A transverse beam profile monitor for p-p studies in the CERN SPS

In the SPS collider, counter-rotating beams of protons and antiprotons will be stored at 270 GeV/c for many hours. Each beam will consist of up to 6 bunches of 10¹¹ particles. A simple device has been developed which allows the transverse profile of each individual bunch to be measured in an almost nondestructive way. ^1,2,3). A fine beryllium wire is passed quickly (/spl I.itilde/4m/s) through the beam. The profile is measured by detecting the high-energy secondary particles produced in the wire. Due to the strong directionality of secondary particle production the profile of each proton and antiproton bunch can be measured simultaneously using two scintillators placed either side of the wire and close to the beam pipe. In addition, profiles of single beams can be obtained by measuring the secondary electron current emitted by the wire. The device has been successfully tested during storage studies with protons.