First generation interferometers

The status and plans for the first generation long baseline suspended mass interferometers TAMA, GEO, LIGO and Virgo are presented, as well as the expected performances

Amaldi Meeting Introduction

Welcome to Caltech and the 3rd Edoardo Amaldi Conference on Gravitational Waves. Obviously, something must be very interesting to bring more than 250 scientists from around the world to Pasadena in July for this particular meeting. In fact, July in Southern California does have many attractions, in addition to the good weather and cool nights. For this conference, we have arranged a visit to the new Getty Museum on our excursion day. This is meant to make your stay more pleasant, but is not the real reason we have gathered here. This meeting addresses the detection of gravitational waves, a much-anticipated event

An Expressive Language and Efficient Execution System for Software Agents

Software agents can be used to automate many of the tedious, time-consuming information processing tasks that humans currently have to complete manually. However, to do so, agent plans must be capable of representing the myriad of actions and control flows required to perform those tasks. In addition, since these tasks can require integrating multiple sources of remote information ? typically, a slow, I/O-bound process ? it is desirable to make execution as efficient as possible. To address both of these needs, we present a flexible software agent plan language and a highly parallel execution system that enable the efficient execution of expressive agent plans. The plan language allows complex tasks to be more easily expressed by providing a variety of operators for flexibly processing the data as well as supporting subplans (for modularity) and recursion (for indeterminate looping). The executor is based on a streaming dataflow model of execution to maximize the amount of operator and data parallelism possible at runtime. We have implemented both the language and executor in a system called THESEUS. Our results from testing THESEUS show that streaming dataflow execution can yield significant speedups over both traditional serial (von Neumann) as well as non-streaming dataflow-style execution that existing software and robot agent execution systems currently support. In addition, we show how plans written in the language we present can represent certain types of subtasks that cannot be accomplished using the languages supported by network query engines. Finally, we demonstrate that the increased expressivity of our plan language does not hamper performance; specifically, we show how data can be integrated from multiple remote sources just as efficiently using our architecture as is possible with a state-of-the-art streaming-dataflow network query engine

Nobel Lecture: LIGO and gravitational waves II

The observation of gravitational waves (see Fig. 1) in the Laser Interferometer Gravitational-wave Observatory (LIGO) was announced on 11 February 2016 (Abbott et al., 2016a), 100 years after Einstein proposed the existence of gravitational waves (Einstein, 1916, 1918). This observation came after more than 50 years of experimental efforts to develop sensitive enough detectors to observe the tiny distortions in spacetime from gravitational waves. The Nobel Prize for 2017 was awarded to Rainer (“Rai”) Weiss, Kip Thorne and myself for decisive contributions to the LIGO detector and the observation of gravitational waves. In fact, the success of LIGO follows from decades of R&D on the concept and techniques, which were covered in Rai Weiss’ Nobel Lecture, followed by the design, construction and evolving the LIGO large-scale interferometers to be more and more sensitive to gravitational waves. This work has been carried through the LIGO Laboratory and the scientific exploitation through the LIGO Scientific Collaboration, having more than 1000 scientists, who author the gravitational wave observational papers. In addition, many others made important contributions to the science of black holes, numerical relativity, etc

Observation of Muon Neutrino Disappearance with the MINOS Detectors in the NuMI Neutrino Beam

This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current ν_μ interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27×10^(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336±14 events. The data are consistent with ν_μ disappearance via oscillations with Δm_(32)^2|=2.74_(-0.26)^(+0.44)×10^(-3)  eV^2 and sin^2(2θ_(23))>0.87 (68% C.L.)

Optimal Strategies for Sinusoidal Signal Detection

We derive and study optimal and nearly-optimal strategies for the detection of sinusoidal signals hidden in additive (Gaussian and non-Gaussian) noise. Such strategies are an essential part of algorithms for the detection of the gravitational Continuous Wave (CW) signals produced by pulsars. Optimal strategies are derived for the case where the signal phase is not known and the product of the signal frequency and the observation time is non-integral.Comment: 18 pages, REVTEX4, 7 figures, 2 table

Thermoelastic Noise and Homogeneous Thermal Noise in Finite Sized Gravitational-Wave Test Masses

An analysis is given of thermoelastic noise (thermal noise due to thermoelastic dissipation) in finite sized test masses of laser interferometer gravitational-wave detectors. Finite-size effects increase the thermoelastic noise by a modest amount; for example, for the sapphire test masses tentatively planned for LIGO-II and plausible beam-spot radii, the increase is less than or of order 10 per cent. As a side issue, errors are pointed out in the currently used formulas for conventional, homogeneous thermal noise (noise associated with dissipation which is homogeneous and described by an imaginary part of the Young's modulus) in finite sized test masses. Correction of these errors increases the homogeneous thermal noise by less than or of order 5 per cent for LIGO-II-type configurations.Comment: 10 pages and 3 figures; RevTeX; submitted to Physical Review

First observations of separated atmospheric ν_μ and ν̅ _μ events in the MINOS detector

The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of ν_μ and ν̅ _μ charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving R^(data)_(up/down/R^(MC)_(up/down) = 0:62^(+0.19)_(0:14)(stat.) ± 0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field ν_μ and ν̅ _μ interactions are separated. The ratio of ν̅ _μ to ν_μ events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R^(data)_(ν_μ/ν̅ _μ) / R^(MC)_(ν_μ/ν̅ _μ) = 0.96^(+0:38)_(0.27)(stat.) ± 0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for ν_μ and ν̅ _μ

Negatively Charged Strangelet Search using the E864 Spectrometer at the AGS

We provide a status report on the progress of searching for negatively charged strangelets using the E864 spectrometer at the AGS. About 200 million recorded events representing approximately 14 billion 10% central interactions of Au + Pt at 11.5 GeV/c taken during the 1996-1997 run of the experiment are used in the analysis. No strangelet candidates are seen for charges Z=-1 and Z=-2, corresponding to a 90% confidence level for upper limits of strangelet production of ~1 x 10^{-8} and ~4 x 10^{-9} per central collision respectively. The limits are nearly uniform over a wide range of masses and are valid only for strangelets which are stable or have lifetimes greater than ~50 ns.Comment: 6 pages, 4 figures; Talk at SQM'98, Padova, Italy (July 20-24, 1998