Impact of cross-section uncertainties on supernova neutrino spectral parameter fitting in the Deep Underground Neutrino Experiment

A primary goal of the upcoming Deep Underground Neutrino Experiment (DUNE) is to measure the $\mathcal{O}(10)$ MeV neutrinos produced by a Galactic core-collapse supernova if one should occur during the lifetime of the experiment. The liquid-argon-based detectors planned for DUNE are expected to be uniquely sensitive to the $\nu_e$ component of the supernova flux, enabling a wide variety of physics and astrophysics measurements. A key requirement for a correct interpretation of these measurements is a good understanding of the energy-dependent total cross section $\sigma(E_\nu)$ for charged-current $\nu_e$ absorption on argon. In the context of a simulated extraction of supernova $\nu_e$ spectral parameters from a toy analysis, we investigate the impact of $\sigma(E_\nu)$ modeling uncertainties on DUNE's supernova neutrino physics sensitivity for the first time. We find that the currently large theoretical uncertainties on $\sigma(E_\nu)$ must be substantially reduced before the $\nu_e$ flux parameters can be extracted reliably: in the absence of external constraints, a measurement of the integrated neutrino luminosity with less than 10\% bias with DUNE requires $\sigma(E_\nu)$ to be known to about 5%. The neutrino spectral shape parameters can be known to better than 10% for a 20% uncertainty on the cross-section scale, although they will be sensitive to uncertainties on the shape of $\sigma(E_\nu)$. A direct measurement of low-energy $\nu_e$-argon scattering would be invaluable for improving the theoretical precision to the needed level.Comment: 25 pages, 21 figure

Collisional broadening and spectral shapes of absorption lines of free and nanopore-confined O-2 gas

This paper presents fully ab initio calculations of the broadenings and spectral shapes of O-2 infrared absorption lines in a free gas and when confined in nanoporous media. These calculations are performed, without use of any adjusted parameter, using a recently proposed approach [Phys. Rev. A 87, 013403 (2013)] that is based on requantized classical molecular-dynamics simulations. This involves studying the time evolutions of the translational and rotational motions of large numbers of molecules taking molecule-molecule and molecule-surface collisions into account through realistic interaction potentials. These simulations enable predictions of dipole autocorrelation functions whose Fourier-Laplace transforms yield the associated spectra. Comparisons are then made with broadening coefficients and line shapes provided by new and previous experiments. The good agreement between calculated and measured results confirms the veracity of the proposed model for a free gas and shows that the effects of confinement, which induce significant modifications to the line shapes, are correctly predicted. The need for improved characterization of the shape and size of pores in random nanoporous media is highlighted. DOI: 10.1103/PhysRevA.87.03251

Reinvestigation of the microwave and new high resolution far-infrared spectra of cis-methyl nitrite, CH3ONO: Rotational study of the two first torsional states

International audienceThe first far-infrared high resolution absorption measurement of the cis-methyl nitrite molecule has been recorded in the range 15-400 cm−1 using the synchrotron AILES beamline radiation at SOLEIL with a resolution of 0.0011 cm−1. First assignments for the pure rotational transitions (15-65 cm−1) belonging to the ground νt (=ν15) = 0 and first νt = 1 excited torsional state are based on measurements from previous studies performed in the 13-40 GHz spectral range, as well as on new millimeter-wave measurements performed at Lille in the spectral range 75-465 GHz. A few measurements and remeasurements in the 1.8-13 GHz were also performed using the chirped FT-MW spectrometer located in North Texas. The pure rotational transitions in the far-infrared and in the microwave spectral range belonging to the two first torsional states have been globally fitted using the RAM ("Rho Axis Method") dealing with the rotation-torsion Hamiltonian and implemented in the BELGI code. A total of 708 and 713 microwave transitions (6 ⩽ J ⩽ 40, View the MathML source ⩽ 23) belonging to the ground torsional state νt = 0 and 1 have been fitted with root-mean-square (rms) deviations of 37.4 kHz and 32.3 kHz respectively, and 3170 pure rotational transitions in the far-infrared range (12 ⩽ Jmax ⩽ 65, 0 ⩽ View the MathML source ⩽ 48) belonging to νt = 0 and 1 have been fitted with a rms deviation of 0.00017 cm−1, using 35 parameters. Since in the far-infrared spectral range, the A-E internal rotor splittings have not been observed for the transitions belonging to the torsional ground νt = 0 state of the cis-methyl nitrite species, another fit was performed on those lines, using a Watson type Hamiltonian for comparison

Liver fibrosis staging with contrast-enhanced ultrasonography: prospective multicenter study compared with METAVIR scoring

International audienceWe prospectively assessed contrast-enhanced sonography for evaluating the degree of liver fibrosis as diagnosed via biopsy in 99 patients. The transit time of microbubbles between the portal and hepatic veins was calculated from the difference between the arrival time of the microbubbles in each vein. Liver biopsy was obtained for each patient within 6 months of the contrast-enhanced sonography. Histological fibrosis was categorized into two classes: (1) no or moderate fibrosis (F0, F1, and F2 according to the METAVIR staging) or (2) severe fibrosis (F3 and F4). At a cutoff of 13 s for the transit time, the diagnosis of severe fibrosis was made with a specificity of 78.57%, a sensitivity of 78.95%, a positive predictive value of 78.33%, a negative predictive value of 83.33%, and a performance accuracy of 78.79%. Therefore, contrast-enhanced ultrasound can help with differentiation between moderate and severe fibrosis.</p