Preamplification structures based on Micromegas

The design of Micromegas is offering, for several applications, substantial advantage in energy, spatial and time resolution, granularity on large surface and simplicity of construction. However the maximum achievable gain is limited, at high hadron rates, because of sparks induced by heavy ionizing particles produced by nuclear interactions. An issue to decrease drastically the sparking rate is to use the conversion space of the detector as a preamplification stage. In this paper, we will describe the design and laboratory results of new amplifying structures, based on the Micromegas concept that can be either used as a preamplification element or stand-alone detector for some specific applications.