|
Cryogenic Underground
|
tarix | 02.10.2018 | ölçüsü | 3,17 Mb. | | #71716 |
|
Cryogenic Cryogenic Underground Resonant Sideband Extraction (RSE) interferometer
BNS range 158 Mpc, BBH(30Msun) range 1.0 Gpc BNS range 158 Mpc, BBH(30Msun) range 1.0 Gpc
Not better even with cryogenic and underground
Basically low, thanks to underground and tower suspensions Basically low, thanks to underground and tower suspensions
Cryogenic temperature high Q (low loss) sapphire reduces thermal noise Cryogenic temperature high Q (low loss) sapphire reduces thermal noise Thick sapphire fibers to extract heat increase suspension thermal noise
23 kg mirror was the largest sapphire mirror we can get (aLIGO: 40 kg, AdVirgo: 42 kg) 23 kg mirror was the largest sapphire mirror we can get (aLIGO: 40 kg, AdVirgo: 42 kg) Smaller mirror increases radiation pressure noise Less laser power because of limited heat extraction increases shot noise Intra-cavity power KAGRA: 400 kW, aLIGO/AdVirgo: 700 kW
Increase the mass - GAST project (upto 30 cm dia. ?) - composite mass - A-axis sapphire (upto 50 kg, 26 cm dia.) - non-cylindrical mass (upto 30 kg) - go silicon (upto 200 kg, 45 cm dia.) Increase the mass - GAST project (upto 30 cm dia. ?) - composite mass - A-axis sapphire (upto 50 kg, 26 cm dia.) - non-cylindrical mass (upto 30 kg) - go silicon (upto 200 kg, 45 cm dia.) Frequency dependent squeezing (Filter cavity) - effectively increase mass and laser power Better coating, low absorption mirror Better cryogenic suspension design ETM different from ITM, half-cryogenic, delay-line, folded arms, higher-order modes, suspension point interferometer …… ???
We need a plan to integrate these ideas We need a plan to integrate these ideas To begin with, some example plans were proposed Plan: Black (by Kentaro Komori) use silicon mirrors Plan: Brown (by Koji Nagano) lower the power to focus on low frequency Plan: Red (by Sadakazu Haino) increase the power to focus on high frequency
Heavier sapphire and heavier IM, 20 K Heavier sapphire and heavier IM, 20 K
Silicon 123 K, 1550 nm, radiative cooling
Same test mass, low power, high detuning, 20 K Same test mass, low power, high detuning, 20 K
Same test mass, high power, 24 K Same test mass, high power, 24 K
Also feasibility study necessary Also feasibility study necessary
Science case discussion is necessary
What is the best figure of merit to compare the plans? - Sensitivity curve (with error bars)? - Inspiral range? What mass? - Event rate (with error bars)? - Parameter estimation accuracy? What is the best figure of merit to compare the plans? - Sensitivity curve (with error bars)? - Inspiral range? What mass? - Event rate (with error bars)? - Parameter estimation accuracy? Broadband or narrowband in high event rate regime by aLIGO + AdVirgo? - Does 4th detector help parameter estimation? What about real 3G detector (~10 km class)? - Asia-Australian 8-km detector? - Where?
Many ideas for improving the sensitivity have been proposed, and some R&D are on going Many ideas for improving the sensitivity have been proposed, and some R&D are on going Sensitivity design study on future KAGRA upgrade to integrate these ideas is necessary There are some example plans Any comments? New ideas?
Optical parameters - Mirror transmission: 0.4 % for ITM, 10 % for PRM, 15.36 % for SRM - Power at BS: 780 W - Detune phase: 3.5 deg (DRSE case) - Homodyne phase: 133 deg (DRSE case) Optical parameters - Mirror transmission: 0.4 % for ITM, 10 % for PRM, 15.36 % for SRM - Power at BS: 780 W - Detune phase: 3.5 deg (DRSE case) - Homodyne phase: 133 deg (DRSE case) Sapphire mirror parameters - TM size: 220 mm dia., 150 mm thick - TM mass: 22.8 kg - TM temperature: 21.5 K - Beam radius at ITM: 3.5 cm - Beam radius at ETM: 3.5 cm - Q of mirror substrate: 1e8 - Coating: tantala/silica - Coating loss angle: 3e-4 for silica, 5e-4 for tantala - Number of layers: 9 for ITM, 18 for ETM - Coating absorption: 0.5 ppm - Substrate absorption: 20 ppm/cm Suspension parameters - TM-IM fiber: 35 cm long, 1.6 mm dia. - IM temperature: 16.3 K - Heat extraction: 6580 W/m/K - Loss angle: 5e-6/2e-7/7e-7 for CuBe fiber?/sapphire fiber/sapphire blade Inspiral range calculation - SNR=8, fmin=10 Hz, sky average constant 0.442478 Seismic noise curve includes vertical coupling, vibration from heatlinks and Newtonian noise from surface and bulk
Measured v = 0.5~2 m/s → seems OK Measured v = 0.5~2 m/s → seems OK
Dostları ilə paylaş: |
|
|