Resistive Micromegas with small-pad readout: towards a higher rate capability

We present here the development of resistive Micromegas with O(mm ² ) pad readout aiming at improving the high rate capability of the detector. The goal application is precision tracking in high rate environment without efficiency loss up to few MHz/cm ² . In the proposed layout, small anode pads are overlayed by an insulating layer with a pattern of resistive pads on top. The readout and resistive pads are connected by intermediate resistors embedded in the insulating layer. A first prototype has been constructed at CERN and thoroughly tested. It consists of a 48×16 matrix of 0.8×2.8 mm ² rectangular pads with a pitch of 1 and 3 mm in the two coordinates. The active surface is 4.8×4.8 cm ² with a total number of 768 channels read-out by 6 APV-25 chips. The drift and amplification gaps of this Micromegas prototype are 5 mm and 128 μm, respectively. The detector is operated with an Ar/CO2 (93:7) gas mixture. Characterization and performance studies of the detector have been carried out by means of radioactive sources, X-Rays and test beam.