AMS Time of Flight (TOF) Scintillators

Contact: Giuliano Laurenti

More information should be available about the scintillators.

• 4 planes (S1-S4), two above and two below the magnet.
• 14 paddles per plane.
• 3 PMT for each end (2) of each paddle.
• 336 = 4*14*2*3 PMTs total.
• For each PMT, 1 electronics channel and one controlled HV supply.
• Paddles in a plane are overlapped slightly in an over/under arrangement and are held in Al brackets. A rough Side view:

                    --+       +--       --+       +--
    S1     ===========|       |===========|       |===========
                    +-+       +-+       +-+       +-+  <- Al Bracket
  Paddles           |===========|       |===========|
            --------+-----------+-------+-----------+--------
  Al        |||||||||||||||||||||||||||||||||||||||||||||||||
   Honey-   |||||||||||||||||||||||||||||||||||||||||||||||||
    Comb    |||||||||||||||||||||||||||||||||||||||||||||||||
  (100mm?)  |||||||||||||||||||||||||||||||||||||||||||||||||
            -------------------------------------------------
    S2      = = = = = = = = = = = = = = = = = = = = = = = = =
            -------------------------------------------------
  Paddles   = = = = = = = = = = = = = = = = = = = = = = = = =
  (orthog.  -------------------------------------------------
   to S1)
  
  

• A Paddle end, from the top, looks like:

        ----------+|+------\ ===============  Mag Shield
                  ||| Light \  +-----+||
                  ||| Guide  ||| PMT |||=== Cables ->
                  |||       /  +-----+||
                  ||+------/ ===============
                  ||+------\ ===============  Mag Shield 
                  |||       \  +-----+||
      SCINT       |||  LG    ||| PMT |||=== Cables ->
                  |||       /  +-----+||
                  ||+------/ ===============
                  ||+------\ ===============  Mag Shield 
                  |||       \  +-----+||
                  |||  LG    ||| PMT |||=== Cables ->
                  |||       /  +-----+|| 
        ----------+|+------/ ================
  
                   ^          ^       ^^ 
                   |          |       ||- HV Board(s)
                   |          + Optical Pad(?)
                   +-Optical Glue 
  

• The scintillator is 10mm thick Bicron BC-408.
• The tapered light guides (one/PMT) are glued on to the ends of the paddles.
• On the other end they connect to the PMT via a Si Optical Pad.
• The PMTs are Hammamatsu R5900's, which are square, with photocathode area of 18x18 mm**2 and size 25x25 mm*2, length 15mm (?). Operating voltage about 900V.
• To operate in the AMS magnetic field, some (soft Fe?) shielding will need to be installed. Calculations in progress.
• The PMTs are mounted on HV board(s), either one/PMT or one/triplet of PMTs.
• The cables (Signal, HV control,...) are flexibly connected to some patch panel mounted on a support structure, from which they are connected to the SFE boards mounted in the electronics crates at each of the 8 corners.

In addition there is a series of reports from LSU (worth reading):

• Test and Evaluation of the AMS Baseline Design for the Time-of-Flight Scintillator Subsystem; AMS report: LA 95-01; 3pg.
• R5600 Photomultiplier Tube Characterization; LSU Technical Note: AMS 95-01; 5pg.
• Materials Enviromental Testing: Hartel HE-17017 Optical Cement; LSU Technical Note: AMS 95-02; 6pg.
• The Pulse Height Response of AMS Test Scintillator Panels; LSU Technical Note: AMS 95-03; 25pg.
• Model Calculations of Scintillator Response; LSU Technical Note: AMS 95-04; 12pg.
• Random Vibration Test of R5600 PMT's; LSU Technical Note: AMS 95-05; 9pg.
• Timing Performance for AMS Test Panels; LSU Technical Note: AMS 95-06; 27pg.

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