Status of Advanced Virgo Jo van den Brand, Nikhef and VU University - - PowerPoint PPT Presentation

Status of Advanced Virgo

Jo van den Brand, Nikhef and VU University Amsterdam, jo@nikhef.nl KAGRA International Workshop, Taiwan, May 22, 2017

Virgo is a European collaboration with about 280 members

Advanced Virgo (AdV): upgrade of the Virgo interferometric detector Participation by scientists from France, Italy, The Netherlands, Poland, Hungary, Spain

• 20 laboratories, about 280 authors

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Advanced Virgo

− APC Paris − ARTEMIS Nice − EGO Cascina − INFN Firenze-Urbino − INFN Genova − INFN Napoli − INFN Perugia − INFN Pisa − INFN Roma La Sapienza − INFN Roma Tor Vergata − INFN Trento-Padova − LAL Orsay – ESPCI Paris − LAPP Annecy − LKB Paris − LMA Lyon − Nikhef Amsterdam − POLGRAW(Poland) − RADBOUD Uni. Nijmegen − RMKI Budapest −

• Univ. of Valencia

Funding approved in Dec 2009

• 21.8 ME CNRS and INFN
• 3.5 ME Nikhef in kind contribution

Goal: be part of the international network

• f 2nd generation detectors

Short-term goal: join the O2 run in 2017 6 European countries

There was a dedication ceremony for Advanced Virgo on February 20, 2017

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Advanced Virgo Dedication

Fulvio Ricci has been leading Virgo through interesting times. Giovanni Losurdo is project leader of Advanced Virgo. Project will end on the day that Virgo joins O2

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Advanced Virgo Dedication

Advanced Virgo features many improvements with respect to Virgo and Virgo+

For 2017

• Larger beam
• Heavier mirrors
• Higher quality optics
• Thermal control of aberrations
• Stray light control
• Improved vacuum

For the period 2018 to 2019

• 200 W laser
• Squeezing
• Signal recycling
• Newtonian noise subtraction

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Advanced Virgo design

Advanced Virgo features many improvements with respect to Virgo and Virgo+

Phase 1: Configuration similar to Virgo+ Phase 2: Configuration for best sensitivity Phasing decided to increase the chance to reduce the time gap with LIGO

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Sensitivity targets

Early configuration Late configuration Virgo+

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What was achieved so far …

Substantial infrastructure work

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What was achieved so far …

MAIN HALL, SPRING 2013 FALL 2013

Mirrors were realized that feature low losses, low absorption, and low scattering properties

Features:

• 42 kg, 35 cm x, 20 cm thick
• Flatness < 0.5 nm rms
• Micro-roughness: 0.1 nm rms
• Optical absorption < 0.5 ppm

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Extreme mirror technology

“Coating of the mirrors at LMA

Features:

• 42 kg, 35 cm x, 20 cm thick
• Flatness < 0.5 nm rms
• Micro-roughness: 0.1 nm rms
• Optical absorption < 0.5 ppm

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Extreme mirror technology

Payloads are designed to suspend both optics and baffles

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Payloads

No principal changes, but significant refurbishing

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Superattenuators

All photodiodes are isolated to minimize effects from scattered light

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Suspended benches

Vibration isolation systems to host sensors

Multi-stage vibration isolation systems (6 + 1) were produced for Advanced Virgo. In addition, 7 pre- isolators have been designed, produced and delivered to KAGRA

One blade failure due hydrogen embrittlement in maraging steel spring blades

Optical systems for linear alignment, vibration isolation, IMC and phase camera’s, etc.

Instrumentation contributions to Advanced Virgo

Detection bench

Optical systems for linear alignment, vibration isolation, IMC and phase camera’s, etc.

Instrumentation contributions to Advanced Virgo

Detection bench

Optical sensors

Linear alignment sensors and phase camera’s have been designed and fabricated at Nikhef. All sensors have been installed, and commissioning is ongoing. Part of Thermal Compensation System Imaging of cavity fields

• Reference beam from carrier

AOM shift by 80 MHz

• Interferometer output

Combine on beam splitter

• Image carrier and side-bands

f1 = 6.270 777 MHz f2 = 56.436 993 MHz f3 = 8.361 036 MHz f4 = 131.686 317 MHz f5 = 22.38 MHz

• Amplitude and phase

High speed imaging of HOM Correct aberrations with CO2 lasers

• Digital demodulation

14 bit ADCs at 500 MSPS Xilinks Virtex-7 FPGA

CO2 laser for adaptive corrections of HOM

Phase camera Reference beam Sample beam

Baffles are applied to minimize scattered light

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Extensive baffling

TCS is applied to compensate thermal induced optical aberrations

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Thermal compensation system

TCS uses CO2 laser beams incident on compensation plates near input test masses

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Thermal compensation system

Biggest ultra-high vacuum system in Europe

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Vacuum system

The pressure in the vacuum system was lowered by applying cryogenic vacuum links

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Vacuum system

Project was completed within budget on August 2016, but schedule slipped by about 9 months w.r.t. TDR (2012). Project performance: sensitivity improvement to be determined soon Fellowships: To reduce performance/schedule risk (at the expense of budget risk), part of project contingency turned into contracts/fellowships upon Council authorization

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Advanced Virgo project logistics

The Advanced Virgo project had to overcome a few hurdles

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Issues

Broken superattenuator blades, and broken monolithic suspensions

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Issues encountered during construction

Mirrors were realized that feature low losses, low absorption, and low scattering properties

System for vertical vibration isolation

• Made of a special steel (maraging) studied to prevent

creep

• In use since ~15 years

13 blades broken (out of about 350) Cause identified: hydrogen embrittlement

• Due to excess H concentration in the bulk

Risk mitigation: all the blades showing possible defects in the protective Ni coating have been replaced

• About 40% of the total

Incurred project delay about several months

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Antispring blades

Damaged maraging steel spring blades

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Filter stage of a Virgo superattenuator

Test masses to be suspended with thin fused silica fibers to reduce suspension thermal noise

Technology already used successfully by Virgo in 2011

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Monolithic suspensions

In AdV: several failures occurred, when mirrors were suspended in vacuum

Technology already used successfully by Virgo in 2011

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Monolithic suspensions

Materials, design, procedures, … were reviewed and studied Meanwhile, test masses were suspended with steel wires in order not to stop the commissioning

Suspension with steel wires leads to a loss of sensitivity at low frequency

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Multi-front investigation into monolithic suspensions

Assuming a loss angle ! = 10%& the BNS range will be limited to 45 Mpc, while BBH range will be limited to 202 Mpc

All four test masses are suspended with steel wires

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Design sensitivity for Virgo’s initial phase

All four test masses are suspended with steel wires

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Design sensitivity for Virgo’s initial phase

Sensitivity with steel wires still compatible with the goal for early phase

All four test masses are suspended with steel wires

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Design sensitivity for Virgo’s initial phase

Weak design of the evacuation and venting system (a single line was employed)

Origin of monolithic suspension failures found in fall 2016 Failures could be reproduced in test facility Risk mitigation plan has been defined

• Detailed implementation plan being prepared
• Will be put in place after O2

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Culprit: contamination generated in the scroll pumps

Improvement of the vacuum pumping/venting system has been studied in collaboration with experts from CERN, DESY, and INFN

Venting system

• Separate piping for evacuation and venting
• Mechanical shields to avoid direct venting flux towards the fibers
• Replacement of scroll pumps with different ones

Installation of “fiber guards” as additional safety

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Risk reduction plan

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Where are we?

The interferometer is stably and reproducibly locked on the dark fringe

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Where are we?

Shot noise limited at high frequencies, while low frequency noise needs to be understood Blue curve: measured noise; green curve: total understood noise

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Noise budget

Engineering run took place from May 5 to 7 to test long-term stability, and effectivity of automation

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Commissioning run C8

Longest lock stretch about 6 hours BNS range 3-5 Mpc Science mode duty cycle about 84%

Coupling between various degrees of freedom, e.g. MICH and DARM

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Commissioning run C8

Intense commissioning program is ongoing

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Commissioning

Coupling between various degrees of freedom, e.g. MICH and DARM

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Noise hunting

Some spectral structure strongly correlate with bench motion, e.g. SIB2

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Noise hunting

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Next steps

2016

Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun

2017

Jul

H1 L1 GEO

Joint Run Planning Committee

Working schedule for O2 (G1501561- v11)

Vent/Commissioning

~75% observing mode

Virgo

Integration/Commissioning Detector in observing mode for a fraction of the time during Engineering Runs (ERs), EM alerts possible 24/7 observing mode (Observing Run, EM alerts) Detector operational,commissioning mode (small fraction of observing mode time) Detector not producing data (Downtime) O2A

Virgo sensitivity TBC 20-50 Mpc

ER10 O2B O2B O2B

O2B end date to be decided https://dcc.ligo.org/LIGO-L1700023 Decision point

• n VIRGO joining O2B,

ER11 dates and configuration, duration of the run

Vent/Commissioning

O2A ER10 O2A O2A ER11 ER11 ER11 Aug

Working schedule discussed in Joint Run Plan Committee (JRPC) for O2 (see G1501561-v11)

Path to join LIGO

• Improve PRC stability with TCS
• Suspend/evacuate SDB2
• Upgrade SSFS to 1 MHz
• Switch to Low Noise 2 actuation
• Engage noise subtraction techniques
• Noise hunting
• Week end engineering/science runs

(as done in Virgo in 2007) ITF input power to 25 W (now 12.5 W)

• Option being considered
• More commissioning and noise

hunting

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Step towards O2

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Advanced Virgo: what’s next?

Goal for the next decade: maximize the scientific output of AdV

Maximizing scientific output of AdV

• Maximize data taking
• Minimize downtime

PH PHASE SE 1 1 (2017 2017-18) 18): First run, priority upgrades PH PHASE SE 2 2 (2018 2018-2022) 2022): pushing toward the nominal sensitivity of AdV PH PHASE SE 3 3 (>2022) 2022): Actions to further enhance the AdV sensitivity, exploiting the limits of the present infrastructure and useful in view of a new 3G infrastructure

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Advanced Virgo: what’s next?

R& R&D Re Requ quired

We need to prepare now for the period between O2 and O3

Run in O2, then… MAIN PRIORITY: Re-install monolithic suspensions NEXT PRIORITIES: Increase of laser power Installation of squeezing Implementation of signal recycling Longer term upgrades to reach the ultimate infrastructure limits (new resources are needed)

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Immediate plans

Sensitivity will be eventually limited by quantum noise

Quantum noise: Shot noise (X1), error on photon counting Radiation pressure noise (X2): back-action noise caused by fluctuating number of photons hitting the mirrors Uncertainty relation: DX1 DX2 ≥ 1 Squeezing: But…we can reduce the uncertainty in one quadrature increasing it in the other This is done by a SQUEEZER. Already demonstrated on interferometers

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Squeezing

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2

10

3

10

−23

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−22

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−21

Frequency (Hz) Strain Sensitivity [1 / √ Hz] Typical noise without squeezing Squeezing−enahnced sensitivity

GEO600 LIGO H1

LIGO Scient. Coll., Nature Physics, 2011 L Barsotti, LIGO-G1300420

Virgo will incorporate AEI Hannover squeezer

Virgo squeezing activities: Experiment to realize a Virgo squeezer already funded by CSN2 Focus on an in-vacuum squeezing bench A goal already achieved: skilled team build up AEI Hannover offered their squeezer (best ever realized) to Virgo! Virgo happy to accept the offer:

• Shorten the time for enhancing the detector
• Creates a collaborative ground crucial for the mid-long term future
• Close Virgo-AEI collaboration started to study the details for the implementation

Work done so far not lost:

• A lot of experience gained, people trained
• Digital electronics developed in house might be used for the controls
• The work done will be reusable to realize an in-vacuum squeezer for the next step: frequency dependent

squeezing

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Squeezing

Offered as in-kind contribution to Virgo. Collaboration for actual implementation has already started

Smaller (25%) compared to GEO-Squeezer

• Dimensions 1.10 m x 1.05 m

Less components but better performance Fully automated analog control On-board subcomponents:

• Two lasers + PLL
• SHG
• 532 nm Mach Zehnder
• 1064 nm mode cleaner
• Homodyne detector
• Double resonant OPA

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New AEI squeezer

Henning Vahlbruch, February 21, 2017; EGO, Cascina, Italy

External contributions are coming also on Newtonian noise research

Shell has funded the development of sensors suitable for realizing a large network dedicated to NN subtraction A ~1 ME grant has been awarded to the Virgo Polish groups to develop the DAQ for NN subtraction

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Newtonian noise subtraction

INNOSEIS

Seismic characterization studies with large arrays of sensors allow us to retrieve the parameters to model Newtonian noise at the detector site

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Newtonian noise modeling

Step 1: Seismic study to understand soil structure Seismic study Virgo site Characteristics

• Large array of

sensors Techniques

• Beamforming
• ESAC
• Inversion

Parameters

• Ground layer depth
• Wave velocities
• Density models
• Damping factors

Step 3: Model NN and subtraction algorithms '()) = * + , -, / 123

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• 2

Status:

• Virgo site simulation in progress
• Collaboration with Shell and TU Delft

Matlab ElastoDynamic toolbox, KU Leuven

Maria Bader

Step 2: Seismic ground model

• Model each soil layer with measured

parameters

• Receivers underground
• Excite: point sources

Advanced Virgo is underway and will join O2 in summer

Advanced Virgo integration completed late 2016 Full ITF commissioning started in November 2016

• First project milestone (1h stable lock) reached in March 2017
• First commissioning run (C8) in May 2017
• Sensitivity is approaching that of Virgo+

Some improvement possible before the last O2 run

• Priority: join O2B to have significant impact on the network

Several upgrades foreseen before the start of O3

• Well identified priorities

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Conclusions