Beam profile monitor for antiproton-nucleus annihilation cross section measurements

The ASACUSA (the Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration is planning to measure the antiproton-nucleus annihilation cross sections at kinetic energy 120 keV on targets of various mass numbers (C, Ni, Sn, and Pt) using the Antiproton Decelerator (AD) of CERN. No previous measurement exists in this region where the A-dependence of this cross section is expected to deviate from the A^(2/3) as reported by the Obelix collaboration. For this measurement, a beam profile monitor based on secondary electron emission with a grid of electrode pads fabricated on an FR4-type glass-epoxy circuit board was developed. The advantage of this detector is that it is simple, lightweight, and low cost. It was used to measure the spatial profile of 100-ns-long beam pulses containing > 6 × 10⁴ antiprotons with an active area of 40 mm × 40 mm and a spatial resolution of 4 mm.