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    User name Reinhold

    Log entry time 10:40:03 on March 26, 2007

    Entry number 197543

    This entry is a followup to: 197542

    Followups:

    keyword=Harp scan history: beam spot was degrading

    Below find a sequence of harp scan results, the most recent one (Fig. 3) from last night. The beam spot is really wide and seems to have a tail on one side. As I don't know the orientation, I don't know which side.

    If the scale on these plots is really in mm, then the tail reaches out to almost 5 mm. If the harp should travel horizontally, that can't fit through the target window with the raster on. The target window is 0.75 inch = 19 mm wide and 0.5 inch = 13 mm deep. At 30 degree, the horizontal clearance is roughly 19 mm x cos(30) - 13mm *sin(30) = 10 mm. The raster itself has been 4 to 5 mm in this direction. If the beam is roughly centered, that leaves only 2.5 to 3 mm on each side.



    A copy of this log entry has been emailed to: jones@jlab.org,camsonne@jlab.org



    Figure 1



    Figure 2



    Figure 3