Rendering of the P2 experiment

The P2 Experiment will make use of the new MESA accelerator in Mainz to measure the weak mixing angle in electron-proton scattering at low momentum transfer with unprecedented precision.

Our group is building a tracking detector to measure the momentum transfer. We have started simulations in order to estimate the expected rates and to find the best possible geometry for the tracker.

P2 Simulation


As the electrons we intend to detect have very low momenta, multiple Coulomb scattering is the main uncertainty affecting the tracking. This together with the high expected rates makes HV-MAPS a natural choice for the tracker technology.

Preliminary design of a P2 tracker module

Bremsstrahlungsphotons from the liquid hydrogen target outnumber the signal electrons in the first tracker planes by about three orders of magnitude. Understanding and controlling this background is thus of utmost importance. To this end, we conduct beam tests at the A2 tagged photon beam facility at MAMI in Mainz.

Beam time picture gallery

HV-MAPS photon beam test setup