Beam pipe pressure and background rate infill 2181. The expected background rate has been estimated using the linear parameterization shown in Fig. 2. VGPB.120.4L2, VGPB.231.4L2, and VGI.514.4L2 are the pressure gauges located in front of the Inner triplet (at 69.7 m from IP2), on the TDI beam stopper (at 80 m from IP2), and on the large recombination chamber (at 109 m from IP2), respectively.