1. BESIII TOF Digitization
Deng ziyan

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

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

4. TOF Geometry
end-cap

5. Digitization from hits
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. Digitization Version 1 Geant Tof digitization ADC
Select Arrival Time
edep to ADC
edep, arrivalTime 1
edep, arrivalTime 2
edep, arrivalTime n
edep (1)
edep (2)
edep (n)
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
Time walk added
TDC = tdc + c(ADC)-0.5
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. Parameters Scintillator PMT 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

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

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 PMT pulse output
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 total energy loss in one scintillator (5cm width)
1GeV/c e- vertical incidence
total energy loss in one scintillator (5cm width)

22. e- 1GeV/c Z=0 : forward TDC resolution = 121
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. Running environment besfarm Genbes BOOST lxplus koala BesGenModule
BesSim
besfarm: old, no maintenance
koala: overwhelmed
lxplus: the last choice!
even problems exist
Using BesGenModule and BesSim
can avoid changing environment

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

29. The end
Thanks!