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International audience; ALTIROC0 is an 8-channel ASIC prototype designed to readout 1x1 or 2x2 mm2 50 µm thick Low Gain Avalanche Diodes (LGAD) of the ATLAS High Granularity Timing Detector (HGTD). The targeted combined time resolution of the sensor and the readout electronics is 30 ps for one MIP. Each analog channel of the ASIC must exhibit an extremely low jitter to ensure this challenging time resolution, while keeping a low power consumption of 2 mW/channel. A “Time Over Threshold” and a “Constant Fraction Discriminator” architecture are integrated to correct for the time walk. Test bench measurements performed on the ASIC received in April 2017 are presented.

EASIROC, standing for Extended Analogue Si-pm Integrated ReadOut Chip is a 32 channels fully analogue front end ASIC dedicated to readout SiPM detectors. This low power and highly versatile ASIC was developed from the chip SPIROC[1] which has been designed for the Analogue Hadronic Calorimeter foreseen at the International Linear Collider. EASIROC integrates a 4.5 V range 8-bit DAC per channel for individual SIPM gain adjustment. A multiplexed charge measurement from 160 fC up to 320 pC is available thanks to 2 analogue outputs. These charge paths are made of 2 variable gain preamplifiers followed by 2 tuneable shapers and a track and hold. A trigger path integrates a fast shaper followed by a discriminator the threshold of which is set by an integrated 10-bit DAC. These 32 trigger outputs can be used for timing measurements. The power consumption is lower than 5 mW/channel and unused features can be powered OFF to decrease the power. The chip has been designed in AMS 0.35 μm SiGe technology and 4000 dies have been produced in 2010. Its versatility allows its use in many photo detector experiments and is already used for PEBS, MuRAY, J-PARC and medical imaging.

Petiroc is a 16-channel front-end ASIC designed to readout silicon photomultipliers (SiPMs) for particle time-of-flight measurement applications. Petiroc combines a very fast and low-jitter trigger with an accurate charge measurement. The concept of the ASIC is to combine two measurement lines that won't interfere one with another to measure both first incident photon timing measurement and whole crystal light charge integration. An adjustment of the SiPM high voltage is possible using a channel-by-channel input DAC. That allows a fine SiPM gain and dark noise adjustment at the system level to correct for the non-uniformity of SiPMs. The power consumption is 3.5 mW/channel, excluding ASIC outing buffer. First measurement on Petiroc shows a time jitter down to 16ps on 20 photoelectrons test pulses and 46ps with 15 photoelectrons from a Hamamatsu MPPC. Charge measurement has been measured and 1% linearity has been measured up to 2000 photoelectrons. Energy resolution has been measured at 9.5% FWMH. The main application of Petiroc is PET time-of-flight prototyping but can be used for any application that requires both sharp time resolution and precise energy measurement.

In hadron therapy, prompt gamma rays are emitted during the treatment from the excited nuclei in the tissue, and can be employed for dose monitoring. A Compton telescope is under development within the ENVISION project for imaging the prompt gamma rays. The telescope will consist of several detector layers, each composed of a continuous LaBr 3 crystal coupled to silicon photomultiplier (SiPM) arrays. A first detector made of a 16×18×5 mm3 LaBr 3 crystal coupled to a SiPM array has been characterized in order to evaluate its performance for the proposed application.