BSMD related information

  1. BSMD gain fluctuations due to the atmospheric pressure variations by Olexandr
    during pp500 data taking (March 1 - April 14 of 2009)
  2. table w/ atmospheric pressure
  3. Relative calibration by Willie
  4. Absolute calib, Willie:
    1. take 1
    2. alignment
  5. Stability of BSMD temperature
    My expectation is that the temperature of the BSMD gas volume itself would be quite stable. The TPC Outer field cage and TOF trays both have water cooling, so the radius inside the BEMC should be at a fairly constant temperature. The Magnet coils have a large rate (~1,200 gpm) of water cooling on the outer radius of the BEMC, and it is regulated to have a constant mean temperature of 80 F. For a rapid temperature excursion to impact the temperature of the BSMD gas volume it has to conduct heat through either the inner radii (Stainless steel plate, then six layers of plastic and five layers of Pb) or the outer radii (S.S. plate and ~ 15 layers of Pb and plastic), which should damp down any such excursion.
    The air temperature in the IR can fluctuate some, and certainly there is a gradient in temperature between the floor level and the top of the BEMC cylinder, but the level of temperature fluctuation is on the order of 3 to 4 degrees F or less, and again, there is a large thermal mass surrounding the BSMD gas volume that should damp out these fluctuations.
    As far as temperature recordings, the IR air temperature is recorded in Slow controls, and stored in the STAR database. The FTPC, and I believe the TPC, also record temperatures at a few places and put the info. into the databases.
    In summary, my expectation Jan is that the mean temperature of the BSMD gas volume probably doesn't change by more than about 1 degree F during steady running. A thought. The change in the IR air temperature between the bottom and top of the BEMC cylinder is probably about 6 F or so. If this outside air temp. had any impact on the BSMD gains one should see some effect in comparing the BSMD gains in the top and bottom of the BEMC cylinder.
    Greetings,
    Bill
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