4 stations,

  • - Look for Clusters in the 5th station within large tolerances

  • around the prediction, no time cut

  • Assume the found cluster multiplicity distribution is due to

    efficiency + poissonian background

  • - Fit with this assumption

  • Data used:

  • - All existing beam TAE=2 events (92K) in range 63454-63990

  • - All existing no-TAE events to increase statistics in some cases


Reconstructed tracks-TAE events

Nev=92000

Reconstructed tracks with 4 stations

  • Ntr-sel:

  • - standalone tracks confirmed by the tracker requiring agreement

  • within 1s between the M1 hit and the Tracker extrapolated point on M1

    In addition:

    On M2, where more physical noise is present, also:

  • only one track per event (avoid clone tracks)

  • < 10 pad/region

  • no Pad ambiguity within the TS, Only combinations (1X, >1 Y)

    or (>1X, 1Y) are kept

    On M5, further cuts were needed, not enough statistics remains

    go to no TAE events


Efficiency calculation

Search window in the 5th station is ~ 6s where s isobtained by fitting

the distributions of the difference between the prediction and the clusters

Example of M4 x coordinate


Efficiency calculation

Number of clusters found within the defined windows in M4

R2

R1

R4

R3


M4

k=# of clusters

If k>0

SUM [(1-e) Pbgk e -Pbg/ k! + e Pbgk-1 e -Pbg/ k-1!]

If k=0

SUM[ e -Pbg(1-e) ]

Where

SUM = Sum of the entries

e = Efficiency

P bg= Background probability

Efficiency calculation

From each histogram the efficiency e and the background probability Pbg

Is extracted by fitting the following function:

In this way the event correlated background is taken into account automatically

since it is estimated in the vicinity of the track


Efficiency calculation

Number of clusters found within the defined windows in M4

R2

R1

R4

R3


Efficiency calculation M4

This is efficiency in infinite time window

M4R2 lower...


M4R2 xy coordinates of predictions where no clusters where found c

Somewhat less efficient but no clear bad regions identified


Efficiency calculation M3 found

This is efficiency in infinite time window

Lower efficiency of M3R2 is due to a particular chamber, excluding it

e rises to normal values


M3R2 – Chamber 16A3 A side found

M3R2 xy coordinates of predictions where no clusters where found c

In some cases hits on wires at the right place but no cathods are hit (double readout), it that region e<~85%


Efficiency calculation M2 found

This is efficiency in infinite time window

- R1 slightly worse, probably due to leakage in the inner hole

of R1. More work on the definition of the inner fiducial volume,

prediction on M2 less well constrained since upstream Calo and M1


Efficiency calculation M2- no TAE events found

Due to additional cuts on M2 low statisticslook also at no TAE events This is the total efficiency, including 25ns time window

  • Bad e on R1 and R2 due to bad timing

    - OK for R2 after having excluded

    the corresponding Trigger

    Sectors

    - ~ OK for R1, some residual time

    misalignment is still present



Efficiency calculation M5 - no TAE found

  • Further cuts to analyze M5 in order to define a penetrating track:

  • Tight matching of Tracker track extrapolated to M4

  • P>8GeV

  • - Bad e on R1 due to a broken TTC

  • on one ODE . Better after having

  • excluded it

  • On R4 lower e due to softer spectrum

    of tracks reaching R4

    Need to work with a bigger sample

    of high momentum tracks.

    Tighter cuts more statistics needed

Clearly

This is efficiency in 25 ns


Conclusions found

  • - A first evaluation of the absolute efficiency gives results well above 99%

  • in almost all cases.

  • - A small clearly inefficient zone on M3R2 has been identified but

  • no explanation so far

  • - As far as efficiency in 25ns, eT, is well above 99% in M2R2-R4, still some residual time misalignment in M2R1

    - More high momentum tracks are needed to analyze M5

  • More work and more statistics to evaluate systematics

    - M1 efficiency to be done, big BG, different approach


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