LCGT Bandwidth Study 2011(with 22cm mirrors), 2011 9/9 2-4pm

Scope of the meeting

It has recently turned out that the largest S-axis Sapphire available right now is not as large as 25cm in diameter but 22cm.
And the measured absorption of a Sapphire substrate is not as low as 20ppm/cm but 70ppm/cm.
It should be also noted that the economic situation is not so good that we cannot expect too much on an additional large budget
within the next few years, and also that it takes three years or more to provide 4 Sapphire mirrors, which means we should
make it in mind that the mirrors we are ordering will be the one we use in 2017.

Scheduled date

If more discussions are necessary, we will have the second meeting on Sep 22nd (Thu).

Reference

• 25W injection
  

  • IR vs Finesse/Rs
    Spectrum with 25W
    Spectra with 25/50/75W
    

• 50W injection
  

  • IR vs Finesse/Rs
    Spectrum with 50W
    Spectra with 25/50/75W
    

• 75W injection
  

  • IR vs Finesse/Rs
    Spectrum with 75W
    Spectra with 25/50/75W
    

The input power refers the level of absorption; if the total absorption is high we can inject only 25W while the default is 75W.
Here the power recycling gain is set 11, i.e. the power on the BS is 275W, 550W, 825W, for 25, 50, 75W, respectively.

• Preliminary cryogenic setup with 1.2W heat and point-scattering effect
  

  • file