Fully FPGA-based and all-reconfigurable TDC for 3D (X, Y, t) Cross Delay-Line detectors

Time-resolved experiments often need detection devices able to provide information about position and arrival time of each detected event. Cross Delay-Lines detectors (CDL), which use arrival time information also for position detection, are the most suited instruments for this task and time resolution is a fundamental requirement, along with the high versatility and fast real-time computing. Typical acquisition architectures, based on Time-to-Digital Converters (TDC) followed by a Field Programmable Gate Array (FPGA), combine very fast parallel computing with a high time precision, allowing to perform state-of-the-art time-resolved experiments. In these devices, time precision as much as time accuracy are fundamental in order to guarantee a homogenous time-to-space conversion. Nevertheless, time resolution is still a limiting factor when time resolved experiments are associated to imaging. In 2017 at Nuclear Science Symposium, inside "Development of fully FPGA-based 3D (X, Y, t) detection systems using multichannel Tapped Delay-Line Time-to-Digital Converter with Cross Delay-Line detectors" we presented a new approach, combining FPGA-based multi-channel TDC and an efficient multipurpose readout logic addressed to CDL detector. In this contribution, thanks to the modularity and reconfigurability offered by the FPGA, we redesigned the firmware that describes the TDC increasing the resolution from 10 ps to 1 ps, the channel precision from 15 ps r.m.s. to 9.7 ps r.m.s. and, reducing the accuracy from 200 ps to 40 ps. As result, we have greatly improved the overall performance and versatility of CDL detector systems allowing image acquisition with spatial precision better than 30 μm. These make possible the application in a multidisciplinary research center like the Elettra and FERMI lightsources where electron analyzers and Time-of-Flight devices endowed with CDL detectors allow very high spatial and time resolved spectroscopy experiments.