MD#2889: 16L2 Event Dynamics and UFO Nature Investigation

Micrometer sized particles (UFOs) entering the beam are a known cause of localized beam losses since the beginning of high intensity beam operation, however the origin of these particles is not fully known. Furthermore, during 2017 a new type of UFO events appeared around the 16L2 interconnection in the LHC, leading to beam instabilities resulting in major impact on beam availability. In MD#2036 a proof-of-concept method utilizing blown-up bunches and a fast loss detection system for studying the dynamics of UFOs, simulated by the wirescanners, was successfully attempted. In this MD it was shown that real UFO dynamics are possible to study employing this method. The MD was done in parallel with MD#2934 and the procedure was adjusted for both MDs to profit as much as possible. In the end a single 16L2 induced beam dump occurred, but several conclusions about the UFO dynamics can already be drawn.