50 mm fused silica disks from University Wafer
2 inches fused silica disks with a-Si coating
Started a measurement for CR1 and CR2 only. CR4 is instaled, centered and ready to be measured later
Measurement for S1600600 started at 11:50am
% Freq First Q of pair Second Q of pair
1117.4 2.3392e+07 2.3392e+07
2555.9 1.8650e+07 1.8650e+07
4441.1 1.3003e+07 1.3003e+07
6759.2 1.6003e+07 1.5656e+07
6781.8 1.4795e+07 1.4795e+07
9499.2 5.6765e+06 5.6765e+06
10219.5 1.3148e+07 2.7060e+06
10222.3 1.3909e+07 4.2609e+04
11444.0 2.0756e+06 6.5364e+05
12649.4 1.0264e+07 8.7228e+06
12650.7 8.6808e+06 8.6808e+06
14176.3 1.0290e+07 1.0290e+07
14177.5 1.0185e+07 1.0185e+07
16113.7 1.0856e+07 9.7535e+06
16202.5 8.6733e+06 5.0176e+06
18619.0 1.3113e+07 1.3113e+07
18622.1 1.4864e+07 1.4864e+07
20149.0 1.4047e+06 1.4047e+06
21348.8 6.9944e+06 6.9944e+06
21353.3 8.0679e+06 3.1734e+05
23529.5 1.3076e+07 1.3076e+07
24482.3 9.6841e+06 9.6841e+06
24669.1 4.8629e+06 4.8629e+06
24670.5 6.3609e+06 6.3609e+06
25499.2 5.2216e+06 5.2216e+06
25828.0 3.3780e+06 3.3780e+06
27101.0 1.4934e+07 1.4934e+07
27103.5 1.4956e+07 1.4956e+07
28883.5 1.2076e+07 1.2076e+07
29068.6 1.1494e+07 1.1494e+07
29072.0 9.7555e+06 9.7555e+06
29190.0 5.9610e+06 5.9610e+06
29193.2 7.9280e+06 7.9280e+06
29502.2 7.8254e+06 7.8254e+06
30867.0 6.3681e+06 6.3681e+06
31267.0 1.6836e+06 1.4541e+05
32194.4 5.3275e+06 5.3275e+06
32200.0 5.9215e+06 2.6587e+06
The following plot compares the Q measured on this sample yesterday here at Caltech with the GeNS system, with the measurement perfomed by Raymond Robie in Glasgow.
- blue dots: measurements on the flame polished sample here at Caltech
- orange crosses and yellow triangles: Raymond’s measurements on the flame polished sample at in Glasgow (after annealing)
- purple crosses: typical Q values measured on disk samples (not annealed nor flame polished) here at Caltech
Flame polishing of the edges did not change significantly the Q we measure with the GeNS system. However, the GeNS system rovide systematically higher Q values for basically all measurable modes.
Cleaning and baking (200 C air foe SS and 120 for Al) parts for the new vacuum chamber
Just for fun, I installed the disk thas has been etched in the center with "1234". I figured out that the ESD PCB was probably too close to the disk, so I moved it a bit up.
Pump down started at about 2:38pm LT.
I realigned all optical levers to measure the 50mm disks. In brief, I moved the input 2" mirrors, the in-vacuum 2" mirrors and the PZT mirrors so that the beam hits the 50mm sample and gets back into the QPD. Re-aligned everything to the horizontal reference using water.
I repeated the analysis for bulk and shear losses described in an early elog entry, with the same coating, but after annealing at 500C for 9 hours.
The COMSOL model is the same as before, so the dilution factors are the same, except that this time I could measure a few more modes at high frequency:
As in the previous analysis, I fitted four different models:
1) one single loss angle for both bulk and shear, constant in frequency
2) one single loss angle for both bulk and shear, linear in frequency
3) separate bulk and shear loss angles, constant
4) separate bulk and shear loss angles, linear in frequency
The data strongly favor the last model: two loss angles for shear and bulk, linearly dependent on frequency (Bayes factor -22.7 for the second best model, which is the frequency dependent single loss angle).
The results are below.