Central vacuum valve in ALICE Pros and Cons ALICE TC – 20.11.2013
20/11/13 Central vacuum valve - Pros and Cons 2
With valve Without valve Done with TPC in parking position Bakeout Done once MNF and RB24 pipe in place a very first bakeout could be done full proof of tightness of the pipe before moving TPC with the TPC in parking position, however we lose one NEG activation ITS-MFT RB24 beampipe (and compensator Must be done with RB24 beampipe installation magnet) can be removed (and compensator magnet) in place (after bakeout) MNF access No risk if valve closed Imperative to protect RB24 pipe in during EOY order to not compromise the vacuum in central and RB26 pipes Compensator No actions on ITS-MFT-central pipe if Implies to extract the ITS-MFT and re- magnet valve is closed bakeout the central and RB26 pipes removal Background Factor 2 higher background (beam gas Less background coming from left side) than without valve Material More material Less material budget in the fw region 20/11/13 Central vacuum valve - Pros and Cons 3
With valve Without valve Done with TPC in parking position Bakeout Done once MNF and RB24 pipe in place a very first bakeout could be done full proof of tightness of the pipe before moving TPC with the TPC in parking position, however we lose one NEG activation ITS-MFT RB24 beampipe (and compensator Must be done with RB24 beampipe installation magnet) can be removed (and compensator magnet) in place (after bakeout) MNF access No risk if valve closed Imperative to protect RB24 pipe in during EOY order to not compromise the vacuum in central and RB26 pipes Compensator No actions on ITS-MFT-central pipe if Implies to extract the ITS-MFT and re- magnet valve is closed bakeout the central and RB26 pipes removal Background Factor 2 higher background (beam gas Less background coming from left side) than without valve Material More material Less material budget in the fw region 20/11/13 Central vacuum valve - Pros and Cons 4
Ion pump and vacuum gauge Meeting with R.Veness, G.Schneider, M.A.Gallilee, J.Perez Espinos, W.Riegler and A.Tauro (10.1.2013) • Ion pump needed to pump out non NEG gases (e.g. methane). There is one ion pump every 26 m max., and it seems not possible to remove the pump. It could be done in Al. • Pirani gauge needed for safety. It tells whether it’s safe to open the valve. It could be moved to the tunnel (SR23 side). New valve fitted with a gauge. 20/11/13 Central vacuum valve - Pros and Cons 5
Backup slides
Al ion pump (ATLAS) 9 Jan 13 A.Tauro 7
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