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BESIII EMC Simulation & Reconstruction He Miao 2006-1-10
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Outline Emc simulation Detector construction Sensitive detector and hits Digitization Emc reconstruction Event model Data flow Algorithm Preliminary performances
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Emc Simulation Detector description Crystal, casing, PD (silicon photodiode), pre- amplifier box, cable, support system. Use G4Trap to construct barrel crystals, and introduce G4IrregBox which is not provided by Geant4 to construct endcap crystals. barrel endcap
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Emc Simulation Sensitive detector Crystal PD (unfinished) Hit Record signal in sensitive detector, including energy, time, position, copy number, etc.
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Emc Digitization Pick up hits in the same crystal, and add their energy together. Add photon statistics. Simulate the readout electronics. Add noise. Add background (unfinished). Get ADC and TDC channel.
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Simulation of Emc readout electronics Calculate the frequency response function of the electronics through the Laplace transform. Acquire the waveform in time domain produced by main amplifier via the inverse Laplace transform. Simulate the sampling and peak searching process by Flash ADC to obtain the energy and time information. Pre Amp Main Amp Flash ADC CsI Photo diode energy deposited time information peak searching
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Emc Reconstruction Event model Data flow Algorithm Clustering Shower splitting Shower attributes Energy and position correction
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Event Model EmcRecDigit EmcRecID EmcRecADC EmcRecTDC EmcRecHit EmcRecID EmcRecEnergy EmcRecTime EmcRecDigitMap EmcRecHitMap EmcRecClusterMap EmcRecShowerMap EmcRecFraction EmcRecFrac EmcRecCluster EmcRecClusterID EmcRecHitMap EmcRecShower EmcRecShowerID EmcRecClusterID EmcRecFracMap EAll, ESeed, E3x3, E5x5 Position, Nearest-Seed EmcRecFracMap
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Data Flow
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i-1 i,j i+1 j-1 j+1 Clustering find connected regions Neighbor definition – barrel: 3x3 Red, green and blue are neighbors Neighbor definition – endcap Various amounts of neighbors: 8,7,6,5…
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Shower Splitting e2 e1 e3 Seed – local maximum. If one seed, cluster = shower. If more seeds, the cluster should be splitted into several showers. Hit in this cluster is shared by every shower. e3=(e3*weight1+e3*weight2)/(weight1+weight2)
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Shower Attributes Energy ESeed E3x3 E5x5 EAll Position Linear weighting function Logarithmic weighting function
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Energy Correction correction parametersenergy spectrum
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Position Correction (unfinished) σ x =4.8mm Use bhabha events with information of track extrapolation to get correction parameters. Theta resolution of single gamma with 1GeV momentum after correction.
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Emc Performances Energy and position resolution (barrel) Energy and position resolution (endcap) π 0 mass resolution and detect efficiency e /π separation Execute time
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Energy Resolution single gamma
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Position Resolution (by Yang Ming) use Logarithmic weighting function thetaphi
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Endcap Performances 1GeV gamma west endeast end σ E /E theta (cm) phi (cm)
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π 0 mass resolution and detect efficiency π 0 detect efficiency: events ratio between the peak of π 0 mass spectrum +- 3.0σ π0.
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e /π separation energy deposited in Emc of 1GeV e - and π -
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Execute Time (by Sun Yongzhao) Happy new year!Happy new year!
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