Study on the performance of the new High Angle Time Projection Chamber prototype for T2K ND280 Upgrade.

The T2K Collaboration is developing new gas-based Time Projection Chamber (TPC) detectors to be exploited in the upgrade of "near" neutrino detector ND280 located in the J-PARC laboratory (Tokai, Japan). HA-TPCs are based on a gaseous active volume contained in a Field Cage, with a central cathode splitting the chamber into two halves, that are devoted to the detection of charged particles at large angle with respect to the neutrino beam. In 2021, a prototype has been built for the validation of the manufacturing process, in order to test the performances and to start the production of five full scale Field Cages. This contribution focuses on the study of the prototype performances, in particular by looking at 1) Electric Field uniformity with a laser source and 2) data collected in a test beam at CERN (2021). An external tracking system consisting of 8 planes of silicon strips will be compared with data from the TPC to investigate possible biases in the position reconstruction. Furthermore, preliminary tests with the full scale Field Cage are currently being performed.