WHAT DO WE KNOW ABOUT UFO?

The term ''UFO'' has been adopted from the plasma physics community, where a phenomena of dust particles falling into plasma has been observed. In LHC, this name is used for the sudden losses with a millisecond-scale duration appearing in any part of the accelerator ring. The properties of these events suggest that they are generated by small objects (dust) falling into the beam or being attracted by the beam electromagnetic fields.

The first UFO event has been observed on July 7th, 2010 as it triggered a beam dump, because of losses observed by the BLM system. The post-mortem data [4] of this event, presented in Figure 3, show a complex time structure with 6 peaks separated by 70 or $\rm 100~\mu s$ . For a detailed analysis see [5].

Figure 3: The post-mortem data of the first UFO event which caused a beam dump.