• K. Thomsen
  PSI, Villigen

For the neutron spallation source SINQ at PSI a novel visual monitor (VIMOS) has been devised to guarantee correct beam conditions, triggered at the occasion of irradiating the delicate liquid metal target during the MEGAPIE project. VIMOS is looking directly for the most relevant parameter: it checks whether any point on the target is hotter than allowed. For this purpose the incandescence of a glowing mesh right in front of the beam entrance window is observed by means of dedicated radiation hard optics and suitable cameras. Starting from the initial goal of reliably detecting beam anomalies in a timely manner the scope of the system has been extended to serve as a standard device for beam monitoring and fine tuning of the settings of the proton beam transport lines. Over the course of the five years of continuous reliable operation of this unique system valuable experience has accumulated, which is employed for steady improvements of the device with respect to endurance in the radiation environment, calibration, maintenance, and price. A summary of the operational experience of VIMOS will be reported as well as steps taken towards further upgrades.