Characterization of resistive Micromegas detectors for the upgrade of the T2K Near Detector Time Projection Chambers

TL;DR

This paper presents the development and testing of resistive Micromegas detectors with innovative charge spreading technology, demonstrating their suitability for upgrading the T2K Near Detector's Time Projection Chambers.

Contribution

It introduces the Encapsulated Resistive Anode Micromegas detector, combining resistive anodes with bulk-Micromegas, and provides experimental characterization data.

Findings

Spatial resolution better than 600 μm

Energy resolution better than 9%

Performance meets upgrade requirements

Abstract

The second phase of the T2K experiment is expected to start data taking in autumn 2022. An upgrade of the Near Detector (ND280) is under development and includes the construction of two new Time Projection Chambers called High-Angle TPC (HA-TPC). The two endplates of these TPCs will be paved with eight Micromegas type charge readout modules. The Micromegas detector charge amplification structure uses a resistive anode to spread the charges over several pads to improve the space point resolution. This innovative technique is combined with the bulk-Micromegas technology to compose the "Encapsulated Resistive Anode Micromegas" detector. A prototype has been designed, built and exposed to an electron beam at the DESY II test beam facility. The data have been used to characterize the charge spreading and to produce a RC map. Spatial resolution better than 600 $\mu$m and energy resolution better than 9% are obtained for all incident angles. These performances fulfil the requirements for the upgrade of the ND280 TPC.