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Entry  Thu Sep 12 18:12:26 2013, Matt A., Summary, NoiseBudget, Coating Thermal Noise Calculator 6x
    Reply  Fri Sep 13 13:40:43 2013, rana, Summary, NoiseBudget, Coating Thermal Noise Calculator MattThermal.pdf
    Reply  Tue Sep 17 19:43:45 2013, tara, Summary, NoiseBudget, Coating Thermal Noise Calculator 
       Reply  Thu Sep 19 14:55:11 2013, tara, Summary, NoiseBudget, Coating Thermal Noise Calculator ThermalUpdateEmbed.pdfThermalUpdateEmbed2.pdf
          Reply  Thu Sep 19 18:09:18 2013, tara, Summary, NoiseBudget, Coating Thermal Noise Calculator 
Message ID: 1342     Entry time: Thu Sep 19 14:55:11 2013     In reply to: 1338     Reply to this: 1343
Author: tara 
Type: Summary 
Category: NoiseBudget 
Subject: Coating Thermal Noise Calculator 

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The attached figures show that the two techniques agree to better than 20% of the GWINC output, with most of the mismatch at higher frequencies. I'm not yet sure why that is. It could be due to my improved integration in calculating Evans' thick coating correction, it could be due to my using a different form of the equation for Braginsky's finite substrate correction for the thermo-elastic noise, or it could just be due to some minor differences in the precision of some of the input values. ..

 

 

 I checked the calculation. I think most of the discrepancies are from the thick coating correction calculation (from Evans etal paper). The error is frequency dependent, and the calculations that involve frequency dependence are temperature fluctuation and thick coating correction. The temperature fluctuations are the same from our results. So it is most likely the thick coating correction. I checked and the corrections did differ at high frequency.

 I need to take a closer look to tell exactly where the errors are. Since the error is small and only at high frequency (around the shot noise limit, 10kHz),  I don't think it will be a problem for us.

Tara noticed an accidental re-definition in my old code. I fixed it, and updated the svn. This fixes most of the discrepancies, but shifts the difference in thermo-optic to the low-frequency region.

Attachment 1 is the comparison from case 3 between mine and Tara's calculations of his optimized coating structure.

Attachment 2 is the comparison from case 2 between mine and Tara's calculations of a 55-layer 1/4-wavelength stack.

Attachment 1: ThermalUpdateEmbed.pdf  44 kB  | Hide | Hide all
ThermalUpdateEmbed.pdf ThermalUpdateEmbed.pdf
Attachment 2: ThermalUpdateEmbed2.pdf  48 kB  | Hide | Hide all
ThermalUpdateEmbed2.pdf ThermalUpdateEmbed2.pdf
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