Proton Beam APerture MoniTor instrument design and overview for the Commissioning and Operation of ESS High Power Beam on Target

This paper presents a detector developed to protect the ESS spallation target. The detector is installed to receive a proton beam that has a peak current of 62.5 mA, an average power of 5 MW, and energy up to 2 GeV. It is designed to detect any part of the proton beam that goes outside a defined aperture, which is deemed as an errant beam condition. This detector is mainly used for machine protection. The detector works based on two physical processes. The first process is the generation of current in metallic blades, which is proportional to the intercepting beam. The second process is heat load from the beam energy deposition in interacting thermocouples. The combination of these two signals allows the detection of events ranging from microseconds to several minutes. This paper also presents the design of the instrument, its efficiency, and its range of operation.