Hamburg 2016 – scientific programme

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T: Fachverband Teilchenphysik

T 98: Experimentelle Methoden III

T 98.4: Talk

Thursday, March 3, 2016, 17:40–17:55, VMP8 SR 105

Parameterization-based tracking for the P2 experiment — •Iurii Sorokin for the P2 collaboration — Institut für Kernphysik and PRISMA cluster of excellence, Mainz, Deutschland

The P2 experiment at the new MESA accelerator in Mainz aims to determine the weak mixing angle by measuring the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. To achieve an unprecedented precision an order of 10¹¹ scattered electrons per second have to be acquired. Whereas the tracking system is not required to operate at such high rates, every attempt is made to achieve as high rate capability as possible.

The P2 tracking system will consist of four planes of high-voltage monolithic active pixel sensors (HV-MAPS). With the present preliminary design one expects about 150 signal electron tracks and 20000 background hits (from bremsstrahlung photons) per plane in every 50 ns readout frame at the full rate.

In order to cope with this extreme combinatorial background in on-line mode, a parameterization-based tracking is considered as a possible solution. The idea is to transform the hit positions into a set of weakly correlated quantities, and to find simple (e.g. polynomial) functions of these quantities, that would give the required characteristics of the track (e.g. momentum). The parameters of the functions are determined from a sample of high-quality tracks, taken either from a simulation, or reconstructed in a conventional way from a sample of low-rate data.