The SST-1M camera will use Silicon PhotoMultipliers (SiPM) which are nowadays commonly used in High Energy Physics experiments and many imaging applications. However the unique pixel shape and size have required a dedicated development by the University of Geneva and Hamamatsu. The resulting sensor has a surface of ∼94 mm2 and a total capacitance of ∼3.4 nF. These unique characteristics, combined with the stringent requirements of the CTA project on timing and charge resolution have led the University of Geneva to develop custom front-end electronics.
The preamplifier stage has been tailored in order to optimize the signal shape using measurement campaigns and electronic simulation of the sensor. A dedicated trans-impedance pre-amplifier topology is used resulting in a power consumption of 400 mW per pixel and a pulse width mmlsi0009" class="mathmlsrc">mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0168900216304788&_mathId=si0009.gif&_user=111111111&_pii=S0168900216304788&_rdoc=1&_issn=01689002&md5=c36b3d700d974d3b6d047bb640c94b51">mg class="imgLazyJSB inlineImage" height="10" width="30" alt="View the MathML source" style="margin-top: -5px; vertical-align: middle" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0168900216304788-si0009.gif">mathContainer hidden">mathCode"><math altimg="si0009.gif" overflow="scroll"><mo><mo><mn>30mn><mspace width="0.25em">mspace><mi>nsmi>math>. The measurements that have led to the choice of the different components and the resulting performance are detailed in this paper.
The slow control electronics was designed to provide the bias voltage with 6.7 mV precision and to correct for temperature variation with a forward feedback compensation with 0.17 °C resolution. It is fully configurable and can be monitored using CANbus interface. The architecture and the characterization of the various elements are presented.