Detection of gravitational wave bursts by interferometric detectors

We study in this paper some filters for the detection of burst-like signals in the data of interferometric gravitational-wave detectors. We present first two general (non-linear) filters with no {\it a priori} assumption on the waveforms to detect. A third filter, a peak correlator, is also introduced and permits to estimate the gain, when some prior information is known about the waveforms. We use the catalogue of supernova gravitational-wave signals built by Zwerger and M\"uller in order to have a benchmark of the performance of each filter and to compare to the performance of the optimal filter. The three filters could be a part of an on-line triggering in interferometric gravitational-wave detectors, specialised in the selection of burst events.Comment: 15 pages, 8 figure

90 m β * optics for ATLAS/ALFA

http://accelconf.web.cern.ch/AccelConf/IPAC2011/papers/tupz002.pdfInternational audienceWe describe a high β∗ optics developed for the ATLAS detector at the LHC interaction point IP1. Roman Pots have been installed 240 m left and right of IP1 to allow to measure the absolute luminosity and the total elastic cross section for ATLAS with ALFA (Absolute Luminosity for ATLAS). Ultimately, it is planned to perform these mea- surements at a very high β∗ of 2625 m. Here we describe a new, intermediate β∗ = 90 m optics, which has been opti- mized for compatibility with the present LHC running con- ditions. We describe the main features and the expected performance of this optics for ALFA

Plans for High Beta Optics in the LHC

ISBN 978-3-95450-115-1 - http://accelconf.web.cern.ch/AccelConf/IPAC2012/papers/moppc007.pdfInternational audienceBased on what has been learned with the first high β* = 90 m operation in 2011, we describe the potential and practical scenarios for reaching very high β* in the LHC in 2012 and beyond. Very high β* optics require dedicated running time and conditions in the LHC. We describe a plan which is optimized to maximize the physics potential in a minimum of dedicated running time

Overall Optics Solutions for Very High Beta in Atlas

accelconf.web.cern.ch/accelconf/e08/papers/wepp004.pdfInternational audienceAn insertion optics with a beta-star of at least 2600 m has been requested by the ATLAS experiment at the LHC. This is very far from the standard LHC physics optics and implies a significant reduction in the phase advance from this insertion corresponding to about half a unit in tune. We describe several alternatives how this could be integrated in overall LHC optics solutions with the possibility to inject, ramp and un-squeeze to the required very high beta

Tracking and Tolerances Study for the ATLAS High Beta Optics

International audienc

Overall Optics Solutions for very high Beta in ATLAS

An insertion optics with a $\beta$* of at least 2600m has been requested by the ATLAS experiment at the LHC. This is very far from the standard LHC physics optics and implies a significant reduction in the phase advance from this insertion corresponding to about half a unit in tune. We describe several alternatives how this could be integrated in overall LHC optics solutions with the possibility to inject, ramp and un-squeeze to the required very high-$\beta$*

Regularization of statistical inverse problems and the Bakushinskii veto

In the deterministic context Bakushinskii's theorem excludes the existence of purely data driven convergent regularization for ill-posed problems. We will prove in the present work that in the statistical setting we can either construct a counter example or develop an equivalent formulation depending on the considered class of probability distributions. Hence, Bakushinskii's theorem does not generalize to the statistical context, although this has often been assumed in the past. To arrive at this conclusion, we will deduce from the classic theory new concepts for a general study of statistical inverse problems and perform a systematic clarification of the key ideas of statistical regularization.Comment: 20 page

About the detection of gravitational wave bursts

Several filtering methods for the detection of gravitational wave bursts in interferometric detectors are presented. These are simple and fast methods which can act as online triggers. All methods are compared to matched filtering with the help of a figure of merit based on the detection of supernovae signals simulated by Zwerger and Muller.Comment: 5 pages, proceedings of GWDAW99 (Roma, Dec. 1999), to appear in Int. J. Mod. Phys.

An efficient filter for detecting gravitational wave bursts in interferometric detectors

Typical sources of gravitational wave bursts are supernovae, for which no accurate models exist. This calls for search methods with high efficiency and robustness to be used in the data analysis of foreseen interferometric detectors. A set of such filters is designed to detect gravitational wave burst signals. We first present filters based on the linear fit of whitened data to short straight lines in a given time window and combine them in a non linear filter named ALF. We study the performances and efficiencies of these filters, with the help of a catalogue of simulated supernova signals. The ALF filter is the most performant and most efficient of all filters. Its performance reaches about 80% of the Optimal Filter performance designed for the same signals. Such a filter could be implemented as an online trigger (dedicated to detect bursts of unknown waveform) in interferometric detectors of gravitational waves

Minimax estimation of the Wigner function in quantum homodyne tomography with ideal detectors

We estimate the quantum state of a light beam from results of quantum homodyne measurements performed on identically prepared pulses. The state is represented through the Wigner function, a ``quasi-probability density'' on $\mathbb{R}^{2}$ which may take negative values and must respect intrinsic positivity constraints imposed by quantum physics. The data consists of $n$ i.i.d. observations from a probability density equal to the Radon transform of the Wigner function. We construct an estimator for the Wigner function, and prove that it is minimax efficient for the pointwise risk over a class of infinitely differentiable functions. A similar result was previously derived by Cavalier in the context of positron emission tomography. Our work extends this result to the space of smooth Wigner functions, which is the relevant parameter space for quantum homodyne tomography.Comment: 15 page