Issues encountered when running the RPC example

Garfield++
1

Hello!

I encountered an issue while running the Garfield++ RPC example.https://gitlab.cern.ch/garfield/garfieldpp/-/blob/master/Examples/RPC/Weight.C?ref_type=heads

A typical output is as follows:

ComponentParallelPlate::Setup: Geometry with N = 15 layers set.

ComponentParallelPlate::AddPlane: Added plane electrode.
MediumMagboltz::LoadGasFile:
Reading file c2h2f4_ic4h10_sf6.gas.
Version 12.
Gas composition set to iC4H10/SF6/C2H2F4 (5/5/90).

MediumMagboltz::Mixer:
4000 linear energy steps between 0 and 40 eV.

ISO-C4H10 2014 ANISOTRPI
mass: 58.1234 amu
ionisation threshold: 10.67 eV
24 inelastic terms (15 excitations, 4 superelastic, 5 other)

SF6 2014 ANISOTROPIC
mass: 146.055 amu
ionisation threshold: 15.67 eV
35 inelastic terms (25 excitations, 3 superelastic, 7 other)

C2H2F4 2024 ANISOTROPIC
mass: 102.031 amu
ionisation threshold: 13.2 eV
19 inelastic terms (10 excitations, 4 superelastic, 5 other)

MediumMagboltz::Mixer:
Lowest ionisation threshold in the mixture: 10.67 eV (iC4H10)

MediumMagboltz::Mixer:
Energy [eV] Collision Rate [ns-1]
2.50 5031.70
7.50 7456.63
12.50 9896.64
17.50 11216.71
22.50 11556.15
27.50 11744.82
32.50 13207.83
37.50 14634.13
MediumMagboltz::ComputePhotonCollisionTable:
Photoabsorption cross-section for iC4H10 not available.

Using n-butane cross-section instead.
Sensor::AddElectrode:
Added readout electrode “ReadoutPlane”.
All signals are reset.
Sensor::SetTimeWindow: Resetting all signals.
Sensor::SetArea: Warning. Infinite x-range.
Sensor::SetArea: Warning. Infinite z-range.
terminate called after throwing an instance of ‘Garfield::Exception’
what(): No ionisable medium at initial position in NewTrack at /home/whisper/garfield/vNew/source/garfieldpp/Source/TrackHeed.cc:99:0
Aborted (core dumped)

I saw in the post that you can add this line of code.https://root-forum.cern.ch/t/q-garfield-example-rpc-issues-with-small-avalanche-size-and-single-gas-gap-avalanche/63661/3?u=whisper

track.CrossInactiveMedia(true);

However, this has not resolved the aforementioned issues. Have I overlooked any crucial points?

Thank you for taking the time to address my concerns.

Best regards,

Sibo Wang

2

Welcome to the ROOT Forum!
I think @hschindl can help

3

Hi,
apologies for the late reply and thanks a lot for reporting this issue! You didn’t overlook anything, the example needed an update. I’ve just pushed a fix:

Can you try changing the line

track.NewTrack(0, totalThickness, 0, 0, 0, -1, 0);

to

 track.NewTrack(0, totalThickness - dMylar - dWindow, 0, 0, 0, -1, 0);

and add a line

track.CrossInactiveMedia(true);

Let me know…

4

Thank you for your assistance; the issue has been successfully resolved!