1,785 research outputs found
Nuclear re-interaction effects in quasi-elastic neutrino nucleus scattering
The quasi-elastic neutrino-nucleus cross section has been calculated by using
a Fermi gas model corrected to consider the re-scattering between the emitted
nucleon and the rest nucleus. As an example of the relevance of this effect we
show results for the muon production cross section on 16O target.Comment: 7 pages, 4 Postscript figures, Contribution to NuInt01 Workshop, KEK,
Tsukuba, Japa
Photodynamics of indole in water
We present a combination of time-dependent density functional theory with the
quantum mechanical/molecular mechanical approach which can be applied to study
nonadiabatic dynamical processes in molecular systems interacting with the
environment. Our method is illustrated on the example of ultrafast excited
statedynamics of indole in water. We compare the mechanisms of nonradiative
relaxation and the electronic state lifetimes for isolated indole, indole in a
sphere of classical water, and indole + 3H2O embedded in a classical water
sphere. In the case of isolated indole, the initial excitation to the S2
electronic state is followed by an ultrafast internal conversion to the S1
state with a time constant of 17 fs. The S1 state is long living (> 30 ps) and
deactivates to the ground state along the N–H stretching coordinate. This
deactivation mechanism remains unchanged for indole in a classical water
sphere. However, the lifetimes of the S2 and S1 electronic states are
extended. The inclusion of three explicit water molecules opens a new
relaxation channel which involves the electron transfer to the solvent,
leading eventually to the formation of a solvated electron. The relaxation to
the ground state takes place on a time scale of 60 fs and contributes to the
lowering of the fluorescence quantum yield. Our simulations demonstrate the
importance of including explicit water molecules in the theoretical treatment
of solvated systems
CORAM (COsmic RAy Mission): An outreach program one century after Pacini and Hess works
Abstract CORAM (COsmic RAy Mission) is an outreach program carried out by INFN and the University of Salento in close collaboration with high schools. Students and their teachers are involved in the design, construction, test and operation of detectors for the measurement of several properties of the cosmic ray flux. The results of a set of measurements, made with a first detector prototype at different altitudes and underground, will be described
Multi-scale analysis of lung computed tomography images
A computer-aided detection (CAD) system for the identification of lung
internal nodules in low-dose multi-detector helical Computed Tomography (CT)
images was developed in the framework of the MAGIC-5 project. The three modules
of our lung CAD system, a segmentation algorithm for lung internal region
identification, a multi-scale dot-enhancement filter for nodule candidate
selection and a multi-scale neural technique for false positive finding
reduction, are described. The results obtained on a dataset of low-dose and
thin-slice CT scans are shown in terms of free response receiver operating
characteristic (FROC) curves and discussed.Comment: 18 pages, 12 low-resolution figure
High Energy & High Luminosity Colliders
With the best of modern standard lasers, high-energy colliders
from electron beams of E larger than 250 GeV are only possible at the expense
of photon luminosity, i.e. 10 times lower than for photon colliders at c.m.
energies below 0.5 TeV. For existing state-of-the art lasers, an optimistic
upper energy limit for x=4.8 is an electron beam of less than 250 GeV. This
Snowmass21 Contributed Paper shows how Free Electron Lasers (FEL) pave the way
for High Energy & High Luminosity colliders. We present and
assess a conceptual design study of a FEL with wavelength of 2.4 m and an
x-factor in the range of 2 to 40, to maximize the luminosity of a
collider as second interaction region of 0.5 TeV to 10 TeV c.m.
colliders.Comment: Contribution to Snowmass 202
Measuring static viscous permeability of porous absorbing materials
International audienceConventional acoustical methods for measuring the permeability or flow resistivity of a porous material require a priori estimation of the porosity. In this work, an acoustical method is presented in which a simplified expression (independent of both the frequency and porosity) for the transmitted waves at the Darcy’s regime (low frequency range) is derived, and used for the inverse determination of both the viscous static permeability (or flow resistivity) and the thickness of air-saturated porous materials. The inverse problem is solved based on the least-square numerical method using transmitted waves in time domain. Tests are performed using industrial plastic foams. Experimental and numerical validation results of this method are presented, which show theadvantage of measuring the viscous permeability and thickness of a porous slab, without the required prior knowledge of the porosity, but by simply using the transmitted waves
Two-colour generation in a chirped seeded Free-Electron Laser
We present the experimental demonstration of a method for generating two
spectrally and temporally separated pulses by an externally seeded, single-pass
free-electron laser operating in the extreme-ultraviolet spectral range. Our
results, collected on the FERMI@Elettra facility and confirmed by numerical
simulations, demonstrate the possibility of controlling both the spectral and
temporal features of the generated pulses. A free-electron laser operated in
this mode becomes a suitable light source for jitter-free, two-colour
pump-probe experiments
Pythia 8 as hadronic interaction model in air shower simulations
Hadronic interaction models are a core ingredient of simulations of extensive air showers and pose the major source of uncertainties of predictions of air shower observables. Recently, Pythia 8, a hadronic interaction model popular in accelerator-based high-energy physics, became usable in air shower simulations as well. We have integrated Pythia 8 with its new capabilities into the air shower simulation framework CORSIKA 8. First results show significantly shallower shower development, which we attribute to higher cross-section predictions by the new simplified nuclear model of Pythia
Effects of nuclear re-interactions in quasi-elastic neutrino-nucleus scattering
The effects of nuclear re-interactions in the quasi-elastic neutrino-nucleus
scattering are investigated with a phenomenological model. We found that the
nuclear responses are lowered and their maxima are shifted towards higher
excitation energies. This is reflected on the total neutrino-nucleus cross
section in a general reduction of about 15% for neutrino energies above 300
MeV.Comment: 15 pages, 5 figures. Submitted to AstroParticle Physic
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