Beam test results of pixel triggerless prototypes for the MVD

Hybrid pixel and double sided silicon microstrip devices will equip the Micro Vertex Detector of the P ¯ ANDA experiment. The most challenging request of the experiment is the continuous readout at the rate of 2 × 10 7 interactions/s. The detector is in an advanced R&D phase and pixel assemblies, composed of thinned epitaxial sensor read out by the custom chip prototype ToPix, developed in the 130 nm CMOS technology, were produced. The triggerless ASIC implements readout channels that are able to detect signals and transmit the information with a precise timestamp. It performs the energy loss measurement using the Time over Threshold technique, in the input range to about 50 fC. A dedicated testing bench allows the control and the readout of each single chip assembly. Two experimental setups were assembled for testing these first single chip prototypes with pions at CERN, T9, in August 2012. The first one is based on a pixel assembly positioned in the middle of a telescope composed of double sided silicon strips sensors. A 50 MHz clock signal synchronizes these two systems, the triggerless pixels and the strip detectors triggered by scintillation detectors. The second experimental setup is a tracking station housing four pixel assemblies. First results will be reported.