Next-to-Leading Order QCD Analysis of Polarized Deep Inelastic Scattering Data

We present a Next-to-Leading order perturbative QCD analysis of world data on the spin dependent structure functions $g_1^p, g_1^n$, and $g_1^d$, including the new experimental information on the $Q^2$ dependence of $g_1^n$. Careful attention is paid to the experimental and theoretical uncertainties. The data constrain the first moments of the polarized valence quark distributions, but only qualitatively constrain the polarized sea quark and gluon distributions. The NLO results are used to determine the $Q^2$ dependence of the ratio $g_1/F_1$ and evolve the experimental data to a constant $Q^2 = 5 GeV^2$. We determine the first moments of the polarized structure functions of the proton and neutron and find agreement with the Bjorken sum rule.Comment: 21 pages, 4 figures; final version to be published in Phys. Lett. B. References updated. Uses elsart.cls version 1996/04/22, 2e-1.4

The energy spectrum of cosmic rays beyond the turn-down around 10^17 eV as measured with the surface detector of the Pierre Auger Observatory

We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is observed, confirming the presence of the so-called second-knee feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays

The FRAM robotic telescope for atmospheric monitoring at the Pierre Auger Observatory

FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Auger Observatory in Argentina for the purposes of atmospheric monitoring using stellar photometry. As a passive system which does not produce any light that could interfere with the observations of the fluorescence telescopes of the observatory, it complements the active monitoring systems that use lasers. We discuss the applications of stellar photometry for atmospheric monitoring at optical observatories in general and the particular modes of operation employed by the Auger FRAM. We describe in detail the technical aspects of FRAM, the hardware and software requirements for a successful operation of a robotic telescope for such a purpose and their implementation within the FRAM system

Measurement of the neutron spin structure function g2ng_{2}^{n} and asymmetry a2na_{2}^{n}

We have measured the neutron structure function g2n_{2}^{n}2n​ and the virtual photon-nucleon asymmetry A2n_{2}^{n}2n​ over the kinematic range 0.014≤x≤0.70.014\leq x \leq 0.70.014≤x≤0.7 and 1.0≤Q2≤17.01.0 \leq Q^{2} \leq 17.01.0≤Q2≤17.0 by scattering 48.3 GeV longitudinally polarized electrons from polarized 3^{3}3He. Results for A2n_{2}^{n}2n​ are significantly smaller than the R\sqrt{R}R​ positivity limit over most of the measured range and data for g2n_2^{n}2n​ are generally consistent with the twist-2 Wandzura-Wilczek prediction. Using our measured g2n_{2}^{n}2n​ we obtain results for the twist-3 reduced matrix element d2nd_{2}^{n}d2n​, and the integral ∫\int∫g2n(x)dx_{2}^{n}(x)dx2n​(x)dx in the range 0.014≤x≤1.00.014\leq x \leq 1.00.014≤x≤1.0. Data from this experiment are combined with existing data for g2n_{2}^{n}2n​ to obtain an average for d2nd_{2}^{n}d2n​ and the integral ∫\int∫g2n(x)dx_{2}^{n}(x)dx2n​(x)dx

Precision determination of the neutron spin structure function g1ng^{n}_{1}

We report on a precision measurement of the neutron spin structure function g1ng^n_1g1n​ using deep inelastic scattering of polarized electrons by polarized ^3He. For the kinematic range 0.014<x<0.7 and 1 (GeV/c)^2< Q^2< 17 (GeV/c)^2, we obtain ∫0.0140.7g1n(x)dx=−0.036±0.004(stat)±0.005(syst)\int^{0.7}_{0.014} g^n_1(x)dx = -0.036 \pm 0.004 (stat) \pm 0.005 (syst)∫0.0140.7​g1n​(x)dx=−0.036±0.004(stat)±0.005(syst) at an average Q2=5(GeV/c)2Q^2=5 (GeV/c)^2Q2=5(GeV/c)2. We find relatively large negative values for g1ng^n_1g1n​ at low xxx. The results call into question the usual Regge theory method for extrapolating to x=0 to find the full neutron integral ∫01g1n(x)dx\int^1_0 g^n_1(x)dx∫01​g1n​(x)dx, needed for testing quark-parton model and QCD sum rules. (arXiv

Next-to-leading order QCD analysis of polarized deep inelastic scattering data

We present a Next-to-Leading order perturbative QCD analysis of world data on the spin dependent structure functions g1p,g1ng_1^p, g_1^ng1p​,g1n​, and g1dg_1^dg1d​, including the new experimental information on the Q2Q^2Q2 dependence of g1ng_1^ng1n​. Careful attention is paid to the experimental and theoretical uncertainties. The data constrain the first moments of the polarized valence quark distributions, but only qualitatively constrain the polarized sea quark and gluon distributions. The NLO results are used to determine the Q2Q^2Q2 dependence of the ratio g1/F1g_1/F_1g1​/F1​ and evolve the experimental data to a constant Q2=5GeV2Q^2 = 5 GeV^2Q2=5GeV2. We determine the first moments of the polarized structure functions of the proton and neutron and find agreement with the Bjorken sum rule

Search for photons above 1019^{19} eV with the surface detector of the Pierre Auger Observatory

International audienceWe use the surface detector of the Pierre Auger Observatory to search for air showers initiated by photons with an energy above $10^{19}$ eV. Photons in the zenith angle range from 30$^\circ$ to 60$^\circ$ can be identified in the overwhelming background of showers initiated by charged cosmic rays through the broader time structure of the signals induced in the water-Cherenkov detectors of the array and the steeper lateral distribution of shower particles reaching ground. Applying the search method to data collected between January 2004 and June 2020, upper limits at 95% CL are set to an $E^{-2}$ diffuse flux of ultra-high energy photons above $10^{19}$ eV, $2{\times}10^{19}$ eV and $4{\times}10^{19}$ eV amounting to $2.11{\times}10^{-3}$, $3.12{\times}10^{-4}$ and $1.72{\times}10^{-4}$ km$^{-2}$ sr$^{-1}$ yr$^{-1}$, respectively. While the sensitivity of the present search around $2 \times 10^{19}$ eV approaches expectations of cosmogenic photon fluxes in the case of a pure-proton composition, it is one order of magnitude above those from more realistic mixed-composition models. The inferred limits have also implications for the search of super-heavy dark matter that are discussed and illustrated

Design, upgrade and characterization of the silicon photomultiplier front-end for the AMIGA detector at the Pierre Auger Observatory

none359AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory to complement the study of ultra-high-energy cosmic rays (UHECR) by measuring the muon content of extensive air showers (EAS). It consists of an array of 61 water Cherenkov detectors on a denser spacing in combination with underground scintillation detectors used for muon density measurement. Each detector is composed of three scintillation modules, with 10 m(2) detection area per module, buried at 2.3 m depth, resulting in a total detection area of 30 m(2). Silicon photomultiplier sensors (SiPM) measure the amount of scintillation light generated by charged particles traversing the modules. In this paper, the design of the front-end electronics to process the signals of those SiPMs and test results from the laboratory and from the Pierre Auger Observatory are described. Compared to our previous prototype, the new electronics shows a higher performance, higher efficiency and lower power consumption, and it has a new acquisition system with increased dynamic range that allows measurements closer to the shower core. The new acquisition system is based on the measurement of the total charge signal that the muonic component of the cosmic ray shower generates in the detector.noneAab A.; Abreu P.; Aglietta M.; Albury J.M.; Allekotte I.; Almela A.; Alvarez-Muniz J.; Alves Batista R.; Anastasi G.A.; Anchordoqui L.; Andrada B.; Andringa S.; Aramo C.; Araujo Ferreira P.R.; Asorey H.; Assis P.; Avila G.; Badescu A.M.; Bakalova A.; Balaceanu A.; Barbato F.; Barreira Luz R.J.; Becker K.H.; Bellido J.A.; Berat C.; Bertaina M.E.; Bertou X.; Biermann P.L.; Bister T.; Biteau J.; Blazek J.; Bleve C.; Bohacova 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.; Caballero-Mora K.S.; Caccianiga L.; Canfora F.; Caracas I.; Carceller J.M.; Caruso R.; 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.; Coleman A.; Coluccia M.R.; Conceicao R.; Condorelli A.; Consolati G.; Contreras F.; Convenga F.; Covault C.E.; Dasso S.; Daumiller K.; Dawson B.R.; Day J.A.; de Almeida R.M.; de Jesus J.; de Jong S.J.; de Mauro G.; de Mello Neto J.R.T.; de Mitri I.; de Oliveira J.; de Oliveira Franco D.; de Souza V.; de Vito E.; Debatin J.; del Rio M.; Deligny O.; Di Matteo A.; Dobrigkeit C.; D'Olivo J.C.; dos Anjos R.C.; Dova M.T.; Ebr J.; Engel R.; Epicoco I.; Erdmann M.; Escobar C.O.; Etchegoyen A.; Falcke H.; Farmer J.; Farrar G.; Fauth A.C.; Fazzini N.; Feldbusch F.; Fenu F.; Fick B.; Figueira J.M.; Filipcic A.; Fodran T.; Freire M.M.; Fujii T.; Fuster A.; Galea C.; Galelli C.; Garcia B.; Garcia Vegas A.L.; Gemmeke H.; Gesualdi F.; Gherghel-Lascu A.; Ghia P.L.; Giaccari U.; Giammarchi M.; Giller M.; Glombitza J.; Gobbi F.; Gollan F.; Golup G.; Gomez Berisso M.; Gomez Vitale P.F.; Gongora J.P.; Gonzalez J.M.; Gonzalez N.; Goos I.; Gora D.; Gorgi A.; Gottowik M.; Grubb T.D.; Guarino F.; Guedes G.P.; Guido E.; Hahn S.; Hampel M.R.; Hansen P.; Harari D.; Harvey V.M.; Haungs A.; Hebbeker T.; Heck D.; Hill G.C.; Hojvat C.; Horandel J.R.; Horvath P.; Hrabovsky M.; Huege T.; Hulsman J.; Insolia A.; Isar P.G.; Johnsen J.A.; Jurysek J.; Kaapa A.; Kampert K.H.; Keilhauer B.; Kemp J.; Klages H.O.; Kleifges M.; Kleinfeller J.; Kopke M.; Lago B.L.; Lang R.G.; Langner N.; Leigui de Oliveira M.A.; Lenok V.; Letessier-Selvon A.; Lhenry-Yvon I.; Lo Presti D.; Lopes L.; Lopez R.; Luce Q.; Lucero A.; Lundquist J.P.; Machado Payeras A.; Mancarella G.; Mandat D.; Manning B.C.; Manshanden J.; Mantsch P.; Marafico S.; Mariazzi A.G.; Maris I.C.; Marsella G.; Martello D.; Martinez H.; Martinez Bravo O.; Mastrodicasa M.; Mathes H.J.; Matthews J.; Matthiae G.; Mayotte E.; Mazur P.O.; Medina-Tanco G.; Melo D.; Menshikov A.; Merenda K.-D.; Michal S.; Micheletti M.I.; Miramonti L.; Mollerach S.; Montanet F.; Morello C.; Mostafa M.; Muller A.L.; Muller M.A.; Mulrey K.; Mussa R.; Muzio M.; Namasaka W.M.; Nellen L.; Niculescu-Oglinzanu M.; Niechciol M.; Nitz D.; Nosek D.; Novotny V.; Nozka L.; Nucita A.; Nunez L.A.; Palatka M.; Pallotta J.; Papenbreer P.; Parente G.; Parra A.; Pech M.; Pedreira F.; Pekala J.; Pelayo R.; Pena-Rodriguez J.; Perez Armand J.; Perlin M.; Perrone L.; Petrera S.; Pierog T.; Pimenta M.; Pirronello V.; Platino M.; Pont B.; Pothast M.; Privitera P.; Prouza M.; Puyleart A.; Querchfeld S.; Rautenberg J.; Ravignani D.; Reininghaus M.; Ridky J.; Riehn F.; Risse M.; Ristori P.; Rizi V.; Rodrigues de Carvalho W.; Rodriguez Rojo J.; Roncoroni M.J.; Roth M.; Roulet E.; Rovero A.C.; Ruehl P.; Saffi S.J.; Saftoiu A.; Salamida F.; Salazar H.; Salina G.; Sanabria Gomez J.D.; Sanchez F.; Santos E.M.; Santos E.; Sarazin F.; Sarmento R.; Sarmiento-Cano C.; Sato R.; Savina P.; Schafer C.M.; Scherini V.; Schieler H.; Schimassek M.; Schimp M.; Schluter F.; Schmidt D.; Scholten O.; Schovanek P.; Schroder F.G.; Schroder S.; Schulte J.; Sciutto S.J.; Scornavacche M.; Shellard R.C.; Sigl G.; Silli G.; Sima O.; Smida R.; Sommers P.; Soriano J.F.; Souchard J.; Squartini R.; Stadelmaier M.; Stanca D.; Stanic S.; Stasielak J.; Stassi P.; Streich A.; Suarez-Duran M.; Sudholz T.; Suomijarvi T.; Supanitsky A.D.; Supik J.; Szadkowski Z.; Taboada A.; Tapia A.; Timmermans C.; Tkachenko O.; Tobiska P.; Todero Peixoto C.J.; Tome B.; Travaini A.; Travnicek P.; Trimarelli C.; Trini M.; Tueros M.; Ulrich R.; Unger M.; Vaclavek L.; Vacula M.; Valdes Galicia J.F.; Valore L.; Varela E.; Varma V.K.C.; Vasquez-Ramirez A.; Veberic D.; Ventura C.; Vergara Quispe I.D.; Verzi V.; Vicha J.; Vink J.; Vorobiov S.; Wahlberg H.; Watson A.A.; Weber M.; Weindl A.; Wiencke L.; Wilczynski H.; Winchen T.; Wirtz M.; Wittkowski D.; Wundheiler B.; Yushkov A.; Zapparrata O.; Zas E.; Zavrtanik D.; Zavrtanik M.; Zehrer L.; Zepeda A.Aab, A.; Abreu, P.; Aglietta, M.; Albury, J. M.; Allekotte, I.; Almela, A.; Alvarez-Muniz, J.; Alves Batista, R.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Araujo Ferreira, P. R.; Asorey, H.; Assis, P.; Avila, G.; Badescu, A. M.; Bakalova, A.; Balaceanu, A.; Barbato, F.; Barreira Luz, R. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Bister, T.; Biteau, J.; Blazek, J.; Bleve, C.; Bohacova, 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.; Caballero-Mora, K. S.; Caccianiga, L.; Canfora, F.; Caracas, I.; Carceller, J. M.; Caruso, R.; 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.; Coleman, A.; Coluccia, M. R.; Conceicao, R.; Condorelli, A.; Consolati, G.; Contreras, F.; Convenga, F.; Covault, C. E.; Dasso, S.; Daumiller, K.; Dawson, B. R.; Day, J. A.; de Almeida, R. M.; de Jesus, J.; de Jong, S. J.; de Mauro, G.; de Mello Neto, J. R. T.; de Mitri, I.; de Oliveira, J.; de Oliveira Franco, D.; de Souza, V.; de Vito, E.; Debatin, J.; del Rio, M.; Deligny, O.; Di Matteo, A.; Dobrigkeit, C.; D'Olivo, J. C.; dos Anjos, R. C.; Dova, M. T.; Ebr, J.; Engel, R.; Epicoco, I.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Falcke, H.; Farmer, J.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Feldbusch, F.; Fenu, F.; Fick, B.; Figueira, J. M.; Filipcic, A.; Fodran, T.; Freire, M. M.; Fujii, T.; Fuster, A.; Galea, C.; Galelli, C.; Garcia, B.; Garcia Vegas, A. L.; Gemmeke, H.; Gesualdi, F.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glombitza, J.; Gobbi, F.; Gollan, F.; Golup, G.; Gomez Berisso, M.; Gomez Vitale, P. F.; Gongora, J. P.; Gonzalez, J. M.; Gonzalez, N.; Goos, I.; Gora, D.; Gorgi, A.; Gottowik, M.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Guido, E.; Hahn, S.; Hampel, M. R.; Hansen, P.; Harari, D.; Harvey, V. M.; Haungs, A.; Hebbeker, T.; Heck, D.; Hill, G. C.; Hojvat, C.; Horandel, J. R.; Horvath, P.; Hrabovsky, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Johnsen, J. A.; Jurysek, J.; Kaapa, A.; Kampert, K. H.; Keilhauer, B.; Kemp, J.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Kopke, M.; Lago, B. L.; Lang, R. G.; Langner, N.; Leigui de Oliveira, M. A.; Lenok, V.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Lo Presti, D.; Lopes, L.; Lopez, R.; Luce, Q.; Lucero, A.; Lundquist, J. P.; Machado Payeras, A.; Mancarella, G.; Mandat, D.; Manning, B. C.; Manshanden, J.; Mantsch, P.; Marafico, S.; Mariazzi, A. G.; Maris, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Mastrodicasa, M.; Mathes, H. J.; Matthews, J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Merenda, K. -D.; Michal, S.; Micheletti, M. I.; Miramonti, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafa, M.; Muller, A. L.; Muller, M. A.; Mulrey, K.; Mussa, R.; Muzio, M.; Namasaka, W. M.; Nellen, L.; Niculescu-Oglinzanu, M.; Niechciol, M.; Nitz, D.; Nosek, D.; Novotny, V.; Nozka, L.; Nucita, A.; Nunez, L. A.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Pech, M.; Pedreira, F.; Pekala, J.; Pelayo, R.; Pena-Rodriguez, J.; Perez Armand, J.; Perlin, M.; Perrone, L.; Petrera, S.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Pont, B.; Pothast, M.; Privitera, P.; Prouza, M.; Puyleart, A.; Querchfeld, S.; Rautenberg, J.; Ravignani, D.; Reininghaus, M.; Ridky, J.; Riehn, F.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Rojo, J.; Roncoroni, M. J.; Roth, M.; Roulet, E.; Rovero, A. C.; Ruehl, P.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salina, G.; Sanabria Gomez, J. D.; Sanchez, F.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarmento, R.; Sarmiento-Cano, C.; Sato, R.; Savina, P.; Schafer, C. M.; Scherini, V.; Schieler, H.; Schimassek, M.; Schimp, M.; Schluter, F.; Schmidt, D.; Scholten, O.; Schovanek, P.; Schroder, F. G.; Schroder, S.; Schulte, J.; Sciutto, S. J.; Scornavacche, M.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Smida, R.; Sommers, P.; Soriano, J. F.; Souchard, J.; Squartini, R.; Stadelmaier, M.; Stanca, D.; Stanic, S.; Stasielak, J.; Stassi, P.; Streich, A.; Suarez-Duran, M.; Sudholz, T.; Suomijarvi, T.; Supanitsky, A. D.; Supik, J.; Szadkowski, Z.; Taboada, A.; Tapia, A.; Timmermans, C.; Tkachenko, O.; Tobiska, P.; Todero Peixoto, C. J.; Tome, B.; Travaini, A.; Travnicek, P.; Trimarelli, C.; Trini, M.; Tueros, M.; Ulrich, R.; Unger, M.; Vaclavek, L.; Vacula, M.; Valdes Galicia, J. F.; Valore, L.; Varela, E.; Varma, V. K. C.; Vasquez-Ramirez, A.; Veberic, D.; Ventura, C.; Vergara Quispe, I. D.; Verzi, V.; Vicha, J.; Vink, J.; Vorobiov, S.; Wahlberg, H.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczynski, H.; Winchen, T.; Wirtz, M.; Wittkowski, D.; Wundheiler, B.; Yushkov, A.; Zapparrata, O.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zehrer, L.; Zepeda, A