Dr.

Week #171

4 – 7 May

With the help of the event display I’m finally able to have more tangible insight into the data. It soon becomes obvious that something strange is going on with the track finding. I use ideal track finding which takes its information from the simulated Monte Carlo data and should give the exact result. Instead, the tracks deviate quite significantly from the original input.

After digging into it with my supervisor, we find out that spurious hits from a tracking detector (GEM) foul the tracking. They seem to originate from ghost hits that are created when two one dimensional detector layers are combined to give a two dimensional information. For just one hit this is unambiguously but with two one gets in total four combinations: two real and two ghost hits.
For future tracking algorithms, this will be solved by only using meaningful hit information and discard the others. The ideal tracking on the other hand is supposed to just assign hits without further algorithms needed. Thus we decide to just ignore hits having two simulated Monte Carlo points.

This solves one problem, another one is generated by the track filter which generates a proper track from a collection of hits. Without the track filter, the parameters seem legit, but after they are off sometimes. Which, in my understanding, shouldn’t be since I’m running with ideal recognition.
I present my findings on both on the Thursday meeting. And after that, the weekend starts for me because I get married on Saturday. A busy weekend ahead.

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