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KAGRA future discussion 1
The 3rd KAGRA International Workshop May 2017
Tokyo Institute of Technology Kentaro Somiya
KAGRA future discussion 1 The 3 rd KAGRA International Workshop May - - PowerPoint PPT Presentation
KAGRA future discussion 1 The 3 rd KAGRA International Workshop May - - PowerPoint PPT Presentation
KAGRA future discussion 1 The 3 rd KAGRA International Workshop May 2017 Tokyo Institute of Technology Kentaro Somiya KAGRA Advanced R&D It is not a subsystem but a group of activities for a future upgrade of KAGRA. KAGRA Advanced R&D
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KAGRA Advanced R&D
Advanced R&D subjects and past presentation slides are listed in the wiki page.
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Discussion on a future upgrade
- Some advanced techniques have been proposed
- We shall integrate them to make a concrete plan(s)
for the future upgrade of KAGRA
- How much can we improve the current sensitivity?
- In which timescale shall we consider the upgrade?
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3G 2G 1G
GW detectors
USA Europe Japan
LIGO Virgo GEO TAMA
Advanced LIGO
GEO‐HF KAGRA
Einstein Telescope Voyager Cosmic Explorer ? A+ Advanced Virgo
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Sensitivities
Inspiral range for BNS
O2 KAGRA aLIGO A+ Voyager ET CE 70Mpc 150Mpc 200Mpc 320Mpc 700Mpc 3200Mpc ?
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LIGOʼs plan in 2022~2024
A+ Voyager is the final upgrade of LIGO in its current facility.
300K Silica 120K Silicon 1064nm 1550nm SQ 4km filter SQ 16m filter
Voyager
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In the case of KAGRA
- QN and Suspension TN limit the sensitivity
- Mirror TN is small in 20K but not too small
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How to calculate noise curves
- Suspension thermal noise
for
- Mirror coating thermal noise
- Quantum noise
Simplified model
* Y:Youngʼs modulus, :Poisson ratio, dw:fiber diameter, l:fiber length, dcoa:coating thickness
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- BNS observation range was 188Mpc (current:158Mpc)
- Susp TN and QN increased for lighter mass (50kg>23kg)
Looking back the design sensitivity in ʻ04
[LCGT document ver.1 (2004)]
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- Adv. R&D (1): Squeezing
[Matsumoto F2F 2011] [Somiya F2F 2014] [Flaminio F2F 2015]
Freq-independent squeezing
equivalent to high laser power
Freq-dependent squeezing
equivalent to heavy mass
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- Adv. R&D (2): non-uniform suspension
[Nishida F2F 2011] [Sekiguchi F2F 2012]
w h
- Ribbon suspension
- Thin-end fiber suspension
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- Adv. R&D (3): Vertical SPI
[Ando F2F 2012]
Measure the distance between upper and lower masses using interferometry
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Integration of the techniques
It is not enough to propose one technique to improve the overall KAGRA sensitivity. We shall combine multiple techniques to make a plan. We would like to have a few candidate plans by the next F2F meeting!
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Trade-offs with some parameters
Parameter Good Bad high laser power low shot noise temperature increase, parametric instability use of Silicon can be larger than Sapphire different wavelength, lower Youngʼs modulus thin fiber low suspension TN less cooling capability large beam low mirror TN diffraction loss, less stable thick mirror (same radius) heavy mass more absorption at ITM large radius (same mass) large beam (low TN) more dissipation (high TN)
A proper combination of the parameters is necessary to achieve a good sensitivity.
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Other ideas to improve the sensitivity
- Non-cylindrical mirror to increase the mass
- Non-cylindrical mirror to decrease TN
- Composite mirror
- 300K Silica ITM + 20K Sapphire ETM
- Evanescent cooling
- Crystaline coating
- Delay line
- Local readout
- Balanced homodyne detector
- EPR entanglement
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