Magnetic and Newtonian noises in Advanced Virgo: evaluation and mitigation strategies

In the present study, I table the first detailed estimation of the magnetic noise contribution to the Advanced Virgo sensitivity to gravitational waves. I tackle the topic by performing experimental assessments and numerical finite element simulations, all accompanied by careful data analysis. Results suggest that the magnetic noise impact for Advanced Virgo is not dramatic, but it will eventually be a considerable issue once the detector will approach its final design. In anticipation of that, I propose a mitigation strategy based on passive magnetic field shielding. In the second part, I deal with seismic newtonian noise, focusing on two crucial aspects involving the noise cancellation pipeline. These are the choice of the subtraction filter and the optimization of the seismic sensor array placement. The former issue required the definition of a machine learning algorithm based on deep neural networks, and its fine tuning. Results give some indication of good performances compared to the standard Wiener filter approach. The problem of the sensors deployment is instead addressed with the finite element analysis of the actual Virgo infrastructure and underground soil layers surrounding the test masses

Gravitational Radiation Detection with Laser Interferometry

Gravitational-wave detection has been pursued relentlessly for over 40 years. With the imminent operation of a new generation of laser interferometers, it is expected that detections will become a common occurrence. The research into more ambitious detectors promises to allow the field to move beyond detection and into the realm of precision science using gravitational radiation. In this article, I review the state of the art for the detectors and describe an outlook for the coming decades.Comment: 38 pages typos, references update

Terrestrial Gravity Fluctuations

The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.Comment: 151 pages, 52 figures; submitted to Living Reviews in Relativit

Present and Future of Gravitational Wave Astronomy

The first detection on Earth of a gravitational wave signal from the coalescence of a binary black hole system in 2015 established a new era in astronomy, allowing the scientific community to observe the Universe with a new form of radiation for the first time. More than five years later, many more gravitational wave signals have been detected, including the first binary neutron star coalescence in coincidence with a gamma ray burst and a kilonova observation. The field of gravitational wave astronomy is rapidly evolving, making it difficult to keep up with the pace of new detector designs, discoveries, and astrophysical results. This Special Issue is, therefore, intended as a review of the current status and future directions of the field from the perspective of detector technology, data analysis, and the astrophysical implications of these discoveries. Rather than presenting new results, the articles collected in this issue will serve as a reference and an introduction to the field. This Special Issue will include reviews of the basic properties of gravitational wave signals; the detectors that are currently operating and the main sources of noise that limit their sensitivity; planned upgrades of the detectors in the short and long term; spaceborne detectors; a data analysis of the gravitational wave detector output focusing on the main classes of detected and expected signals; and implications of the current and future discoveries on our understanding of astrophysics and cosmology

Absolute frequency measurement of an 171Yb lattice clock and optical clock comparisons

The measurement of time and frequency is at the heart of many technological applications and scientific measurements alike. In fact, the SI-unit the second is by quite a margin the SI-unit with the best relative uncertainty (ca. 10^{-16}), given by the accuracies of Cs fountain clocks probing the F = 3 - F = 4 ground-state transition in 133Cs. Still, demands for even higher accuracy and especially stability (a Cs fountain needs up to two weeks for the statistics to reach its declared uncertainty) are uttered in support of technological advancements (e.g. geodesy and GNSS systems) as well as fundamental science (physics beyond the standard model, tests of relativity). Nowadays optical lattice clocks confining a large number of neutral atoms in Stark shift free optical traps (the Stark shift free condition is characterised by a so-called magic wavelength of the trap) propose good candidates for a future redefinition of the SI-second in terms of an optical transition. Their accuracy and stability already surpass the Cs-fountains by two and three orders of magnitude, respectively. With further improvements to be expected in the near future, the application of optical lattice clocks to relativistic gravimetry, quantum computing, quantum simulation and fundamental physics keeps evolving. This thesis describes the development and characterisation of an 171Yb lattice clock at INRIM as well as its first frequency measurement campaigns and technolo- gies towards improved optical frequency measurements. The lattice clock confines cold atoms in a 1D optical dipole trap at the magic wavelength, which also cancels any Doppler- and recoil-related effects on the ultra-narrow clock transition. The first chapter offers a general overview of the physics behind lattice clocks and opti- cal frequency measurements. In the second chapter the 171Yb lattice clock developed during this work is expounded, including the trapping, state-preparation and state-probing of ultracold atoms inside the optical lattice. An exhaustive uncertainty budget for the clock transition is given and discussed showing already a performance beyond state-of- the-art Cs fountain clocks. An absolute frequency measurement obtained during this work is laid out. The result represents the lowest uncertainty achieved in a measurement of this transition against a primary frequency standard so far and is in agreement with previous values obtained by other groups around the world. A proof-of-principle experiment demonstrating for the first time the feasibility of transportable optical lattice clocks for geodesy and metrology applications outside of laboratory environments is described in chapter three. This experiment was conducted in collaboration with PTB and NPL and included a geodetic measurement with a transportable optical lattice clock that agreed with conventional methods as well as an optical 171Yb-87Sr frequency ratio measurement, enlarging the database on this particular ratio and thereby contributing to a possible redefinition of the SI-unit the second in terms of an optical transition or frequency-ratio matrix in the future. The fourth chapter discusses improvements added to the Yb lattice clock after the aforementioned measurements, in particular the stabilisation of the cooling and trapping lasers on a single stable low-drift cavity using mirrors coated for three disparate wavelengths across the optical spectrum. The simultaneous offset sideband locking and a throughout characterisation of the cavity are discussed. The last chapter is about the characterisation and optimisation of the NPL universal oscillator, which was conducted during my secondment at the NPL research facilities in the UK. The universal oscillator consists out of a femtosecond frequency comb, an ultra stable master laser and six slave oscillators. The femtosecond comb is transferring the stability of the superior master oscillator cavity to all six slave oscillators, which includes five lasers ranging from the infrared to the visible region. The principle of operation is explained and the obtained high performance of the spectral purity transfer set forth and discussed. This experiment demonstrated an unprecedented spectral purity transfer performance in a multi-branch configuration, opening the way for the interrogation of whole clock ensembles by just one master oscillator

3G R&D: R&D for the Next Generation of Ground-based Gravitational-wave Detectors

To deliver on the promise of next generation gravitational-wave observatories, a sustained and coordinated detector research and development program is required. This report examines in detail the wide range of nearer- and longer-term detector R&D programs needed for next generation GW detectors commensurate with the key science targets presented in "The Next Generation Global Gravitational Wave Observatory: The Science Book", including considerations of site selection and large-scale vacuum infrastructure. The report makes a series of detailed recommendations on the needed advances in detector technology and the timescales needed to achieve those advances. It also identifies areas where larger-scale globally coordinated R&D efforts will be critical to ensuring success while minimizing costs. This report is the third 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 (this report), 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

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade. Highlights of the NuMass 2013 Workshop. Milano, Italy, February 4 - 7, 2013

The third Workshop of the NuMass series ("The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade: NuMass 2013") was held at Dipartimento di Fisica "G. Occhialini, University of Milano-Bicocca in Milano, Italy, on 4-7 February 2013. The goal of this international workshop was to review the status and future of direct and indirect neutrino mass measurements in the laboratory as well as from astrophysical and cosmological observations. This paper collects most of the contributions presented during the Workshop

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure