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Superconducting tensor gravitational wave detector (Superconducting Omni-directional Gravitational Radiation Observatory) SOGRO Rayleigh NN must be mitigated by 102 at 0.1 Hz for SOGRO 1 Infrasound NN must be mitigated by 103 at 0.1 Hz for SOGRO 1. Paik
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Ho Jung PaikDepartment of Physics, University of Maryland
8th Japan-Korea Joint WorkshopJune 27, 2015
Newtonian Noise Mitigationwith Tensor Gravitational Wave
Detector
Paik 2
Superconducting tensor gravitational wave detector
SOGRO (Superconducting Omni-directional Gravitational Radiation Observatory)
Rayleigh NN must be mitigated by 102 at 0.1 Hz for SOGRO 1 Infrasound NN must be mitigated by 103 at 0.1 Hz for SOGRO 1.
Paik 3
Newtonian gravity noise Seismic and atmospheric density
modulations cause Newtonian gravity gradient noise.
At 0.1 Hz, s ~ 35 km >> L. Gravity gradient noise L. Detecting and removing the gravity gradient noise appears to be very challenging.
GWs are transverse and cannot have longitudinal components whereas the Newtonian gradient does.
GW could be distinguished from near-field gradients, if all the tensor components are detected.
.)(')(')(')(')(')()(')()(')(')()(')(
)('
axis, 3' along traveling wave with theframe,GW In
33,23,13,
23,22,12,
13,12,11,
NGNGNG
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hhhhhhhhhhhhh
h
Paik 4
iii
R
iiii
R
iii
iR
iiii
R
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R
izc
h
izc
h
iizc
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izc
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izc
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233
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222
211
]cossin))[cos((exp)('
]cossin))[cos(sin()(exp)('
]cossin)][cos(sincos)[cos()(exp)('
]sincos))[cos(sin()(exp)()('
)(sin)(exp)()('
]sincos))[cos((exp)()('
NN due to Rayleigh waves Metric perturbation tensor in the source frame:
Paik 5
Removal of Rayleigh NN
)(expcsc)('cot)('cot2)(')( 32
332
1311
zR
azc
hhhh
With tensor + vertical CM (0 noise)
With tensor (SNR 103)+ vertical CM (SNR 106)+ 7 seism (5 km, SNR 103)
az() is measured by the vertical CM channel.
Paik 6
Removal of infrasound NN sinexp sin)(
π4csc )('cot)('cot2)(')( i
22
233
21311
i
ISii z
cG
hhhh
Harms and Paik, PRD (2015)
With tensor + 15 mikes (0, 0.6, 1 km, SNR 104)
Is there any way that we can mitigate NN by using the tensor channels alone?
Infrasound waves come from half space with an additional unknown: polar angle of incidence .
Microphones are required to measure the air density fluctuations.
Satisfies SOGRO 1 requirement
Paik 7
NN mitigation by correlation? Rayleigh and infrasound waves incident in different angles
are uncorrelated with each other and with the GW signal. This allows us to determine autocorrelations of h+() and h()
by combining correlations of various tensor outputs.
Fourier transform of autocorrelation is power spectral density.
2cos53161','
2cos35161','
2cos35161,','
83,','
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hhhh
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Problem: It takes a long time to mitigate the NN by using correlation method.
s 105/ 10 Hz, 20
time)sampling :( )( :factor Mitigation642
4/1
ss
ss
fSTSf
fTfS
Paik 8
Could SOGRO help advanced detectors mitigate NN? (HW from R.
Weiss)
Newtonian noise
Worthy mitigation goal: A factor of ~10 to 10-23 Hz-1/2 at 10 Hz and 10-21 Hz-1/2 at 1 Hz.
Worthy mitigation goal
Paik 9
KAGRA sensitivity curve
The low-frequency noise of KAGRA could benefit from a similar NN rejection.
Paik 10
Sensitivities to GW and NN
2/1202/121
2/1212/123
1212
Hz 1022
1 needs one ,Hz 1at Hz 10 resolve To
Hz 1022
1 needs one ,Hz 10at Hz 10 resolve To
)()( )()('
km), 10 (eter interferomlaser a from NN theremove To
hcL
h
hcL
h
xxLci
LL
hxxciLL
L
R
R
RR
.negligible is infrasound todue NN
)()(
: measures SOGRO)()(
:measureseter interferomLaser
12
RiRi
RR
ci
xXhx
xXxXhLL
At 1-10 Hz, cR = 250 m/s (surface), 3.5 km/s (deep underground). NN is uncorrelated between detector test masses.
AdV) (aLIGO,detector surface afor m 40.010102
250
ET) (KAGRA,detector dundergrounan for m 6.510102
3500
Hz, 10at 10 achieve To
1
1
2
ScSc
S
c
CS
R
R
R
SN
Paik 11
Incomplete correlation of NN Mitigation factor S is given by the correlation CSN between
the detector and the NN sensor:
Beker et al., GRG 43, 623 (2011)
It is much more challenging to mitigate the NN of ground detectors.
Paik 12
Mini-SOGRO with 5-m arm length
Mini-SOGRO with L = 5 m, M = 1 ton, T = 0.1 K could mitigate the NN at 1-10 Hz by a factor 5. NN mitigation appears very challenging but not impossible.
L = 5 m, M = 1 t, T = 0.1 K, Q = 109, n = 2, fD = 1 Hz