The readout of the LHCb calorimeters

This document describes the readout of the LHCb calorimeters. The front-end electronics has been described in a note [l), which is mainly devoted to the shaping, integration and digitisation at 40 MHz of the PM signals. Once digitised, the signal is sent to the trigger part of the front-end board, described in [2], and also to a pipeline, waiting for the trigger decision. This note describes how the digitised values are handled, up to the interface with the DAQ system. The readout of the PreShower and SPD information will follow a very similar path. We in fact intend to use the same design for this part of the front-end board, and the same Calorimeter Read Out Card (CROC) to format the data for the DAQ. While the design of the front-end board is advanced, and a prototype already available, the CROC, which are needed in a smaller number (26), are still at the conceptual design stage.