1. BESIII EMC Simulation & Reconstruction He Miao 2006-1-10

2. Outline  Emc simulation  Detector construction  Sensitive detector and hits  Digitization  Emc reconstruction  Event model  Data flow  Algorithm  Preliminary performances

3. 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

4. Emc Simulation  Sensitive detector  Crystal  PD (unfinished)  Hit  Record signal in sensitive detector, including energy, time, position, copy number, etc.

5. 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.

6. 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

7. Emc Reconstruction  Event model  Data flow  Algorithm  Clustering  Shower splitting  Shower attributes  Energy and position correction

8. 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

9. Data Flow

10. 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…

11. 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)

12. Shower Attributes  Energy  ESeed  E3x3  E5x5  EAll  Position  Linear weighting function  Logarithmic weighting function

13. Energy Correction correction parametersenergy spectrum

14. 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.

15. Emc Performances  Energy and position resolution (barrel)  Energy and position resolution (endcap)  π 0 mass resolution and detect efficiency  e /π separation  Execute time

16. Energy Resolution single gamma

17. Position Resolution (by Yang Ming) use Logarithmic weighting function thetaphi

18. Endcap Performances 1GeV gamma west endeast end σ E /E theta (cm) phi (cm)

19. π 0 mass resolution and detect efficiency π 0 detect efficiency: events ratio between the peak of π 0 mass spectrum +- 3.0σ π0.

20. e /π separation energy deposited in Emc of 1GeV e - and π -

21. Execute Time (by Sun Yongzhao) Happy new year!Happy new year!