KAGRA Domestic MeetingMirror

17 April, 2013

Norikatsu MioEiichi Hirose

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Current status (Fabrication)

• The first-stage contract for polish and coating for BS has been finished.

• The first-stage contract for polishing RMs and SRMs has been finished.

• The second-stage contract for polishing RMs and SRMs has been made.

• As for preparation of ITMs for iKAGRA , the quotation for the changing the wedge angle of the iLIGO mirrors has been obtained.

• The measurement for the ROC of MC curved mirror has not been finished.

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Current status (BS)• Preparation of the tooling has been done.• Anneal test of the silica (AGC AQ2) has been done (heated up to 400 C at

a rate of 2 degC/minute, remained 10 hours and cooled to ambient temperature at a rate of < 2 degC/minute); the deformation due to the anneal was small enough for the BS fabrication.

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Current status (PRMs and SRMs)

• The first and second stages of the polish for the transmission spheres have been done.

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R=-3.2m R=4.58m R=24.9m

Sapphire mirrors• Pathfinder polish of sapphire has been done.• The realized surface distortions are 0.34nm/140mm,

0.42nm/180mm; these values are better than our requirement 0.5nm/140mm.

• ROC with 0.15% error over 180mm (2002.98m/2000m)

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Polished sapphire crystal of 200-mm diameter

Sapphire mirrors• ESR measurement to investigate the cause of

the optical absorption has been started at Prof. Ono’s lab at Toyama Univ.

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C-axis

Field(G) Field(G)

Inte

nsity

(a.u

.)

Inte

nsity

(a.u

.)

High absorption sample

Low absorption sampleThe high absorption sample only shows the peak signal at around 5.3 kG magnetic field.

Summary

• Preparations for core optics have been well proceeded.

• In this year, BS (polish and coating), PR2, PR3, SR2, SR3 (polish) will be completed.

• ITMs for iKAGRA will also be delivered.• MC and MT should be made.• Absorption of large sapphire crystals must be

measured.

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