Hi.
I am generating gas file using ./generate in example in Geant4GarfieldInterface. I have some issue making Xe 100% 10 bar 173 Kelvin gas file with 440 kV/cm E field.
It is generating now but there is no ionisation rate Garfield++ says and making some error in picture. And I am generating gas file with ncoll = 500 but it is taking more than 3 days now.
Is there anybody how to solve this issue?
Ncol=500 is an extremely high precision. Is this justified? How long does it take to generate your file with more standard, but already very high precision ncol=10?
Actually I have already tried ncoll = 20 but Garfield says there is no ionisation rates just like in the figure. Since some says low ncoll may occur error so, I have grown it. Is there any doubtable reason for this error except ncoll?
I am not sure but ncoll = 20 took around 1 or 2 day to simulation.
Can you do a print-out of your gastable or make a plot of the townsend coefficient and other swarm parameters?
Sorry for late reply. This is table using ./printTable program. Its ncoll = 20 and I stopped generating file ncoll = 500.
Hi,
the message “present gas table has no ionisation rates” is printed when you call the EnablePenningTransfer. This doesn’t really matter for your simulation though since in pure noble gases there is no Penning effect. The error message No ionisable medium at initial position must be due to something else.
I’m still curious why you get the “gas table has no ionisation rates” warning. If you could upload your .gas file, I’ll have a look if there are really no ionisation rates stored in the gas file or if there is an issue with the import of the file.
Also, as Piet already commented, ncol = 500 seems indeed excessive.
Hi,
Thanks for your answer. This is .gas file I used in txt file.
xe_100.gas.txt (59.0 KB)
And in the log output file after I operate Geant4 Garfield Interface program, it says Avalanche = 0 and Ionisation = 0. Is it have any connection with this problem?
Hi,
thanks for the gas file! I’m afraid I don’t manage to reproduce the issue you encountered. I used the following simple program to import your gas file and set the Penning transfer probability:
MediumMagboltz gas;
gas.LoadGasFile("xe_100.gas");
gas.PrintGas();
gas.EnablePenningTransfer(0.5, 0.);
The output I got is
MediumMagboltz::EnablePenningTransfer:
Global Penning transfer parameters set to:
r = 0.5
lambda = 0 cm
MediumMagboltz::EnablePenningTransfer:
Warning: present gas table has no eligible excitation rates.
Ignore this message if you are using microscopic tracking only.
which makes sense because in pure Xe there are indeed no excitation levels that are eligible for excitation transfer.
In any case, you should remove the call to the function EnablePenningTransfer from your program, it doesn’t make sense for pure Xe.
I also noticed that your gas file has an extremely narrow range of electric fields, covering 439999 - 440001 V/cm, with 19 steps. Is that on purpose?
Hi,
I set E field to minimise time to generate .gas file. I only simulate on uniform 440 kV/cm. If there is any worry to simulation because of it, please let me know.
Also, what you are saying is that my gas file is normally generated, is it right? I also checked EnablePenningTransfer is not on simulation src code and first warning is removed!
MediumMagboltz::EnablePenningTransfer:
Warning: present gas table has no ionisation rates.
Ignore this message if you are using microscopic tracking only.
Thanks for your solution 
But a serious warning about TrackHeed is still here. Is it problem about Garfield structure not gas file?
Hi,
ok, I see. If you only need the transport parameters at 440 kV/cm, then the range of the electric field is indeed ok. But then you don’t need to use 19 grid points…
The error message No ionisable medium at initial position. means pretty much what it says. Can you check your program to make sure the starting point of your delta electrons are indeed in an active medium?
Hi,
sorry for late answer.
I have checked if position of particle is in the gas for a number of times and it is.
However, I tried editing physics.mac and have seen that error is removed when line number 21 - 25 is removed. I think it is deeply connected to the error and its solve.
Do you have any idea of it?
ps. line 21 - 25 may be about PAI model.
