Improved Block DFE Equalization for Mobile WiMAX OFDM Systems

In this paper an improved decision feedback equalizer (DFE) for mobile orthogonal frequency division modulation (OFDM) systems is presented. The time-varying nature of the channel, due to the Doppler effect, produces inter carrier interference (ICI) that may be counteracted by using a DFE frequency-domain OFDM symbol equalizer. The proposed algorithm is base on a recently proposed block DFE equalizer exploiting an LDL decomposition. The main novelty of this work is the idea to modify the backward filter in order to have a complete MMSE linear equalization before the decisions needed for the interference cancellation. Performance may be further improved by re-filtering the signal in an iterative algorithm which makes use of the proposed backward filter at the first iteration. The proposed scheme performance is evaluated by considering a mobile WiMAX IEEE 812.16e standard transceiver

GeoTools

GeoTools is an open source Java library that provides tools for geospatial data

The FOOT FragmentatiOn Of Target Experiment

International audienceIn proton-therapy clinical practice a constant RBE equal to 1.1 is adopted, regardless of the demonstrated RBE variations, which depends on physical and biological parameters. Among other mechanisms, nuclear interactions might influence the proton-RBE due to secondary heavier particles produced by target fragmentation that can significantly contribute to the total dose: an un-wanted and undetermined increase of normal tissues complications probability may occur. The FOOT experiment is designed to study these processes. Target ($^{16}$O,$^{12}$C) fragmentation induced by 150 − 250 M eV proton beam will be studied via inverse kinematic approach, where $^{16}$O and $^{12}$C therapeutic beams, with the same kinetic energy per nucleon of the proton, collide on graphite and hydrocarbons target to provide the cross section on Hydrogen (to explore also the projectile fragmentation). The detector design, the performances and expected resolution results obtained form Monte Carlo study, based on the FLUKA code will be presented

The Drift Chamber detector of the FOOT experiment: Performance analysis and external calibration

The study that we present is part of the preparation work for the setup of the FOOT (FragmentatiOn Of Target) experiment whose main goal is the measurement of the double differential cross sections of fragments produced in nuclear interactions of particles with energies relevant for particle therapy. The present work is focused on the characterization of the gas-filled drift chamber detector composed of 36 sensitive cells, distributed over two perpendicular views. Each view consists of six consecutive and staggered layers with three cells per layer. We investigated the detector efficiency and we performed an external calibration of the space–time relations at the level of single cells. This information was then used to evaluate the drift chamber resolution. An external tracking system realized with microstrip silicon detectors was adopted to have a track measurement independent on the drift chamber. The characterization was performed with a proton beam at the energies of 228 and 80 MeV. The overall hit detection efficiency of the drift chamber has been found to be 0.929±0.008 , independent on the proton beam energy. The spatial resolution in the central part of the cell is about 150±10 μ m and 300±10 μ m and the corresponding detector angular resolution has been measured to be 1.62±0.16 mrad and 2.1±0.4 mrad for the higher and lower beam energies, respectively. In addition, the best value on the intrinsic drift chamber resolution has been evaluated to be in the range 60−100 μ m. In the framework of the FOOT experiment, the drift chamber will be adopted in the pre-target region, and will be exploited to measure the projectile direction and position, as well as for the identification of pre-target fragmentation events

Development and characterization of a Δ E-TOF detector prototype for the FOOT experiment

This paper describes the development and characterization of a ΔE-TOF detector composed of a plastic scintillator bar coupled at both ends to silicon photomultipliers. This detector is a prototype of a larger version which will be used in the FOOT (FragmentatiOn Of Target) experiment to identify the fragments produced by ion beams accelerated onto a hydrogen-enriched target. The final ΔE-TOF detector will be composed of two layers of plastic scintillator bars with orthogonal orientation and will measure, for each crossing fragment, the energy deposited in the plastic scintillator (ΔE), the time of flight (TOF), and the coordinates of the interaction position in the scintillator. To meet the FOOT experimental requirements, the detector should have energy resolution of a few percents and time resolution of 70 ps, and it should allow to discriminate multiple fragments belonging to the same event. To evaluate the achievable performances, the detector prototype was irradiated with protons of kinetic energy in the 70–230 MeV range and interacting at several positions along the bar. The measured energy resolution σΔE∕ΔE was 6–14%, after subtracting the fluctuations of the deposited energy. A time resolution σ between 120 and 180 ps was obtained with respect to a trigger detector. A spatial resolution σ of 1.9 cm was obtained for protons interacting at the center of the bar