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K.Somiya

Cryogenic Xylophone. GWADW @ Kyoto May. 2010 Kentaro Somiya Waseda Inst. for Adv. Study. Collaboration work with S.Hild, K.Kokeyama, H.Mueller-Ebhardt, R.Nawrodt, P.Puppo, etc. K.Somiya. Xylophone. Heat absorption via suspension fiber. ET-LF: 10K, 20kW, Silicon, DRSE + 10dB SQ

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K.Somiya

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  1. Cryogenic Xylophone GWADW @ Kyoto May. 2010 Kentaro Somiya Waseda Inst. for Adv. Study Collaboration work with S.Hild, K.Kokeyama,H.Mueller-Ebhardt,R.Nawrodt, P.Puppo, etc. K.Somiya

  2. Xylophone Heat absorption via suspension fiber ET-LF: 10K, 20kW, Silicon, DRSE + 10dB SQ ET-HF: 290K, 3MW, Silica, BRSE + 10dB SQ Single Low-T High-power IFO Problem in cooling Xylophone Cryogenic Low power + Room-T High power

  3. An issue in ET-HF heat problem • Thermal lensing • TCS noise • Parametric instability RSE Squeezing 1st generation detector: ~30kW in arm 2nd generation detector: ~800kW in arm ET-HF: 3MW in arm Can we really realize such high power?

  4. Contents of talk • Proposal of cryogenic ET-HF • Suspension-TN issue • Substrate-TE issue • Suspension-TE issue • Optimization of ET-LF

  5. Cryogenics to avoid the heat problems • Almost no thermal lensing • Room to reduce beam radius • ~0.03% deviation of T • ~50km ROC of lensing calculation by M.A.Arain • Same TN with small beam • Less overlap of opt modes • PI is eased calculation by K.Yamamoto

  6. Can we cool down the 3MW IFO? • 1ppm absorption per mirror -> 3W • f3cm Silicon fiber absorbs only 200mW Susp TN limits the sensitivity 5K Solutions • Ribbon suspension • Increase test-mass temperature ~ thin in longitudinal direction 10K ~ heat flow increases increase But thermoelastic noise becomes high.

  7. Substrate TE noise TE noise ET-HF sensitivity at 100Hz Thermal expansion is zero at T=18K,121K. Big susp TN Big TE noise Free from both problems at around 121K

  8. Thermoelastic noise of suspension Silicon ribbon w=1cm, l=60cm 5K f=2.4e-6 121K Suspension TE noise could limit the sensitivity

  9. 290K vs. 121K ET-HF sensitivity (290K) ET-HF sensitivity (121K) QN QN mirror mirror susp gravity gravity susp • l=60cm, f0.6mm silica fiber • LG33 beam • T=290K • l=60cm, 1cm x 1mm silicon ribbon (bad) • 3cm x 0.4mm ribbon (good) • TEM00 beam, w=10cm • T=121K • Mirror TN levels are almost equal • Suspension TN is low enough with the 3cm ribbon

  10. Summary of Low-T ET-HF • Thermal lensing and PI problems will be eased • With T=20K, suspension is too thick • With higher T, suspension can be thin, but TE is high • With T=121K, suspension is thin and TE is zero • Suspension TE is large, but a thin ribbon will help.

  11. Before ET-LF optimization (dashed: freq-dependent squeezing, solid: fixed squeezing) ET-LF quantum ET-HF quantum gravity gradient mirror TN susp TN opt losses are included • We could omit filter cavities to realize FD squeezing • Especially if we can make ET-LF a little wider

  12. RSE vs. Speed-meter RSE + filter cavity Resonant Sagnac (Speedmeter) • Broadband with more power • Less sensitive to mass • Less power required • Narrow-band

  13. ET-LF optimization 10kW 100kW in arm 18kW DRSE 2MW in arm 20MW in arm gravity gradient opt losses are included • The more power, the better SM sensitivity • The more power, the more thermal noise • Homodyne phase can be tuned

  14. ET-LF optimization 18kW DRSE 10kW 100kW in arm 2MW in arm 20MW in arm ET-HF (w/o filter) gravity gradient opt losses are included • Thermal noise is included • Homo-phase and mass temperature are optimized • DRSE (not yet optimized) seems better than SM?

  15. Summary and discussions • I would recommend… • 20K ET-LF + 121K ET-HF • ET-HF as an SPI for ET-LF • No filter cavity for ET-HF • Probably DRSE w/filter for ET-LF • TBD: • Payload thermal noise (Puppo. et al) • High power 1550nm LASER • DRSE optimization • Other options

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