Reconstruction of Λ hyperons in an inhomogeneous magnetic field with a Kalman Filter based tracking algorithm

Abstract

The high interaction rate, fixed target experiment HADES at GSI, located in Darmstadt, Germany, investigates collisions of heavy-ion, proton and secondary pion beams with a target material. Hyperons are one of the key observables for both heavy-ion and elementary collisions [1] [2]. The challenge is to detect displaced vertices with good accuracy without having a dedicated vertex detector, by employing state-of-the-art techniques. In this contribution we discuss a newly developed tracking algorithm that uses both a Kalman Filter (KF) and the high performance KF Particle package to further boost the reconstruction performance for hyperon decays with displaced vertices [3]. With the use of the covariance matrices, which take into account effects from multiple scattering and energy loss of the particles in the material, the reconstruction performance of the tracking algorithm can be significantly improved. The KF Particle utilises these covariance matrices together with its own internal KF to reconstruct primary and secondary decay vertices.