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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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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

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

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


Digitization Version 1

  • 1GeV e-

  • Theta=90

  • Phi: 0-360

  • Sigma = 84 ps


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


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


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


Scintillation light emission

  • Number of photons is proportional to edep

    • 10000/MeV

  • Uniform distribution

  • Emission time: a time profile assumed

temit


Light propagation

  • Lpro = d / cosθ

  • Propagation time: tpro= Lpro/ vel

  • Attenuation in TOF counter is simulated

  • Part Lights escape or lost

PMT

θ

d


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


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


PMT response

endTime

PMT response for single pe

Rise time = 2.5 ns

PMT pulse output


Time distribution

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


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


TOF Front_End Electronics


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


β vs P

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

Running environment


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


The end

Thanks!


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