Reducing Polarization Mode Dispersion With Controlled Polarization Rotations

One of the fundamental limitations to high bit rate, long distance, telecommunication in optical fibers is Polarization Mode Dispersion (PMD). Here we introduce a conceptually new method to reduce PMD in optical fibers by carrying out controlled rotations of polarization at predetermined locations along the fiber. The distance between these controlled polarization rotations must be less than both the beat length and the mode coupling length of the fiber. This method can also be combined with the method in which the fiber is spun while it drawn. The incidence of imperfections on the efficiency of the method is analysed.Comment: 4 page

Mass correlation between light and heavy reaction products in multinucleon transfer Au 197 + Te 130 collisions

We studied multinucleon transfer reactions in the Au197+Te130 system at Elab=1.07 GeV by employing the PRISMA magnetic spectrometer coupled to a coincident detector. For each light fragment we constructed, in coincidence, the distribution in mass of the heavy partner of the reaction. With a Monte Carlo method, starting from the binary character of the reaction, we simulated the de-excitation process of the produced heavy fragments to be able to understand their final mass distribution. The total cross sections for pure neutron transfer channels have also been extracted and compared with calculations performed with the grazing code

Le catastrofi naturali: dalla memoria storica all'intervento pubblico

La resilienza dei territori rispetto a fenomeni catastrofici legati al cambiamento climatico, è un tema di discussione sempre più diffuso a livello di enti pubblici e privati ed istituti di ricerca, reso urgente dalla congiuntura climatica sfavorevole. Tuttavia, un'analisi condotta su una scala territoriale frammentata e in un'ottica slegata da analisi di lungo periodo, rischia di portare a soluzioni temporanee e poco efficaci. Data questa convinzione, il team, composto da giovani studiosi di varia provenienza Istituzionale, ha impostato una serie di ricerche e di azioni mirate a valutare queste criticità per mettere il proprio know how a servizio della collettività. Il dialogo instaurato col mondo della ricerca, della formazione, delle professioni, con gli amministratori e gli enti di gestione delle acque, approfondisce le criticità legate alla carenza o all'eccesso d'acqua, sotto il profilo infrastrutturale, economico e socio-culturale, attraverso l'analisi di vari tipi di fonti e la comunicazione con vari media

Intervista a Walter Panciera: Insegnare il metodo storico e la sua utilità

The interview with one of the major specialists in Didactics of modern italian History concerns the subject of teaching the discipline, renewed since the late nineties of the XIX centurythanks to the emergence of new historiographical addresses, advancements in the legislative field and the contribution of pedagogical disciplines. The manual, a controversial but valuable literary genre, remains a useful teaching tool for a new teaching profession, which contemplates a more precise awareness of the historical method and its implications. The history laboratory appears to be the place where the use of sources, experimentations, interdisciplinarity and problematicity are highlighted; further, today the problem arises of breaking into the educational systems from everyday reality. Thus, even the Eighteenth-century cultural debate, such as the history of colonization or epidemics, can undoubtedly contribute to the formation of a citizen who is aware and oriented on the level of historical vision

Visual-Inertial Indoor Navigation Systems and Algorithms for UAV Inspection Vehicles

In UAV navigation, one of the challenges in which considerable efforts are being focused is to be able to move indoors. Completing this challenge would imply being able to respond to a series of industrial market needs such as the inspection of internal environments for safety purpose or the inventory of stored material. Usually GPS is used for navigation, but in a closed or underground environment, its signal is almost never available. As a consequence, to achieve the goal and ensure that the UAV is able to accurately estimate its position and orientation without the usage of GPS, an alternative navigation system based on visual-inertial algorithms and the SLAM will be proposed using data fusion techniques. In addition to the navigation system, we propose an obstacle avoidance method based on a Lidar sensor that allows navigation even in the absence of light

GALTRACE: A highly segmented silicon detector array for charged particle spectroscopy and discrimination

GALTRACE is an array of segmented silicon detectors specifically built to work as an ancillary of the GALILEO γ-ray spectrometer at Legnaro National Laboratory of INFN. GALTRACE consists of four telescopic ΔE-E detectors which allow discriminating light charged particles also via pulse-shape analysis techniques. The good angular and energy resolutions, together with particle discrimination capabilities, make GALTRACE suitable for experiments where coincidences with specific emitted particles allow for the selection of reaction channels with very low cross section. The first in-beam experiment is reported here, aiming at identifying a narrow resonance, near-proton-threshold state in 11B, currently under discussion

Polarization-Dependent Phase of Light Propagating in Optical Fibers

As it propagates in a real single-mode fiber, light accumulates a phase delay and undergoes variations of its polarization state. These two phenomena are partly related to each other, owing to both well known geometric effects, i.e. the Pancharatnam's phase, and less known dynamic ones. This paper aims at reviewing these concepts, highlighting the polarization-depended phase of light that propagates in a single-mode fiber. We present a mathematical treatment using the familiar language of Jones and Stokes vectors and report experiments supporting the theory. The presented analysis has a general validity, and it can describe phase variation with respect to several parameters, such as distance, frequency and time. Its extension to multimode and multi-core fibers is also discussed. The results can be used for a better modelling and understanding of coherent transmission systems and interferometric fiber optic sensors