Giuseppe Roselli (CMS-RPC) Università degli Studi di Bari – INFN RPC Efficiency with Track...

Giuseppe Roselli (CMS-RPC) Università degli Studi di Bari – INFN Giuseppe Roselli (CMS-RPC) Università degli Studi di Bari – INFN

RPC Efficiency with RPC Efficiency with Track Reconstruction Track Reconstruction

Giuseppe RoselliGiuseppe Roselli


Muon ReconstructionMuon Reconstruction

• Four steps:Four steps:

1.1. DigitizationDigitization2.2. Local ReconstructionLocal Reconstruction3.3. Stand Alone ReconstructionStand Alone Reconstruction4.4. Global ReconstructionGlobal Reconstruction

• In the Stand-Alone reconstruction the RPC can be excluded (or DT or CSC) giving In the Stand-Alone reconstruction the RPC can be excluded (or DT or CSC) giving

the possibility to reconstruct the track on the detector surface and calculate the the possibility to reconstruct the track on the detector surface and calculate the

efficiency. efficiency.

• Z°-> µ+µ-Z°-> µ+µ- samples have been used for this analysis. samples have been used for this analysis.


1- Chamber selection1- Chamber selection

• We can see how the chambers are selected in the We can see how the chambers are selected in the

algorithm without bias:algorithm without bias:

1.1. Read Trajectory (not persistent objects, that are deleted at the end Read Trajectory (not persistent objects, that are deleted at the end

of the reconstruction chain and contains all the information on the of the reconstruction chain and contains all the information on the

track propagation track propagation need to run the reconstruction in the same job need to run the reconstruction in the same job

of analysis)of analysis)

2.2. Loop over all the CMS RPC Roll Loop over all the CMS RPC Roll (Barrel + EndCap)(Barrel + EndCap)

3.3. Extrapolation of the impact point on each encountered surfaceExtrapolation of the impact point on each encountered surface

4.4. Coordinates conversion in the Local FrameCoordinates conversion in the Local Frame

5.5. Roll selection.Roll selection.


2- Efficiency - selection2- Efficiency - selection

• Matching between the extrapolated point and the rechit point, can be Matching between the extrapolated point and the rechit point, can be

calculated residuals distribution, giving the possibility to estimate the calculated residuals distribution, giving the possibility to estimate the

RPC resolution and understand which kind of cuts can be applied to RPC resolution and understand which kind of cuts can be applied to

decide the efficiency of the single chamber.decide the efficiency of the single chamber.Stand-Alone Muon Track

RPC extrapolation

On surface

Residuals

Efficiency

µ

RB1IN

RB1out

RB2IN

RB2out

RB3

RB4

x

z

yLocal coordinate


More rec-hitsMore rec-hits

• If there are more than one rec-hit we can select the only one that gives the minimum residual!

Best RecHit1 µ µ 11 µ µ 22 Best RecHit2


Parameters• We can decide:

1. Kind of track to read:

a) StandAloneMuons

b) StandAloneMuons + Vertex

c) GlobalMuons

2. Set the cut value on the residuals:

a) Default cut = 6 cm.

3. Start directly from digi of DT or CSC and RPC.

4. Create the following plots:a) Efficiencyb) Residualsc) Real Occupancy and predicted from the track extrapolationd) Residuals vs reconstructed Pte) Global Residuals and Efficiency


Results• Residuals distribution for all the chambers:


Pull and error associated to the Rec-Hit

• To find the functional form of the Resolution, can be investigated

the Pull distribution, defined as:

• If the estimation of σx on the average value is correct, the Pull

distribution must be fitted with a Gaussian curve having a standard

deviation of about “ 1 ”.

x

xPull

)(


Pull Distribution

Errors on Rec-Hit overestimated


Reconstructed Pt• Pt distribution calculated in correspondence of the RPC surface.


GREN Track ReconstructionGREN Track Reconstruction


GREN Results

Local Efficiency with an average

value of about 94%

Residuals


Inefficient casesInefficient cases

Real Inefficient case

Inefficient case due to the track reconstruction


Stand Alone Reconstruction

• The same package can be used also track reconstructed

only with the RPC and obtain the “Stand Alone Efficiency”.

• Status:

1. At the moment the RPC seed can be read and from it can be

activated the reconstruction chain (there are cases in which it

does not works and so the tracks are not reconstructed) (P. NoliP. Noli)


Stand Alone options


RPC Stand Alone Residuals


RPC Stand Alone Pull

Errors on Rec-Hit underestimated


Work in progressWork in progress

• At the moment this algorithm has been tested only on simulated At the moment this algorithm has been tested only on simulated

data and a real test can be done with thedata and a real test can be done with the Cosmic Runs. Cosmic Runs.

• The main topic for the future is to evaluate the The main topic for the future is to evaluate the “intrinsic “intrinsic

efficiency”efficiency” for each chamber using the following method: for each chamber using the following method:

1. Match between simulated and reconstructed tracks;

2. Calculate the efficiency vs Pt;

3. Calculate the efficiency vs eta.

Giuseppe Roselli (CMS-RPC) Università degli Studi di Bari – INFN RPC Efficiency with Track...

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