BESIII TOF Digitization Deng ziyan 2005.10.26

Outline TOF Geometry TOF Digitization version 1 Something about running BOOST

TOF Geometry Wrapping Al + PVF layer1 layer2 88 barrel

TOF Geometry end-cap

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

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

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

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

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

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

e- 1GeV/c Z=0 : forward TDC resolution = 121 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

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

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 http://boss.ihep.ac.cn/SofPro/simulation.html

The end Thanks!