The large-area micro-channel plate entrance detector of the heavy-ion magnetic spectrometer PRISMA

This paper describes the entrance detector of the magnetic spectrometer PRISMA recently installed at Legnaro. The detector is based on rectangular (80×100mm2) Micro-Channel Plates (MCP). It provides a fast time signal and its position-sensitive anode allows to extract the X and Y information. It exploits an electrostatic field for the acceleration of secondary electrons from a thin Carbon foil (≃20μg/cm2) onto the MCP assembly. The electrons are guided by a parallel magnetic field. Good performances were obtained in the laboratory tests. The detector is presently installed at the entrance of PRISMA and gives resolutions ⩽400ps in time, and 1 mm in both X and Y-axes, with efficiency ≃100%, in typical experiments with heavy-ion beams.