Usage of the TPC & ITS Standalone Track Parameters (and Track Time0) Together with the Combined Track for Fake Tagging and Track Reassociation

[miranov25]

Usage of the TPC & ITS Standalone Track Parameters (and Track Time0) Together with the Combined Track for Fake Tagging and Track Reassociation

The TPC and ITS standalone track parameters are by default not written to the AO2D, as the AO2D structure is optimized for output storage and physics analysis size. These parameters were not originally intended for systematic detector and reconstruction performance studies.

However, the TPC and ITS track parameters, and their deltas, can be very effectively used to improve the systematic and statistical error of the physics measurements. These measurements will be utilized in "simple" systematic track cut variations and also in advanced precise analysis using machine learning techniques.

Goal:

1. Storage: Store the TPC and ITS standalone track parameters at the reference radius in the trackQA table, for performance parameterization and further physics studies.
2. Optimization of Data Storage: Store the delta of the track parameters using the precision of the measurement. In total, 10 bytes—2 x 5 bytes—should be allocated for encoding the TPC and ITS standalone track parameters.

Proposed Implementation and Data Compression:

1. Propagation: TPC and ITS standalone tracks and the combined track are propagated to the reference radius (R_{\text{ref}}) (radius with minimal average delta parameters between ITS and TPC).

2. Normalized Delta: Store the normalized delta between the TPC+ITS parameters at this radius. This delta will later be used for "fake removal" and track splitting.

3. Error Normalization: Normalize deltas to the effective error of the track parameters determined by multiple scattering, space point error, and errors in alignment and calibration.

   [ \text{error} \approx k_{\text{offset}} + \frac{k_{\text{slope}}}{\beta \times p_t} ]

4. Normalized Delta Calculation: Calculate the normalized delta between the average of TPC and ITS parameters and the combined track at the reference radius, utilizing a similar normalized error parameterization.