Update on out-gassing tests 2-May-06 A. Gonidec & V. Falaleev

Reminder: - 10-6 mbar vacuum needed in a decay volume to keep the background to less than one fake even per year - according to preliminary estimations the main gas load source is outgassing of the decay (“blue”) tube and photon veto scintillator - a pump choice depends not only on vacuum needed but also on gas composition (mass spectrometry) Blue tube New test: - longer pumping time - mass spectrometer measurements Two methods of outgassing estimation: - dynamic: when a stable vacuum is reached an outgassing load is equal to pumping speed (unfortunately the pumping speed and outlet conductance is not well know) - static: when the pump is off the outgassing is the main reason of a pressure rise 2-May-06 A. Gonidec & V. Falaleev

2-May-06 A. Gonidec & V. Falaleev

Duration of pumping, days 10 15 Blue tube - results 2005 test 2006 test Duration of pumping, days 10 15 Vacuum reached, mbar 3 ·10-5 6 · 10-6 Average outgassing, (mbar l)/(sec cm2) 1.6 · 10-9 4.5 · 10-10 High vacuum outgassing, (mbar l)/(sec cm2) 3 · 10-9 1.35 · 10-9 High vacuum outgassing load (mbar l)/sec 1 · 10-2 Worst (dynamic) outgassing, (mbar l)/(sec cm2) 6.5 · 10-9 Worst (dynamic) outgassing load, (mbar l)/sec 4.8 · 10-2 Mass spectrometer measurement shows that the main gas component is water. 2-May-06 A. Gonidec & V. Falaleev

New test: - smaller and better prepared vacuum tank Scintillator New test: - smaller and better prepared vacuum tank - pure scintillator measurement 2005 test: 20 plates proto in big tank 2006 test: 2 plates in small tank CKM Number of days to reach stable pressure 25 14 5 days of pumping Average outgassing, (mbar l)/(sec cm2) 7 ·10-10 1.3 · 10-9 6.7·10-9 Worst outgassing , (mbar l)/(sec cm2) 2 · 10-9 2-May-06 A. Gonidec & V. Falaleev

2-May-06 A. Gonidec & V. Falaleev

Blue tube + Scintillator Blue tube Scintillator “Reasonable” outgassing, (mbar l)/(sec cm2) 1.35 · 10-9 1.3 · 10-9 Worst case outgassing, (mbar l)/(sec cm2) 6.5 · 10-9 2 · 10-9 Surface, cm2 7.4 · 106 3.9 · 107 Reasonable case Worst case Blue tube outgassing load (mbar l)/sec 1 · 10-2 4.8 · 10-2 Scintillator outgassing load (mbar l)/sec 5.1 · 10-2 7.8 · 10-2 Total outgassing load (mbar l)/sec 6.1 · 10-2 12.6 · 10-2 Pump power needed to reach 1 · 10-6 mbar (100% conductance), l/sec 6.1 · 104 12.6 · 104 Reminder: 5 · 104 l/sec pumps are available on the market 2-May-06 A. Gonidec & V. Falaleev

Ongoing tests and planned work Outgassing measurement of : TYVEC lead spaghetti prototype straws prototype Mass spectrometer analysis 2-May-06 A. Gonidec & V. Falaleev