For position and momentum measurements of the particle emitted in the collisions we rely on the information from high resolution vertex detectors
The VerteX Detector (VXD) system of Belle II is fundamental to reconstruct the vertex of B-mesons decays, with lifetimes of the order of the picosecond (one trillionth of a second), and of the other short-lived particle decays.
The Belle II VXD consists of two inner layers of a silicon PiXel Detector (PXD) followed by four layers of a Silicon Vertex Detector (SVD), which is composed by double sided silicon strips sensors. The whole VXD is immersed in a 1.5T magnetic field parallel to the beam axis.
A central drift chamber (CDC) that measures trajectories, momenta and dE/dx information of charged particles.