Optical Fiber Sensor Technology in Portugal

Abstract

A general overview of the R&D activity in fiber optic sensing developed over the last fifteen years in Portugal is given. Different topics are addressed, including interferometric, intensity and Bragg grating based fiber optic sensors, signal processing and multiplexing techniques, optical current sensors, together with some references to field trials and applications. Possible guidelines for present and future national R&D activity on this subject are outlined.     

Development of 2D particle-in-cell code to simulate high current,low energy beam in a beam transport system

A code for 2D space-charge dominated beam dynamics study in beam transport lines is developed. The code is used for particle-in-cell (PIC) simulation of z-uniform beam in a channel containing solenoids and drift space. It can also simulate a transport line where quadrupoles are used for focusing the beam. Numerical techniques as well as the results of beam dynamics studies are presented in the paper.      

First samples of Ti and Nb tubes explosion welding joint with stainless steel for ILC 1.8 K cryomodule

The world first samples of Ti and Nb tubes joint with stainless steel ones by an explosion welding by the JINR-VNIIEF-FNAL-INFN cooperation were manufactured in the frame of ILC R&D programe. An applying methods of relaxation of residual tensions (after explosion and electron beam welding), macro- and microanalyses of welding seam and cryogenic tests of the samples produced manifest the achievement of high mechanic strength (≈250 MPa/share) of welding seam, solidity and leak absence on 10^?10 l atm/s level at 1.8 K. The explosion welding technology and methods introducing to industrial manufacturing of the 4-th generation of cryomodule of TESLA TYPE DESIGN can exclude the Ti—communications, connect the Nb—cavity with stainless steel vessel and reduce significantly the accelerator cost.     

Coherent Excitation of Optical Oscillations in a Metal Nanosphere by a 2D Electric Current

We propose a new concept of localized surface plasmon polariton (SPP) mode excitation in a spherical nanoparticle, which utilizes a collective mechanism of dissipative instability in an adjacent 2D plasma carrying a DC electric current. We show that 2D DC current becomes unstable at optical frequencies when the drift velocity exceeds the speed of sound in the 2D plasma. Dissipative instability emerges as a result of self-consistent 2D plasma oscillations coupled to the electromagnetic modes of the nanosphere, the material of which is absorbing at given frequency (i.e., the dielectric permittivity Imε > 0), and instability is absent in the case of transparent material. We derive the dispersion equation for this dissipative instability by a self-consistent solution of the Maxwell equations for the electromagnetic modes and the hydrodynamic equations for the 2D plasma current. Our estimates demonstrate attainment of very high instability increments Imω ~ 10¹⁵ s^?1, which makes the proposed concept very promising for excitation of plasmonic nanoantennas.     

Studies on the drift properties and spatial resolution using a microMEGAS-equipped time projection chamber

R&D studies on the performance as well as on the gas properties of the microMEGAS-based time projection chamber with standard readout were carried out in June 2005 using 4 GeV/c pion beam in a magnetic field from 0 to 1 T at the proton synchrotron beam line at KEK, Japan. Analysis of the electron drift velocity, diffusion constant and point resolution of padrow measurement for MicroMEGAS TPC filled with 95% argon and 5% isobutane gas are presented. The underlying physical mechanism which determines the optimal TPC performance are briefly discussed. Preliminary measurements of gas properties and spatial resolution in close agreement with the analytical calculation and MAGBOLTZ simulation are summarized and presented in this paper.      

Fabrication of lithium-drifted silicon detectors by constant temperature method

A new approach for lithium drifting in silicon is described where the silicon devices under drift are held at constant temperature and bias at normal air ambient, and the drift process is terminated at the end of an estimated time depending upon the thickness of wafers. A 4-channel lithium drifting unit with electronically controlled oven has been constructed for this purpose. Full details of the fabrication procedure are given. A sizable number of Si(Li) detectors have been fabricated using this approach. The quality of the detectors is tested with²⁴¹Am alphas and conversion electrons from²⁰⁹Bi and¹³⁷Cs sources. The detectors are regularly used for nuclear physics experiments at this Centre.     

Full-scale prototype of the circular track detector for the multipurpose detector facility at the NICA acceleration complex

The development of the NICA heavy ion collider, which is now under way, assumes the development of a Multipurpose Detector (MPD), including an end-cap tracker (EC) (which can be a wheel-type tracker based on thin-wall drift tubes (straws) similar to the inner detector of the transition radiation tracker (TRT) in the ATLAS experiment). The identical front and back tracker modules mounted behind the TPC are to ensure the detection of Au-Au ion collision products in the pseudorapidity range from 1.4 to 2.1 with good track parameters of reconstructed events. Each module will contain 60 circular straw planes and maximum straw occupancy will be no higher than 0.2 particle per collision. The NICA EC is substantially different from its analogue and requires a certain amount of R&D. The first results from applying new technology to make a full-scale prototype of the circular EC detector for NICA are presented.     

Optical Communications Research Activities at COM RD1 Siemens S.A.

Abstract

This article summarizes the research activities carried out by the R&D Optical Networks Communications group (COM RD1), at Siemens S.A., in collaboration with both universities and other research institutes. These activities cover various aspects of advanced modulation formats, all optical wavelength conversion, optical quality of signal monitoring in transparent WDM networks, routing, and wavelength assignment in optical networks.     

The NEMO-3 experiment and the SuperNEMO project

The NEMO experiment investigates the neutrinoless double beta decay. The NEMO-3 detector is collecting data in the Frejus Underground Laboratory.The goal of the SuperNEMO detector is to reach a sensitivity of the order of 10²⁶ year on the half-life of the ββ0ν process. The chosen isotopes for the future detector are ⁸²Se and ¹⁵⁰Nd, because of the reduced background. The collaboration has started a 3-year R& D development on all components: tracking detector, calorimeter, source enrichment and purification and radiopurity measurements.     

Nonlinear reflection of an electromagnetic wave from bismuth with supersonic drift of carriers

It has been shown experimentally that the supersonic Hall drift of carriers in bismuth in magnetic fields H = 20?100 kOe stimulates nonlinear reflection of 9.2 GHz electromagnetic wave: the second harmonic power increases by a factor of 10² to 10³. According to the model proposed this effect is related to amplification by the supersonic drift of the hypersonic wave generated at the surface of the crystal.     

Release time calculations for the SPES direct UCx target

A Direct Target for a mid-term RIB ISOL-type facility is being developed at LNL, in the framework of the R&D for the SPES project [1]. Using a 40 MeV proton beam impinging on a UCx thick target of 2.5 g/cm³ density, a production rate of 10¹³ in target fissions per second is expected [2]. The crucial point, when short-lived isotopes are produced in the target, is to build systems (target + ion source) with good release properties and high efficiency. Monte Carlo simulations were performed using the GEANT4 toolkit [3] and the RIBO code [4] in order to optimize our target geometry and to estimate the average release time.     

Modeling and simulations of the cascading failure of multiple interdependent R&D networks under risk propagation

In this paper, we study the robustness of multiple interrelated R&D networks under risk propagation. Firstly, using a bi-partite graph to represent the interrelated R&D networks is emphasized and proposed. Secondly, a risk propagation model is built by defining risk load and risk capacity of each enterprise on a specific R&D network, Thirdly, we use simulations to study risk propagation in interrelated R&D networks. Our results indicate that there exist three critical thresholds to quantify the robustness of R&D networks. Risk propagation in R&D networks is highly affected by the heterogeneity of all enterprises' scales and risk capacities.     

New type of drift tubes for gas-discharge detectors operating in vacuum: Production technology and quality control

A device for fabricating thin-wall (straw) drift tubes using polyethylene terephthalate film 36 μm thick by ultrasonic welding is described together with the technique for controlling their quality. The joint width amounts to 0.4–1.0 mm. The joint breaking strength is 31.9 kg/mm². The argon leakage from a tube of volume 188.6 cm³ under a pressure gradient of 1.0 atm does not exceed 0.3 × 10^–3 cm³/min, which is mainly related to the absence of metallization in the joint vicinity. The high strength, the low tensile creep due to the absence of glued layers, the small value of gas leakage makes the new tubes capable of reliable and long-term operation in vacuum, which is confirmed by the operation of 7168 straw tubes for two years in the NA62 experiment.     

Matter-wave vortices and solitons in anisotropic optical lattices

Using numerical methods, we construct families of vortical, quadrupole, and fundamental solitons in a two-dimensional (2D) nonlinear-Schrödinger/Gross-Pitaevskii equation which models Bose-Einstein condensates (BECs) or photonic crystals. The equation includes the attractive or repulsive cubic nonlinearity and an anisotropic periodic potential. Two types of anisotropy are considered, accounted for by the difference in the strengths of the 1D sublattices, or by a difference in their periods. The limit case of the quasi-1D optical lattice (OL), when one sublattice is missing, is included too. By means of systematic simulations, we identify stability limits for two species of vortex solitons and quadrupoles, of the rhombus and square types. In the attraction model, rhombic vortices and quadrupoles remain stable up to the limit case of the quasi-1D lattice. In the same model, finite stability limits are found for vortices and quadrupoles of the square type, in terms of the anisotropy parameter. In the repulsion model, rhombic vortices and quadrupoles are stable in large parts of the first finite bandgap (FBG). Another species of partly stable anisotropic states is found in the second FBG, subfundamental dipoles, each squeezed into a single cell of the OL. Square-shaped quadrupoles are completely unstable in the repulsion model, while vortices of the same type are stable only in weakly anisotropic OL potentials.     

The (3He,t) reaction on 24Mg and 28Si

The (³He, t) charge exchange reaction on ²⁴Mg and ²⁸Si has been studied at 38.5 MeV. The angular distributions provide a number of new spin assignments in ²⁴Al and ²⁸P. A two-step excitation through intermediate α-particle channels was used to predict the ²⁴Al cross sections. The fits are fair in shape, but about a factor of three too large when a perfect overlap of initial and final shapes is assumed. The data to three 1⁺ states of ²⁸P are compared to the known electromagnetic reduced transition rate B(M1) to the analog states in ²⁸Si.     

Field theory onR×S 3 topology. V:SU 2 gauge theory

A gauge theory on R×S ³ topology is developed. It is a generalization to the previously obtained field theory on R×S ³ topology and in which equations of motion were obtained for a scalar particle, a spin one-half particle, the electromagnetic field of magnetic moments, and a Shrödinger-type equation, as compared to ordinary field equations defined on a Minkowskian manifold. The new gauge field equations are presented and compared to the ordinary Yang-Mills field equations, and the mathematical and physical differences between them are discussed.On leave from Center for Theoretical Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.     

HTSC Maglev Systems for IFE Target Transport Applications

A challenge in inertial fusion energy (IFE) research is to deliver the target to the target chamber center at a high repetition rate. Therefore, the problem of target fabrication and delivery is focused on methods that scale to highly repeatable and cost-effective target production. In this paper, we investigate the possibility of using magnetic-levitation (maglev) transport systems for noncontact manipulation, positioning, and delivery of the cryogenic targets. We focus on the development of transport systems based on movement of high-temperature superconductors (HTSC) over a permanent magnet guideway (PMG). Active guidance is achieved using the HTSC ceramics YBa₂Cu₃O₇? _X and PMG, where an ordered motion is initiated by a special arrangement of the permanent magnets. At present, significant R&D programs are ongoing in order to fulfill the technical requirements and basic elements of the system’s operation as a maglev target accelerator. We present here the main results of this work along with recent results.     

Ion Mobility Measurements of Carbon Tetrachloride

Abstract

The ion mobility and drift velocity of carbon tetrachloride have been measured at various ratios of E/P_o, ranging from 1.0 to 9 volts/ (cm-Torr). The technique employed for these measurements utilizes a polonium alpha particle source which serves both as the source for ionization as well as the means for producing a reference pulse from a solid state silicon barrier detector. The thermal electrons which are produced are readily captured by carbon tetrachloride and the resulting negative ion, assumed to be CC1₄ ^?, is detected by means of a proportional counter located at the end of the drift path. The zero field reduced mobility obtained for CC1₄ ^?was 0.42 cm²/(volt-sec). The nature of the ionic species is explained in terms of the quantum mechanical theory of ionic mobility as put forth by Dalgarno.     

Neutron-rich isotope production using the uranium carbide multi-foil SPES target prototype

In the framework of the R&D program for the SPES (Selective Production of Exotic Species) project of the Istituto Nazionale di Fisica Nucleare (INFN), production yields of neutron-rich isotopes have been measured at the Holifield Radioactive Ion Beam Facility (HRIBF, Oak Ridge National Laboratory, USA). This experiment makes use of the multi-foil SPES target prototype composed of 7 uranium carbide discs, with excess of graphite (ratio C/U = 4 . 77 isotopes of medium mass (between 72 and 141amu), produced via proton-induced fission of uranium using a 40MeV proton beam, have been collected and analyzed for the target heated at 2000 ^° C target temperature.     

基于智能剥离技术的SOI材料制备

优化了硅片低温直接键合与智能剥离技术的工艺流程，在550℃，2.1×10^-2 Pa条件下制备了SOI材料，其顶层单晶Si膜的表面粗糙度为8.5 nm，缺陷密度为90 cm^-2，键合强度达到153.7 kg/cm²，形成的SOI结构除了可以形成三维集成电路中有源层间良好的绝缘层，避免了高温过程对有源层器件结构、材料及性能的影响，还能为三维集成电路后续有源层的制造提供高质量的单晶硅材料. 关键词： 绝缘体上硅 智能剥离 低温直接键合