Andreas Stefl

to make this easier to reproduce: this is one of the particles that will fail fatras in the ODD ``` particle_id,particle_type,process,vx,vy,vz,vt,px,py,pz,m,q 360287970424520704,-211,0,0,0,0,0,0.20463942,0.0932567492,-15.041235,0.139569998,-1 ```

all the failed particles in 100 events ``` particle_id,particle_type,process,vx,vy,vz,vt,px,py,pz,m,q 360287970424520704,-211,0,0,0,0,0,0.20463942,0.0932567492,-15.041235,0.139569998,-1 387309570353004544,211,0,0,0,0,0,-0.0336664878,0.402350187,27.0093441,0.139569998,1 680043546903838720,-211,0,0,0,0,0,-1.22771633,-1.10539758,107.704742,0.139569998,-1 540431956173651968,211,0,0,0,0,0,0.189463511,0.0681857541,-13.1236868,0.139569998,1 490892360205467648,211,0,0,0,0,0,0.0608617477,0.166004553,17.5319443,0.139569998,1 630503948251299840,211,0,0,0,0,0,0.196608573,-0.460996509,32.6732216,0.139569998,1 702561546449977344,211,0,0,0,0,0,-0.0961737335,0.128603414,16.2868423,0.139569998,1 418834765496451072,211,0,0,0,0,0,-0.177656621,0.159051478,15.9489403,0.139569998,1 495395961074352128,-211,0,0,0,0,0,-0.00978880469,0.673449039,66.8108521,0.139569998,-1 252201587672350720,-211,0,0,0,0,0,-0.127471477,-0.488562971,33.7782784,0.139569998,-1 382805969333125120,211,0,0,0,0,0,-0.457007766,-0.276580334,-52.9892273,0.139569998,1 9007199875497984,211,0,0,0,0,0,-0.274833918,-0.350640118,-44.1918106,0.139569998,1 513410358124216320,-2212,0,0,0,0,0,0.128905028,-0.00736087142,8.63115692,0.938269973,-1 31525197962018816,-211,0,0,0,0,0,0.446970522,-0.13388215,-31.2132721,0.139569998,-1 490892360859779072,-211,0,0,0,0,0,-0.0914542228,0.669969797,-67.0758286,0.139569998,-1 729583140942643200,-211,0,0,0,0,0,0.192513958,0.226287067,-19.8732033,0.139569998,-1 626000348472934400,211,0,0,0,0,0,-0.585558176,0.762062788,-64.2928619,0.139569998,1 351280771002007552,321,0,0,0,0,0,-0.625899851,0.0681778342,-41.0471954,0.49368,1 756604739327623168,-211,0,0,0,0,0,-0.0528257377,-0.0299943779,4.04915953,0.139569998,-1 382805969249239040,211,0,0,0,0,0,-0.291572392,-0.142850697,32.2053375,0.139569998,1 135107990465282048,-211,0,0,0,0,0,0.869374216,0.295557469,59.8638687,0.139569998,-1...

looks like we bounce between two geometries back and forth update happens here https://github.com/acts-project/acts/blob/main/Core/include/Acts/Propagator/Navigator.hpp#L963 ``` EigenStepper: step (1833.005505, -0.086267, 228591.005006, +∞) Acts::DiscSurface Center position (x, y, z) = (0.0000, 0.0000,...

thank you for your response @FabianKlimpel ! I was also unsure about the geometry because of the gap. in other cases it looked like it matched. I will try to...

from the log output I see like 10-100 GeV pions which all seem to have the same problem. I thought the curvature should be fairly small for them the `updateStepSize`...

the fatras errors seem to be gone after #1433 - 100 pythia events with 200 pileup without error I will look into the other propagation failure next

The track finding propagation error is due to high energy losses in thick material slabs. E.g. there are pions with ~1 GeV which get completely stopped in ~3 m material....

with truth seeding and filtering the problem seems to disappear but at the same time while lowering `ptMin` the problem re-appears. ``` addSeeding( s, trackingGeometry, field, geoSelectionConfigFile=oddSeedingSel, truthSeedRanges=TruthSeedRanges(pt=(500.0 * u.MeV,...

with #1454 the stopped particle propagation failures seem to disappear but some of them will now result in ``` 17:05:32 TrackFinding ERROR CombinatorialKalmanFilter failed: CombinatorialKalmanFilterError:5 No track is found with...

https://github.com/acts-project/acts/pull/1454 fixes the problem but will lead to ``` 14:40:46 TrackFinding ERROR CombinatorialKalmanFilter failed: CombinatorialKalmanFilterError:5 No track is found with the initial parameters 44539 : ``` for stopped particles.