A search for energy deposition by neutrinos in matter

An exploratory search for an anomalous energy deposition by neutrinos in a germanium crystal was performed in the CERN high energy neutrino beam. No signal was found and a limit is set at a level of about 10^-12 of the normal dE/dx for a minimum ionizing particle.Comment: 7 pages, 3 figures Paper accepted by Physics Letters B on March 4th, 199

Lossless polarization attraction of co-propagating beams in telecom fibers

4We study the performance of a nonlinear lossless polarizer (NLP), the device that transforms an input arbitrary state of polarization (SOP) of a signal beam into one and the same SOP toward the output and, unlike conventional passive polarizers, performs this transformation without polarization-dependent losses. The operation principle of this device is based on the nonlinear rotation of the SOP of the strong signal beam under the interaction with a copropagating strong pump beam in a Kerr medium, which in our case is a telecom fiber. We quantify the performance of this NLP by introducing the notion of instantaneous degree of polarization, which is a natural extension of the conventional notion of the degree of polarization appropriate for CW beams to the case of pulses whose SOP is not constant across the pulse. We pay particular attention to the regime when signal and pump beams experience a walk-off in the dispersive medium. In particular, we demonstrate that a signal pulse experiences much stronger repolarization when the walk-off effect is present as compared with the case of no walk-off. We also study the degradation of the efficiency of the NLP in the presence of polarization mode dispersion.openopenV. Kozlov; M. Barozzi; A. Vannucci; S. WabnitzKozlov, Victor; M., Barozzi; A., Vannucci; Wabnitz, Stefa

Iterative receiver design for the estimation of Gaussian samples in impulsive noise

Impulsive noise is the main limiting factor for transmission over channels affected by elec-tromagnetic interference. We study the estimation of (correlated) Gaussian signals in an impulsive noise scenario. In this work, we analyze some of the existing, as well as some novel estimation algorithms. Their performance is compared, for the first time, for different channel conditions, including the Markov–Middleton scenario, where the impulsive noise switches between different noise states. Following a modern approach in digital communications, the receiver design is based on a factor graph model and implements a message passing algorithm. The correlation among signal samples, as well as among noise states brings about a loopy factor graph, where an iterative message passing scheme should be employed. As is well known, approximate variational inference techniques are necessary in these cases. We propose and analyze different algorithms and provide a complete performance comparison among them, showing that the expectation propagation, transparent propa-gation, and parallel iterative schedule approaches reach a performance close to optimal, at different channel conditions