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    User name R. Michaels

    Log entry time 12:35:27 on October27,2000

    Entry number 51054

    Followups:

    keyword=re: trigger for reversed polarity

    There is a "theorem" that the trigger supervisor must be on
    the spectrometer which has the slowest particles (but it doesn't
    matter if the time difference is less than ~25 nsec). So, for
    reversed polarity, the trigger doesn't work well unless we move
    a bunch of cables. Anyway, the following MIGHT work (at
    least to obtain T5). All this on adaqh2:
    Compute the delay of the protons. From adaqh2 type "hdelay p 0.88"
    to compute the time in nsec.
    Go to the right directory, typing "gotrigger"
    Start XTrigMang.
    Select Right spectrometer
    Select trigR_delay3
    Enter channel # and set time (the units of set time are 8 nsec per set number,
    e.g. a setting of 5 = 40 nsec.)
    Don't forget: Press "set" to read in, then "down" to download to crate.
    And here are the relevant channels, remember channel # start at 0
    Affecting the R-arm trig delay: channels 4,5,6
    Affecting the R-arm delay to its own retiming: 10,11,12,13
    The R-arm delay + R-delay-retime must add to a constant.
    So, if the L-arm is now much slower, you need to add delay
    to R-arm to wait. Example
    P_L = 0.86 (protons), R-arm are relativistic electrons
    adaqh2> hdelay p 0.86
    delay = 40.777640 nsec for a proton
    Ok, first run 'trigsetup' with 'infinite' momentum (4 GeV). Then
    in trigR_delay3, add 5 units to channel 4-6 (NOTE: max is 15 units
    on any one channel, you may have to distribute among channels).
    Then, subtract 5 units in the channel range 10-13.
    And hope it works (I didn't anticipate this request).