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    Make New Entry, Make Followup Entry

    User name V. Sulkosky

    Log entry time 11:16:15 on February 26, 2011

    Entry number 348775

    This entry is a followup to: 348709

    keyword=BB-LHRS Timing Information and setup (T6)

    Prior to the final setup this morning, I made sure the delays on T3 and T1 were zeroed. I then used the edtmsetup script as described in Halog entry # 348767
     Times to get from target to point at which EDTM is injected
     Proton into BigBite:
        0.875     0.450     0.404     0.300 GeV/c
        0.682     0.432     0.395     0.304   Beta 
         17.1      27        29.5      38.3   TOF (3.5 m to E-plane)
        226       226       226       226     Signal cable from PMT
        -----     ---       -----     -----
        243 ns    253 ns    256 ns    264 ns
     Electron into L-HRS: (1.0 to 3.6 GeV/c)
       87   TOF (26 m to s2m)
       60   Signal cable from PMT
      147 ns
     Time difference between proton and electron signals to EDTM
     injection point:
        0.875     0.450     0.404     0.300 GeV/c
    B-L = 96 ns    106 ns    109 ns    117 ns
    The edtm configuration for this is set to 
    ./edtmsetup 0 92 232  
    The T6 coincidence is formed with an overlap between T3 and the E-plane
    singles trigger (formerly T6).  The electron (T3) was chosen to carry
    the T6 time.  For this trigger setup, the scripts t1_delay and t3_delay
    are not used.  Instead I used old fashioned cable delay and a LeCroy
    dual gate generator model 222.  
    I took a copy of T3 and E-plane singles that were relatively undelayed
    from where they originate at the weldment.  The timing difference at
    this point has the E-plane trigger generation 136 ns before the T3 
    trigger reaches the weldment and is massaged.  I used the LeCroy 222 to
    delay a copy of T6 by 140 ns.  I then delayed the un-delayed copy of T3
    by 66 ns to form T6 coincidence.  T3 comes inside the E-plane window
    about 50 ns after the E-plane trigger opens.
    All these numbers are based on the slowest proton in BigBite 
    (300 MeV/c).  The time difference between slowest and fastest proton in
    BigBite is only 21 ns.  Hence between 300 MeV/c and 875 MeV/c the 
    E-plane trigger window will slip forward by 21 ns preserving the 
    coincidence time setup for all BigBite momenta.
    At the point the coincidence is formed, the E-plane trigger width is
    set to about 140 ns (coincidence window).  The delayed T3 copy is set
    to be about 50-60 ns wide.
    Not that it matters for the N-Delta settings, but T5 comes before T6 at
    the Trigger supervisor by 18 ns.  However a real T5 does not exist for
    the BigBite elastic (e,e'p) settings.

    A copy of this log entry has been emailed to: nmuangma,rshneor,kalyan,danez,yez,doug,eip,orchen,igorko