Search

Among other detectors, the T2K neutrino experiment comprises three large time projection chambers segmented into over 124.000 electronics channels. The back-end electronics system is designed to distribute a reference clock to the front-end electronics, aggregate event data over seventy-two 2 Gbit/s optical links and format events that are sent via a standard PC to the global data acquisition system of the experiment. The core of this system is a set of 18 Data Concentrator Cards based on an inexpensive commercial Field Programmable Gate Array evaluation kit with specific add-ons. We describe the adaptations that were made to the original platform, and detail the design of the firmware and software running on the embedded PowerPC processor of the FPGA of a Data Concentrator Card. We show how the intrinsic parallelism and a mixed firmware and software implementation of the data reduction and acquisition tasks lead to a flexible system capable of extracting in real time meaningful information from the 2.5 GByte/s of raw event data produced by the front-end electronics at a nominal rate of 20 Hz. [ABSTRACT FROM PUBLISHER]

A new data acquisition (DAQ) system for the H1 Luminosity measurement at HERA II has been commissioned in 2002 in parallel with the machine; aiming at 1% precision measurement on each of the 186 colliding bunches in less than 1 mm, it is based on a commercial mezzanine processing card mounted on a VME station, reading custom-designed analog-to-digital converter (ADC) and time-to-digital converter (TDC) VME cards via a dedicated bus. The protocol on this 20-MHz data bus is implemented on a field-programmable gate array (FPGA), which also performs the triggering for two acquisition modes (triggered and by train), the synchronization of the digitization boards and the formatting of the data in an internal FIFO. The data are then fetched and histogramined by a dedicated PowerPC processor. The online analysis of the distributions takes place on the VME station. Maximum histogramming rates of 0.5 MHz have been reached in the train mode (three channels readout) and about 110 kHz in the triggered mode (26 channels readout). [ABSTRACT FROM AUTHOR]