Test beam measurements of an irradiated prototype pixel sensor designed for the CEPC vertex detector

The Circular Electron Positron Collider (CEPC) has been proposed as a Higgs factory to measure the properties of the Higgs boson with unprecedented precision and to guide the searches for new physics. To meet the stringent physics requirements, it is necessary to design and construct its vertex detector with the state-of-the-art silicon detector technologies. The first prototype CMOS pixel sensor, named JadePix-1, was developed for the CEPC vertex detector and its performance was already characterized with radioactive sources in laboratory. This prototype sensor was further characterized at the DESY test beam facility. Results are reported on charge collection, cluster size, position resolution and detection efficiency before and after the sensor samples exposed to neutron irradiation up to the fluence level of 10131 MeVneq∕cm2.