MKD dust related actions Viliam Senaj Technical Coordination Meeting 27/01/2015

Erratic of 2 nd family on MKD A/B2 on 18/01 at 6.5 TeV Presence of some amount of dust inside generators MKD confirmed (B1: B+N; B2: A+B+N+O) Cleaning – delicate Incorrect cleaning - worse Done during WE /01/2015: – Conditioning up to 6.8 TeV – OK – 1 ES up to 7.1 TeV – OK Plan: – TeV (cycle test) – If problem again on A/B2 – replacement – If problem on more generators – cleaning of all of them – Otherwise waiting with cleaning till confirmation of possibility to cover the perforation (overheating?) to obtain “dust proof MKD rack” Cleaning strategy

Dust proofing the MKD Reliability run in 2008 – with side panels non-perforated Perforated panels installed at the beginning of 2009 (cooling reason?) Temperature stabilisation (Peltier module) added to the GTO stack compartment during the same period Self triggering started in July 2009 To avoid dust penetration – blinding of perforation Test of temperature rise inside “Main capacitor compartment” with perforation blinded – ongoing in 867 Certain temperature rise expected with some influence to a pulse current value: main capacitor temperature dependence ~ ppm/K; +10 deg ~ % of Imax1 Temperature rise so far observed (after 3h at 2 TeV) ~ + 3 deg ~ % on Imax1 (in reality no visible change of magnet current)