How could I define the gas and ion not in the garfieldpp list

Garfield++
1

Dear all,
I am beginner of Garfieldpp. I want to simulate the induced ion signal in SeF6, which is not defined in the medium gas. So is there a method to define SeF6 besides hacking the file /garfield/Source/ MediumGas.cc ?
The ion is still not defined in Ion mobility data. But with the help of quantum chemistry, I could calculate it. How could I use the calculating mobility result in simulation?

2

I guess @hschindl can help you.

3

Hi,
do you mean SF6? Magboltz does have cross-sections for SF6.

There is also a mobility file included in the Data directory of the project source tree, but it’s for negative ions:

If you have a set of mobilities as function of the electric field, you can just create a file in the same format and load the data in Garfield++.

4

No, I mean SeF6, selenium hexafluoride. Of course it’s not common gas so it’s hard to find some information about it.

5

Dear @dm-leo, if you really mean SeF6 and not SF6 you are quite in uncharted territory. That gas is not implemented in Magboltz, and it also has not cross sections uploaded in lxcat [1].
I would suggest you study some literature to understand how much the behaviour of SeF6 differs from SF6, (under the pressure, temperature and concentration conditions of your setup), such as [2], but you can find maybe more and better yourself. If the differences are not substantial, you could get some first estimates using SF6 instead of SeF6.

[1] https://www.lxcat.net/data/set_specA.php
[2] Redirecting

6

Hi,Piet
I do have studied some researches about SeF6. And by some methods about quantum chemistry and density functional theory, the reduced mobility of SeF5- and collision cross section in SeF6 gas were calculated (not from experiment). Maybe the W value and Fano factor of SF6 could be used for simulation of SeF6. Maybe it’s hard to define a new gas and new ion if there is no detail information in garfieldpp?

7

Dear @dm-leo
You can create a file with your calculated values of the reduced mobility of SeF5-, in a similar way as SF6- mobility. For defining SeF6 in Magboltz, you will have to implement this in Magboltz (Fortran), but before embarking on such a titanic work, i would compare your calculated SeF6 and SF6 cross sections and if possible use SF6 for your simulations.

8

Thanks. And the Fortran code is terrible to me :scream:. The collision cross section (ion interact with gas molecule) was calculated by the Mason-Schamp’s first approximation of two-temperature theory. It’s a pity that I can’t find the information about ion- gas interaction (but lots of datas about electron - ion and electron -gas) to compare.