16 research outputs found
Measurement of the small-scale 3D Lyman- forest power spectrum
Small-scale correlations measured in the Lyman- (Ly) forest
encode information about the intergalactic medium and the primordial matter
power spectrum. In this article, we present and implement a simple method to
measure the 3-dimensional power spectrum, , of the Ly
forest at wavenumbers corresponding to small, Mpc scales. In order
to estimate from sparsely and unevenly distributed data samples,
we rely on averaging 1-dimensional Fourier Transforms, as previously carried
out to estimate the 1-dimensional power spectrum of the Ly forest,
. This methodology exhibits a very low computational cost. We
confirm the validity of this approach through its application to Nyx
cosmological hydrodynamical simulations. Subsequently, we apply our method to
the eBOSS DR16 Ly forest sample, providing as a proof of principle, a
first measurement averaged over two redshift bins and
. This work highlights the potential for forthcoming
measurements, from upcoming large spectroscopic surveys, to untangle
degeneracies in the cosmological interpretation of .Comment: 27 pages, 9 figure
A comprehensive revision of the summation method for the prediction of reactor antineutrino fluxes and spectra
The summation method for the calculation of reactor fluxes and
spectra is methodically revised and improved. For the first time, a complete
uncertainty budget accounting for all known effects likely to impact these
calculations is proposed. Uncertainties of a few percents at low energies and
ranging up to 20% at high energies are obtained on the calculation of a typical
reactor spectrum. Although huge improvements have been achieved
over the past decade, the quality and incompleteness of the present day
evaluated nuclear decay data still limit the accuracy of the calculations and
therefore dominate by far these uncertainties. Pushing the -decay
modeling of the thousands of branches making a reactor spectrum
to a high level of details comparatively brings modest changes. In particular,
including nuclear structure calculations in the evaluation of the non-unique
forbidden transitions gives a smaller impact than anticipated in past studies.
Finally, this new modeling is challenged against state-of-the-art predictions
and measurements. While a good agreement is observed with the most recent
Inverse Beta Decay measurements of reactor fluxes and spectra, it
is unable to properly describe the reference aggregate spectra measured
at the Institut Laue-Langevin High-Flux reactor in the 80s. This result adds to
recent suspicions the reliability of these data and preferentially
points toward a misprediction of the U spectrum.Comment: 34 pages, 16 figures. Submitted to PR
Reacor Shape Anomaly Explained by Energy Scale Nonlinearities?
<p>Reacor Shape Anomaly Explained by Energy Scale Nonlinearities?</p
Étude des sensibilités et bruits de fond de l'expérience Double Chooz pour la recherche du paramètre de mélange leptonique 13
L'expérience Double Chooz étudiera les oscillations des antineutrinos électroniques produits par la centrale nucléaire de Chooz pour mesurer l'angle de mélange 13. La connaissance actuelle sur ce paramètre, apportée par CHOOZ, peut être améliorée en réduisant les erreurs statistiques et systématiques. Afin de réduire la première de ces deux incertitudes, Double Chooz observera un échantillon de données conséquent. Cette expérience utilisera deux détecteurs identiques pour s'affranchir de la plupart des incertitudes expérimentales intervenant dans les processus de production et de détection. Une attention particulière sera portée sur les bruits de fond engendrés par la radioactivité naturelle et les interactions des rayons cosmiques. Nous présentons, dans cette thèse, la simulation que nous avons mise en place pour calculer la sensibilité sur la mesure de 13 et le potentiel de découverte de l'expérience. Nous nous sommes intéressé en particulier à quantifier les incertitudes liées aux détecteurs limitant la sensibilité sur 13. Nous avons également pris en compte certains bruits de fond tels que les événements accidentels engendrés par la radioactivité des PM, les événements corrélés produits par les neutrons de spallation ainsi qu'un bruit de fond hypothétique (celui ayant la forme du signal d'oscillation recherché). Après trois années de prise de données, Double Chooz permettra d'observer un signal d'oscillation pour sin2(2 13)>0,05 (à 3 ) ou bien, si aucune oscillation n'est découverte, de mettre une limite de sin2(2 13)<0,03 à 90 % de confianceLYON1-BU.Sciences (692662101) / SudocSTRASBOURG-Bib.Central Recherche (674822133) / SudocSudocFranceF
Measurement of the small-scale 3D Lyman- forest power spectrum
International audienceSmall-scale correlations measured in the Lyman- (Ly) forest encode information about the intergalactic medium and the primordial matter power spectrum. In this article, we present and implement a simple method to measure the 3-dimensional power spectrum, , of the Ly forest at wavenumbers corresponding to small, Mpc scales. In order to estimate from sparsely and unevenly distributed data samples, we rely on averaging 1-dimensional Fourier Transforms, as previously carried out to estimate the 1-dimensional power spectrum of the Ly forest, . This methodology exhibits a very low computational cost. We confirm the validity of this approach through its application to Nyx cosmological hydrodynamical simulations. Subsequently, we apply our method to the eBOSS DR16 Ly forest sample, providing as a proof of principle, a first measurement averaged over two redshift bins and . This work highlights the potential for forthcoming measurements, from upcoming large spectroscopic surveys, to untangle degeneracies in the cosmological interpretation of
Measurement of the small-scale 3D Lyman- forest power spectrum
International audienceSmall-scale correlations measured in the Lyman- (Ly) forest encode information about the intergalactic medium and the primordial matter power spectrum. In this article, we present and implement a simple method to measure the 3-dimensional power spectrum, , of the Ly forest at wavenumbers corresponding to small, Mpc scales. In order to estimate from sparsely and unevenly distributed data samples, we rely on averaging 1-dimensional Fourier Transforms, as previously carried out to estimate the 1-dimensional power spectrum of the Ly forest, . This methodology exhibits a very low computational cost. We confirm the validity of this approach through its application to Nyx cosmological hydrodynamical simulations. Subsequently, we apply our method to the eBOSS DR16 Ly forest sample, providing as a proof of principle, a first measurement averaged over two redshift bins and . This work highlights the potential for forthcoming measurements, from upcoming large spectroscopic surveys, to untangle degeneracies in the cosmological interpretation of
Measurement of the small-scale 3D Lyman- forest power spectrum
International audienceSmall-scale correlations measured in the Lyman- (Ly) forest encode information about the intergalactic medium and the primordial matter power spectrum. In this article, we present and implement a simple method to measure the 3-dimensional power spectrum, , of the Ly forest at wavenumbers corresponding to small, Mpc scales. In order to estimate from sparsely and unevenly distributed data samples, we rely on averaging 1-dimensional Fourier Transforms, as previously carried out to estimate the 1-dimensional power spectrum of the Ly forest, . This methodology exhibits a very low computational cost. We confirm the validity of this approach through its application to Nyx cosmological hydrodynamical simulations. Subsequently, we apply our method to the eBOSS DR16 Ly forest sample, providing as a proof of principle, a first measurement averaged over two redshift bins and . This work highlights the potential for forthcoming measurements, from upcoming large spectroscopic surveys, to untangle degeneracies in the cosmological interpretation of