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KAGRA MIR (Absorption)
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SimonZeidler - 17:57, Friday 30 August 2019 (1583)Get code to link to this report
New spare ETMY maps in XY and YZ direction

Simon

With the recent recalibration of the PCI, I took another XY-map at the center in longitudinal direction. The results are attached as png pictures.
Compared with the results of the measurements before, we can see that the mean value of the absorption coefficient is much lower now (all given in ppm/cm):

  Center + 33mm Center Center - 33mm
Measurement on Aug. 15-20 159 ± 77 195 ± 102 342 ± 189
Measurement on Aug. 29 (107) 120 ± 69 (231)
Measurements from Caltech 83 ± 31 99 ± 50 216 ± 108

The numbers in parentheses are those for the older measurements but with the recalibrated bulk-reference value. Note that for the "Center" value of the most recent measurement the absorption coefficient would increase to 177 if using the old reference value.

It would be of course better to see the measured mean-values also for the other Z-positions but I don't know whether there is time.

Attached is also a map in YZ-direction, taken at X = 398 (also the center). It clearly shows an increase in absorption toward the outgoing surface (smaller Z) and oriented on the left-hand side (the map shows the situation as seen from above the test-mass with the incoming surface on the bottom).
The mean value within the relevant region (the substrate without the surface) is 148 ± 115 ppm/cm.

Images attached to this report
1583_20190830105656_map20190828.png 1583_20190830105700_dist20190828.png 1583_20190830105705_map20190829yz.png