|Message: Re: Could Geant4 simulate the number of secondary electron in the TPC gas||Not Logged In (login)|
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On Mon, 21 Jan 2013 07:30:39 GMT, Anna Wang wrote:
> Hi, > I want to simulate primary ionization distance and the number of secondary electron produced by primary ionization per unit length when a charged particle passes through TPC gas. For TPC gas mixture 70% Ar+30%Isobutant, at normal condition the average distance between primary ionizations for fast particle should be around 300 um. > > But my simulation result is about 1 mm for 500MeV electron when I set " G4ProductionCutsTable::GetProductionCutsTable()->SetEnergyRange(10*eV, 1*GeV)" in PhysicsList and "/testem/phys/addPhysics livermore". > Now I suspect whether Geant4 could simulate the number of secondary electron in the TPC gas >
I took TestEm1, added in PhysicsList G4ProductionCutsTable::GetProductionCutsTable()->SetEnergyRange(10*eV, 1*GeV) and ran following macro
# Ionisation only # /control/verbose 2 /run/verbose 2 # /testem/det/setMat ArgonButane /testem/det/setSize 1 cm # /testem/phys/addPhysics local # /run/initialize # # prevent any gamma production /testem/phys/setGCut 1 km # # no multiple scattering /process/inactivate msc # # set cut for ionisation /testem/phys/setECut 1 um # /testem/gun/setDefault /gun/particle e- /gun/energy 500 MeV # /analysis/setFileName ionis /analysis/h1/set 2 100 0 100 none #nb steps of primary /analysis/h1/set 3 100 0 2000 um #step size of primary /analysis/h1/set 5 100 0 200 eV #energy of charged secondaries # /testem/event/printModulo 1000 # /run/beamOn 10000
Here, only ionisation is active, eg. the step size is detemined by ionisation. The plots are in attachement. I hope they are self explanatory. - from histo 3, we see all step sizes, from few um, with a mean ~500 um - from histo 5, we see the 10 eV production threshold.
Notice that an alternative to 'normal' ionisation process is the PAI model (see example TestEm8)
Attachment: http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/01/25/11.40-28722-awang.log.txt http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/01/25/11.40-84278-nbSteps.jpg http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/01/25/11.40-38205-stepSize.jpg http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/01/25/11.40-12536-energy.jpg