Upper Limits in the Case That Zero Events are Observed: An Intuitive Solution to the Background Dependence Puzzle

We compare the ``unified approach'' for the estimation of upper limits with an approach based on the Bayes theory, in the special case that no events are observed. The ``unified approach'' predicts, in this case, an upper limit that decreases with the increase in the expected level of background. This seems absurd. On the other hand, the Bayesian approach leads to a result which is background independent. An explanation of the Bayesian result is presented, together with suggested reasons for the paradoxical result of the ``unified approach''.Comment: Latex file (compiled with cernrep.cls included) 5 pages, no figures. To appear in the Proceed. of the workshop on ''Confidence limits'' (CERN, Jan 2000). This paper and related papers also available at http://grwav3.roma1.infn.it

Energy spectrums for proton /200 eV + or = E + or = 1 MeV/ intensities in the outer radiation zone

Energy spectrums for proton intensities in outer radiation zon

Note on the Electron Energy Spectrum in the Inner Van Allen Belt

Electron energy spectrum in the inner van allen bel

Measuring Propagation Speed of Coulomb Fields

The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planets motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Li\'enard-Weichert retarded potential leads to a formula indistinguishable from the one obtained assuming that the electric field propagates with infinite velocity. Feyman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformely moving electron beam. The results we obtain on such a finite lifetime kinematical state seem compatible with an electric field rigidly carried by the beam itself.Comment: 23 pages, 15 figure

Studying the coincidence excess between EXPLORER and NAUTILUS during 1998

The coincidences between EXPLORER and NAUTILUS during 1998 (Astone et al. 2001) are more deeply studied. It is found that the coincidence excess is greater in the ten-day period 7-17 September 1998 and it occurs at the sidereal hour 4, when the detectors axes are perpendicular to the Galactic Disk. The purpose of this paper is to bring our results with the GW detectors to the attention of scientists working in the astrophysical field, and ask them whether are they aware of any special phenomenon occurring when EXPLORER and NAUTILUS showed a coincidence excess.Comment: 5 pages, 7 figures, submitted to A &

The fast matched filter for gravitational-wave data analysis: Characteristics and applications

We report on the application of a matched filter to the data of two-mode resonant gravitational-wave antennas for the detection of burst signals, with reference to data obtained by direct acquisition, i.e. without going through lock-in amplifiers, sampled at relatively high speed. After a review of the basic model of resonant detectors, that includes a discussion of the signal and of the noise, we present a detailed mathematical derivation of the optimum filter matched to an input burst. We then analyze and discuss the performance of the matched filter as regards both the improvement of the signal-to-noise ratio and the observation bandwidth, also considering the adaptive realization of the filter, based on the actual spectrum of the noise as estimated from the data. The discussion that follows is centered on various aspects concerning the practical application of the matched filter as well as the loss of performance due both to uncertainties on the parameters used for building the filter and to various discretization effects, both in the time and frequency domains. Finally, we consider some experimental results obtained by applying the matched filter to the data of the Explorer detector, also providing a comparison with what we obtained by applying an optimum filter to data processed by lock-in amplifiers, sampled at lower speed