Intermittent Missing Hits in Vertex/Tracker During Reconstruction Process

[gaswk]

I have encountered an intermittent issue where a hit is occasionally missing in the vertex or tracker during the reconstruction process. This seems to occur randomly and is not specific to any detector model, theta, or momentum. This problem does not correspond to a specific event but affects the entire reconstruction process. Interestingly, relaunching the reconstruction with the same conditions resolves the issue.

I add some examples:
1-
First reconstruction for 80 and 89 deg (third set of points) and r position of the hits in the vertex:

Second reconstruction with the same input resulted in:

2-
With the CLD_o3_v01 geometry, the first reconstruction showed these pT and d0 resolution:

While a simple relaunch altered the results, indicating a possible missing hit in the tracker as the difference in d0 is quite small. Unfortunately, I no longer have access to the files for further analysis

This issue has been observed multiple times, although it appears to be random.
Do you any idea what could be the problem?

[Zehvogel]

Hi Gaelle, thx for reporting this issue.

Unfortunately I have no direct suspicion what the problem could be. If it only shows up "randomly" it will be hard to figure out :/ Please let us know if you discover any kind of pattern when this happens

Below some thoughts

I assume the r position in 1 is plotted in the same way as in 2, i.e. it is the VXDTrackerHits collection? Then it looks like you are missing all the hits from the inner two double layers?
They only way I know of how all hits of a layer can miss from that one is by having the layer in a different position during reconstruction than during simulation, i.e. a geometry mismatch.

For the pT and d_0 resolutions in 2 you did just run the reconstruction twice with no changes?
I am very suspicious of the last d_0 plot where there is no difference at all between the two geometries.

[Zehvogel]

@gaswk Is this still a problem?