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This study investigates the changes in floor sagging and laser shifts in disk profiles over a span of 6 days. The findings reveal significant variations in floor sagging and identify the laser direction as the primary cause. The relative positions of key disk points remain stable within a few pixels over the duration of the study.
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Looking for Floor Sagging James N. Bellinger University of Wisconsin-Madison 11-Mar-2010 James N. Bellinger 11-March-2010
Survey found changes in floor • Up to 20-30mm change from 2006 to 2010 • Do disks shift wrt each other? • Can only use Transfer Lines when field is on: 6 days worth of data
James N. Bellinger 12-March-2010 Selected Transfer Lines Transfer Lines 1 and 4 + + 1 + + Disk shift 4 + +
James N. Bellinger 12-March-2010 Layout ME-4 ME+4 YB+0
James N. Bellinger 12-March-2010 Distributions of Profile Center w/ Time at TP1 using Radial CCD ME+4 ME+3 ME+2 ME+4 laser Time is along vertical axis 3 periods of full-field YB+3 YB+0 ME+1
James N. Bellinger 12-March-2010 Distributions of Profile Center w/ Time at TP4 Using Radial CCD ME+4 ME+3 ME+2 ME+4 laser Time is along vertical axis YB+3 YB+0 ME+1 MAB out of range MAB out of range
James N. Bellinger 12-March-2010 Features to note • In the middle time period, in both TP1 and TP4 (on opposite sides!) the profile shifts to higher pixel values—radially away from the center of the disk • The shapes are similar • (Ignore missing profiles or profiles reconstructed on the edge) • A shift in YE3 would result in opposite shifts
James N. Bellinger 12-March-2010 Looks like laser sag ME+4 ME+2 ME+3 ME-4 laser Time is along vertical axis 3 periods of full-field YB+3 ME+1 YB+0 Slice this time
James N. Bellinger 12-March-2010 Compare ME+4 and YB+0 • Take middle interval, slice into 10 time bins • Plot average of ME+4 vs YB+0 profile centers • If variation is due to laser mount tilt these will lie on a line with slope 1.57 (ratio of distances from laser)
James N. Bellinger 12-March-2010 Compare ME+4 and YB+0
James N. Bellinger 12-March-2010 Looking at TP2 Minus side laser Radial CCD Same shape as before Thermal shifts of laser mounts? YB+3/TP2 ME+2/TP2
James N. Bellinger 12-March-2010 Conclusion • Variation over 6 days ranges as high as 30 pixels (*.014 microns/pixel=420microns) for Transfer Lines 1 and 4, or 60 (=840microns) for Transfer Line 2 • Bulk of variation is due to changes in the laser direction. • Relative disk positions of YE-3, YE+3, and YB0 are stable within a few pixels over 6 days