Abstract
The event time describes the time the collision producing a physically interesting event with a positive trigger decision happened. Because of the integration time of the subdetectors, each recorded event includes the data of more than a single collision.
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Notes
- 1.
Since the probability to have multiple collisions with tracks is low for a detector readout, this assumption is valid.
- 2.
Assuming a hit in the first CDC layer, the difference between the pion and the proton mass hypothesis is only in the order of 0.2 ns. Additionally, the momentum requirements discussed below cut away protons in most of the cases.
- 3.
As the x–t is too complicated to be analytically invertible, a numeric iterative inversion is performed.
- 4.
A natural solution to this problem would be to use a Kalman-based approach without the downweighting of hits. However this leads to track parameter estimations too bad to use the residuals reliable for time estimation.
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Braun, N. (2019). Event Timing. In: Combinatorial Kalman Filter and High Level Trigger Reconstruction for the Belle II Experiment. Springer Theses. Springer, Cham. https://doi.org/10.1007/978-3-030-24997-7_5
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