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BESIII TOF Digitization

BESIII TOF Digitization. Deng ziyan 2005.10.26. Outline. TOF Geometry TOF Digitization version 1 TOF Digitization version 2 Something about running BOOST. TOF Geometry. Wrapping Al + PVF. layer1. 0. layer2. 88. barrel. TOF Geometry. end-cap. Digitization from hits. digitization.

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BESIII TOF Digitization

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  1. BESIII TOF Digitization Deng ziyan 2005.10.26

  2. Outline • TOF Geometry • TOF Digitization version 1 • TOF Digitization version 2 • Something about running BOOST

  3. TOF Geometry Wrapping Al + PVF layer1 0 layer2 88 barrel

  4. TOF Geometry end-cap

  5. Digitization from hits digitization Hit digi Hit edep digi time Hit position event digi Hit Hit digi Hit Hit forwADC forwTDC forward: east backward: west backADC No backward output for endcap tof backTDC

  6. edep, arrivalTime 1 edep (1) edep, arrivalTime 2 edep (2) edep, arrivalTime n edep (n) Time walk added TDC = tdc + c(ADC)-0.5 Digitization Version 1 Select Arrival Time edep to ADC • Select first Arrival time • Apply dE/dx threshold cut Geant arrivalTime (initial) ADC edep :-dE/dx in scintillator arrivalTime : time of flight + dz/vel Tof digitization PMT resolution tdc smeared by Gaussian with s(f(ADC)) tdc ADC TDC ADC

  7. Digitization Version 1 • 1GeV e- • Theta=90 • Phi: 0-360 • Sigma = 84 ps

  8. More to do about version 1 • Correction on ADC and TDC • ADC vs z-hit • TDC Resolution vs ADC • Time-walk correction • TDC vs ADC • Parameters will be taken from data fitting

  9. Digitization Version 2 • Full simulation • Scintillation light emission in each step • Light propagation in scintillator upto PMT • PMT response • Photoelectron production • Signal pulse production • Discrimation of PMT signal at two levels • If pulse height>HL, then make T,Q output

  10. Scintillator Emit time parameters Light attenuation length Refractive index Light output PMT Gain Rise time Effective area Transit time(and spread) Collection factor Quantum efficiency HL, LL Parameters

  11. Scintillation light emission • Number of photons is proportional to edep • 10000/MeV • Uniform distribution • Emission time: a time profile assumed temit

  12. Light propagation • Lpro = d / cosθ • Propagation time: tpro= Lpro/ vel • Attenuation in TOF counter is simulated • Part Lights escape or lost PMT θ d

  13. PMT response • Photoelectron production • Photoelectrons are produced with quantum efficiency • Number of photoelectrons is reduced due to the dynode structure • Transit time is added • PMT response for single photon electron

  14. PMT response Hit 1 direction Path length Pro time Photon 1 reach PMT Transit time end time endTime = flightTime+emitTime+ProTime+TransitTime ……….. Photon N ….. Hit N Integration of arrival photon times with PMT response function

  15. PMT response endTime PMT response for single pe Rise time = 2.5 ns PMT pulse output

  16. Time distribution flight time delta T in one step 1GeV/c e- vertical incidence

  17. Time distribution emitting time propagation time 1GeV/c e- vertical incidence

  18. Time distribution PMT transit time end time 1GeV/c e- vertical incidence

  19. Simulation of readout electronics • Each PMT signal is examined using double threshold (LL,HL) • A signal larger than HL threshold provides a gate to measure TDC • TDC is given at the moment when PMT pulse crosses LL threshold HL LL TDC

  20. TOF Front_End Electronics

  21. Energy deposit 1GeV/c e- vertical incidence total energy loss in one scintillator (5cm width)

  22. e- 1GeV/c Z=0 :forward TDC resolution = 121.6ps backward TDC resolution = 121.4ps

  23. TDC vs z-hit forward Veff=17.16 cm/ns backward Veff=17.19 cm/ns

  24. β vs P particles: random P: 0-1.6GeV random

  25. ADC vs z-hit log(forwADC/backADC) vs z-hit

  26. TDC sigma vs z-hit

  27. besfarm: old, no maintenance koala: overwhelmed lxplus: the last choice! even problems exist Using BesGenModule and BesSim can avoid changing environment Running environment

  28. Running environment • lxplus04, 05 • /ihepbatch/bes/dengzy • /afs/ihep.ac.cn/users/d/dengzy (2G) • /ihepbatch/besdata/public/dengzy (5G) • more document • G4ParticleList • GenbesParticleId • PDGscheme http://boss.ihep.ac.cn/SofPro/simulation.html

  29. The end Thanks!

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