A collimation system for ELI-NP Gamma Beam System – design and simulation of performance

The purpose of this study was to evaluate the performance and refine the design of the collimation system for the gamma radiation source (GBS) currently being realised at ELI-NP facility. The gamma beam, produced by inverse Compton scattering, will provide a tunable average energy in the range between 0.2 and 20 MeV, an energy bandwidth 0.5% and a flux of about 108 photons/s. As a result of the inverse Compton interaction, the energy of the emitted radiation is related to the emission angle, it is maximum in the backscattering direction and decreases as the angle increase [1,2]. Therefore, the required energy bandwidth can be obtained only by developing a specific collimation system of the gamma beam, i.e. filtering out the radiation emitted at larger angles. The angular acceptance of the collimation for ELI-NP-GBS must be continuously adjustable in a range from about 700 to 60 μrad, to obtain the required parameters in the entire energy range. The solution identified is a stack of adjustable slits, arranged with a relative rotation around the beam axis to obtain an hole with an approximately circular shape. In this contribution, the final collimation design and its performance evaluated by carrying out a series of detailed Geant4 simulations both of the high-energy and the low-energy beamline are presented

Costruzione e sperimentazione di una turbina cross-flow per acquedotti

La memoria descrive una nuova micro turbina idraulica con capacità di regolazione della portata, per installazioni in piccoli corsi d’acqua, su acquedotti esistenti o a valle di impianti di depurazione delle acque. Viene inoltre descritta l’installazione del prototipo della turbina nella rete idropotabile di un comune siciliano

PG 1613+426: a new sdB pulsator

We report the detection of short period oscillations in the hot subdwarf B (sdB) star PG 1613+426 from time-series photometry carried out with the 91-cm Cassegrain telescope of the Catania Astrophysical Observatory. This star, which is brighter than the average of the presently known sdB pulsators, with B = 14.14 mag, has $T_{\rm eff}=34 400 {\rm K}$ and $\log g = 5.97$, its position is near the hot end of the sdB instability strip, and it is a pulsator with a well observed peak in the power spectrum at $144.18\pm 0.06 \rm s$. This star seems to be well suited for high precision measurements, which could detect a possible multi-mode pulsation behaviourComment: 3 pages, 4 figures. to appear on A&

A collimation system for ELI-NP Gamma Beam System - design and simulation of performance

The purpose of this study was to evaluate the performance and refine the design of the collimation system for the gamma radiation source (GBS) currently being realised at ELI-NP facility. The gamma beam, produced by inverse Compton scattering, will provide a tunable average energy in the range between 0.2 and 20 MeV, an energy bandwidth 0.5% and a flux of about 108 photons/s. As a result of the inverse Compton interaction, the energy of the emitted radiation is related to the emission angle, it is maximum in the backscattering direction and decreases as the angle increase [1,2]. Therefore, the required energy bandwidth can be obtained only by developing a specific collimation system of the gamma beam, i.e. filtering out the radiation emitted at larger angles. The angular acceptance of the collimation for ELI-NP-GBS must be continuously adjustable in a range from about 700 to 60 μrad, to obtain the required parameters in the entire energy range. The solution identified is a stack of adjustable slits, arranged with a relative rotation around the beam axis to obtain an hole with an approximately circular shape. In this contribution, the final collimation design and its performance evaluated by carrying out a series of detailed Geant4 simulations both of the high-energy and the low-energy beamline are presented

All-polymer methylammonium lead iodide perovskite microcavities

open8Thanks to a high photoluminescence quantum yield, large charge carrier diffusion, and ease of processing from solution, perovskite materials are becoming increasingly interesting for flexible optoelectronic devices. However, their deposition requires wide range solvents that are incompatible with many other flexible and solution-processable materials, including polymers. Here, we show that methylammonium lead iodide (MAPbI3) films can be directly synthesized on all-polymer microcavities via simple addition of a perfluorinated layer which protects the polymer photonic structure from the perovskite processing solvents. The new processing provides microcavities with a quality factor Q = 155, that is in agreement with calculations and the largest value reported so far for fully solution processed perovskite microcavities. Furthermore, the obtained microcavity shows strong spectral and angular redistribution of the the MAPbI3 photoluminescence spectrum, which shows a 3.5 fold enhanced intensity with respect to the detuned reference. The opportunity to control and modify the emission of a MAPbI3 film via a simple spun-cast polymer structure is of great interest in advanced optoelectronic applications requiring high colour purity or emission directionality.openLova, Paola; Giusto, Paolo; Di Stasio, Francesco; Manfredi, Giovanni; Paternò, Giuseppe M; Cortecchia, Daniele; Soci, Cesare; Comoretto, DavideLova, Paola; Giusto, Paolo; DI STASIO, Francesco; Manfredi, Giovanni; Paternò, Giuseppe M; Cortecchia, Daniele; Soci, Cesare; Comoretto, David

Finding iteration patterns in dynamic Web page authoring

The final publication is available at Springer via http://dx.doi.org/10.1007/11431879_10Revised Selected Papers of the Joint Working Conferences EHCI-DSVIS 2004, Hamburg, Germany, July 11-13, 2004Most of the current WWW is made up of dynamic pages. The development of dynamic pages is a difficult and costly endeavour, out-of-reach for most users, experts, and content producers. We have developed a set of techniques to support the edition of dynamic web pages in a WYSIWYG environment. In this paper we focus on specific techniques for inferring changes to page generation procedures from users actions on examples of the pages generated by these procedures. More specifically, we propose techniques for detecting iteration patterns in users’ behavior in web page editing tasks involving page structures like lists, tables and other iterative HTML constructs. Such patterns are used in our authoring tool, DESK, where a specialized assistant, DESK-A, detects iteration patterns and generates, using Programming by Example, a programmatic representation of the user’s actions. Iteration patterns help obtain a more detailed characterization of users’ intent, based on user monitoring techniques, that is put in relation to application knowledge automatically extracted by our system from HTML pages. DESK-A relieves end-users from having to learn programming and specification languages for editing dynamic-generated web pages.The work reported in this paper is being supported by the Spanish Ministry of Science and Technology (MCyT), project number TIC2002-194

Gamma beam collimation and characterization system for ELI-NP-GBS

ELI-NP-GBS is a gamma source based on inverse Compton interaction that will provide photons with tunable average energy ranging from 0.2 to 19.5 MeV, energy bandwidth down to 0.5% and average flux of about 108 photons/s in ultra-short pulses. Given these challenging characteristics, dedicated devices and techniques were developed to measure and monitor the gamma beam parameters during the commissioning and the operational phase. Futhermore an adjustable collimation system was developed to fulfill the beam monochromaticity requirement. The gamma beam characterization and collimation apparatus, currently assembled and under test at INFN-Ferrara laboratories, is described in this work

Correction: Near-infrared emitting single squaraine dye aggregates with large Stokes shifts

Correction for 'Near-infrared emitting single squaraine dye aggregates with large Stokes shifts' by G. M. Paternò et al., J. Mater. Chem. C, 2017, 5, 7732–7738

Nanoscale Photoluminescence Manipulation in Monolithic Porous Silicon Oxide Microcavity Coated with Rhodamine-Labeled Polyelectrolyte via Electrostatic Nanoassembling

Porous silicon (PSi) is a promising material for future integrated nanophotonics when coupled with guest emitters, still facing challenges in terms of homogenous distribution and nanometric thickness of the emitter coating within the silicon nanostructure. Herein, it is shown that the nanopore surface of a porous silicon oxide (PSiO2) microcavity (MC) can be conformally coated with a uniform nm-thick layer of a cationic light-emitting polyelectrolyte, e.g., poly(allylamine hydrochloride) labeled with Rhodamine B (PAH-RhoB), leveraging the self-tuned electrostatic interaction of the positively-charged PAH-RhoB polymer and negatively-charged PSiO2 surface. It is found that the emission of PAH-RhoB in the PSiO2 MC is enhanced (≈2.5×) and narrowed (≈30×) at the resonant wavelength, compared with that of PAH-RhoB in a non-resonant PSiO2 reference structure. The time-resolved photoluminescence analysis highlights a shortening (≈20%) of the PAH-RhoB emission lifetime in the PSiO2 MC at the resonance versus off-resonance wavelengths, and with respect to the reference structure, thereby proving a significant variation of the radiative decay rate. Remarkably, an experimental Purcell factor Fp = 2.82 is achieved. This is further confirmed by the enhancement of the photoluminescence quantum yield of the PAH-RhoB in the PSiO2 MC with respect to the reference structure. Application of the electrostatic nanoassembling approach to other emitting dyes, nanomaterials, and nanophotonic systems is envisaged