Browsing by Author "Aab A."
  • Institution Publication
    Cosmic-Ray Anisotropies in Right Ascension Measured by the Pierre Auger Observatory
    ( 2020-03-10)
    Aab A.
    ;
    Abreu P.
    ;
    Aglietta M.
    ;
    Aglietta M.
    ;
    Albuquerque I.F.M.
    ;
    Albury J.M.
    ;
    Allekotte I.
    ;
    Almela A.
    ;
    Almela A.
    ;
    Castillo J.A.
    ;
    Alvarez-Muiz J.
    ;
    Anastasi G.A.
    ;
    Anastasi G.A.
    ;
    Anchordoqui L.
    ;
    Andrada B.
    ;
    Andringa S.
    ;
    Aramo C.
    ;
    Ferreira P.R.A.
    ;
    Asorey H.
    ;
    Assis P.
    ;
    Avila G.
    ;
    Avila G.
    ;
    Badescu A.M.
    ;
    Bakalova A.
    ;
    Balaceanu A.
    ;
    Barbato F.
    ;
    Barbato F.
    ;
    Luz R.J.B.
    ;
    Becker K.H.
    ;
    Bellido J.A.
    ;
    Berat C.
    ;
    Bertaina M.E.
    ;
    Bertaina M.E.
    ;
    Bertou X.
    ;
    Biermann P.L.
    ;
    Bister T.
    ;
    Biteau J.
    ;
    Blanco A.
    ;
    Blazek J.
    ;
    Bleve C.
    ;
    Boháčová M.
    ;
    Boncioli D.
    ;
    Boncioli D.
    ;
    Bonifazi C.
    ;
    Arbeletche L.B.
    ;
    Borodai N.
    ;
    Botti A.M.
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    Botti A.M.
    ;
    Brack J.
    ;
    Bretz T.
    ;
    Briechle F.L.
    ;
    Buchholz P.
    ;
    Bueno A.
    ;
    Buitink S.
    ;
    Buscemi M.
    ;
    Buscemi M.
    ;
    Caballero-Mora K.S.
    ;
    Caccianiga L.
    ;
    Calcagni L.
    ;
    Cancio A.
    ;
    Cancio A.
    ;
    Canfora F.
    ;
    Canfora F.
    ;
    Caracas I.
    ;
    Carceller J.M.
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    Caruso R.
    ;
    Caruso R.
    ;
    Castellina A.
    ;
    Castellina A.
    ;
    Catalani F.
    ;
    Cataldi G.
    ;
    Cazon L.
    ;
    Cerda M.
    ;
    Chinellato J.A.
    ;
    Choi K.
    ;
    Chudoba J.
    ;
    Chytka L.
    ;
    Clay R.W.
    ;
    Cerutti A.C.C.
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    Colalillo R.
    ;
    Colalillo R.
    ;
    Coleman A.
    ;
    Coluccia M.R.
    ;
    Coluccia M.R.
    ;
    Conceica¸õ R.
    ;
    Condorelli A.
    ;
    Condorelli A.
    ;
    Consolati G.
    ;
    Consolati G.
    ;
    Contreras F.
    ;
    Contreras F.
    ;
    Convenga F.
    ;
    Convenga F.
    ;
    Covault C.E.
    ;
    Dasso S.
    ;
    Dasso S.
    ;
    Daumiller K.
    ;
    Dawson B.R.
    ;
    Day J.A.
    ;
    De Almeida R.M.
    ;
    De Jesús J.
    ;
    De Jesús J.
    ;
    De Jong S.J.
    ;
    De Jong S.J.
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    De Mauro G.
    ;
    De Mauro G.
    ;
    De Mello Neto J.R.T.
    ;
    De Mello Neto J.R.T.
    ;
    De Mitri I.
    ;
    De Mitri I.
    ;
    De Oliveira J.
    ;
    De Oliveira Franco D.
    ;
    De Souza V.
    ;
    Debatin J.
    ;
    Del Rió M.
    ;
    Deligny O.
    ;
    Dhital N.
    ;
    Di Matteo A.
    ;
    Castro M.L.D.
    ;
    Dobrigkeit C.
    ;
    D'Olivo J.C.
    ;
    Dorosti Q.
    ;
    Dos Anjos R.C.
    ;
    Dova M.T.
    ;
    Ebr J.
    We present measurements of the large-scale cosmic-ray (CR) anisotropies in R.A., using data collected by the surface detector array of the Pierre Auger Observatory over more than 14 yr. We determine the equatorial dipole component, through a Fourier analysis in R.A. that includes weights for each event so as to account for the main detector-induced systematic effects. For the energies at which the trigger efficiency of the array is small, the "east-west" method is employed. Besides using the data from the array with detectors separated by 1500 m, we also include data from the smaller but denser subarray of detectors with 750 m separation, which allows us to extend the analysis down to ∼0.03 EeV. The most significant equatorial dipole amplitude obtained is that in the cumulative bin above 8 EeV, %, which is inconsistent with isotropy at the 6σ level. In the bins below 8 EeV, we obtain 99% CL upper bounds on d ⊥ at the level of 1%-3%. At energies below 1 EeV, even though the amplitudes are not significant, the phases determined in most of the bins are not far from the R.A. of the Galactic center, at GC =-94°, suggesting a predominantly Galactic origin for anisotropies at these energies. The reconstructed dipole phases in the energy bins above 4 EeV point instead to R.A. that are almost opposite to the Galactic center one, indicative of an extragalactic CR origin.
  • Institution Publication
    Direct measurement of the muonic content of extensive air showers between 2× 1017 and 2×1018 eV at the Pierre Auger Observatory
    ( 2020-08-01)
    Aab A.
    ;
    Abreu P.
    ;
    Aglietta M.
    ;
    Aglietta M.
    ;
    Albury J.M.
    ;
    Allekotte I.
    ;
    Almela A.
    ;
    Almela A.
    ;
    Alvarez Castillo J.
    ;
    Alvarez-Muñiz J.
    ;
    Anastasi G.A.
    ;
    Anastasi G.A.
    ;
    Anchordoqui L.
    ;
    Andrada B.
    ;
    Andringa S.
    ;
    Aramo C.
    ;
    Araújo Ferreira P.R.
    ;
    Asorey H.
    ;
    Assis P.
    ;
    Avila G.
    ;
    Avila G.
    ;
    Badescu A.M.
    ;
    Bakalova A.
    ;
    Balaceanu A.
    ;
    Barbato F.
    ;
    Barbato F.
    ;
    Barreira Luz R.J.
    ;
    Becker K.H.
    ;
    Bellido J.A.
    ;
    Berat C.
    ;
    Bertaina M.E.
    ;
    Bertaina M.E.
    ;
    Bertou X.
    ;
    Biermann P.L.
    ;
    Bister T.
    ;
    Biteau J.
    ;
    Blanco A.
    ;
    Blazek J.
    ;
    Bleve C.
    ;
    Boháčová M.
    ;
    Boncioli D.
    ;
    Bonifazi C.
    ;
    Bonneau Arbeletche L.
    ;
    Borodai N.
    ;
    Botti A.M.
    ;
    Brack J.
    ;
    Bretz T.
    ;
    Briechle F.L.
    ;
    Buchholz P.
    ;
    Bueno A.
    ;
    Buitink S.
    ;
    Buscemi M.
    ;
    Buscemi M.
    ;
    Caballero-Mora K.S.
    ;
    Caccianiga L.
    ;
    Calcagni L.
    ;
    Cancio A.
    ;
    Cancio A.
    ;
    Canfora F.
    ;
    Canfora F.
    ;
    Caracas I.
    ;
    Carceller J.M.
    ;
    Caruso R.
    ;
    Caruso R.
    ;
    Castellina A.
    ;
    Castellina A.
    ;
    Catalani F.
    ;
    Cataldi G.
    ;
    Cazon L.
    ;
    Cerda M.
    ;
    Chinellato J.A.
    ;
    Choi K.
    ;
    Chudoba J.
    ;
    Chytka L.
    ;
    Clay R.W.
    ;
    Cobos Cerutti A.C.
    ;
    Colalillo R.
    ;
    Colalillo R.
    ;
    Coleman A.
    ;
    Coluccia M.R.
    ;
    Coluccia M.R.
    ;
    Conceição R.
    ;
    Condorelli A.
    ;
    Condorelli A.
    ;
    Consolati G.
    ;
    Consolati G.
    ;
    Contreras F.
    ;
    Contreras F.
    ;
    Convenga F.
    ;
    Convenga F.
    ;
    Covault C.E.
    ;
    Dasso S.
    ;
    Dasso S.
    ;
    Daumiller K.
    ;
    Dawson B.R.
    ;
    Day J.A.
    ;
    de Almeida R.M.
    ;
    de Jesús J.
    ;
    de Jesús J.
    ;
    de Jong S.J.
    ;
    de Jong S.J.
    ;
    De Mauro G.
    ;
    De Mauro G.
    ;
    de Mello Neto J.R.T.
    ;
    de Mello Neto J.R.T.
    ;
    De Mitri I.
    ;
    De Mitri I.
    ;
    de Oliveira J.
    ;
    de Oliveira Franco D.
    ;
    de Souza V.
    ;
    Debatin J.
    ;
    del Río M.
    ;
    Deligny O.
    ;
    Dhital N.
    ;
    Di Matteo A.
    ;
    Díaz Castro M.L.
    ;
    Dobrigkeit C.
    ;
    D’Olivo J.C.
    ;
    Dorosti Q.
    ;
    dos Anjos R.C.
    ;
    Dova M.T.
    ;
    Ebr J.
    ;
    Engel R.
    ;
    Engel R.
    The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between 2 × 10 17 and 2 × 10 18 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at 1017.5eV and 1018eV. We find that, for the models to explain the data, an increase in the muon density of 38 % ± 4 % (12 %) ±18%21% for EPOS-LHC, and of 50 % (53 %) ± 4 % (13 %) ±20%23% for QGSJetII-04, is respectively needed.
  • Institution Publication
    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
    ( 2017-12-15)
    Aab A.
    ;
    Abreu P.
    ;
    Aglietta M.
    ;
    Aglietta M.
    ;
    Al Samarai I.
    ;
    Albuquerque I.F.M.
    ;
    Allekotte I.
    ;
    Almela A.
    ;
    Almela A.
    ;
    Alvarez Castillo J.
    ;
    Alvarez-Muñiz J.
    ;
    Anastasi G.A.
    ;
    Anastasi G.A.
    ;
    Anchordoqui L.
    ;
    Andrada B.
    ;
    Andringa S.
    ;
    Aramo C.
    ;
    Arqueros F.
    ;
    Arsene N.
    ;
    Asorey H.
    ;
    Asorey H.
    ;
    Assis P.
    ;
    Aublin J.
    ;
    Avila G.
    ;
    Avila G.
    ;
    Badescu A.M.
    ;
    Balaceanu A.
    ;
    Barbato F.
    ;
    Barreira Luz R.J.
    ;
    Beatty J.J.
    ;
    Becker K.H.
    ;
    Bellido J.A.
    ;
    Berat C.
    ;
    Bertaina M.E.
    ;
    Bertaina M.E.
    ;
    Bertou X.
    ;
    Biermann P.L.
    ;
    Biteau J.
    ;
    Blaess S.G.
    ;
    Blanco A.
    ;
    Blazek J.
    ;
    Bleve C.
    ;
    Bleve C.
    ;
    Boháčová M.
    ;
    Boncioli D.
    ;
    Boncioli D.
    ;
    Bonifazi C.
    ;
    Borodai N.
    ;
    Botti A.M.
    ;
    Botti A.M.
    ;
    Brack J.
    ;
    Brancus I.
    ;
    Bretz T.
    ;
    Bridgeman A.
    ;
    Briechle F.L.
    ;
    Buchholz P.
    ;
    Bueno A.
    ;
    Buitink S.
    ;
    Buscemi M.
    ;
    Buscemi M.
    ;
    Caballero-Mora K.S.
    ;
    Caccianiga L.
    ;
    Cancio A.
    ;
    Cancio A.
    ;
    Canfora F.
    ;
    Caramete L.
    ;
    Caruso R.
    ;
    Caruso R.
    ;
    Castellina A.
    ;
    Castellina A.
    ;
    Catalani F.
    ;
    Cataldi G.
    ;
    Cazon L.
    ;
    Chavez A.G.
    ;
    Chinellato J.A.
    ;
    Chudoba J.
    ;
    Clay R.W.
    ;
    Cobos A.
    ;
    Colalillo R.
    ;
    Colalillo R.
    ;
    Coleman A.
    ;
    Collica L.
    ;
    Coluccia M.R.
    ;
    Coluccia M.R.
    ;
    Conceição R.
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    Consolati G.
    ;
    Consolati G.
    ;
    Contreras F.
    ;
    Contreras F.
    ;
    Cooper M.J.
    ;
    Coutu S.
    ;
    Covault C.E.
    ;
    Cronin J.
    ;
    D'Amico S.
    ;
    D'Amico S.
    ;
    Daniel B.
    ;
    Dasso S.
    ;
    Dasso S.
    ;
    Daumiller K.
    ;
    Dawson B.R.
    ;
    De Almeida R.M.
    ;
    De Jong S.J.
    ;
    De Jong S.J.
    ;
    De Mauro G.
    ;
    De Mello Neto J.R.T.
    ;
    De Mello Neto J.R.T.
    ;
    De Mitri I.
    ;
    De Mitri I.
    ;
    De Oliveira J.
    ;
    De Souza V.
    ;
    Debatin J.
    ;
    Deligny O.
    ;
    Díaz Castro M.L.
    ;
    Diogo F.
    ;
    Dobrigkeit C.
    ;
    D'Olivo J.C.
    ;
    Dorosti Q.
    ;
    Dos Anjos R.C.
    ;
    Dova M.T.
    ;
    Dundovic A.
    ;
    Ebr J.
    ;
    Engel R.
    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.
  • Institution Publication
    Measurement of the cosmic-ray energy spectrum above 2.5×1018 eV using the Pierre Auger Observatory
    ( 2020-09-16)
    Aab A.
    ;
    Abreu P.
    ;
    Aglietta M.
    ;
    Aglietta M.
    ;
    Albury J.M.
    ;
    Allekotte I.
    ;
    Almela A.
    ;
    Almela A.
    ;
    Alvarez Castillo J.
    ;
    Alvarez-Muñiz J.
    ;
    Alves Batista R.
    ;
    Anastasi G.A.
    ;
    Anastasi G.A.
    ;
    Anchordoqui L.
    ;
    Andrada B.
    ;
    Andringa S.
    ;
    Aramo C.
    ;
    Araújo Ferreira P.R.
    ;
    Asorey H.
    ;
    Assis P.
    ;
    Avila G.
    ;
    Avila G.
    ;
    Badescu A.M.
    ;
    Bakalova A.
    ;
    Balaceanu A.
    ;
    Barbato F.
    ;
    Barbato F.
    ;
    Barreira Luz R.J.
    ;
    Becker K.H.
    ;
    Bellido J.A.
    ;
    Berat C.
    ;
    Bertaina M.E.
    ;
    Bertaina M.E.
    ;
    Bertou X.
    ;
    Biermann P.L.
    ;
    Bister T.
    ;
    Biteau J.
    ;
    Blanco A.
    ;
    Blazek J.
    ;
    Bleve C.
    ;
    Boháčová M.
    ;
    Boncioli D.
    ;
    Boncioli D.
    ;
    Bonifazi C.
    ;
    Bonneau Arbeletche L.
    ;
    Borodai N.
    ;
    Botti A.M.
    ;
    Brack J.
    ;
    Bretz T.
    ;
    Briechle F.L.
    ;
    Buchholz P.
    ;
    Bueno A.
    ;
    Buitink S.
    ;
    Buscemi M.
    ;
    Buscemi M.
    ;
    Caballero-Mora K.S.
    ;
    Caccianiga L.
    ;
    Caccianiga L.
    ;
    Calcagni L.
    ;
    Cancio A.
    ;
    Cancio A.
    ;
    Canfora F.
    ;
    Canfora F.
    ;
    Caracas I.
    ;
    Carceller J.M.
    ;
    Caruso R.
    ;
    Caruso R.
    ;
    Castellina A.
    ;
    Castellina A.
    ;
    Catalani F.
    ;
    Cataldi G.
    ;
    Cazon L.
    ;
    Cerda M.
    ;
    Chinellato J.A.
    ;
    Choi K.
    ;
    Chudoba J.
    ;
    Chytka L.
    ;
    Clay R.W.
    ;
    Cobos Cerutti A.C.
    ;
    Colalillo R.
    ;
    Colalillo R.
    ;
    Coleman A.
    ;
    Coluccia M.R.
    ;
    Coluccia M.R.
    ;
    Conceição R.
    ;
    Condorelli A.
    ;
    Condorelli A.
    ;
    Consolati G.
    ;
    Consolati G.
    ;
    Contreras F.
    ;
    Contreras F.
    ;
    Convenga F.
    ;
    Convenga F.
    ;
    Covault C.E.
    ;
    Covault C.E.
    ;
    Dasso S.
    ;
    Dasso S.
    ;
    Daumiller K.
    ;
    Dawson B.R.
    ;
    Day J.A.
    ;
    De Almeida R.M.
    ;
    De Jesús J.
    ;
    De Jesús J.
    ;
    De Jong S.J.
    ;
    De Jong S.J.
    ;
    De Mauro G.
    ;
    De Mauro G.
    ;
    De Mello Neto J.R.T.
    ;
    De Mello Neto J.R.T.
    ;
    De Mitri I.
    ;
    De Mitri I.
    ;
    De Oliveira J.
    ;
    De Oliveira Franco D.
    ;
    De Souza V.
    ;
    De Vito E.
    ;
    De Vito E.
    ;
    Debatin J.
    ;
    Del Río M.
    ;
    Deligny O.
    ;
    Dembinski H.
    ;
    Dhital N.
    ;
    Di Giulio C.
    ;
    Di Giulio C.
    ;
    Di Matteo A.
    ;
    Díaz Castro M.L.
    ;
    Dobrigkeit C.
    ;
    D'Olivo J.C.
    ;
    Dorosti Q.
    We report a measurement of the energy spectrum of cosmic rays for energies above 2.5×1018 eV based on 215,030 events recorded with zenith angles below 60°. A key feature of the work is that the estimates of the energies are independent of assumptions about the unknown hadronic physics or of the primary mass composition. The measurement is the most precise made hitherto with the accumulated exposure being so large that the measurements of the flux are dominated by systematic uncertainties except at energies above 5×1019 eV. The principal conclusions are(1) The flattening of the spectrum near 5×1018 eV, the so-called "ankle,"is confirmed.(2) The steepening of the spectrum at around 5×1019 eV is confirmed.(3) A new feature has been identified in the spectrum: in the region above the ankle the spectral index γ of the particle flux (∝E-γ) changes from 2.51±0.03 (stat)±0.05 (syst) to 3.05±0.05 (stat)±0.10 (syst) before changing sharply to 5.1±0.3 (stat)±0.1 (syst) above 5×1019 eV.(4) No evidence for any dependence of the spectrum on declination has been found other than a mild excess from the Southern Hemisphere that is consistent with the anisotropy observed above 8×1018 eV.
  • Institution Publication
    Reconstruction of events recorded with the surface detector of the Pierre Auger Observatory
    ( 2020-10-01)
    Aab A.
    ;
    Abreu P.
    ;
    Aglietta M.
    ;
    Aglietta M.
    ;
    Albury J.M.
    ;
    Allekotte I.
    ;
    Almela A.
    ;
    Almela A.
    ;
    Castillo J.A.
    ;
    Alvarez-Muñiz J.
    ;
    Batista R.A.
    ;
    Anastasi G.A.
    ;
    Anastasi G.A.
    ;
    Anchordoqui L.
    ;
    Andrada B.
    ;
    Andringa S.
    ;
    Aramo C.
    ;
    Ferreira P.R.A.
    ;
    Asorey H.
    ;
    Assis P.
    ;
    Avila G.
    ;
    Avila G.
    ;
    Badescu A.M.
    ;
    Bakalova A.
    ;
    Balaceanu A.
    ;
    Barbato F.
    ;
    Barbato F.
    ;
    Luz R.J.B.
    ;
    Becker K.H.
    ;
    Bellido J.A.
    ;
    Berat C.
    ;
    Bertaina M.E.
    ;
    Bertaina M.E.
    ;
    Bertou X.
    ;
    Biermann P.L.
    ;
    Billoir P.
    ;
    Bister T.
    ;
    Biteau J.
    ;
    Blanco A.
    ;
    Blazek J.
    ;
    Bleve C.
    ;
    Boháčová M.
    ;
    Boncioli D.
    ;
    Boncioli D.
    ;
    Bonifazi C.
    ;
    Arbeletche L.B.
    ;
    Borodai N.
    ;
    Botti A.M.
    ;
    Brack J.
    ;
    Bretz T.
    ;
    Bridgeman A.
    ;
    Briechle F.L.
    ;
    Buchholz P.
    ;
    Bueno A.
    ;
    Buitink S.
    ;
    Buscemi M.
    ;
    Buscemi M.
    ;
    Caballero-Mora K.S.
    ;
    Caccianiga L.
    ;
    Caccianiga L.
    ;
    Calcagni L.
    ;
    Cancio A.
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    Cancio A.
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    Canfora F.
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    Canfora F.
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    Caracas I.
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    Carceller J.M.
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    Caruso R.
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    Caruso R.
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    Castellina A.
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    Castellina A.
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    Catalani F.
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    Cataldi G.
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    Cazon L.
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    Cerda M.
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    Chinellato J.A.
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    Choi K.
    ;
    Chudoba J.
    ;
    Chytka L.
    ;
    Clay R.W.
    ;
    Cerutti A.C.C.
    ;
    Colalillo R.
    ;
    Colalillo R.
    ;
    Coleman A.
    ;
    Coluccia M.R.
    ;
    Coluccia M.R.
    ;
    Conceição R.
    ;
    Condorelli A.
    ;
    Condorelli A.
    ;
    Consolati G.
    ;
    Consolati G.
    ;
    Contreras F.
    ;
    Contreras F.
    ;
    Convenga F.
    ;
    Convenga F.
    ;
    Covault C.E.
    ;
    Dasso S.
    ;
    Dasso S.
    ;
    Daumiller K.
    ;
    Dawson B.R.
    ;
    Day J.A.
    ;
    De Almeida R.M.
    ;
    De Jesús J.
    ;
    De Jesús J.
    ;
    De Jong S.J.
    ;
    De Jong S.J.
    ;
    Mauro G.D.
    ;
    Mauro G.D.
    ;
    Neto J.R.T.D.M.
    ;
    Neto J.R.T.D.M.
    ;
    Mitri I.D.
    ;
    Mitri I.D.
    ;
    De Oliveira J.
    ;
    Franco D.D.O.
    ;
    De Souza V.
    ;
    Vito E.D.
    ;
    Vito E.D.
    ;
    Debatin J.
    ;
    Río M.D.
    ;
    Deligny O.
    ;
    Dhital N.
    ;
    Matteo A.D.
    ;
    Castro M.L.D.
    ;
    Dobrigkeit C.
    ;
    D'Olivo J.C.
    ;
    Dorosti Q.
    Cosmic rays arriving at Earth collide with the upper parts of the atmosphere, thereby inducing extensive air showers. When secondary particles from the cascade arrive at the ground, they are measured by surface detector arrays. We describe the methods applied to the measurements of the surface detector of the Pierre Auger Observatory to reconstruct events with zenith angles less than 60 using the timing and signal information recorded using the water-Cherenkov detector stations. In addition, we assess the accuracy of these methods in reconstructing the arrival directions of the primary cosmic ray particles and the sizes of the induced showers.