Study of pedestals and noise of an IROC prototype for the upgrade of the ALICE TPC

In the LHC Run 3 period (2021 and beyond) the collision rate in Pb-Pb will be increased to 50 kHz. To cope with this data rate, the Time Projection Chamber (TPC) of ALICE will be upgraded with a GEM-based readout system for continous readout. In the course of that, also the front-end electronics will be replaced. The requirements to this new readout system are stable pedestal values and a noise level of around 1 ADC value. In May 2017, a test beam campaign at the CERN Proton Synchroton was performed, employing a preproduction Inner Readoutchamber (IROC) module of the final design.The detector is equipped with advanced prototypes of the new Front-End Cards (FECs), employing the newly developed SAMPA readout chip. The aim of this test is to demonstrate that the readout requirements are fulfilled in a realistic setup, and finally to verify the PID performance of the system using pion and electron beams. This poster shows investigations on pedestal and noise values in data from the beam test in May 2017.