TOF Reconstruction, Calibration & Test-beam Simulation

1. TOF Reconstruction, Calibration & Test-beam Simulation Jiang Linli 2005/6/1 (13th BES Annual Meeting )

2. Outline • TOF reconstruction software status • TOF primary calibration introduction • A Geant4 simulation of the TOF model test-beam • Summary

3. Measure the flight time of charged particles. Comparing the measured time against the predicted time. Particle identification. BESIII Design TOF Physics Target : Particle ID

4. Barrel TOF Endcap TOF

5. TOF Reconstruction Principle

6. TOF Reconstruction Software Feature • Experience from Belle TOF reconstruction • C++ code • Developed in the Gaudi framework (Boss)

7. TOF Reconstruction Class Design • Main class TofRec TofSys TofGeom TofCalib TofData TofTrk TofHits • Barrel Tof BTofSysBTofMod BTofCnt BTofScint BTofPhotoTube BTofDat BTofCal • Endcap Tof ETofSys ETofMod ETofCnt ETofScint ETofPhotoTube ETofDat ETofCal

8. TOF Reconstruction Process

9. Current Status • All the code has been debugged in the Boss4.1, a primary version has been put to the CVS web. http://koala.ihep.ac.cn/cgibin/viewcvs.cgi/BossCvs/Reconstruction/TofRec/ • MDC reconstructed track and the extrapolated track are replaced by the MC track truth.

10. Use MC data to do the test A example : 1000 events electron data (single track ) Reconstruction process as showed above Primary reconstructed result TOF Reconstruction Code Test Now The efficiency of the matching hits and tracks is100%

11. χ for Different Charged Particles χ2 for Different Charged Particles

12. TOF Primary Calibration • Time calibration • Attenuation length calibration • Effective velocity calibration

13. Calibration Software Status • Some program has been developed • Mainly use ROOT • Use the MC data to do the calibration

14. Time Calibration Result Before Calibration After Calibration σ=125 ps σ=83 ps

15. Attenuation LengthCalibration Effective VelocityCalibration Bulk attenuation length: 4 m

16. TOF Model Test-beam Setting Chart Target C :10×80mm In one room Magnet to choose particle’s momentum Pb wall T01 S1 Cherenkov MWPC 80mm×80mm T02 TOF Model S2

17. A Geant4 Simulation of the TOF Test-beam • Geant4 is a detector simulation toolkit. • It can model the optics of the scintillator. • The processes include refraction and reflection at medium boundaries, bulk absorption and Rayleigh scattering. • It is ideal to simulate the TOF

18. A Geant4 Simulation of the TOF Test-beam • The simulation program has been finished and used • The detector construct as the test-beam • PMT response is simulated

19. Simulate Comparison Different thickness scintillator • BC408 4 cm • BC408 5 cm • BC408 6 cm Different reflectivity wrap material • Al r = 82 % • ESR r = 98 %

20. Different Size Simulation Result Why 5 cm has the best time resolution?

21. ADC Comparison 275.7±1.3 pc 282.7±1.3 pc 288.5±1.3 pc ADC 4 cm < 5 cm < 6 cm

22. Pulse Rise Time Comparison 3.719±0.005 ns 3.736±0.005 ns 3.758±0.005 ns Rise time 4cm<5cm<6cm

23. ADC 6 cm > 5cm > 4cm Rise time 4 cm < 5cm < 6cm So σ5cm< σ6cm< σ4cm

24. Different Reflectivity Simulation • ESR r = 98 % • Al r = 82 % • Npe ESR > Al σAl <σESR ?

25. ADC Comparison 282.7±1.3 pc 394.9±1.7 pc ADC Al < ESR

26. Pulse Rise Time Comparison 3.736±0.005 ns 3.956±0.006 ns ADC ESR>Al but Rise time Al<ESR SoσAl <σESR

27. Summary • TOF reconstruction software has been developed, and there is a primary version. • Primary TOF calibration has been done. • A Geant4 simulation of the TOF test-beam has been done, Some experiment result can be explained by simulation.

28. Next to do • More TOF reconstruction work • A complete TOF calibration software development • Calibration methods study • More detailed simulation work

29. Thank you !