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Silicon photomultipliers (SiPMs) have become an alternative to traditional tubes due to several features. However, their implementation to form large arrays is still a challenge especially due to their relatively high intrinsic noise, depending on the chosen readout. In this contribution, two modules composed of 12 \times 12 SiPMs with an area of roughly 50~\mm\times 50~\mm are used in coincidence. Coincidence resolving time (CRT) results with a field-programmable gate array, in combination with a time to digital converter, are shown as a function of both the sensor bias voltage and the digitizer threshold. The dependence of the CRT on the sensor matrix temperature, the amount of SiPM active area and the crystal type is also analyzed. Measurements carried out with a crystal array of 2 mm pixel size and 10 mm height have shown time resolutions for the entire 288 SiPM two-detector set-up as good as 800 ps full width at half maximum (FWHM). [ABSTRACT FROM PUBLISHER]

This contribution describes an accurate approach implementing a Time-to-Digital Converter using a Field-Programmable Gate Array (FPGA) device. Time differences with a FWHM better than 100 ps for 24 pairs of channels working simultaneously have been achieved. This was possible through the proper management of FPGA internal resources and by an accurate device calibration process minimizing the effect of temperature and voltage fluctuations. The system calibration results and the time differences between multiple channels are presented. The current approach suggests the possibility of carrying out precise Time of Flight (TOF) measurements with, for instance, Positron Emission Tomography (PET) systems. [ABSTRACT FROM PUBLISHER]

This paper describes the development of the optical multiplexer board (OMB), also known as PreROD board, for the TileCal readout system in the ATLAS experiment. The aim of this board is to overcome the problems that may arise in the integrity of data due to radiation effects. The solution adopted has been to add redundancy to data transmission and so two optical fibers with the same data come out from the detector front end boards. The OMB has to decide in real time which fiber, eventually, carries data with no errors switching it to the output link connected to the read out driver (ROD) motherboard where data processing takes place. Besides, the board may be also used as a data injector for testing purposes of the ROD motherboard. The paper describes the design and tests of the first prototype, implemented as a 6U VME64x slave module, including both hardware aspects, focusing on signal integrity problems, and firmware aspects, dealing with the cyclic redundancy code algorithms used to check data consistency used to make the decision. [ABSTRACT FROM AUTHOR]