Low-mass radiation-hard beam profile monitors for high energy protons using microfabricated metalthin-films

In High Energy Physics (HEP) experiments built at the European Organization for Nuclear Research (CERN) it is a common practice to expose electronic components and systems to particle beams, in order to assess their level of radiation tolerance and reliability when operating in a radiation environment. One of the facilities used for such tests is the CERN Proton Irradiation Facility (IRRAD), where several hundreds of samples are irradiated yearly with a 24 GeV/c proton beam extracted from the CERN Proton Synchrotron (PS) accelerator. In order to properly control the irradiation beam and guarantee reliable results during the tests, Beam Profile Monitor (BPM) devices are used. The current BPMs are fabricated as standard flexible PCBs featuring a matrix of metallic sensing pads. When exposed to the particle beam, secondary electrons are emitted from each pad, thus generating a charge proportional to the particle flux crossing the pads. The charge is measured individually for each pad using a dedicated readout system, and so the shape, the position and the intensity of the beam-spot are obtained. Beam profile determination of high intensity beams implies the usage of non-invasive and radiation tolerant (~1018 p/cm2/year) devices. This study proposes a new fabrication method using standard microfabrication techniques in order to improve the radiation tolerance of the BPMs while greatly reducing the device thickness, thus making them also appropriate to be used for the monitoring of lower energy particle beams.