Search

Abstract: Time to Digital Converters (TDCs) are very common devices in particles physics experiments. A lot of “off-the-shelf” TDCs can be employed but the necessity of a custom DAta acQuisition (DAQ) system makes the TDCs implemented on the Field-Programmable Gate Arrays (FPGAs) desirable. Most of the architectures developed so far are based on the tapped delay lines with precision down to 10ps, obtained with high FPGA resources usage and non-linearity issues to be managed. Often such precision is not necessary; in this case TDC architectures with low resources occupancy are preferable allowing the implementation of data processing systems and of other utilities on the same device. In order to reconstruct γγ physics events tagged with High Energy Tagger (HET) in the KLOE-2 (K LOng Experiment 2), we need to measure the Time Of Flight (TOF) of the electrons and positrons from the KLOE-2 Interaction Point (IP) to our tagging stations (11m apart). The required resolution must be better than the bunch spacing (2.7ns). We have developed and implemented on a Xilinx Virtex-5 FPGA a 32 channel TDC with a precision of 255ps and low non-linearity effects along with an embedded data acquisition system and the interface to the online FARM of KLOE-2. The TDC is based on a low resources occupancy technique: the 4×Oversampling technique which, in this work, is pushed to its best resolution and its performances were exhaustively measured. [Copyright &y& Elsevier]

Abstract: The gamma–gamma physics is a relevant part of the physics programme of KLOE2 project at . In particular, there is a strong interest to measure the cross-section for the process in the low energy region for its relevance in the context of the assessing the existence and nature of the sigma meson. In this talk we present the tagging system for the final leptons which we are developing. We will illustrate the characteristics and performance required for the detectors and the acquisition system. In particular, this system should be able to acquire data for each bunch crossing and therefore to a frequency of 368MHz. [Copyright &y& Elsevier]