Search results for "Particules"
showing 10 items of 53 documents
IceCube search for neutrinos coincident with compact binary mergers from LIGO-Virgo's first gravitational-wave transient catalog
2020
Using the IceCube Neutrino Observatory, we search for high-energy neutrino emission coincident with compact binary mergers observed by the LIGO and Virgo gravitational-wave (GW) detectors during their first and second observing runs. We present results from two searches targeting emission coincident with the sky localization of each GW event within a 1000 s time window centered around the reported merger time. One search uses a model-independent unbinned maximum-likelihood analysis, which uses neutrino data from IceCube to search for pointlike neutrino sources consistent with the sky localization of GW events. The other uses the Low-Latency Algorithm for Multi-messenger Astrophysics, which …
IceCube Search for High-Energy Neutrino Emission from TeV Pulsar Wind Nebulae
2020
Pulsar wind nebulae (PWNe) are the main gamma-ray emitters in the Galactic plane. They are diffuse nebulae that emit nonthermal radiation. Pulsar winds, relativistic magnetized outflows from the central star, shocked in the ambient medium produce a multiwavelength emission from the radio through gamma-rays. Although the leptonic scenario is able to explain most PWNe emission, a hadronic contribution cannot be excluded. A possible hadronic contribution to the high-energy gamma-ray emission inevitably leads to the production of neutrinos. Using 9.5 yr of all-sky IceCube data, we report results from a stacking analysis to search for neutrino emission from 35 PWNe that are high-energy gamma-ray…
Contribution à l'étude des liaisons optiques atmosphériques : propagation, disponibilité et fiabilité.
2005
In this work we study the fog attenuation in the visible and infrared spectral band related to Free Space Optics (FSO). Based on the Mie scattering theory, fog extinction coefficients for different particle size distributions as a function of wavelength were derived. A simple analytical model allowing the prediction of atmospheric transmission for the 0.69 - 1.55 µm spectral band was developed. This model is valid for advection and convection fog and for visibility range between 50 to 1000 m. This model, implemented into software developed at FT R&D, allows the prediction of the Quality of Service of FSO links. Finally, we performed an experimental study to compare the fog effect on two FSO…
Eco-extraction and encapsulation of carotenoid and anthocyanin pigments from tropical plants
2018
This thesis deals with extraction processes using assistance technologies or green solvents and encapsulation systems of natural pigments in order to exploit and apply them in the food, cosmetic and pharmaceutical industries. In this goal, microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE) and Ionic liquids (IL) were evaluated for the extraction of carotenoids and anthocyanins from Vietnamese plants. The results obtained show that the MAE was always a rapid and helpful system for all types of extraction tested whereas ultrasounds were particularly efficient when pigments are present on the surface of plant tissues. However, UAE was also improving results compared to c…
GW190521: A Binary Black Hole Merger with a Total Mass of 150 M⊙
2020
LIGO Scientific Collaboration and Virgo Collaboration: et al.
Constraints on neutrino emission from nearby galaxies using the 2MASS redshift survey and IceCube
2020
The distribution of galaxies within the local universe is characterized by anisotropic features. Observatories searching for the production sites of astrophysical neutrinos can take advantage of these features to establish directional correlations between a neutrino dataset and overdensities in the galaxy distribution in the sky. The results of two correlation searches between a seven-year time-integrated neutrino dataset from the IceCube Neutrino Observatory, and the 2MASS Redshift Survey (2MRS) catalog are presented here. The first analysis searches for neutrinos produced via interactions between diffuse intergalactic Ultra-High Energy Cosmic Rays (UHECRs) and the matter contained within …
Astrophysical neutrinos and cosmic rays observed by IceCube
2018
The core mission of the IceCube neutrino observatory is to study the origin and propagation of cosmic rays. IceCube, with its surface component IceTop, observes multiple signatures to accomplish this mission. Most important are the astrophysical neutrinos that are produced in interactions of cosmic rays, close to their sources and in interstellar space. IceCube is the first instrument that measures the properties of this astrophysical neutrino flux and constrains its origin. In addition, the spectrum, composition, and anisotropy of the local cosmic-ray flux are obtained from measurements of atmospheric muons and showers. Here we provide an overview of recent findings from the analysis of Ic…
Charged particle multiplicity distributions in restricted rapidity intervals in Z0 hadronic decays.
1991
The multiplicity distributions of charged particles in restricted rapidity intervals in Z0 hadronic decays measured by the DELPHI detector are presented. The data reveal a shoulder structure, best visible for intervals of intermediate size, i.e. for rapidity limits around ±1.5. The whole set of distributions including the shoulder structure is reproduced by the Lund Parton Shower model. The structure is found to be due to important contributions from 3-and 4-jet events with a hard gluon jet. A different model, based on the concept of independently produced groups of particles, "clans", fluctuating both in number per event and particle content per clan, has also been used to analyse the pres…
Characteristics of the diffuse astrophysical electron and Tau neutrino flux with six years of IceCube high energy cascade data
2020
We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of φastro=1.66-0.27+0.25 at E0=100 TeV, in agreement with IceCube's complementary muon neutrino results and wit…
Constraints on Minute-Scale Transient Astrophysical Neutrino Sources
2019
High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Here, we calculate generic bounds on the neutrino flux of short-lived transient so…