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    User name mcnulty

    Log entry time 04:48:15 on August28,2009

    Entry number 286469

    This entry is a followup to: 286457


    keyword=Rarm Hapdet alignment study

    Rarm Hapdet alignment study:
    See comments from Larm alignment study.
    Figure 1 is Ta spectrum from run 4351.
    Figure 2 is H2 spectrum from run 4382.

    The high rate region of the spectra is at x=~0.2 and y=~0.2. It looks like for the Rarm, we need to shift the hapdet toward negative y (this means away from the beamline for the Rarm).
    Again, the super-elastic edge is ~0.3m from the photo-cathode--note that from my measurements in the hall, the right arm photo-cathode is ~0.04m more upstream (relative to the VDC fiducials) than the left arm photo-cathode. The x-y rotation (yaw angle) looks about right for the Rarm Hapdet.

    Note that for both the Left and Right Hapdets, the pitch and roll angles were leveled to zero (using simple bubble level).

    FIGURE 1

    FIGURE 2