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BESIII TOF DigitizationPowerPoint Presentation

BESIII TOF Digitization

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BESIII TOF Digitization

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BESIII TOF Digitization

Deng ziyan

2005.10.26

- 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

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

edep, arrivalTime 1

edep (1)

edep, arrivalTime 2

edep (2)

edep, arrivalTime n

edep (n)

Time walk added

TDC = tdc + c(ADC)-0.5

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

- 1GeV e-
- Theta=90
- Phi: 0-360
- Sigma = 84 ps

- 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

- 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

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

- Number of photons is proportional to edep
- 10000/MeV

- Uniform distribution
- Emission time: a time profile assumed

temit

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

PMT

θ

d

- 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

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

endTime

PMT response for single pe

Rise time = 2.5 ns

PMT pulse output

flight time

delta T in one step

1GeV/c e- vertical incidence

Time distribution

emitting time

propagation time

1GeV/c e- vertical incidence

Time distribution

PMT transit time

end time

1GeV/c e- vertical incidence

- 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

Energy deposit

1GeV/c e- vertical incidence

total energy loss in one scintillator (5cm width)

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

TDC vs z-hit

forward Veff=17.16 cm/ns

backward Veff=17.19 cm/ns

particles: random

P: 0-1.6GeV random

ADC vs z-hit

log(forwADC/backADC) vs z-hit

TDC sigma vs z-hit

besfarm: old, no maintenance

koala: overwhelmed

lxplus: the last choice!

even problems exist

Using BesGenModule and BesSim

can avoid changing 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

The end

Thanks!