Vacuum

• Vacuum pressure at H1 in 2000 (red, log) and e⁺ current (black, lin):

  
  The vacuum pressure is determined by the positron current, reaching 6 10^-9 mbar at 50 mA.
   

• 19.5.2002: leak at SR 13m, venting the ZEUS interaction region:

  
   

• 2.6.2002: small vacuum leak close to H1:

  
   

• Pressure at z = -6m at H1 and at ZEUS during June:

  

  The base pressure in South shows good recovery after the leak, but the pressure in North shows no improvement.
   

• Maintenance day Wed 3.7.2002:
  Non-evaporative getter pumps regenerated, Ti sublimation pumps fired

  

  No improvement seen. The pump NR:HP3.6 (at ABS-1, between GG and GI1, at z=-3.6m) shows some effect from the cold beam pipe in GG, which was warmed up to about 100K and then cooled down again to the standard 70K.
   

• Pressure profile with 21 mA e⁺ beam at 12 GeV on July 5:

  
   

• The pumps on the left of H1 are also problematic:

  

  Again, no improvement seen after the maintenance day.
   

• Another nasty feature are sudden pressure bumps:

  

  The pressure increases by a factor of 40 within 1 minute, leading to chamber and even LAR calorimeter HV trips.

  Another one, with aftershocks:

  

  These pressure bumps occur quite frequently during a fill