Inferences on mass composition and tests of hadronic interactions from 0.3 to 100 EeV using the water-Cherenkov detectors of the Pierre Auger Observatory

We present a new method for probing the hadronic interaction models at ultrahigh energy and extracting details about mass composition. This is done using the time profiles of the signals recorded with the water-Cherenkov detectors of the Pierre Auger Observatory. The profiles arise from a mix of the muon and electromagnetic components of air showers. Using the risetimes of the recorded signals, we define a new parameter, which we use to compare our observations with predictions from simulations. We find, first, inconsistencies between our data and predictions over a greater energy range and with substantially more events than in previous studies. Second, by calibrating the new parameter with fluorescence measurements from observations made at the Auger Observatory, we can infer the depth of shower maximum Xmax for a sample of over 81,000 events extending from 0.3 to over 100 EeV. Above 30 EeV, the sample is nearly 14 times larger than what is currently available from fluorescence measurements and extending the covered energy range by half a decade. The energy dependence of ?Xmaxcopyright is compared to simulations and interpreted in terms of the mean of the logarithmic mass. We find good agreement with previous work and extend the measurement of the mean depth of shower maximum to greater energies than before, reducing significantly the statistical uncertainty associated with the inferences about mass composition

farriae

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Angular resolution at map level in the QUBIC instrument

Since its discovery in the 1960s, the cosmic microwave background (CMB) radiation has become a very important observational tool to understand the physics of the early universe. The parameter r, defined as the relative amplitude of tensor to scalar perturbations, is currently constrained to the range r < 0.056. QUBIC is a ground-based instrument designed to search for very weak B-mode signals in polarization anisotropies at intermediate angular scales (l 3c 30 12 200). To achieve this goal, QUBIC combines two widely used techniques in the CMB community: interferometry and bolometry. In this work, we compute the angular resolution for an end-to-end simulation using two independent methods: Fit and Sigma. We conclude that the reconstruction performed by the software is appropriate since the resolution measured with both calibrated methods coincides with the theoretical value of the expected resolution.Desde su descubrimiento en los a\u2dcnos 1960, el fondo c\ub4osmico de microondas (CMB, por sus siglas en ingl\ub4es) se ha convertido en una importante herramienta observacional para entender la f\ub4\u131sica del universo temprano. El par\ub4ametro r, definido como la amplitud de las perturbaciones tensoriales relativas a las escalares, est\ub4a acotado actualmente al rango r < 0.056. QUBIC es un instrumento terrestre dise\u2dcnado para buscar se\u2dcnales muy d\ub4ebiles de los modos B en las anisotrop\ub4\u131as de la polarizaci\ub4on a escalas angulares intermedias (l 3c 30 12 200). Para lograr este objetivo, QUBIC combina dos t\ub4ecnicas muy usadas en la comunidad CMB: interferometr\ub4\u131a y bolometr\ub4\u131a. En este trabajo calculamos la resoluci\ub4on angular de una simulaci\ub4on end-to-end con dos m\ub4etodos independientes: Fit y Sigma. Concluimos que la reconstrucci\ub4on que realiza el software es apropiada ya que la resoluci\ub4on medida con ambos m\ub4etodos calibrados coincide con los valores te\ub4oricos de la resoluci\ub4on esperada