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Beam steering in phased array antennas for some demanding terrestrial and space applications needs ultra-wide band true-time tunable delay lines preventing the beam squint phenomenon. Recent advances in the field of integrated microphotonics have allowed the demonstration of compact chip-scale delay lines with fast and low-power tuning mechanisms. For the tuning, several approaches have been theoretically and experimentally investigated and among them, very promising results have been obtained by using graphene in resonant delay lines based on the slow light effect. In this paper, after a brief review on resonant microphotonic tunable delay lines, some selected recent results on an ultra-compact graphene-based optical delay line including a silicon Bragg grating, are proposed.

The final oscillation analysis of the complete set of data collected by CHORUS in the years 1994-1997 is presented. Reconstruction algorithms of data extracted by electronic detectors were improved and the data recorded in the emulsion target were analysed by new automated scanning systems, allowing the use of a new method for event reconstruction in emulsion. CHORUS has applied these new techniques to the sample of 1996-1997 events for which no muons were observed in the electronic detectors. Combining the new sample with the data analysed in previous papers, the overall sensitivity of the experiment to the ?? appearance is thus improved. In a two-neutrino mixing scheme, a 90% C.L. upper limit of sin2 2 ?µ ? < 4.4 × 10-4 is set for large ? m2, improving by a factor 1.5 the previously published CHORUS result. © 2007 Elsevier B.V. All rights reserved. Bundesministerium für Bildung und Forschung: 05 7MS12P, 05 6BU11P Grant Foundation: KRF-2003-005-C00014 Promotion and Mutual Aid Corporation for Private Schools of Japan CERN Israel Science Foundation: 328/94 Brussels Instituut voor Milieubeheer Istituto Nazionale di Fisica Nucleare Foundation for Fundamental Research on Matter Korean Foundation for Cancer Research Walter Burke Institute for Theoretical Physics We gratefully acknowledge the help and support of the neutrino beam staff and of the numerous technical collaborators who contributed to the detector construction, operation, emulsion pouring, development, and scanning. The experiment has been made possible by grants from the Institut Interuniversitaire des Sciences Nucléaires and the Interuniversitair Instituut voor Kernwetenschappen (Belgium), the Israel Science Foundation (grant 328/94) and the Technion Vice President Fund for the Promotion of Research (Israel), CERN (Geneva, Switzerland), the German Bundesministerium für Bildung und Forschung (contract numbers 05 6BU11P and 05 7MS12P) (Germany), the Institute of Theoretical and Experimental Physics (Moscow, Russia), the Istituto Nazionale di Fisica Nucleare (Italy), the Promotion and Mutual Aid Corporation for Private Schools of Japan and Japan Society for the Promotion of Science (Japan), the Korea Research Foundation Grant (KRF-2003-005-C00014) (Republic of Korea), the Foundation for Fundamental Research on Matter FOM and the National Scientific Research Organization NWO (The Netherlands), and the Scientific and Technical Research Council of Turkey (Turkey). We gratefully acknowledge their support.

The WA95/CHORUS experiment at CERN is a dedicated nu(mu)-nu(tau) oscillation search experiment. Using the wide band neutrino beam of the CERN-SPS accelerator, with an exposure of 2.4 X 10(19) protons on the target, this experiment will explore the domain of small mixing angles down to sin(2) 2 theta(mu tau) approximate to 3 X 10(-4) for mass differences Delta m(2) > 1 eV(2), more than one order of magnitude better than the current limits. The conceptual design of the CHORUS experiment and data on the detector performances are reported.

In this paper, the optical and structural characteristics of Z-cut LiNbO/sub 3/ optical waveguides are experimentally investigated. The waveguides have been fabricated by fully immersing the samples in a closed beaker containing a mixture of benzoic and adipic acid at different concentration ratio. The influence of the dilution ratio on crystallographic phases, wavelength dispersion, diffusion coefficient, and index profile has been determined by using infrared absorption spectroscopy and optical characterization. The control of the thickness of guiding layers corresponding to /spl beta//sub 1/ and /spl beta//sub 2/ phases can be realized by varying the dilution ratio of the melt.

waveguides is demonstrated by the Raman scattering technique. Multimode waveguides have been produced by using pyrophosphoric, benzoic, and diluted benzoic acids as a proton source. The proton-exchanged (PE) layers are subjected to annealing (APE samples) with different rates of cooling: slow (s) and quick (q). The effect of Li-H replacing is considered in the frequency range below 800 cm-1 and about 3500 cm-1 (OH modes). The analysis of the spectral data leads to some important conclusions about the changes in the H:LiNbO3 lattice. We demonstrate that applying (s) ? (q) procedures on HxLi1-xNbO3 waveguides with x>0.56 leads to phase transitions between different states. The high-temperature phase modifications (metastable at room temperature) are characterized by strongly broadened q-Raman bands which imply a high degree of disorder. Although the Raman measurements support the presence of different phases in H:LiNbO3 waveguides, some conclusions, different from those reported elsewhere, have been made.

Recent results from the CERN Omega spectrometer on the enhancement of strange and multiply strange particle production in nucleus-nucleus with respect to proton-nucleus collisions are summarized. In particular, the new data from the WA97 experiment on Ω, Ξ and Λ production in PbPb and p-Pb collisions are presented and discussed.

A, Ξ and Ω yields and transverse mass spectra have been measured in Pb-Pb and p-Pb collisions at 158A GeV/c. The yields in Pb-Pb interactions are presented as a function of the collision centrality and compared with those obtained from p-Pb collisions. Strangeness enhancement is observed which increases with centrality and with the strangeness content of the hyperon.

Enhanced production of strange baryons and anti-baryons at central rapidity in S-W and S-z.sbnd;S with respect to p-A reactions has been reported by the CERN experiments WA85 and WA94. The WA97 experiment is extending such a study to Pb Pb collisions making use of the newly developed silicon pixel detectors. Results on Λ, Ξ − and Ω − production in Pb Pb collisions at 158 A GeV/ c at central rapidity are presented. Transverse mass spectra and particle ratios are presented. Hyperon yields are given as a function of the collision centrality and compared with those obtained from p-Pb collisions using the same experimental setup.

Part of the neutrino events collected in 1994-1995 by the CHORUS experiment has been analysed. A search was performed for ντ charged current interactions followed by the τ lepton decay into a single charged negative hadron, a possible indication for νμ→ντ oscillation. A sample of 6844 events without an identified muon has been located in the emulsion target. Within the selection criteria, no τ− candidate has been found. Combining this result with the one from the search for ντ interactions using the muonic decay mode (36 182 events with an identified muon), a 90% C.L. limit on the mixing angle sin22θμτ

The influence of cooling rate on the refractive index of proton-exchanged z-cut waveguides has been investigated. After short annealing at about C, the waveguide mode indices of as-exchanged and annealed samples are different for quick and slow cooling. A hypothesis explaining this effect by assuming a diffuse phase transition in the protonated crystal lattice is given. The possible changes in the macroscopic parameters responsible for the index differences are analysed.

We present an original detailed theoretical modeling of guided-wave noncollinear acoustooptic (AO) interaction produced by a multifrequency surface acoustic wave (SAW) in planar guided-wave structures. The modeling of the multifrequency AO interaction is based on a modified version of the coupled-mode theory. The first- and third-order diffraction efficiency and optimum dynamic range of the Bragg cell have been calculated as a function of acoustic power, acoustic radiofrequency, and optical waveguide parameters in Y-cut Ti:LiNbO/sub 3/ planar waveguides. Polynomial approximations, describing the first and third order diffraction efficiency versus normalized acoustic power in the cases of two- and three-frequency interactions, are derived and presented for the first time for arbitrarily large RF signals.

Preliminary results from WA97 measurements on Λ, Ξ and Ω production in lead-lead and proton-lead collisions are presented, along with a comparison of WA97 proton-lead data with previous WA85 proton-tungsten results. The ratio Ω/Ξ seems to be enhanced in lead initiated reactions compared to proton initiated reactions.

We present a theoretical study of guided-wave acoustooptic (AO) Bragg cells produced by a single surface acoustic wave (SAW) in PE:LiNbO/sub 3//LiNbO/sub 3/- and ZnO/GaAs/AlGaAs-based structures. A rigorous modeling of the SAW propagation in multilayered structures has been used and the analysis of the AO interaction has been performed by using a generalized multimode formulation of the coupled-mode theory. High-performance configurations, particularly advantageous in wide-band optical communication and signal processing applications are presented.

Electro-optic properties of proton-exchanged (PE) waveguide layers in LiTaO/sub 3/ and LiNbO/sub 3/ are studied and related to their optical characteristics. The proton-exchange process induces a degradation of the electro-optic activity in both types of waveguides, PE LiNbO/sub 3/ and PE LiTaO/sub 3/. The measured electro-optic effect is close to the detection sensitivity even when the exchange regime is performed at low temperatures for short periods of time. The PE samples have been annealed (APE waveguides) and the changes of their r/sub 33/ electro-optic coefficient has been followed at successively higher temperatures and periods of time. Subjected to annealing at temperatures between 265-420/spl deg/C, the LiTaO/sub 3/ layers show a partially recovered r/sub 33/ coefficient, the recovering being different for quick and slow cooling of the samples. In thin APE LiNbO/sub 3/ waveguiding layers a restoration of r/sub 33/ up to 75% of the bulk value is observed due to the annealing at temperatures between 200-340/spl deg/C.

In this paper, we present a new accurate numerical method, named leaky mode propagation method, to analyze the radiation loss in grating-assisted codirectional couplers. The complex propagation constant and electromagnetic field distribution of the normal modes are evaluated by using a space harmonic field expansion derived from the Floquet theorem. In order to prove the accuracy of our method, a comparison between our results and those calculated by the most used method, i.e., the transfer matrix method, is carried out in terms of power attenuation coefficient and total radiation loss. Quantitative and qualitative discrepancies between the two methods are widely discussed. In particular, an oscillatory variation of radiation loss with grating depth and gap thickness in contrast to the monotonic behavior predicted by the transfer matrix method has been found. >

Commercial success of the He–Ne Ring Laser Gyroscope (RLG) began in the late 1980s and early 1990s. Since He–Ne RLG first demonstration in 1963 (Macek and Davis, Appl Phys Lett 2:67–68, 1963 [1]), a number of industrial companies have developed a great research effort for RLG technology improvement so that this optical sensor has become a widely diffused commercial device. For instance, navigation systems based on He–Ne RLGs has been installed on over 50 different aircrafts (Barbour, AiAA Guidance, Navigation and Control Conference, Montreal, Canada, 2001 [2]). Since several years, He–Ne RLG dominates the high-performance gyros market.

Recently developed angular rate sensors are all based on two fundamental physical effects, i.e. Sagnac and Coriolis effects. In this chapter these physical effects are briefly discussed to allow the comprehension of different gyroscope technologies reviewed in the following chapters.

The coherent production of 3π systems by charged current antineutrino interactions on neon nuclei is studied in the bubble chamber BEBC exposed to the CERN SPS wide band beam. The coherent signal is attributed mainly to (ρπ) production, where the (ρπ) system is either non-resonant or comes from the decay of a1 mesons. The kinematical variables and the total cross section are compared with the predictions of the meson dominance model. © 1991 Springer-Verlag.

Multimode proton exchanged waveguides HxLi1−xNbO3 have been formed in congruent z-cut substrates using benzoic acid for proton source. The H concentration was changed by annealing, applying two different rates of cooling – quick (q) and slow (s). The samples were characterized by measuring their extraordinary refractive index profiles and waveguide Raman scattering. At high proton concentrations (x>0.56), where the βi phases are supposed to be existing the s- (equilibrium β2/β1 combination) and q- (metastable β1 phase) type of samples show very different Raman spectra, being also different from the scattering of the pure substrate. This is an evidence for lattice transformations probably related to the large differences in the electrooptic and nonlinear properties of the phases.

A search for non-statistical fluctuations was performed in 200 GeV per nucleon oxygen and sulphur ion-emulsion interactions selected by a high transverse energy trigger. No clear signal of dynamical correlations or of unusual fluctuations was found.

The HELIOS experiment has measured inclusivep⊥ spectra of negative particles in the rapidity region 1.0 is found to be approximately constant up to the highest accessible values ofE⊥.

In this paper report on the design of a 2D PBG filter in polymeric material. The filter is a Fabry-Perot cavity having a self-sustained membrane configuration. A deep parametric analysis has been carried out for improving the performance, taking also into account the fabrication tolerances Best performance in terms of lateral confinement have been obtained in case of square lattice. As for materials, polystyrene shown best in terms of refractive index value, length of the photonic crystal structure and attenuation value in the band gap. The filter can be used either in sensing applications or in telecommunication field.

We report on a search for associated charm production in neutrino charged-current interactions in the CHORUS experiment, based on the visual observation of charmed-particle decays. The search differs from those carried out so far in which the production of cc has been inferred from measurements of events with two or three muons in the final state, resulting from the decay of charmed hadrons. One event with a double charm-decay topology has been found and a corresponding background of 0.04 events has been evaluated. © 2002 Elsevier Science B.V. All rights reserved. CERN Promotion and Mutual Aid Corporation for Private Schools of Japan Bundesministerium für Bildung und Forschung Grant Foundation: KRF-2001-005-D00006 Israel Science Foundation: 328/94 Instituto Nazionale di Fisica Nucleare Foundation for Fundamental Research on Matter Korean Foundation for Cancer Research We gratefully acknowledge the help and support of the neutrino-beam staff and of the numerous technical collaborators who contributed to the detector construction, operation, emulsion pouring, development and scanning. The experiment has been made possible by grants from the Institut Interuniversitaire des Sciences Nucléaires and the Interuniversitair Instituut voor Kernwetenschappen (Belgium); the Israel Science Foundation (grant 328/94) and the Technion Vice President Fund for the Promotion of Research (Israel); CERN (Geneva, Switzerland); the German Bundesministerium für Bildung und Forschung (Germany); the Institute of Theoretical and Experimental Physics (Moscow, Russia); the Istituto Nazionale di Fisica Nucleare (Italy); the Promotion and Mutual Aid Corporation for Private Schools of Japan and Japan Society for the Promotion of Science (Japan); the Korea Research Foundation Grant (KRF-2001-005-D00006) (Republic of Korea); the Foundation for Fundamental Research on Matter FOM and the National Scientific Research Organization NWO (The Netherlands); and the Scientific and Technical Research Council of Turkey (Turkey). We gratefully acknowledge their support.

A great research effort has been spent in recent years for the use of guided-wave optoelectronic technologies for signal processing in space applications, because they allow to reduce size, weight, power consumption and system complexity with respect to electronic ones. Based on these motivations, we have conceived, designed and simulated a number of original integrated optical signal processors, such as 2D correlators for imaging reconstruction in SAR applications, both airborne and spaceborne, preprocessors for data classification and identification in satellite applications for remote sensing, beam formers and steerers in active phased array antennas, heterodyne spectrum analyzers, and so on. The substrate materials considered for these circuits are both ferroelectric and III-V semiconductor materials. Original modeling and numerical techniques have been developed to analyze and design the guided-wave components included in the optical architectures. In this paper, the most significant developments of this research activity are reviewed.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A large amount of data are usually transmitted, stored and processed by big digital systems in satellite remote sensing applications. To alleviate this situation, an on-board data processing system can be of significant help if it allows only the useful information data be transmitted to the ground station. To this end, a new architecture of a LiNbO3 integrated optic pre-processor is proposed in this paper. Its operation is based on the holographic substraction between two incident waves and depends on the relative phase shift. In such a way on-board identification and classification of data are allowed. The proposed device is formed by channel-planar composite waveguides to increase the number of parallel channels. Channel waveguides, which can be excited through a microlens array, allow to obtain the best performance of the electro-optic modulators, each of them is placed on a single channel waveguide, in terms of low losses and high modulation efficiency.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present the theoretical investigation, including design criteria, of a new optical beam former for phased-array active antennas. The device is formed by a Z-cut LiNbO3 channel- planar composite waveguide, an array of interferometric modulators and a linear microlens array. The basic element of the new architecture is the array of Mach-Zehnder Ti:liNbO3 intensity modulators having asymmetric coplanar-strip traveling-wave electrodes in which a relatively thick SiO2 buffer layer is utilized to reduce the phase velocity mismatch between the microwaves and optical waves. A comparison with other optical and electronic architectures already proposed shows a number of significant advantages. In particular, our device can be used in multichannel optical computing systems as well as in optical communication and RF signal processing systems allowing to overcome severe frequency limitations typical of devices reported in literature since it can work at frequencies greater than 30 GHz. So the very large transmission rate typical of the optical fiber communication systems may be conveniently exploited.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Guided-wave Mach-Zehnder intensity modulators are key elements for a variety of applications in optical communications. They usually present a broad operation band and low drive voltages. Two general ways for fabrication of such modulators on LiNbCO3 are known - by standard Ti-indiffusion and by proton exchange with additional annealing.

Most of the electrooptic guided-wave devices in lithium niobate utilise the r33 electrooptic coefficient. The devices made by using proton exchange (PE) process have indicated that their experimental efficiency is lower than that of devices based on “standard” waveguides produces by Ti-indiffusion. The most probable reason is that there may be a degradation of the electrooptic properties during the fabrication process. Although some measurements of r33 in PE layers were already performed [1,2], the data obtaned are far from complete understanding.

In the last few years, a considerable effort has been expended on the development of a number of both active and passive guided-wave devices, such as laser diodes, electrooptic modulators, acoustooptic transducers, photodetectors and microlens arrays, for optical signal processing applications including optical computing 1-3. Many simple optical devices can be easily fabricated by using mature and reproducible technologies. The interest in optical processors involving simple devices is mainly due to a lower power consumption, reduced size, cost and weight and high throughput with respect to the corresponding electronic processors. A number of guided-wave optical circuits for communications, signal processing and optical computing have been demonstrated using the acoustooptic, magnetooptic and electrooptic effects 4. Moreover, fields of application of particular interest are synthetic aperture radar (SAR), remote sensing and beam forming of linear array antennas, which are all well suited for optics-based processing because of the parallel processing allowed by optical architectures. Therefore, guided-wave optical processors can be successfully applied to the optical control of microwaves, to the reconstruction of two-dimensional images using both spatial and time integration, to data classification and identification in satellite applications and for performing a number of signal processing and optical computing functions.

A detailed four-wave model of acousto-optic (AO) interaction1 in devices formed by planar waveguides and interdigital AO transducers has been used in this paper to identify the highest Bragg diffraction efficiency configurations with reference to the crystal orientation, monomodal guiding parameters, transducer driving radio frequency, f and acoustic loss.

Vertical integration of high-silica channel waveguides on Si substrate has been recently demonstrated by flame hydrolysis deposition.

The superiority of the three-wave-guide directional coupler (3WC) in filtering operations over the conventional 2WC is well known, the main advantage being a spectral response that is the square of that of the 2WC.

The acousto-optic transducer (AOT) is a fundamental component of a number of hybrid circuits for optical computing and optical signal processing. The grating created by the surface acoustic wave (SAW) in an AOT generates Bragg diffraction of an incident optical wave, and the intensity of the diffracted wave is proportional to the product of the incident light intensity and the power of the acoustic wave. This fundamental property of AOTs is widely used for spectral analysis and correlation of wide-band signals. Therefore, the theoretical analysis of an AOT involves both the optical and acoustic modal investigation. In most applications the role of the optical mode analysis is predominant over the acoustic mode analysis because the SAW propagation speed does not depend on the acoustic frequency, as occurs in the LiNbO3 devices.

In the paper, the conceptual scheme of a LiNbO3 integrated optical circuit for on-board data processing is proposed. The design of each integrated component and fabrication techniques are discussed. Finally, a simulation of the whole circuit performance is presented.

A beam dump experiment has been performed at CERN in Gargamelle using the neutrino facility to look for penetrating particles produced either directly in the beam interaction or by prompt decay of new particles. A total of 32 interactions with a visible energy greater than 10 GeV has been found, classified, aftercorrections, into 18 charged current ν μ or ν μ , 5.1 neutral current and 8.9 ν e or ν e charged current events. An excess of ν e events remains after all subtractions from any established sources. Results are presented in terms of the product of the cross section and the leptonic decay branching ratio of the possible source.

Charged-current neutrino interactions have been analysed in a sample of pictures from BEBC equipped with a TST. Using a method independent of both the neutrino flux and nuclear interaction corrections, the ratio R= σn/σp has been measured. The result is R=1.98±0.19 for the ratio of total cross sections. Bjorken x distributions for proton and neutron targets and for u and d quarks are compared. © 1981., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

From the reaction π−n→pπ−π−π0 at 9.140 GeV/c the Δ0ϱ− reaction has been selected. The upper limit in the cross-section of Open image in new window μb, corresponding to an overall cross-section for the Δ0ϱ− channel σ=225 μb; the study of the dN/dt′ distribution shows the high peripherism of the reaction, yet the values of ϱik elements at the two vertex are uncompatible with a pure OPE mechanism. A small correlation between cos θΔ− and cos θΔ0 is found by observing the values of statistical tensors related to the joint decay distribution or by direct analysis in the correlation plots.

This paper describes an interactive system to analyze large samples of collected data. The first application has been developed to ensure a significant improvement in the efficiency of data management in recent high energy physics experiments (Ω-project). However, the system is also suitable in all experiments treating large volumes of experimental data. The relevant features of the system are: 1. u| 2. - the possibility to select a subsample of experimental data in real time with a response time smaller (by an order of magnitude) than other programs used at present; 3. - the possibility to display data in monodimensional distributions and scatter-plots; 4. - the possibility to store in real time selection procedures to be used later. Editing facilities are provided. A few different terminals (video or teletype) can interact with the system, that has been designed for a multi-user environment.

In this paper we present a study of the reaction π − d → π − π − π + d at 9 GeV/ c . The mass spectra are in fair agreement with the predictions of a reggeized pion-exchange Deck model. However, the s -channel azimuthal angular distribution indicates a ϱ-exchange Deck contribution. The results of the partial-wave analysis of the (3 π ) − system are compared with those obtained in a hydrogen target: the J P = 2 + contribution is very small (at most 1.5 ± 1.2)% in our data, which are dominated by J P = 1 + for low mass, whereas the J P = 0 − , 1 + , 2 − have comparable importance in the higher mass region.

A search for the purely leptonic neutral current process induced by antineutrinos: v μ + e − → v μ + e − , has been performed in the BEBC “TST” experiment. No contradiction has been observed with the Salam-Weinberg model.

Using BEBC equipped with a hydrogen-filled neon-surrounded track-sensitive target, the charged current cross sections and structure functions of hydrogen and neon targets traversed by the same neutrinos and antineutrinos are compared directly. The measured total cross-section ratios between hydrogen and neon allow precise total cross-section values for hydrogen to be inferred. Using this normalization, the ν and ν hydrogen data are combined and the quark distributions in free nucleons, parametrised as functions of ξ, are extracted. This free-nucleon parametrisation is then compared directly with the neon data in order to measure nuclear effects such as those recently reported by the EMC collaboration. Only small effects are seen, in excellent agreement with recent SLAC data in a more similar A and q2 range. © 1984., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

First observation is reported of semi-inclusive coherent diffractive charged current interactions of antineutrinos on neon nuclei. A sharp peaking towards zero is observed in the, 0, SCOPUS: ar.j, info:eu-repo/semantics/published