Small-pad Resistive Micromegas for Operation at Very High Rates

Abstract

Resistive Micromegas detectors have proved to be suitable for precision tracking in dense particle rate environment up to few kHz/cm$^2$. Rate capability up to few MHz/cm$^2$ and low occupancy can be achieved by using few mm$^2$ readout pads. Such a rate capability will be required in upgrades of forward muon detectors of LHC experiments as well as in experiments at future colliders. We present the development of resistive micromegas with O(mm$^2$) pad readout aiming at precision tracking in high rate environment without efficiency loss up to several MHz/cm$^2$. A first small-pad prototype has been designed, constructed and tested. It consists of a matrix of 48x16 pads. Each pad has rectangular shape with a pitch of 1 and 3 mm in the two coordinates. The active surface is 4.8x4.8 cm$^2$ with a total number of 768 channels. Characterization and performance studies of the detector have been carried out by means of radioactive sources, high irradiation X-Rays and test beam. The results will be presented, along with recent developments aiming at the construction of fully scalable, thousands-channels small-pad detectors.