14 October 2010Eddy Jans 0 VELO-vacuum “problem” VELO Meeting On Sunday October 3 at 10h15 a sudden increase of a factor 6 of the pressure in the beam volume was observed. Both PE411 and PE412 indicate a rise from 1e-9 to 6e-9. See next two slides for the pressure and HV/I of the ion pumps.

14 October 2010Eddy Jans 1 VELO Meeting e-9 e-8 e-7 e-6 [mbar] detector volume beam volume beams dumped beams injected and ramped

14 October 2010Eddy Jans 2 VELO Meeting Ion pumps IP431 and IP441 HV I Also observed near other experiments. Presumably due to electron cloud that is produced. Effect can locally be reduced with a solenoid.

14 October 2010Eddy Jans 3 VELO Meeting VELO-cooling “problem” Evaporator pressure of the A-side, during last the 7 months. TL_PT003

14 October 2010Eddy Jans 4 VELO Meeting A small increase of the evaporator pressure on the C-side, over the last 8 months causes a small increase of the operational temperature replacement of obstructed filters TR_PT003

14 October 2010Eddy Jans 5 VELO Meeting VELO-motion “problems” command sequence “move out”, “abort movement” and another “move out” within 5 seconds results in a hanging PLC with inconsistent readings of potmeters and resolvers. in the weekend a potmeter calibration was done ((ir)relevant info ??) in the first closing thereafter, the Top-potmeter on the C-side went into error, causing the DCS to go into error, while moving was still possible.

14 October 2010Eddy Jans 6 VELO Meeting LHC-“problems” Up to 248 bunches/beam have been injected, ramped, stored, squeezed and brought into collision. Since last weekend severe injection problems with Beam1, i.e. the one that goes via TI2 to Alice They think there is an obstruction somewhere in the pipe …………….