Frequency domain interferometer simulation with higher-order spatial modes

FINESSE is a software simulation that allows to compute the optical properties of laser interferometers as they are used by the interferometric gravitational-wave detectors today. It provides a fast and versatile tool which has proven to be very useful during the design and the commissioning of gravitational-wave detectors. The basic algorithm of FINESSE numerically computes the light amplitudes inside an interferometer using Hermite-Gauss modes in the frequency domain. In addition, FINESSE provides a number of commands to easily generate and plot the most common signals like, for example, power enhancement, error or control signals, transfer functions and shot-noise-limited sensitivities. Among the various simulation tools available to the gravitational wave community today, FINESSE is the most advanced general optical simulation that uses the frequency domain. It has been designed to allow general analysis of user defined optical setups while being easy to install and easy to use.Comment: Added an example for the application of the simulation during the commisioning of the GEO 600 gravitational-wave detecto

Demonstration of detuned dual recycling at the Garching 30m laser interferometer

Dual recycling is an advanced optical technique to enhance the signal-to-noise ratio of laser interferometric gravitational wave detectors in a limited bandwidth. To optimise the center of this band with respect to Fourier frequencies of expected gravitational wave signals detuned dual recycling has to be implemented. We demonstrated detuned dual recycling on a fully suspended 30m prototype interferometer. A control scheme that allows to tune the detector to different frequencies will be outlined. Good agreement between the experimental results and numerical simulations has been achieved.Comment: 9 page

Cost-benefit analysis for commissioning decisions in GEO600

Gravitational wave interferometers are complex instruments, requiring years of commissioning to achieve the required sensitivities for the detection of gravitational waves, of order 10^-21 in dimensionless detector strain, in the tens of Hz to several kHz frequency band. Investigations carried out by the GEO600 detector characterisation group have shown that detector characterisation techniques are useful when planning for commissioning work. At the time of writing, GEO600 is the only large scale laser interferometer currently in operation running with a high duty factor, 70%, limited chiefly by the time spent commissioning the detector. The number of observable gravitational wave sources scales as the product of the volume of space to which the detector is sensitive and the observation time, so the goal of commissioning is to improve the detector sensitivity with the least possible detector down time. We demonstrate a method for increasing the number of sources observable by such a detector, by assessing the severity of non-astrophysical noise contaminations to efficiently guide commissioning. This method will be particularly useful in the early stages and during the initial science runs of the aLIGO and adVirgo detectors, as they are brought up to design performance.Comment: 17 pages, 17 figures, 2 table

Observation of a kilogram-scale oscillator near its quantum ground state

We introduce a novel cooling technique capable of approaching the quantum ground state of a kilogram-scale system-an interferometric gravitational wave detector. The detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) operate within a factor of 10 of the standard quantum limit (SQL), providing a displacement sensitivity of 10(-18) m in a 100 Hz band centered on 150 Hz. With a new feedback strategy, we dynamically shift the resonant frequency of a 2.7 kg pendulum mode to lie within this optimal band, where its effective temperature falls as low as 1.4 mu K, and its occupation number reaches about 200 quanta. This work shows how the exquisite sensitivity necessary to detect gravitational waves can be made available to probe the validity of quantum mechanics on an enormous mass scale.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of NiedersachsenAustralian Research CouncilCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Educacion y CienciaConselleria d’Economia Hisenda i Innovacio of the Govern de les Illes BalearsScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan Foundatio

Future Ground-Based Gravitational-Wave Observatories: Synergies with Other Scientific Communities

Planning for the development of a 3rd generation global gravitational-wave detector array is a multifaceted and complex effort that will necessarily need a high level of community input. Interfacing to extant and new stakeholders in the broader scientific constituencies is necessary to keep them aware of the activities taking place in the ground-based gravitational-wave community and receive input to inform and evolve the planning. In this report, we present the approaches GWIC and gravitational-wave collaborations and projects should consider taking to engage with broader community. This report is the fifth in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe, ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities (this report), and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network

Charge neutralization in vacuum for non-conducting and isolated objects using directed low-energy electron and ion beams

We propose using ions and electrons of energy 1 eV–10 eV for neutralizing the charges on the non-conducting or isolated surfaces of high-sensitivity experiments. The mirror surfaces of the test masses of the laser interferometer gravitational observatory are used as an example of the implementation of this method. By alternatively directing beams of positive and negative charges towards the mirror surfaces, we ensure the neutralization of the total charge as well as the equalization of the surface charge distribution to within a few eV of the potential of the ground reference of the vacuum system. This method is compatible with operation in high vacuum, does not require measuring the potential of the mirrors and is expected not to damage sensitive optical surfaces

Expanding the Reach of Gravitational Wave Astronomy to the Edge of the Universe: The Gravitational-Wave International Committee Study Reports on Next Generation Ground-based Gravitational-Wave Observatories

The first direct detection of gravitational waves emitted from a pair of merging black holes in 2015 has been heralded as one of most significant scientific breakthroughs in physics and astronomy of the 21st century. Motivated by the tremendous scientific opportunities now opened by gravitational-wave observatories and recognizing that to fully exploit the new field will require new observatories that may take 15 to 20 years from conception until operations begin, the Gravitational Wave International Committee (GWIC) convened a subcommittee to examine the path to build and operate a network of future ground-based observatories, capable of extending the observational GW horizon well beyond that currently attainable with the current generation of detectors. This report is the first in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe (this report), ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network

Gravitational Wave Data Analysis: Computing Challenges in the 3G Era

Cyber infrastructure will be a critical consideration in the development of next generation gravitational-wave detectors. The demand for data analysis computing in the 3G era will be driven by the high number of detections as well as the expanded search parameter space for compact astrophysical objects and the subsequent parameter estimation follow-up required to extract the nature of the sources. Additionally, there will be an increased need to develop appropriate and scalable computing cyberinfrastructure, including data access and transfer protocols, and storage and management of software tools, that have sustainable development, support, and management processes. This report identifies the major challenges and opportunities facing 3G gravitational-wave observatories and presents recommendations for addressing them. This report is the fourth in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe, ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era (this report), v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network

The Belle II SVD detector

The Silicon Vertex Detector (SVD) is one of the main detectors in the Belle II experiment at KEK, Japan. In combination with a pixel detector, the SVD determines precise decay vertex and low-momentum track reconstruction. The SVD ladders are being developed at several institutes. For the development of the tracking algorithm as well as the performance estimation of the ladders, beam tests for the ladders were performed. We report an overview of the SVD development, its performance measured in the beam test, and the prospect of its assembly and commissioning until installation

An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network

The construction of a global network of detectors is the cornerstone to scientific success for 3rd generation gravitational wave astronomy. If carried out with a vision to the future, the third generation implementation, in its infrastructure, technology base and governance can provide the point of departure for subsequent developments beyond the third generation, a path to the long and revolutionary future of gravitational wave astrophysics. The goal of this document is to lay out considerations that influence the optimal choice of governance and to lay out a possible path that can lead the community to an optimal governance model. This report is the six in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe, ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network (this report)