4,706 research outputs found
Chirped seeded free-electron lasers: self-standing light sources for two-colour pump-probe experiments
We demonstrate the possibility to run a single-pass free-electron laser in a
new dynamical regime, which can be exploited to perform two-colour pump-probe
experiments in the VUV/X-ray domain, using the free-electron laser emission
both as a pump and as a probe. The studied regime is induced by triggering the
free-electron laser process with a powerful laser pulse, carrying a significant
and adjustable frequency chirp. As a result, the emitted light is eventually
split in two sub-pulses, whose spectral and temporal separations can be
independently controlled. We provide a theoretical description of this
phenomenon, which is found in good agreement with experiments performed on the
FERMI@Elettra free-electron laser
First deep underground observation of rotational signals from an earthquake at teleseismic distance using a large ring laser gyroscope
Recent advances in large ring laser gyroscopes (RLG) technologies opened the
possibility to observe rotations of the ground with sensitivities up to
over the frequency band of seismological interest
(0.01-1Hz), thus opening the way to a new geophysical discipline, i.e.
rotational seismology. A measure of rotations in seismology is of fundamental
interest for (a) the determination of all the six degrees of freedom that
characterize a rigid body motion, and (b) the quantitative estimate of the
rotational motions contaminating ground translation measurements obtained from
standard seismometers. Within this framework, this paper presents and describes
GINGERino, a new large observatory-class RLG located in Gran Sasso underground
laboratory (LNGS), one national laboratories of the INFN (Istituto Nazionale di
Fisica Nucleare). We also report unprecedented observations and analyses of the
roto-translational signals from a tele-seismic event observed in such a deep
underground environment
The Global Electroweak and Higgs Fits in the LHC era
We update the global fit to electroweak precision observables, including the
effect of the latest measurements at hadron colliders of the and top-quark
masses and the effective leptonic weak mixing angle. We comment on the impact
of these measurements in terms of constraints on new physics. We also update
the bounds derived from the fit to the Higgs-boson signal strengths, including
the observables measured at the LHC Run 2, and compare the improvements with
respect to the 7 and 8 TeV results.Comment: 5+1 pages, 3 figures, 2 tables. Prepared for the Proceedings of the
5th LHCP Conference -Shanghai, May 2017- and the EPS-HEP 2017 Conference
-Venice, July 2017. (LHCP version.
Electroweak precision constraints at present and future colliders
We revisit the global fit to electroweak precision observables in the
Standard Model and present model-independent bounds on several general new
physics scenarios. We present a projection of the fit based on the expected
experimental improvements at future colliders, and compare the
constraining power of some of the different experiments that have been
proposed. All results have been obtained with the HEPfit code.Comment: 6 + 1 pages, 4 figures, 6 tables. Minor corrections. Contribution to
the Proceedings of the 38th International Conference on High Energy Physics,
3-10 August 2016, Chicago, U.S.
Electroweak precision observables and Higgs-boson signal strengths in the Standard Model and beyond: present and future
We present results from a state-of-the-art fit of electroweak precision
observables and Higgs-boson signal-strength measurements performed using 7 and
8 TeV data from the Large Hadron Collider. Based on the HEPfit package, our
study updates the traditional fit of electroweak precision observables and
extends it to include Higgs-boson measurements. As a result we obtain
constraints on new physics corrections to both electroweak observables and
Higgs-boson couplings. We present the projected accuracy of the fit taking into
account the expected sensitivities at future colliders.Comment: 34 pages, 30 figures, 23 table
Tandem Dye-Doped Nanoparticles for NIR Imaging via Cerenkov Resonance Energy Transfer
The detection of the Cerenkov radiation (CR) is an emerging preclinical imaging technique which allows monitoring the in vivo distribution of radionuclides. Among its possible advantages, the most interesting is the simplicity and cost of the required instrumentation compared, e.g., to that required for PET scans. On the other hand, one of its main drawbacks is related to the fact that CR, presenting the most intense component in the UV-vis region, has a very low penetration in biological tissues. To address this issue, we present here multifluorophoric silica nanoparticles properly designed to efficiently absorb the CR radiation and to have a quite high fluorescence quantum yield (0.12) at 826 nm. Thanks to a highly efficient series of energy transfer processes, each nanoparticle can convert part of the CR into NIR light, increasing its detection even under 1.0-cm thickness of muscle
Global Bayesian Analysis of the Higgs-boson Couplings
We present preliminary results of a bayesian fit to the Wilson coefficients
of the Standard Model gauge invariant dimension-6 operators involving one or
more Higgs fields, using data on electroweak precision observables and Higgs
boson signal strengths.Comment: Based on a talk given by Diptimoy Ghosh in ICHEP 2014, Valenci
Numerical evaluation of temperature fields and residual stresses in butt weld joints and comparison with experimental measurements
This paper presents a novel numerical model, based on the finite element (FE) method, for the simulation of a welding process aimed to make a twopass V-groove butt joint, paying attention on the prediction of residual stresses and distortions. The âelement birth and deathâ technique for the simulation of the weld filler supply has been considered within this paper. The main advancements with respect to the state of the art herein proposed concern: (i) the development of a modelling technique able to simulate the plates interaction during the welding operation when an only plate is modelled. This phenomenon is usually neglected in literature; (ii) the heat amount is supplied to the FEs as volumetric generation of the internal energy, allowing overcoming the time-consuming calibration phase needed to use the Goldak's model, commonly adopted in literature. Predicted results showed a good agreement with experimental ones
Calibration techniques for binary classification problems: A comparative analysis
Calibrating a classiïŹcation system consists in transforming the output scores, which somehow state the conïŹdence of the classiïŹer regarding the predicted output, into proper probability estimates. Having a well-calibrated classiïŹer has a non-negligible impact on many real-world applications, for example decision making systems synthesis for anomaly detection/fault prediction. In such industrial scenarios, risk assessment is certainly related to costs which must be covered. In this paper we review three state-of-the-art calibration techniques (Plattâs Scaling, Isotonic Regression and SplineCalib) and we propose three lightweight procedures based on a plain ïŹtting of the reliability diagram. Computational results show that the three proposed techniques have comparable performances with respect to the three state-of-the-art approaches
Probabilistic Analysis of Fatigue Behavior of Single Lap Riveted Joints
This research deals with the fatigue behavior of 200 small single lap multiple-riveted joint specimens, widely used for aeronautic structures. The tests were performed with three different levels of stress with stress ratio R = 0.05; three levels were set: 90 MPa, 120 MPa and 160 MPa. The fatigue life and critical crack size for all tested specimens were analyzed. According to the resultsâ analysis, two types of fracture, through-hole and in proximity of the hole, were observed, depending on the level of stress: the higher the applied stress, the more through-hole cracking. Indeed, under the fatigue load with a stress level of 90 MPa, less than 30% of specimens showed cracks propagating through the hole, while, at the stress level of 120 MPa, the percentage reaches 36.3%. At the stress level of 160 MPa, 100% of specimens failed through the hole. Moreover, aimed to use experimental data for probabilistic methods, a statistical analysis was performed according to the AndersonâDarling test. This method allowed the analysis of the datasets, in terms of both fatigue life and critical crack size, providing information about the best distribution function able to fit experimental results
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