NEWTONIAN NOISE CANCELLATION

Jan HarmsGran Sasso Science Institute

INFN - National Laboratory of Gran Sasso

Photo: Venkateswara

NN CANCELLATION AT VIRGO

GWADW; J Harms

DAQ_NEB

DAQ_WEB

DAQ_CEB

5/18/2020

Magic linear box -

NN estimate

Noisy GW data

Clean GW data

2

30 sensors

30 sensors

50 sensors

Recent deployed seismometer arrays for NNC sub-system

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ARRAY OPTIMIZATION(1) Site characterization

(2) Optimal seismometer placement

15Hz

(3) Performance prediction

(4) Final array configuration at Virgo

Badaracco et al (2020)

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DESIGN ELEMENTS OF ANN CANCELLATION SYSTEM

Bayesian array optimization

ULUL

Choice of noise-cancellation

filter

NN modeling

• CT: Cancellation Target

• UL: Ultimate Limitations

• SM: Surrogate Model

Sensor noise and number of

sensors

Site properties

CT, UL, SM

CT, SM

NN cancellation system

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FIR WIENER FILTER

Wiener filter(FIR order M)

Correlations between seismometer and GW data

Seismometer correlation matrix

• Requires a huge number (millions) of correlation estimates.

• Leads to accumulation of high statistical errors in the estimate of the Wiener filter

Novel filter designs:

• Optimized linear-filter designs (gradient descent)

• Kalman filter

• Non-linear filter

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OPTIMAL LINEAR FILTERING

Rumors: Wiener filter is the optimal linear filter for the cancellation of stationary noise.

Reality: It depends on details. Statistical errors can limit cancellation performance. Filter optimization can be made less susceptible to statistical errors, e.g., using gradient descent.

Original spectrum

Residual with linear filter calculated by gradient descent

Residual of FIR Wiener filter

Both linear filters have the same number of coefficients

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THE LIGO HANFORD NN EXPERIMENTWiener filter to h(t) noise projection

(several months of data for correlation required)

Hanford array in 2016/17

Harms et al (2020)

Potential future noise reduction

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ET NEWTONIAN-NOISE MODELS

Seismic NNif ET where built at the surface

Seismic NNunderground

Badaracco/Harms (2019)

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ET NN CANCELLATION

• Deploy borehole seismometers around the test masses (24 test masses in total of which 12 couple significantly to gravitational fluctuations).

• Horizontal boring and seismometer deployment, and deployment of several seismic sensors per borehole could greatly reduce cost of such a system.

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NUMERICAL NN SIMULATIONS

Andric/Harms (2020)

Andric/Harms (2020)

A vertex location at Sardina candidate site

Two candidate sites

EURegion Meuse-Rhine

Sardinia

Gravitoelastic correlations and Wiener filter(SPECFEM3D)

EXTRA SLIDES

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ACOUSTIC NN

NN from atmosphere NN from cavern

• Already at 100m depth, if the site is sufficiently remote with low acoustic noise, ET is not limited by atm, acoustic NN anymore

• Acoustic NN originating from the caverns will likely require cancellation.

Fiorucci et al (2016)

INFRASTRUCTURE NOISE

GWADW; J Harms

Excess NN to be avoided(example: Virgo)

Vacuum pumps

Ventilation

Chillers

Credit: I Fiori

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SEISMIC FIELDSLIGO Livingston

March

September

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Wood logging

Local (mostly infrastructural) seismic sources produce dominant perturbations above a few Hz at LIGO/Virgo

LIGO Hanford Power outage

On

Off

KAGRA

KAGRA has managed to preserve an almost prestine environment below 20Hz (infrastructure produces excess noise above 20Hz)

Ocean waves

R Schofield

F Badaracco

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