A common data acquisition system for high intensity beam experiments

The J-PARC [Ref.1] facility, where many physics experiments for nuclear physics, kaon physics and neutrino oscillation measurement are proposed, will be ready in 2008. The required trigger frequency ranges from 500 Hz to over 10 kHz depending on the aim of the experiment. We developed a commonly usable data acquisition (DAQ) system for these wide range experiments. The design concepts are as follows: 1) read-out modules have front-end buffers and an on-board data reduction function to cope with up to 10 kHz trigger frequency, 2) anyone can easily use the default setup and develop auxiliary modules, and 3) components of the system are maintained at a low cost. We adopted the VME and PCI mezzanine card (PMC) standards for the readout module. Our system consists of a VME-based crate with a power supply extension, modularized read-out boards which contain built-in PMC PCs, and several signal handling boards. We use a network based back-end system, to which the data from the read-out boards are transferred. Data are converted by the read-out board and transferred to the back-end system with the network or serial link. Trigger signals are distributed by a general purpose FPGA module. Additional systems based on traditional standards such as CAMAC can be integrated into the system, when the trigger rate is low, at the back-end system.