The mini 2S (strip-strip) module for the High Luminosity upgrade of the CMS Outer Tracker consists of a stack of two 5cm Si strip sensors read out by two CBC2 (CMS Binary Chip 2) ASICs. The module is assembled on a high-density hybrid and it is intended to prove the viability and the performance of the stacked sensor concept for selecting high Pt-tracks, as well as a demonstrator for the assembly and component developments.
In November 2013 the 2S prototype module passed an important milestone with the first beam test with 4GeV positrons at DESY. Such test was a first in many ways: the first beam test of the stacked silicon sensors concept, but also the opportunity to test the bespoke, Phase-II oriented uTCA DAQ, the first test of the performance of the CBC2 in beam and the first test with both p-on-n and n-on-p sensors, one of which not tested before.
During one week more than 120M events were recorded and this allowed extensive tuning of the commissioning steps, with trigger and stub latency scans and offset tuning, but also importantly to study the performance of the module with angular and threshold scans. The results from the analysis of these data will be presented: among these turn-on curves for the Pt selection cut, efficiency plots and cluster-width distribution as function of the particle incident angle.
Other recent activities such as the TID irradiation of the CBC2 ASIC are also presented.