A beam size monitor based on velocity spectrum measurements of the rest gas ions accelerated by the space-charge force

In the design stage of the LHC (Large Hadron Collider/CERN, Switzerland), it is necessary to develop non-destructive beam size monitors. In this framework a profile monitor (BIGP) was proposed based on velocity spectrum measurements of the rest gas ions accelerated by the beam space-charge force. The paper presents simulation studies of the detector, a description of the prototype installed in the SPS and first measurement results.