UWB Circular Slot Antenna Provided with an Inverted-L Notch Filter for the 5 GHz WLAN Band

Abstract—The study of a planar circular slot antenna for Ultrawideband (UWB) communications is presented. The integration on this antenna of a notch filter, to reduce the possible interferences with the 5GHz WLAN communications, has been discussed in detail. Four different structures, achieved by etching a suitable pattern on the antenna circular stub, have been considered, and their features have been compared. The antenna with symmetrical and inverted-L cuts shows the best performance, and it has been therefore realized and fully characterized. It shows very good matching features over the UWB band, and notable rejection of the 5 GHz WLAN band

Second resonance of the Higgs field: more signals from the LHC experiments

It has been proposed that, beside the known resonance with mass $m_h=$ 125 GeV, the Higgs field might exhibit a second resonance with a larger mass $(M_H)^{\rm Theor} = 690 \pm 10 ~({\rm stat}) \pm 20 ~({\rm sys})$ GeV which, however, would couple to longitudinal W's with the same typical strength as the low-mass state at $125$ GeV and thus represent a relatively narrow resonance. Looking for evidences in the LHC data, from two analyses published in 2021 by ATLAS (searching for heavy resonances decaying into final states with 4 charged leptons or with photon pairs) we have found combined indications for a new resonance of mass $(M_H)^{\rm Exp} \sim$ 680 (15) GeV and total width $(\Gamma_H)^{\rm Exp} \sim$ 45 (15) GeV. More recent results by CMS (searching for heavy resonances decaying into a pair of h(125) Higgs bosons or looking for high-mass photon pairs produced in pp-diffractive scattering) also show definite excesses pointing toward a new resonance of mass $(M_H)^{\rm Exp} \sim$ 660(30) GeV. However, beside the agreement with the predicted mass range, a clean indication derives from the ATLAS 4-lepton data which reproduce to high accuracy the expected correlation between resonating peak cross section $\sigma_R(pp\to H \to 4l)$ and the ratio $\gamma_H=\Gamma_H/M_H$. This correlation is mainly determined by the lower mass $m_h=$ 125 GeV and supports the view that the known $m_h$ and the new heavy resonance are two different excitations of the same Higgs field by effectively eliminating the spin-zero vs. spin-2 ambiguity in the interpretation of the heavy state. The overall statistical evidence might now be above the traditional 5-sigma discovery threshold because, when comparing with a definite theoretical prediction as in our case, local excesses should maintain intact their statistical significance and not be downgraded by the so called "look-elsewhere" effect.Comment: 14 pages, 4 figures, 4 table

Laser irradiated foam targets: absorption and radiative properties

An experimental campaign to characterize the laser radiation absorption of foam targets and the subsequent emission of radiation from the produced plasma was carried out in the ABC facility of the ENEA Research Center in Frascati (Rome). Different targets have been used: plastic in solid or foam state and aluminium targets. The activated different diagnostics allowed to evaluate the plasma temperature, the density distribution, the fast particle spectrum and the yield of the X-Ray radiation emitted by the plasma for the different targets. These results confirm the foam homogenization action on laser-plasma interaction, mainly attributable to the volume absorption of the laser radiation propagating in such structured materials. These results were compared with simulation absorption models of the laser propagating into a foam target

Simultaneous observation of ultrafast electron and proton beams in TNSA

The interaction of ultra-intense high-power lasers with solid-state targets has been largely studied for the past 20 years as a future compact proton and ion source. Indeed, the huge potential established on the target surface by the escaping electrons provides accelerating gradients of TV/m. This process, called target normal sheath acceleration, involves a large number of phenomena and is very difficult to study because of the picosecond scale dynamics. At the SPARC_LAB Test Facility, the high-power laser FLAME is employed in experiments with solid targets, aiming to study possible correlations between ballistic fast electrons and accelerated protons. In detail, we have installed in the interaction chamber two different diagnostics, each one devoted to characterizing one beam. The first relies on electro-optic sampling, and it has been adopted to completely characterize the ultrafast electron components. On the other hand, a time-of-flight detector, based on chemical-vapour-deposited diamond, has allowed us to retrieve the proton energy spectrum. In this work, we report preliminary studies about simultaneous temporal resolved measurements of both the first forerunner escaping electrons and the accelerated protons for different laser parameters

Dependence on Frequency of the Electromagnetic Field Distribution inside a Cylindrical CavityExcited through an Off-Axis Aperture

To explain the relevant changes in the electron cyclotron resonance ion source behaviour for small variations of the exciting radiation frequency, we determine the spatial distribution of the field within the cavity for every resonant mode

Diagnostic Methodologies of Laser-Initiated 11B(p,α)2α Fusion Reactions

The detection of the ionic products of low-rate fusion reactions, and in particular of the 11B(p,α)2α, is one of the recognized main problems in experiments where these reactions are initiated by tailored interaction of intense and high-energy lasers with matter. A thorough description of this important issue, with a critical comparison of the diagnostic opportunities, is indeed so far. In this work, we describe the common diagnostic methodologies used for the detection of the alpha particles generated by the 11B(p,α)2α reaction and, for each, we outline advantages and limitations, with considerations that can also be applied to other low-rate fusion reactions. We show here that, in general, the univocal characterization of the α products coming from this reaction can be achieved by the simultaneous use of several diagnostic tools placed in close proximity

Electro-optic analysis of the influence of target geometry on electromagnetic pulses generated by petawatt laser-matter interactions

We present an analysis of strong laser-driven electromagnetic pulses using novel electro-optic diagnostic techniques. A range of targets were considered, including thin plastic foils (20-550 nm) and mass-limited, optically-levitated micro-targets. Results from foils indicate a dependence of EMP on target thickness, with larger peak electric fields observed with thinner targets. Spectral analysis suggests high repeatability between shots, with identified spectral features consistently detected with 30 MeV energies, suggesting the discharge current contribution to EMP is dominant

Policaptil Gel Retard® reduces body weight and improves insulin sensitivity in obese subjects

Policaptil Gel Retard® (PGR), a natural fiber-based molecule, has been shown to prevent weight gain and ameliorate insulin-resistance indices in obese children and adolescents. The aim of this study was to compare the effects of 12 weeks of low calories and low glycemic index (LC-LGI) diet associated or not with the intake of PGR on anthropometric, bioimpedance, and metabolic parameters. Data from 20 obese adult subjects (10 per group) were analyzed. An LC-LGI diet with or without PGR intake reduced weight, BMI, and waist circumference. PGR intake elicited a reduction in fasting plasma insulin and insulin resistance index together with an improvement in insulin sensitivity

Directional Track Selection Technique in CR39 SSNTD for lowyield reaction experiments

There is a great interest in the study of p-11B aneutronic nuclear fusion reactions, both for energy production and for determination of fusion cross-sections at low energies. In this context we performed experiments at CELIA in which energetic protons, accelerated by the laser ECLIPSE, were directed toward a solid Boron target. Because of the small cross-sections at these energies the number of expected reactions is low. CR39 Solid-State Nuclear Track Detectors (SSNTD) were used to detect the alpha particles produced. Because of the low expected yield, it is difficult to discriminate the tracks due to true fusion products from those due to natural background in the CR39. To this purpose we developed a methodology of particle recognition according to their direction with respect to the detector normal, able to determine the position of their source. We applied this to the specific experiment geometry, so to select from all the tracks those due to particles coming from the region of interaction between accelerated protons and solid boron target. This technique can be of great help on the analysis of SSNTD in experiments with low yield reactions, but can be also generally applied to any experiment where particles reach the track detector with known directions, and for example to improve the detection limit of particle spectrometers using CR39

Study on a compact and adaptable Thomson Spectrometer for laser-initiated 11B(p,α)8Be reactions and low-medium energy particle detection

Thomson Spectrometers are of primary importance in the discrimination of particles produced by laser-plasma interaction, according to their energy and charge-mass ratio. We describe here a detailed study on a set of Thomson Spectrometers, adaptable to different experimental situations, with the aim of being placed directly within the experimental chamber, rather than in additional extensions, in order to increase the solid angle of observation. These instruments are suitable for detection of low-medium energy particles and can be effectively employed in laser-plasma experiments of 11B(p,α)8Be fusion. They are provided with permanent magnets, have small dimensions and compact design. In these small configurations electric and magnetic fringing fields play a primary role for particle deflection, and their accurate characterization is required. It was accomplished by means of COMSOL electromagnetic solver coupled to an effective analytical model, very suitable for practical use of the spectrometers. Data from experimental measurements of the magnetic fields have been also used. We describe the application of the spectrometers to an experiment of laser-plasma interaction, coupled to Imaging Plate detectors. Data analysis for spectrum and yield of the detected radiation is discussed in detail. © 2016 ENEA