DAQ upgrade for the use of the high intensity π beam in the Σp scattering experiment (J-PARC E40)

The short range repulsion of the baryon-baryon interaction is phenomenally known but its origin is not conclusive. One possible source is the Pauli blocking in the quark level and the quite strong repulsion in the Σ⁺p (S=1, I=3/2) channel is expected. Thus, we planed to perform a high statistics Σp scattering experiment to investigate the origin of the repulsive core through the Σ⁺p scattering and to reveal the nature of the ΣN interaction through the Σ^- p scatterings.

In order to perform this experiment within the reasonable beam time, the use of the high intensity π beam up to 10 MHz is the key. However, as the increase of the beam intensity makes the trigger rate high, the significant data loss is expected with the present DAQ system. Thus, we upgraded our DAQ system. One upgraded point is to shorten the hardware busy time by replacing several electronics and by improving the readout method. The next one is to introduce the specified trigger system to reduce the trigger rate.

In this talk, we will report the upgrade of the DAQ system and its performance obtained in the last June beam time.