== LCGT Bandwidth Study 2011 (new design with 22cm mirrors) ==
1st meeting: 2011 9/9 2pm-4pm [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=590|slides]]<<BR>>
2nd meeting: 2011 9/22 10am-12pm [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=599|slides1]],[[attachment:Tagoshi_20110922.pdf|slides2]].<<BR>>
Final report is [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=644|here]]. (Summary letter is [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=643|here]])<<BR>>


=== 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.<<BR>> And the measured absorption of a Sapphire substrate is not as low as 20ppm/cm but 50-70ppm/cm.<<BR>> It should be also noted that the economic situation is not so good that we cannot expect too much on an additional large budget<<BR>> within the next few years, and also that it takes three years or more to provide 4 Sapphire mirrors,  which means we should<<BR>> make it in mind that the mirrors we are ordering will be the one we use in 2017.

=== 1st meeting reference ===
 * 25W injection <<BR>>
  . [[attachment:25Wcontour.pdf|IR vs Finesse/Rs]]<<BR>> [[attachment:25Wplot.pdf|Spectrum with 25W]]<<BR>> [[attachment:25Wspectra.pdf|Spectra with 25/50/75W]]<<BR>>
 * 50W injection <<BR>>
  . [[attachment:50Wcontour.pdf|IR vs Finesse/Rs]]<<BR>> [[attachment:50Wplot.pdf|Spectrum with 50W]]<<BR>> [[attachment:50Wspectra.pdf|Spectra with 25/50/75W]]<<BR>>
 * 75W injection <<BR>>
  . [[attachment:75Wcontour.pdf|IR vs Finesse/Rs]]<<BR>> [[attachment:75Wplot.pdf|Spectrum with 75W]]<<BR>> [[attachment:75Wspectra.pdf|Spectra with 25/50/75W]]<<BR>>

The input power refers the level of absorption; if the total absorption is high we can inject only 25W while the default is 75W.<<BR>> 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 (It seems that we can inject 75W into <<BR>> the interferometer, allowing the mirror temperature to be 23.5K instead of 20K).
  . [[attachment:newconfig.pdf|file]]<<BR>>

=== Influence on the detection of high frequency gravitational waves ===
 * GWs from supernovae [[attachment:hayama09092011.pdf|FILE]]

=== Minutes of the 1st meeting ===
 * [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=600|Minutes]]<<BR>>

=== 2nd meeting reference ===

 * Slides are [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=599|here]]<<BR>>
 * Data sets are [[attachment:ToTagoshisan.txt|here]].<<BR>>
 * Tagoshi-san's slides are [[attachment:Tagoshi_20110922.pdf|here]].<<BR>>

=== Minutes of the 2nd meeting ===
 * [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=611|Minutes]]<<BR>>