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1. Measurement of the cosmic-ray energy spectrum above 2.5 x 10(18) eV using the Pierre Auger Observatory

Author

Pierre Auger Collaboration, Aab, A., Abreu, P., Aglietta, M., Albury, J. M., Allekotte, I., Almela, A., Alvarez Castillo, J., Alvarez-Muñiz, J., Alves Batista, R., Anastasi, G. A., Anchordoqui, L., Andrada, B., Andringa, S., Aramo, C., Araújo 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., 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., Caballero-Mora, K. S., Caccianiga, L., Calcagni, L., Cancio, A., 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., Conceição, R., Condorelli, A., Consolati, G., Contreras, F., Convenga, F., Covault, C. E., Dasso, S., Daumiller, K., Dawson, B. R., Day, J. A., Almeida, R. M. de, Jesús, J. de, Jong, S. J. de, De Mauro, G., Mello Neto, J. R. T. de, De Mitri, I., Oliveira, J. de, Oliveira Franco, D. de, Souza, V. de, De Vito, E., Debatin, J., Río, M. del, Deligny, O., Dembinski, H., Dhital, N., Di Giulio, C., Di Matteo, A., Díaz Castro, M. L., Dobrigkeit, C., D’Olivo, J. C., Dorosti, Q., Anjos, R. C. dos, 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., Filipčič, A., Fodran, T., Freire, M. M., Fujii, T., Fuster, A., Galea, C., Galelli, C., García, 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., Gómez Berisso, M., Gómez Vitale, P. F., Gongora, J. P., González, N., Goos, I., Góra, D., Gorgi, A., Gottowik, M., Grubb, T. D., Guarino, F., Guedes, G. P., Guido, E., Hahn, S., Halliday, R., Hampel, M. R., Hansen, P., Harari, D., Harvey, V. M., Haungs, A., Hebbeker, T., Heck, D., Hill, G. C., Hojvat, C., Hörandel, J. R., Horvath, P., Hrabovský, M., Huege, T., Hulsman, J., Insolia, A., Isar, P. G., Johnsen, J. A., Jurysek, J., Kääpä, A., Kampert, K. H., Keilhauer, B., Kemp, J., Klages, H. O., Kleifges, M., Kleinfeller, J., Köpke, M., Kukec Mezek, G., Lago, B. L., LaHurd, D., Lang, R. G., Leigui de Oliveira, M. A., Lenok, V., Letessier-Selvon, A., Lhenry-Yvon, I., Lo Presti, D., Lopes, L., López, R., Lorek, R., Luce, Q., Lucero, A., Machado Payeras, A., Malacari, M., Mancarella, G., Mandat, D., Manning, B. C., Manshanden, J., Mantsch, P., Marafico, S., Mariazzi, A. G., Mariş, I. C., Marsella, G., Martello, D., Martinez, H., Martínez 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., Mockler, D., Mollerach, S., Montanet, F., Morello, C., Mostafá, M., Müller, A. L., Muller, M. A., Mulrey, K., Mussa, R., Muzio, M., Namasaka, W. M., Nellen, L., Nguyen, P. H., Niculescu-Oglinzanu, M., Niechciol, M., Nitz, D., Nosek, D., Novotny, V., Nožka, L., Nucita, A., Núñez, L. A., Palatka, M., Pallotta, J., Panetta, M. P., Papenbreer, P., Parente, G., Parra, A., Pech, M., Pedreira, F., Pȩkala, J., Pelayo, R., Peña-Rodriguez, J., Perez Armand, J., Perlin, M., Perrone, L., Peters, C., 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 Fernandez, G., 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., Sánchez, F., Santos, E. M., Santos, E., Sarazin, F., Sarmento, R., Sarmiento-Cano, C., Sato, R., Savina, P., Schäfer, C., Scherini, V., Schieler, H., Schimassek, M., Schimp, M., Schlüter, F., Schmidt, D., Scholten, O., Schovánek, P., Schröder, F. G., Schröder, S., Schulz, A., Sciutto, S. J., Scornavacche, M., Shellard, R. C., Sigl, G., Silli, G., Sima, O., Šmída, R., Sommers, P., Soriano, J. F., Souchard, J., Squartini, R., Stadelmaier, M., Stanca, D., Stanič, S., Stasielak, J., Stassi, P., Streich, A., Suárez-Durán, M., Sudholz, T., Suomijärvi, T., Supanitsky, A. D., Šupík, J., Szadkowski, Z., Taboada, A., Tapia, A., Timmermans, C., Tkachenko, O., Tobiska, P., Todero Peixoto, C. J., Tomé, B., Torralba Elipe, G., Travaini, A., Travnicek, P., Trimarelli, C., Trini, M., Tueros, M., Ulrich, R., Unger, M., Urban, M., Vaclavek, L., Vacula, M., Valdés Galicia, J. F., Valiño, I., Valore, L., Vliet, A. van, Varela, E., Vargas Cárdenas, B., Vásquez-Ramírez, A., Veberič, D., Ventura, C., Vergara Quispe, I. D., Verzi, V., Vicha, J., Villaseñor, L., Vink, J., Vorobiov, S., Wahlberg, H., Watson, A. A., Weber, M., Weindl, A., Wiencke, L., Wilczyński, H., Winchen, T., Wirtz, M., Wittkowski, D., Wundheiler, B., Yushkov, A., Zapparrata, O., Zas, E., Zavrtanik, D., Zavrtanik, M., Zehrer, L., Zepeda, A., Ziolkowski, M., and Zuccarello, F.

Subjects
Physics, ddc:530
Abstract

We report a measurement of the energy spectrum of cosmic rays for energies above 2.5×10$^{18}$ 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 5×10$^{19}$ eV. The principal conclusions are (1) The flattening of the spectrum near 5×10$^{18}$ eV, the so-called “ankle,” is confirmed. (2) The steepening of the spectrum at around 5×10$^{Z19}$ 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 5×10$^{19}$ 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 8×10$^{18}$ eV.

Published
2020

2. High-precision B(E2) measurements of semi-magic Ni 58,60,62,64 by Coulomb excitation

Author

Allmond, J.M., Brown, B.A., Stuchbery, Andrew, Galindo-Uribarri, A., Padilla-Rodal, E, Radford, D C, Batchelder, J C, Howard, M.E., Liang, J.F., Manning, B., Varner, R.L., Yu, C.-H, Allmond, J.M., Brown, B.A., Stuchbery, Andrew, Galindo-Uribarri, A., Padilla-Rodal, E, Radford, D C, Batchelder, J C, Howard, M.E., Liang, J.F., Manning, B., Varner, R.L., and Yu, C.-H

Abstract

High-precision reduced electric-quadrupole transition probabilities B(E2;01+→21+) have been measured from single-step Coulomb excitation of semi-magic Ni58,60,62,64 (Z=28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the n

Published
2014

3. Electromagnetic properties of the 21+ state in 134Te: Influence of core excitation on single-particle orbits beyond 132Sn

Author

Stuchbery, Andrew, Allmond, J.M., Galindo-Uribarri, A., Padilla-Rodal, E, Radford, D C, Stone, N J, Batchelder, J C, Beene, J, Benczer-Koller, N, Bingham, C.R., Howard, M.E., Kumbartzki, G, Liang, J.F., Manning, B., Stracener, D.W., Yu, C.-H, Stuchbery, Andrew, Allmond, J.M., Galindo-Uribarri, A., Padilla-Rodal, E, Radford, D C, Stone, N J, Batchelder, J C, Beene, J, Benczer-Koller, N, Bingham, C.R., Howard, M.E., Kumbartzki, G, Liang, J.F., Manning, B., Stracener, D.W., and Yu, C.-H

Abstract

The g factor and B(E2) of the first excited 2+ state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide 134Te (two protons outside 132Sn) produced as a radioactive beam. The precision achieved matches related g-factor me

Published
2013

4. Informing direct neutron capture on tin isotopes near the N=82 shell closure.

Author

Manning, B., Arbanas, G., Cizewski, J. A., Kozub, R. L., Ahn, S., Allmond, J. M., Bardayan, D. W., Chae, K. Y., Chipps, K. A., Howard, M. E., Jones, K. L., Liang, J. F., Matos, M., Nesaraja, C. D., Nunes, F. M., O'Malley, P. D., Pain, S. D., Peters, W. A., Pittman, S. T., and Ratkiewicz, A.

Subjects
*TIN isotopes, *NEUTRON capture, *NUCLEOSYNTHESIS, *RADIOACTIVE nuclear beams, *HEAVY nuclei, *SILICON detectors, *HEAVY elements
Abstract

Half of the elements heavier than iron are believed to be produced through the rapid neutron-capture process (r process). The astrophysical environment(s) where the r process occurs remains an open question, even after recent observations of neutron-star mergers and the associated kilonova. Features in the abundance pattern of r-process ashes may provide critical insight for distinguishing contributions from different possible sites, including neutron-star mergers and core-collapse supernovae. In particular, the largely unknown neutron-capture reaction rates on neutron-rich unstable nuclei near 132Sn could have a significant impact on the final r-process abundances. To better determine these neutron-capture rates, the (d,p) reaction has been measured in inverse kinematics using radioactive ion beams of 126Sn and 128Sn and a stable beam of 124Sn interacting with a (CD2)n target. An array of position-sensitive silicon strip detectors, including the Super Oak Ridge Rutgers University Barrel Array, was used to detect light reaction products. In addition to the present measurements, previous measurements of 130,132Sn(d,p) were reanalyzed using state-of-the-art reaction theory to extract a consistent set of spectroscopic factors for (d,p) reactions on even tin nuclei between the heaviest stable isotope 124Sn and doubly magic 132Sn. The spectroscopic information was used to calculate direct-semidirect (n,γ) cross sections, which will serve as important input for r-process abundance calculations. [ABSTRACT FROM AUTHOR]

Published
2019
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5. Investigation into the semimagic nature of the tin isotopes through electromagnetic moments.

Author

Allmond, J. M., Stuchbery, A. E., Galindo-Uribarri, A., Padilla-Rodal, E., Radford, D. C., Batchelder, J. C., Bingham, C. R., Howard, M. E., Liang, J. F., Manning, B., Pain, S. D., Stone, N. J., Varner, R. L., and Yu, C.-H.

Subjects
*ELECTROMAGNETISM, *COULOMB excitation, *MAGNETIC dipole moments, *DOPPLER effect, *ISOTOPES
Abstract

A complete set of electromagnetic moments, B(E2;Q1+ → 21+), Q(21+), and g(21+), have been measured from Coulomb excitation of semimagic 112,114,116,118,120,122,124Sn (Z = 50) on natural carbon and titanium targets. The magnitude of the B(E2) values, measured to a precision of ~4%, disagree with a recent lifetime study [Phys. Lett. B 695, 110 (2011)] that employed the Doppler-shift attenuation method. The B(E2) values show an overall enhancement compared with recent theoretical calculations and a clear asymmetry about midshell, contrary to naive expectations. A new static electric quadrupole moment, Q(21+), has been measured for 114Sn. The static quadrupole moments are generally consistent with zero but reveal an enhancement near midshell; this had not been previously observed. The magnetic dipole moments are consistent with previous measurements and show a near monotonic decrease in value with neutron number. The g-factor measurements in 112,114Sn establish the recoil-in-vacuum method for states with → ~ 0.5 ps and hence demonstrate that this method can be used for future g-factor measurements on proton-rich isotopes toward 100Sn. Current theory calculations tail to reproduce the electromagnetic moments of the tin isotopes. The role of 2p-2h and 4p-4h intruders, which are lowest in energy at midshell and outside of current model spaces, needs to be investigated in the future. [ABSTRACT FROM AUTHOR]

Published
2015
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6. Elastic breakup cross sections of well-bound nucleons.

Author

Wimmer, K., Bazin, D., Gade, A., Tostevin, J. A., Baugher, T., Chajecki, Z., Coupland, D., Famiano, M. A., Ghosh, T. K., Grinyer, G. F., Howard, M. E., Kilburn, M., Lynch, W. G., Manning, B., Meierbachtol, K., Quarterman, P., Ratkiewicz, A., Sanetullaev, A., Showalter, R. H., and Straberg, S. R.

Subjects
*ELASTIC cross sections, *PARTICLES (Nuclear physics), *MAGNESIUM isotopes, *EIKONAL equation, *COULOMB barriers (Nuclear fusion)
Abstract

The 9Be(28Mg,27Na) one-proton removal reaction with a large proton separation energy of Sp(28Mg) = 16.79 MeV is studied at intermediate beam energy. Coincidences of the bound 27Na residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleón removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the removal of more weakly bound protons from lighter nuclei. The role of transitions of the proton between different bound single-particle configurations upon the elastic breakup cross section is also quantified in this well-bound case. The measured and calculated elastic breakup fractions are found to be in good agreement. [ABSTRACT FROM AUTHOR]

Published
2014
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7. High-precision B(E2) measurements of semi-magic 58, 60, 62, 64Ni by Coulomb excitation.

Author

Allmond, J. M., Brown, B. A., Stuchbery, A. E., Galindo-Uribarri, A., Padilla-Rodal, E., Radford, D. C., Batchelder, J. C., Howard, M. E., Liang, J. F., Manning, B., Varner, R. L., and Yu, C.-H.

Subjects
*QUADRUPOLES, *COULOMB functions, *COULOMB barriers (Nuclear fusion), *BRAGG gratings, *NUCLEAR particle research
Abstract

High-precision reduced electric-quadrupole transition probabilities B(E2;0+1→2+1) have been measured from single-step Coulomb excitation of semi-magic 58,60,62,64Ni (Z=28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the nickel beams through the carbon target were directly measured with a zero-degree Bragg detector and the absolute B(E2) values were normalized by Rutherford scattering. The B(E2) values disagree with recent lifetime studies that employed the Doppler-shift attenuation method. The present high-precision B(E2) values reveal an asymmetry about 62Ni, midshell between N=28 and 40, with larger values towards 56Ni (Z=N=28). The experimental B(E2) values are compared with shell-model calculations in the full pf model space and the results indicate a soft 56Ni core. [ABSTRACT FROM AUTHOR]

Published
2014
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8. 2π1V states populated in 135Te from 9Be-induced reactions with a 132Sn beam.

Author

Allmond, J. M., Stuchbery, A. E., Brown, B. A., Beene, J. R., Galindo-Uribarri, A., Gross, C. J., Liang, J. F., Padilla-Rodal, E., Radford, D. C., Varner, R. L., Ayres, A., Batchelder, J. C., Bey, A., Bingham, C. R., Howard, M. E., Jones, K. L., Manning, B., Mueller, P. E., Nesaraja, C. D., and Pain, S. D.

Subjects
*PHASE transitions, *NUCLEAR energy, *NUCLEAR reactions, *COULOMB barriers (Nuclear fusion), *PARTICLES (Nuclear physics)
Abstract

γ-ray transitions in 134Te, 135Te, and 136Te were measured from 9Be-induced reactions with a radioactive 132Sn beam at a sub-Coulomb barrier energy of 3 MeV per nucleón using particle-y coincidence spectroscopy. The transitions were selected by gating on alpha-like particles in a Csl detector following a combination of (9Be,aln), (9Be,α2n), and (9Be,α3n) incomplete fusion-evaporation reactions. Distorted-wave Born approximation calculations suggest little to no contribution from the (9Be,7He), (9Be,6He), and (9Be,5He) direct reactions, γ-ray transitions from previously known 2+ ⊗ v2∫/7/2 and 4+ ⊗ v2∫/7/2 multiplet members in 135Te are observed. A new y ray is observed, assigned to the third-excited state in 135Te, and new 2+ ⊗ v2∫/7/2 multiplet members are suggested. In addition, spin assignments are made by using recent one-neutron transfer data. The updated experimental data for, 135Te are compared to shell-model calculations for a relatively complete set of states up to the yrast 15/2-,4+⊗ v2∫/7/2 multiplet member at 1505 keV. [ABSTRACT FROM AUTHOR]

Published
2014
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9. Double-Magic Nature of 132Sn and 208Pb through Lifetime and Cross-Section Measurements.

Author

Allmond, J. M., Stuchbery, A. E., Beene, J. R., Galindo-Uribarri, A., Liang, J. F., Padilla-Rodal, E., Radford, D. C., Vamer, R. L., Ayres, A., Batchelder, J. C., Bey, A., Bingham, C. R., Howard, M. E., Jones, K. L., Manning, B., Mueller, P. E., Nesaraja, C. D., Pain, S. D., Peters, W. A., and Ratkiewicz, A.

Subjects
*TIN, *LEAD, *NEUTRON transport theory, *ALKALI metals, *SPECTRUM analysis
Abstract

Single-neutron states in 132Sn and 208Pb , which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the (9Be, 8Be) one-neutron transfer reaction in inverse kinematics using particleγ coincidence spectroscopy. In addition, the s 1/2 single-neutron hole-state candidate in 131 Sn was populated by (9Be, 10Be). Doubly closed-shell 132Sn (radioactive) and 208Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, γ-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared with shell-model expectations. The results include a new transition and precise level energy for the 3p1/2 candidate in 133 Sn, new absolute cross sections for the 1 h9/2 candidate in 133Sn and 3s1/2 candidate in 131Sn, and new lifetimes for excited states in 133Sn and 209Pb. This is the first report on excited-state lifetimes of 133Sn, which allow for a unique test of the nuclear shell model and 132Sn double-shell closure. [ABSTRACT FROM AUTHOR]

Published
2014
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10. Electromagnetic properties of the 21+ state in 134Te: Influence of core excitation on single-particle orbits beyond 132Sn.

Author

Stuchbery, A. E., Allmond, J. M., Galindo-Uribarri, A., Padilla-Rodal, E., Radford, D. C., Stone, N. J., Batchelder, J. C., Beene, J. R., Benczer-Koller, N., Bingham, C. R., Howard, M. E., Kumbartzki, G. J., Liang, J. F., Manning, B., Stracener, D. W., and C.-H. Yu

Subjects
*NUCLIDES, *COULOMB excitation, *ATOMS, *NUCLEAR excitation, *PROTONS
Abstract

The g factor and B(E2) of the first excited 2+ state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide 134Te (two protons outside 132Sn) produced as a radioactive beam. The precision achieved matches related g-factor measurements on stable beams and distinguishes between alternative models. The B(E2) measurement exposes quadrupole strength in the 21+state beyond that predicted by current large-basis shell-model calculations. This additional quadrupole strength can be attributed to coupling between the two valence protons and excitations of the 132Sn core. However, the wave functions of the low-excitation positive-parity states in 134Te up to 61+ remain dominated by the π(g7/2)2 configuration. [ABSTRACT FROM AUTHOR]

Published
2013
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11. Correlations in Intermediate Energy Two-Proton Removal Reactions.

Author

Wimmer, K., Bazin, D., Gade, A., Tostevin, J. A., Baugher, T., Chajecki, Z., Coupland, D., Famiano, M. A., Ghosh, T. K., Grinyer, G. F., Hodges, R., Howard, M. E., Kilburn, M., Lynch, W. G., Manning, B., Meierbachtol, K., Quarterman, P., Ratkierwicz, A., Sanetullaev, A., and Simpson, E. C.

Subjects
*STATISTICAL correlation, *PROTONS, *NUCLEIC acids, *NEUTRONS, *KINEMATICS
Abstract

We report final-state-exclusive measurements of the light charged fragments in coincidence with 26Ne residual nuclei following the direct two-proton removal from a neutron-rich 28Mg secondary beam. A Dalitz-plot analysis and comparisons with simulations show that a majority of the triple-coincidence events with two protons display phase-space correlations consistent with the (two-body) kinematics of a spatially correlated pair-removal mechanism. The fraction of such correlated events, 56(12)%, is consistent with the fraction of the calculated cross section, 64%, arising from spin S = 0 two-proton configurations in the entrance-channel (shell-model) 28Mg ground state wave function. This result promises access to an additional and more specific probe of the spin and spatial correlations of valence nucleon pairs in exotic nuclei produced as fast secondary beams. [ABSTRACT FROM AUTHOR]

Published
2012
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12. Transient field g factor and mean-life measurements with a rare isotope beam of 126Sn.

Author

Kumbartzki, G. J., Benczer-Koller, N., Torres, D. A., Manning, B., O'Malley, P. D., Sharon, Y. Y., Zamick, L., Gross, C. J., Radford, D. C., Robinson, S. J. Q., Allmond, J. M., Stuchbery, A. E., Speidel, K.-H., Stone, Ν. J., and Bingham, C. R.

Subjects
*TRANSIENTS (Dynamics), *PHYSICAL measurements, *RADIOISOTOPES, *NEUTRONS, *COULOMB excitation, *ATTENUATION (Physics), *NUCLEAR facilities, *QUASIPARTICLES
Abstract

Background: The g factors and lifetimes of the 2+1 states in the stable, proton-rich Sn isotopes have been measured, but there is scant information on neutron-rich Sn isotopes. Purpose: Measurement of the g factor and the lifetime of the 2\ state at 1.141 MeV in neutron-rich I26Sn (Γ1/2 = 2.3 χ 105y). Purpose: Measurement of the g factor and the lifetime of the 2+1 state at 1.141 MeV in neutron-rich 126Sn (T1/2 = 2.3 χ 105y). Method: Coulomb excitation in inverse kinematics together with the transient field and the Doppler shift attenuation techniques were applied to a radioactive beam of 126Sn at the Holifield Radioactive Ion Beam Facility. Results: g(2+1) = -0.25(21) and r(2+1) = 1.5(2) ps were obtained. Conclusions: The data are compared to large-scale shell-model and quasiparticle random-phase calculations. Neutrons in the h 11/2 and d3/2 Orbitals play an important role in the structure of the 2+1 state of 126Sn. Challenges, limitations, and implications for such experiments at future rare isotope beam facilities are discussed. [ABSTRACT FROM AUTHOR]

Published
2012
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13. Probing elastic and inelastic breakup contributions to intermediate-energy two-proton removal reactions.

Author

Wimmer, K., Bazin, D., Gade, A., Tostevin, J. A., Baugher, T., Chajecki, Z., Coupland, D., Famiano, M. A., Ghosh, T. K., Grinyer, G. F., Hodges, R., Howard, M. E., Kilburn, M., Lynch, W. G., Manning, B., Meierbachtol, K., Quarterman, P., Ratkiewicz, A., Sanetullaev, A., and Stroberg, S. R.

Subjects
*ELASTIC scattering, *NUCLEAR energy, *NUCLEAR reactions, *MAGNESIUM isotopes, *HEAVY nuclei, *QUANTITATIVE research, *NUCLEAR shell theory
Abstract

The two-proton removal reaction from 28Mg projectiles has been studied at 93 MeV/u. First coincidence measurements of the heavy 26Ne projectile residues, the removed protons, and other light charged particles enabled the relative cross sections from each of the three possible elastic and inelastic proton removal mechanisms to be determined. These more final-state-exclusive measurements are key for further interrogation of these reaction mechanisms and use of the reaction channel for quantitative spectroscopy of very neutron-rich nuclei. The relative and absolute yields of the three contributing mechanisms are compared to reaction model expectations based on the use of eikonal dynamics and sd-shell-model structure amplitudes. [ABSTRACT FROM AUTHOR]

Published
2012
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14. Measurement of the 96Ru g(41+) factor and its nuclear structure interpretation.

Author

Torres, D. A., Kumbartzki, G. J., Sharon, Y. Y., Zamick, L., Manning, B., Benczer-Koller, N., Speidel, K.-H., Ahn, T., Anagnostatou, V., Elvers, M., Goddard, P., Heinz, A., Iile, G., Radeck, D., Savran, D., Werner, V., Gürdal, G., Taylor, M. J., Maier-Komor, P., and Hjorth-Jensen, M.

Subjects
*NUCLEAR structure, *HYDRODYNAMICS, *NUCLEAR models, *KINEMATICS, *PREDICTION models, *NUCLEAR spin, *WAVE functions, *MICROSCOPY, RUTHENIUM isotopes
Abstract

Background: The experimental study of g(I > 2) factors of nuclear states can provide information about the evolution of collectivity in certain regions of the nuclear chart, and assist in obtaining a microscopic description of the nuclear wave functions. The measurements and explanations of g{I > 2) factors are still a challenge for experiments and theory. Purpose: Measurement of the g(2+1) and g(41) factors, the latter for the first time, in the 9644Ru nucleus. Comparison of the experimental results with calculations using the shell model and collective models. Methods: The experiments made use of the transient field technique, using a Coulomb-excitation reaction in inverse kinematics. Large scale shell model calculations were performed; comparisons with previous theoretical predictions, using the tidal-wave model and the hydrodynamical model, were carried out. Results: The values of g(2+1) = +0.46(2) and g(4+-) = +0.58(8) were experimentally obtained. While the g(2+1) value agrees with the hydrodynamical model prediction of g = Z/A = +0.46. the g(4+1 ) is in agreement with the shell model predictions. The trend of the experimental g factors, as a function of nuclear spin, is not reproduced by the theoretical models discussed. Conclusions: Measurements of g(2+1 ) and g(4+1 ) in 96Ru were performed. Further theoretical efforts are necessary to explain the trend of the g factors as a function of nuclear spin for the 96Ru nucleus. Future measurements of g(4+1) should reduce the uncertainty of the result. [ABSTRACT FROM AUTHOR]

Published
2012
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15. First g-factor measurements of the … and the … states of radioactive 100Pd.

Author

Torres, D. A., Kumbartzki, G. J., Sharon, Y. Y., Zamick, L., Manning, B., Benczer-Koller, N., Gürdal, G., Speidel, K.-H., Hjorth-Jensen, M., Maier-Komor, P., Robinson, S. J. Q., Ahn, T., Anagnostatou, V., Elvers, M., Goddard, P., Heinz, A., Ilie, G., Radeck, D., Savran, D., and Werner, V.

Subjects
*PALLADIUM isotopes, *ENERGY levels (Quantum mechanics), *ALPHA decay, *RADIATIVE transfer, *NUCLEAR shell theory, *SPIN excitations, *KINEMATICS
Abstract

The g factors of the first 2+ and 4+ states of the radioactive 100Pd nucleus have been investigated for the first time, using an α-particle transfer reaction from 12C to 96Ru. The transient magnetic field technique in inverse kinematics was used. The Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. nucleus is a suitable candidate for studying single-particle proton and neutron effects in the nuclear wave functions near the N = Z = 50 shell closures. The results are discussed within the frameworks of both large-scale shell-model calculations and collective-model predictions. [ABSTRACT FROM AUTHOR]

Published
2011
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16. Fission fragment mass yields and total kinetic energy release in neutron-induced fission of 233U from thermal energies to 40 MeV.

Author

Higgins, D., Greife, U., Tovesson, F., Manning, B., Mayorov, D., Mosby, S., and Schmitt, K.

Subjects
*KINETIC energy, *HEAT, *NEUTRON emission, *NEUTRON temperature, *IONIZATION chambers, *FUEL cycle
Abstract

Properties of fission in 233U were measured at the Los Alamos Neutron Science Center at incident neutron energies from thermal to 40 MeV. Fragments were observed in coincidence by using a twin ionization chamber with Frisch grids. The average total kinetic energy released and fragment mass yields were determined by using the double energy analysis method based on conservation of mass and momentum. The experimental method was validated by using 232Th and absolute energy was calibrated by using thermal-neutron-induced fission of 235U. This work incorporates novel applications of multi-chance fission channel cross sections and fission models to account for the complexities introduced by prompt neutron emission at high energy and extends results up to higher incident neutron energies than previously measured. Accurate experimental measurements of these parameters are necessary to better understand the fission process in isotopes central to the thorium fuel cycle. [ABSTRACT FROM AUTHOR]

Published
2020
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17. Direct neutron capture cross section on 80Ge and probing shape coexistence in neutron-rich nuclei.

Author

Ahn, S., Bardayan, D. W., Jones, K. L., Adekola, A. S., Arbanas, G., Blackmon, J. C., Chae, K. Y., Chipps, K. A., Cizewski, J. A., Hardy, S., Howard, M. E., Kozub, R. L., Manning, B., Matoš, M., Nesaraja, C. D., O'Malley, P. D., Pain, S. D., Peters, W. A., Pittman, S. T., and Rasco, B. C.

Subjects
*NEUTRON capture, *RADIOACTIVE nuclear beams, *ION bombardment, *NUCLEAR shapes, *GOVERNMENT laboratories, *GEOMETRIC shapes
Abstract

Results are presented from the first neutron-transfer measurement on 80Ge using an exotic beam from the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Newly measured spins and spectroscopic factors of low-lying states of 81Ge are determined, and the neutron capture cross section on 80Ge was calculated in a direct-semidirect model to provide a more realistic (n,γ) reaction rate for r-process simulations. Furthermore, a region of shape coexistence around N≈50 is confirmed and implications for the magic nature of 78Ni are discussed. [ABSTRACT FROM AUTHOR]

Published
2019
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18. Constraining spectroscopic factors near the r-process path using combined measurements: 86Kr (d, p)87Kr.

Author

Walter, D., Pain, S. D., Cizewski, J. A., Nunes, F. M., Ahn, S., Baugher, T., Bardayan, D. W., Baumann, T., Bazin, D., Burcher, S., Chipps, K. A., Cerizza, G., Jones, K. L., Kozub, R. L., Lonsdale, S. J., Manning, B., Montes, F., O'Malley, P. D., Ota, S., and Pereira, J.

Subjects
*SILICON detectors, *NUCLEAR structure, *MOMENTUM transfer, *NUCLEAR models, *ANGULAR momentum (Mechanics), *NEUTRONS
Abstract

Background: Modern nuclear structure models suggest that the shell structure near the valley of stability, with well-established shell closures at N=50, for example, changes in very neutron-rich nuclei far from stability. Single-particle properties of nuclei away from stability can be probed in single-neutron (d,p) transfer reactions with beams of rare isotopes. The interpretation of these data requires reaction theories with various effective interactions. Often, approximations made to the final bound-state potential introduce a large uncertainty in the extracted single-particle properties, in particular the spectroscopic factor. Purpose: Mitigate this uncertainty using a combined measurement method to constrain the shape of the bound-state potential and to reliably extract the spectroscopic factor. Methods: The ²H(86Kr,p)87Kr reaction was measured at 33 MeV/u at the National Superconducting Cyclotron Laboratory (NSCL) as a test of the combined method. The reaction protons were detected with the Oak Ridge Rutgers University Barrel Array (ORRUBA) of position sensitive silicon strip detectors, the first implementation of ORRUBA coupled to the S800 spectrograph with fast beams at NSCL. Results: These measurements at 33 MeV/u are combined with previous studies of the 86Kr(d,p) reaction at 5.5 MeV/u to demonstrate a successful case of the combined method to constrain the shape of the single-particle potential and deduce asymptotic normalization coefficients and spectroscopic factors. In particular, the single-particle asymptotic normalization coefficient for the ground state of 87Kr was constrained to bd5/2=6.46+1.12-0.57fm-1/2, and therefore the deduced spectroscopic factor is S=0.44+0.09-0.13 with uncertainties dominated by experimental statistics. Conclusions: By combining measurements at two very different beam energies, single-particle asymptotic normalization coefficients, at least for low angular momentum transfers, can be constrained. Therefore, spectroscopic factors can be deduced with uncertainties dominated by experimental uncertainties, rather than limited knowledge of bound-state potential parameters. [ABSTRACT FROM AUTHOR]

Published
2019
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19. Towards Neutron Capture on Exotic Nuclei: Demonstrating (d,pγ) as a Surrogate Reaction for (n,γ).

Author

Ratkiewicz, A., Cizewski, J. A., Escher, J. E., Potel, G., Burke, J. T., Casperson, R. J., McCleskey, M., Austin, R. A. E., Burcher, S., Hughes, R. O., Manning, B., Pain, S. D., Peters, W. A., Rice, S., Ross, T. J., Scielzo, N. D., Shand, C., and Smith, K.

Subjects
*NEUTRON capture, *EXOTIC nuclei, *NEUTRON stars
Abstract

The neutron-capture reaction plays a critical role in the synthesis of the elements in stars and is important for societal applications including nuclear power generation and stockpile-stewardship science. However, it is difficult--if not impossible--to directly measure neutron capture cross sections for the exotic, short-lived nuclei that participate in these processes. In this Letter we demonstrate a new technique which can be used to indirectly determine neutron-capture cross sections for exotic systems. This technique makes use of the (d,p) transfer reaction, which has long been used as a tool to study the structure of nuclei. Recent advances in reaction theory, together with data collected using this reaction, enable the determination of neutron-capture cross sections for short-lived nuclei. A benchmark study of the 95Mo(d,p) reaction is presented, which illustrates the approach and provides guidance for future applications of the method with short-lived isotopes produced at rare isotope accelerators. [ABSTRACT FROM AUTHOR]

Published
2019
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20. Spectroscopic study of 20Ne+p reactions using the JENSA gas-jet target to constrain the astrophysical 18F(p,α)15O rate.

Author

Bardayan, D. W., Chipps, K. A., Ahn, S., Blackmon, J. C., Carmichael, S., Greife, U., Jones, K. L., José, J., Kontos, A., Kozub, R. L., Linhardt, L., Manning, B., Matoš, M., O'Malley, P. D., Ota, S., Pain, S. D., Peters, W. A., Pittman, S. T., Sachs, A., and Schmitt, K. T.

Subjects
*ASTROPHYSICS, *FLUORINE isotopes, *NEON isotopes
Abstract

The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas-jet target was used to perform spectroscopic studies of 20Ne+p reactions. Levels in 19Ne were probed via the 20Ne(p,d)19Ne reaction to constrain the astrophysical rate of the 18F(p,α)15O reaction. Additionally, the first spectroscopic study of the 20Ne(p,3He)18F reaction was performed. Angular distribution data were used to determine or confirm the spins of several previously observed levels, and the existence of a strong subthreshold 18F(p,α)15O resonance was verified. [ABSTRACT FROM AUTHOR]

Published
2017
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21. Spectroscopic study of the radionuclide 21Na for the astrophysical 17F(α,p)20Ne reaction rate.

Author

Cha, S. M., Chae, K. Y., Ahn, S., Bardayan, D. W., Chipps, K. A., Cizewski, J. A., Howard, M. E., Kozub, R. L., Kwak, K., Manning, B., Matos, M., O'Malley, P. D., Pain, S. D., Peters, W. A., Pittman, S. T., Ratkiewicz, A., Smith, M. S., and Strauss, S.

Subjects
*NEON, *SPECTROMETRY, *SILICON
Abstract

The 24Mg(p,α)21Na reaction was measured at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory to study the spectroscopy of the radionuclide 21Na. A 31-MeV proton beam from the 25 MV tandem accelerator bombarded isotopically enriched 24Mg targets. Recoiling 4He particles were identified by an annular silicon strip detector array. Two energy levels at Ex=6.594 and 7.132 MeV were observed for the first time. By comparing the experimentally obtained angular distributions and distorted wave Born approximation calculations, the spins and parities of 21Na energy levels were constrained. The astrophysically-important 17F(α,p)20Ne reaction rate was also calculated for the first time using resonance parameters for 12 energy levels. [ABSTRACT FROM AUTHOR]

Published
2017
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22. Total kinetic energy release in 239Pu(n,f) post-neutron emission from 0.5 to 50 MeV incident neutron energy.

Author

Meierbachtol, K., Tovesson, F., Duke, D. L., Geppert-Kleinrath, V., Manning, B., Meharchand, R., Mosby, S., and Shields, D.

Subjects
*KINETIC energy, *NEUTRON emission, *IONIZATION chambers
Abstract

The average total kinetic energy (TKE) in Pu239(n,f) has been measured for incident neutron energies between 0.5 and 50 MeV. The experiment was performed at the Los Alamos Neutron Science Center (LANSCE) using the neutron time-of-flight technique, and the kinetic energy of fission fragments post-neutron emission was measured in a double Frisch-gridded ionization chamber. This represents the first experimental study of the energy dependence of TKE in 239Pu above neutron energies of 6 MeV. [ABSTRACT FROM AUTHOR]

Published
2016
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23. Evidence for Gamow-Teller Decay of 78Ni Core from Beta-Delayed Neutron Emission Studies.

Author

Madurga, M., Paulauskas, S. V., Grzywacz, R., Miller, D., Bardayan, D. W., Batchelder, J. C., Brewer, N. T., Cizewski, J. A., Fijałkowska, A., Gross, C. J., Howard, M. E., Ilyushkin, S. V., Manning, B., Matoš, M., Mendez II, A. J., Miernik, K., Padgett, S. W., Peters, W. A., Rasco, B. C., and Ratkiewicz, A.

Subjects
*NEUTRON emission, *NICKEL compounds, *POTENTIAL barrier
Abstract

The β-delayed neutron emission of Ga83,84 isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to Ni78 core-excited states in Ge83,84 favored by shell effects. We developed shell model calculations in the proton fpg9/2 and neutron extended fpg9/2+d5/2 valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models. [ABSTRACT FROM AUTHOR]

Published
2016
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24. Inference of the Mass Composition of Cosmic Rays with Energies from 10^{18.5} to 10^{20}  eV Using the Pierre Auger Observatory and Deep Learning.

Author

Abdul Halim A, Abreu P, Aglietta M, Allekotte I, Almeida Cheminant K, Almela A, Aloisio R, Alvarez-Muñiz J, Ammerman Yebra J, Anastasi GA, Anchordoqui L, Andrada B, Andrade Dourado L, Andringa S, Apollonio L, Aramo C, Araújo Ferreira PR, Arnone E, Arteaga Velázquez JC, Assis P, Avila G, Avocone E, Bakalova A, Barbato F, Bartz Mocellin A, Berat C, Bertaina ME, Bhatta G, Bianciotto M, Biermann PL, Binet V, Bismark K, Bister T, Biteau J, Blazek J, Bleve C, Blümer J, Boháčová M, Boncioli D, Bonifazi C, Bonneau Arbeletche L, Borodai N, Brack J, Brichetto Orchera PG, Briechle FL, Bueno A, Buitink S, Buscemi M, Büsken M, Bwembya A, Caballero-Mora KS, Cabana-Freire S, Caccianiga L, Campuzano F, Caruso R, Castellina A, Catalani F, Cataldi G, Cazon L, Cerda M, Čermáková B, Cermenati A, Chinellato JA, Chudoba J, Chytka L, Clay RW, Cobos Cerutti AC, Colalillo R, Coluccia MR, Conceição R, Condorelli A, Consolati G, Conte M, Convenga F, Correia Dos Santos D, Costa PJ, Covault CE, Cristinziani M, Cruz Sanchez CS, Dasso S, Daumiller K, Dawson BR, de Almeida RM, de Errico B, de Jesús J, de Jong SJ, de Mello Neto JRT, De Mitri I, de Oliveira J, de Oliveira Franco D, de Palma F, de Souza V, De Vito E, Del Popolo A, Deligny O, Denner N, Deval L, di Matteo A, do JA, Dobre M, Dobrigkeit C, D'Olivo JC, Domingues Mendes LM, Dorosti Q, Dos Anjos JC, Dos Anjos RC, Ebr J, Ellwanger F, Emam M, Engel R, Epicoco I, Erdmann M, Etchegoyen A, Evoli C, Falcke H, Farrar G, Fauth AC, Fehler T, Feldbusch F, Fenu F, Fernandes A, Fick B, Figueira JM, Filip P, Filipčič A, Fitoussi T, Flaggs B, Fodran T, Fujii T, Fuster A, Galea C, García B, Gaudu C, Gherghel-Lascu A, Ghia PL, Giaccari U, Glombitza J, Gobbi F, Gollan F, Golup G, Gómez Berisso M, Gómez Vitale PF, Gongora JP, González JM, González N, Góra D, Gorgi A, Gottowik M, Guarino F, Guedes GP, Guido E, Gülzow L, Hahn S, Hamal P, Hampel MR, Hansen P, Harari D, Harvey VM, Haungs A, Hebbeker T, Hojvat C, Hörandel JR, Horvath P, Hrabovský M, Huege T, Insolia A, Isar PG, Janecek P, Jilek V, Johnsen JA, Jurysek J, Kampert KH, Keilhauer B, Khakurdikar A, Kizakke Covilakam VV, Klages HO, Kleifges M, Knapp F, Köhler J, Krieger F, Kunka N, Lago BL, Langner N, Leigui de Oliveira MA, Lema-Capeans Y, Letessier-Selvon A, Lhenry-Yvon I, Lopes L, Lu L, Luce Q, Lundquist JP, Machado Payeras A, Majercakova M, Mandat D, Manning BC, Mantsch P, Mariani FM, Mariazzi AG, Mariş IC, Marsella G, Martello D, Martinelli S, Martínez Bravo O, Martins MA, Mathes HJ, Matthews J, Matthiae G, Mayotte E, Mayotte S, Mazur PO, Medina-Tanco G, Meinert J, Melo D, Menshikov A, Merx C, Michal S, Micheletti MI, Miramonti L, Mollerach S, Montanet F, Morejon L, Mulrey K, Mussa R, Namasaka WM, Negi S, Nellen L, Nguyen K, Nicora G, Niechciol M, Nitz D, Nosek D, Novotny V, Nožka L, Nucita A, Núñez LA, Oliveira C, Palatka M, Pallotta J, Panja S, Parente G, Paulsen T, Pawlowsky J, Pech M, Pȩkala J, Pelayo R, Pelgrims V, Pereira LAS, Pereira Martins EE, Pérez Bertolli C, Perrone L, Petrera S, Petrucci C, Pierog T, Pimenta M, Platino M, Pont B, Pothast M, Pourmohammad Shahvar M, Privitera P, Prouza M, Querchfeld S, Rautenberg J, Ravignani D, Reginatto Akim JV, Reininghaus M, Reuzki A, Ridky J, Riehn F, Risse M, Rizi V, Rodrigues de Carvalho W, Rodriguez E, Rodriguez Rojo J, Roncoroni MJ, Rossoni S, Roth M, Roulet E, Rovero AC, Saftoiu A, Saharan M, Salamida F, Salazar H, Salina G, Sanabria Gomez JD, Sánchez F, Santos EM, Santos E, Sarazin F, Sarmento R, Sato R, Savina P, Schäfer CM, Scherini V, Schieler H, Schimassek M, Schimp M, Schmidt D, Scholten O, Schoorlemmer H, Schovánek P, Schröder FG, Schulte J, Schulz T, Sciutto SJ, Scornavacche M, Sedoski A, Segreto A, Sehgal S, Shivashankara SU, Sigl G, Simkova K, Simon F, Smau R, Šmída R, Sommers P, Squartini R, Stadelmaier M, Stanič S, Stasielak J, Stassi P, Strähnz S, Straub M, Suomijärvi T, Supanitsky AD, Svozilikova Z, Szadkowski Z, Tairli F, Tapia A, Taricco C, Timmermans C, Tkachenko O, Tobiska P, Todero Peixoto CJ, Tomé B, Torrès Z, Travaini A, Travnicek P, Tueros M, Unger M, Uzeiroska R, Vaclavek L, Vacula M, Valdés Galicia JF, Valore L, Varela E, Vašíčková V, Vásquez-Ramírez A, Veberič D, Vergara Quispe ID, Verzi V, Vicha J, Vink J, Vorobiov S, Watanabe C, Watson AA, Weindl A, Wiencke L, Wilczyński H, Wittkowski D, Wundheiler B, Yue B, Yushkov A, Zapparrata O, Zas E, Zavrtanik D, and Zavrtanik M

Abstract

We present measurements of the atmospheric depth of the shower maximum X_{max}, inferred for the first time on an event-by-event level using the surface detector of the Pierre Auger Observatory. Using deep learning, we were able to extend measurements of the X_{max} distributions up to energies of 100 EeV (10^{20}  eV), not yet revealed by current measurements, providing new insights into the mass composition of cosmic rays at extreme energies. Gaining a 10-fold increase in statistics compared to the fluorescence detector data, we find evidence that the rate of change of the average X_{max} with the logarithm of energy features three breaks at 6.5±0.6(stat)±1(syst)  EeV, 11±2(stat)±1(syst)  EeV, and 31±5(stat)±3(syst)  EeV, in the vicinity to the three prominent features (ankle, instep, suppression) of the cosmic-ray flux. The energy evolution of the mean and standard deviation of the measured X_{max} distributions indicates that the mass composition becomes increasingly heavier and purer, thus being incompatible with a large fraction of light nuclei between 50 and 100 EeV.

Published
2025
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25. Demonstrating Agreement between Radio and Fluorescence Measurements of the Depth of Maximum of Extensive Air Showers at the Pierre Auger Observatory.

Author

Abdul Halim A, Abreu P, Aglietta M, Allekotte I, Cheminant KA, Almela A, Aloisio R, Alvarez-Muñiz J, Yebra JA, Anastasi GA, Anchordoqui L, Andrada B, Andringa S, Anukriti, Apollonio L, Aramo C, Ferreira PRA, Arnone E, Velázquez JCA, Assis P, Avila G, Avocone E, Bakalova A, Barbato F, Mocellin AB, Bellido JA, Berat C, Bertaina ME, Bhatta G, Bianciotto M, Biermann PL, Binet V, Bismark K, Bister T, Biteau J, Blazek J, Bleve C, Blümer J, Boháčová M, Boncioli D, Bonifazi C, Arbeletche LB, Borodai N, Brack J, Orchera PGB, Briechle FL, Bueno A, Buitink S, Buscemi M, Büsken M, Bwembya A, Caballero-Mora KS, Cabana-Freire S, Caccianiga L, Caruso R, Castellina A, Catalani F, Cataldi G, Cazon L, Cerda M, Cermenati A, Chinellato JA, Chudoba J, Chytka L, Clay RW, Cerutti ACC, Colalillo R, Coleman A, Coluccia MR, Conceição R, Condorelli A, Consolati G, Conte M, Convenga F, Dos Santos DC, Costa PJ, Covault CE, Cristinziani M, Sanchez CSC, Dasso S, Daumiller K, Dawson BR, de Almeida RM, de Jesús J, de Jong SJ, Neto JRTM, De Mitri I, de Oliveira J, Franco DO, de Palma F, de Souza V, de Errico BPS, De Vito E, Del Popolo A, Deligny O, Denner N, Deval L, di Matteo A, Dobre M, Dobrigkeit C, D'Olivo JC, Mendes LMD, Dorosti Q, Dos Anjos JC, Dos Anjos RC, Ebr J, Ellwanger F, Emam M, Engel R, Epicoco I, Erdmann M, Etchegoyen A, Evoli C, Falcke H, Farmer J, Farrar G, Fauth AC, Fazzini N, Feldbusch F, Fenu F, Fernandes A, Fick B, Figueira JM, Filipčič A, Fitoussi T, Flaggs B, Fodran T, Fujii T, Fuster A, Galea C, Galelli C, García B, Gaudu C, Gemmeke H, Gesualdi F, Gherghel-Lascu A, Ghia PL, Giaccari U, Glombitza J, Gobbi F, Gollan F, Golup G, Berisso MG, Vitale PFG, Gongora JP, González JM, González N, Goos I, Góra D, Gorgi A, Gottowik M, Grubb TD, Guarino F, Guedes GP, Guido E, Gülzow L, Hahn S, Hamal P, Hampel MR, Hansen P, Harari D, Harvey VM, Haungs A, Hebbeker T, Hojvat C, Hörandel JR, Horvath P, Hrabovský M, Huege T, Insolia A, Isar PG, Janecek P, Jilek V, Johnsen JA, Jurysek J, Kampert KH, Keilhauer B, Khakurdikar A, Covilakam VVK, Klages HO, Kleifges M, Knapp F, Köhler J, Kunka N, Lago BL, Langner N, de Oliveira MAL, Lema-Capeans Y, Letessier-Selvon A, Lhenry-Yvon I, Lopes L, Lu L, Luce Q, Lundquist JP, Payeras AM, Majercakova M, Mandat D, Manning BC, Mantsch P, Marafico S, Mariani FM, Mariazzi AG, Mariş IC, Marsella G, Martello D, Martinelli S, Bravo OM, Martins MA, Mathes HJ, Matthews J, Matthiae G, Mayotte E, Mayotte S, Mazur PO, Medina-Tanco G, Meinert J, Melo D, Menshikov A, Merx C, Michal S, Micheletti MI, Miramonti L, Mollerach S, Montanet F, Morejon L, Morello C, Mulrey K, Mussa R, Namasaka WM, Negi S, Nellen L, Nguyen K, Nicora G, Niechciol M, Nitz D, Nosek D, Novotny V, Nožka L, Nucita A, Núñez LA, Oliveira C, Palatka M, Pallotta J, Panja S, Parente G, Paulsen T, Pawlowsky J, Pech M, Pękala J, Pelayo R, Pereira LAS, Martins EEP, Armand JP, Bertolli CP, Perrone L, Petrera S, Petrucci C, Pierog T, Pimenta M, Platino M, Pont B, Pothast M, Shahvar MP, Privitera P, Prouza M, Puyleart A, Querchfeld S, Rautenberg J, Ravignani D, Akim JVR, Reininghaus M, Ridky J, Riehn F, Risse M, Rizi V, de Carvalho WR, Rodriguez E, Rojo JR, Roncoroni MJ, Rossoni S, Roth M, Roulet E, Rovero AC, Ruehl P, Saftoiu A, Saharan M, Salamida F, Salazar H, Salina G, Gomez JDS, Sánchez F, Santos EM, Santos E, Sarazin F, Sarmento R, Sato R, Savina P, Schäfer CM, Scherini V, Schieler H, Schimassek M, Schimp M, Schmidt D, Scholten O, Schoorlemmer H, Schovánek P, Schröder FG, Schulte J, Schulz T, Sciutto SJ, Scornavacche M, Segreto A, Sehgal S, Shivashankara SU, Sigl G, Silli G, Sima O, Simkova K, Simon F, Smau R, Šmída R, Sommers P, Soriano JF, Squartini R, Stadelmaier M, Stanič S, Stasielak J, Stassi P, Strähnz S, Straub M, Suomijärvi T, Supanitsky AD, Svozilikova Z, Szadkowski Z, Tairli F, Tapia A, Taricco C, Timmermans C, Tkachenko O, Tobiska P, Peixoto CJT, Tomé B, Torrès Z, Travaini A, Travnicek P, Trimarelli C, Tueros M, Unger M, Vaclavek L, Vacula M, Galicia JFV, Valore L, Varela E, Vásquez-Ramírez A, Veberič D, Ventura C, Quispe IDV, Verzi V, Vicha J, Vink J, Vorobiov S, Watanabe C, Watson AA, Weindl A, Wiencke L, Wilczyński H, Wittkowski D, Wundheiler B, Yue B, Yushkov A, Zapparrata O, Zas E, Zavrtanik D, and Zavrtanik M

Abstract

We show, for the first time, radio measurements of the depth of shower maximum (X_{max}) of air showers induced by cosmic rays that are compared to measurements of the established fluorescence method at the same location. Using measurements at the Pierre Auger Observatory we show full compatibility between our radio and the previously published fluorescence dataset, and between a subset of air showers observed simultaneously with both radio and fluorescence techniques, a measurement setup unique to the Pierre Auger Observatory. Furthermore, we show radio X_{max} resolution as a function of energy and demonstrate the ability to make competitive high-resolution X_{max} measurements with even a sparse radio array. With this, we show that the radio technique is capable of cosmic-ray mass composition studies, both at Auger and at other experiments.

Published
2024
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26. Limits to Gauge Coupling in the Dark Sector Set by the Nonobservation of Instanton-Induced Decay of Super-Heavy Dark Matter in the Pierre Auger Observatory Data.

Author

Abreu P, Aglietta M, Albury JM, Allekotte I, Almeida Cheminant K, Almela A, Aloisio R, Alvarez-Muñiz J, Alves Batista R, Ammerman Yebra J, Anastasi GA, Anchordoqui L, Andrada B, Andringa S, Aramo C, Araújo Ferreira PR, Arnone E, Arteaga Velázquez JC, Asorey H, Assis P, Avila G, Avocone E, Badescu AM, Bakalova A, Balaceanu A, Barbato F, Bellido JA, Berat C, Bertaina ME, Bhatta G, Biermann PL, Binet V, Bismark K, Bister T, Biteau J, Blazek J, Bleve C, Blümer J, Boháčová M, Boncioli D, Bonifazi C, Bonneau Arbeletche L, Borodai N, Botti AM, Brack J, Bretz T, Brichetto Orchera PG, Briechle FL, Buchholz P, Bueno A, Buitink S, Buscemi M, Büsken M, Caballero-Mora KS, Caccianiga L, Canfora F, Caracas I, Caruso R, Castellina A, Catalani F, Cataldi G, Cazon L, Cerda M, Chinellato JA, Chudoba J, Chytka L, Clay RW, Cobos Cerutti AC, Colalillo R, Coleman A, Coluccia MR, Conceição R, Condorelli A, Consolati G, Contreras F, Convenga F, Correia Dos Santos D, Covault CE, Dasso S, Daumiller K, Dawson BR, Day JA, de Almeida RM, de Jesús J, de Jong SJ, de Mello Neto JRT, De Mitri I, de Oliveira J, de Oliveira Franco D, de Palma F, de Souza V, De Vito E, Del Popolo A, Del Río M, Deligny O, Deval L, di Matteo A, Dobre M, Dobrigkeit C, D'Olivo JC, Domingues Mendes LM, Dos Anjos RC, Dova MT, Ebr J, Engel R, Epicoco I, Erdmann M, Escobar CO, Etchegoyen A, Falcke H, Farmer J, Farrar G, Fauth AC, Fazzini N, Feldbusch F, Fenu F, Fick B, Figueira JM, Filipčič A, Fitoussi T, Fodran T, Fujii T, Fuster A, Galea C, Galelli C, García B, Garcia Vegas AL, Gemmeke H, Gesualdi F, Gherghel-Lascu A, Ghia PL, Giaccari U, Giammarchi M, Glombitza J, Gobbi F, Gollan F, Golup G, Gómez Berisso M, Gómez Vitale PF, Gongora JP, González JM, González N, Goos I, Góra D, Gorgi A, Gottowik M, Grubb TD, Guarino F, Guedes GP, Guido E, Hahn S, Hamal P, Hampel MR, Hansen P, Harari D, Harvey VM, Haungs A, Hebbeker T, Heck D, Hill GC, Hojvat C, Hörandel JR, Horvath P, Hrabovský M, Huege T, Insolia A, Isar PG, Janecek P, Johnsen JA, Jurysek J, Kääpä A, Kampert KH, Keilhauer B, Khakurdikar A, Kizakke Covilakam VV, Klages HO, Kleifges M, Kleinfeller J, Knapp F, Kunka N, Lago BL, Langner N, Leigui de Oliveira MA, Lenok V, Letessier-Selvon A, Lhenry-Yvon I, Lo Presti D, Lopes L, López R, Lu L, Luce Q, Lundquist JP, Machado Payeras A, Mancarella G, Mandat D, Manning BC, Manshanden J, Mantsch P, Marafico S, Mariani FM, Mariazzi AG, Mariş IC, Marsella G, Martello D, Martinelli S, Martínez Bravo O, Mastrodicasa M, Mathes HJ, Matthews J, Matthiae G, Mayotte E, Mayotte S, Mazur PO, Medina-Tanco G, Melo D, Menshikov A, Michal S, Micheletti MI, Miramonti L, Mollerach S, Montanet F, Morejon L, Morello C, Mostafá M, Müller AL, Muller MA, Mulrey K, Mussa R, Muzio M, Namasaka WM, Nasr-Esfahani A, Nellen L, Nicora G, Niculescu-Oglinzanu M, Niechciol M, Nitz D, Norwood I, Nosek D, Novotny V, Nožka L, Nucita A, Núñez LA, Oliveira C, Palatka M, Pallotta J, Papenbreer P, Parente G, Parra A, Pawlowsky J, Pech M, Pękala J, Pelayo R, Peña-Rodriguez J, Pereira Martins EE, Perez Armand J, Pérez Bertolli C, Perrone L, Petrera S, Petrucci C, 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, Rizi V, Rodrigues de Carvalho W, Rodriguez Rojo J, Roncoroni MJ, Rossoni S, Roth M, Roulet E, Rovero AC, Ruehl P, Saftoiu A, Saharan M, Salamida F, Salazar H, Salina G, Sanabria Gomez JD, Sánchez F, Santos EM, Santos E, Sarazin F, Sarmento R, Sarmiento-Cano C, Sato R, Savina P, Schäfer CM, Scherini V, Schieler H, Schimassek M, Schimp M, Schlüter F, Schmidt D, Scholten O, Schoorlemmer H, Schovánek P, Schröder FG, Schulte J, Schulz T, Sciutto SJ, Scornavacche M, Segreto A, Sehgal S, Shellard RC, Sigl G, Silli G, Sima O, Smau R, Šmída R, Sommers P, Soriano JF, Squartini R, Stadelmaier M, Stanca D, Stanič S, Stasielak J, Stassi P, Streich A, Suárez-Durán M, Sudholz T, Suomijärvi T, Supanitsky AD, Szadkowski Z, Tapia A, Taricco C, Timmermans C, Tkachenko O, Tobiska P, Todero Peixoto CJ, Tomé B, Torrès Z, Travaini A, Travnicek P, Trimarelli C, Tueros M, Ulrich R, Unger M, Vaclavek L, Vacula M, Valdés Galicia JF, Valore L, Varela E, Vásquez-Ramírez A, Veberič D, Ventura C, Vergara Quispe ID, Verzi V, Vicha J, Vink J, Vorobiov S, Wahlberg H, Watanabe C, Watson AA, Weindl A, Wiencke L, Wilczyński H, Wittkowski D, Wundheiler B, Yushkov A, Zapparrata O, Zas E, Zavrtanik D, Zavrtanik M, and Zehrer L

Abstract

Instantons, which are nonperturbative solutions to Yang-Mills equations, provide a signal for the occurrence of quantum tunneling between distinct classes of vacua. They can give rise to decays of particles otherwise forbidden. Using data collected at the Pierre Auger Observatory, we search for signatures of such instanton-induced processes that would be suggestive of super-heavy particles decaying in the Galactic halo. These particles could have been produced during the post-inflationary epoch and match the relic abundance of dark matter inferred today. The nonobservation of the signatures searched for allows us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: α&#95;{X}≲0.09, for 10^{9}≲M&#95;{X}/GeV<10^{19}. Conversely, we obtain that, for instance, a reduced coupling constant α&#95;{X}=0.09 excludes masses M&#95;{X}≳3×10^{13}  GeV. In the context of dark matter production from gravitational interactions alone, we illustrate how these bounds are complementary to those obtained on the Hubble rate at the end of inflation from the nonobservation of tensor modes in the cosmological microwave background.

Published
2023
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27. Measurement of the Fluctuations in the Number of Muons in Extensive Air Showers with the Pierre Auger Observatory.

Author

Aab A, Abreu P, Aglietta M, Albury JM, Allekotte I, Almela A, Alvarez-Muñiz J, Alves Batista R, Anastasi GA, Anchordoqui L, Andrada B, Andringa S, Aramo C, Araújo Ferreira PR, Asorey H, Assis P, Avila G, Badescu AM, Bakalova A, Balaceanu A, Barbato F, Barreira Luz RJ, Becker KH, Bellido JA, Berat C, Bertaina ME, Bertou X, Biermann PL, Bister T, Biteau J, Blazek J, Bleve C, Boháčová M, Boncioli D, Bonifazi C, Bonneau Arbeletche L, Borodai N, Botti AM, Brack J, Bretz T, Briechle FL, Buchholz P, Bueno A, Buitink S, Buscemi M, Caballero-Mora KS, Caccianiga L, Cancio A, Canfora F, Caracas I, Carceller JM, Caruso R, Castellina A, Catalani F, Cataldi G, Cazon L, Cerda M, Chinellato JA, Choi K, Chudoba J, Chytka L, Clay RW, Cobos Cerutti AC, Colalillo R, Coleman A, Coluccia MR, Conceição R, Condorelli A, Consolati G, Contreras F, Convenga F, Covault CE, Dasso S, Daumiller K, Dawson BR, Day JA, de Almeida RM, de Jesús J, de Jong SJ, De Mauro G, de Mello Neto JRT, De Mitri I, de Oliveira J, de Oliveira Franco D, de Souza V, De Vito E, Debatin J, Del Río M, Deligny O, Dembinski H, Dhital N, Di Matteo A, Dobrigkeit C, D'Olivo JC, Dos Anjos RC, Dova MT, Ebr J, Engel R, Epicoco I, Erdmann M, Escobar CO, Etchegoyen A, Falcke H, Farmer J, Farrar G, Fauth AC, Fazzini N, Feldbusch F, Fenu F, Fick B, Figueira JM, Filipčič A, Fodran T, Freire MM, Fujii T, Fuster A, Galea C, Galelli C, García B, Garcia Vegas AL, Gemmeke H, Gesualdi F, Gherghel-Lascu A, Ghia PL, Giaccari U, Giammarchi M, Giller M, Glombitza J, Gobbi F, Gollan F, Golup G, Gómez Berisso M, Gómez Vitale PF, Gongora JP, González N, Goos I, Góra D, Gorgi A, Gottowik M, Grubb TD, Guarino F, Guedes GP, Guido E, Hahn S, Halliday R, Hampel MR, Hansen P, Harari D, Harvey VM, Haungs A, Hebbeker T, Heck D, Hill GC, Hojvat C, Hörandel JR, Horvath P, Hrabovský M, Huege T, Hulsman J, Insolia A, Isar PG, Johnsen JA, Jurysek J, Kääpä A, Kampert KH, Keilhauer B, Kemp J, Klages HO, Kleifges M, Kleinfeller J, Köpke M, Kukec Mezek G, Lago BL, LaHurd D, Lang RG, Langner N, Leigui de Oliveira MA, Lenok V, Letessier-Selvon A, Lhenry-Yvon I, Lo Presti D, Lopes L, López R, Lorek R, Luce Q, Lucero A, Lundquist JP, Machado Payeras A, Mancarella G, Mandat D, Manning BC, Manshanden J, Mantsch P, Marafico S, Mariazzi AG, Mariş IC, Marsella G, Martello D, Martinez H, Martínez Bravo O, Mastrodicasa M, Mathes HJ, Matthews J, Matthiae G, Mayotte E, Mazur PO, Medina-Tanco G, Melo D, Menshikov A, Merenda KD, Michal S, Micheletti MI, Miramonti L, Mollerach S, Montanet F, Morello C, Mostafá M, Müller AL, Muller MA, Mulrey K, Mussa R, Muzio M, Namasaka WM, Nellen L, Niculescu-Oglinzanu M, Niechciol M, Nitz D, Nosek D, Novotny V, Nožka L, Nucita A, Núñez LA, Palatka M, Pallotta J, Papenbreer P, Parente G, Parra A, Pech M, Pedreira F, Pȩkala J, Pelayo R, Peña-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 MJ, Roth M, Roulet E, Rovero AC, Ruehl P, Saffi SJ, Saftoiu A, Salamida F, Salazar H, Salina G, Sanabria Gomez JD, Sánchez F, Santos EM, Santos E, Sarazin F, Sarmento R, Sarmiento-Cano C, Sato R, Savina P, Schäfer CM, Scherini V, Schieler H, Schimassek M, Schimp M, Schlüter F, Schmidt D, Scholten O, Schovánek P, Schröder FG, Schröder S, Schulte J, Sciutto SJ, Scornavacche M, Shellard RC, Sigl G, Silli G, Sima O, Šmída R, Sommers P, Soriano JF, Souchard J, Squartini R, Stadelmaier M, Stanca D, Stanič S, Stasielak J, Stassi P, Streich A, Suárez-Durán M, Sudholz T, Suomijärvi T, Supanitsky AD, Šupík J, Szadkowski Z, Taboada A, Tapia A, Timmermans C, Tkachenko O, Tobiska P, Todero Peixoto CJ, Tomé B, Torralba Elipe G, Travaini A, Travnicek P, Trimarelli C, Trini M, Tueros M, Ulrich R, Unger M, Vaclavek L, Vacula M, Valdés Galicia JF, Valiño I, Valore L, Varela E, Varma K C V, Vásquez-Ramírez A, Veberič D, Ventura C, Vergara Quispe ID, Verzi V, Vicha J, Vink J, Vorobiov S, Wahlberg H, Watson AA, Weber M, Weindl A, Wiencke L, Wilczyński H, Winchen T, Wirtz M, Wittkowski D, Wundheiler B, Yushkov A, Zapparrata O, Zas E, Zavrtanik D, Zavrtanik M, Zehrer L, and Zepeda A

Abstract

We present the first measurement of the fluctuations in the number of muons in extensive air showers produced by ultrahigh energy cosmic rays. We find that the measured fluctuations are in good agreement with predictions from air shower simulations. This observation provides new insights into the origin of the previously reported deficit of muons in air shower simulations and constrains models of hadronic interactions at ultrahigh energies. Our measurement is compatible with the muon deficit originating from small deviations in the predictions from hadronic interaction models of particle production that accumulate as the showers develop.

Published
2021
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28. Features of the Energy Spectrum of Cosmic Rays above 2.5×10^{18}  eV Using the Pierre Auger Observatory.

Author

Aab A, Abreu P, Aglietta M, Albury JM, Allekotte I, Almela A, Alvarez Castillo J, Alvarez-Muñiz J, Alves Batista R, Anastasi GA, Anchordoqui L, Andrada B, Andringa S, Aramo C, Araújo Ferreira PR, Asorey H, Assis P, Avila G, Badescu AM, Bakalova A, Balaceanu A, Barbato F, Barreira Luz RJ, Becker KH, Bellido JA, Berat C, Bertaina ME, Bertou X, Biermann PL, Bister T, Biteau J, Blanco A, Blazek J, Bleve C, Boháčová M, Boncioli D, Bonifazi C, Bonneau Arbeletche L, Borodai N, Botti AM, Brack J, Bretz T, Briechle FL, Buchholz P, Bueno A, Buitink S, Buscemi M, Caballero-Mora KS, Caccianiga L, Calcagni L, Cancio A, Canfora F, Caracas I, Carceller JM, Caruso R, Castellina A, Catalani F, Cataldi G, Cazon L, Cerda M, Chinellato JA, Choi K, Chudoba J, Chytka L, Clay RW, Cobos Cerutti AC, Colalillo R, Coleman A, Coluccia MR, Conceição R, Condorelli A, Consolati G, Contreras F, Convenga F, Covault CE, Dasso S, Daumiller K, Dawson BR, Day JA, de Almeida RM, de Jesús J, de Jong SJ, De Mauro G, de Mello Neto JRT, De Mitri I, de Oliveira J, de Oliveira Franco D, de Souza V, De Vito E, Debatin J, Del Río M, Deligny O, Dembinski H, Dhital N, Di Giulio C, Di Matteo A, Díaz Castro ML, Dobrigkeit C, D'Olivo JC, Dorosti Q, Dos Anjos RC, Dova MT, Ebr J, Engel R, Epicoco I, Erdmann M, Escobar CO, Etchegoyen A, Falcke H, Farmer J, Farrar G, Fauth AC, Fazzini N, Feldbusch F, Fenu F, Fick B, Figueira JM, Filipčič A, Fodran T, Freire MM, Fujii T, Fuster A, Galea C, Galelli C, García B, Garcia Vegas AL, Gemmeke H, Gesualdi F, Gherghel-Lascu A, Ghia PL, Giaccari U, Giammarchi M, Giller M, Glombitza J, Gobbi F, Gollan F, Golup G, Gómez Berisso M, Gómez Vitale PF, Gongora JP, González N, Goos I, Góra D, Gorgi A, Gottowik M, Grubb TD, Guarino F, Guedes GP, Guido E, Hahn S, Halliday R, Hampel MR, Hansen P, Harari D, Harvey VM, Haungs A, Hebbeker T, Heck D, Hill GC, Hojvat C, Hörandel JR, Horvath P, Hrabovský M, Huege T, Hulsman J, Insolia A, Isar PG, Johnsen JA, Jurysek J, Kääpä A, Kampert KH, Keilhauer B, Kemp J, Klages HO, Kleifges M, Kleinfeller J, Köpke M, Kukec Mezek G, Lago BL, LaHurd D, Lang RG, Leigui de Oliveira MA, Lenok V, Letessier-Selvon A, Lhenry-Yvon I, Lo Presti D, Lopes L, López R, Lorek R, Luce Q, Lucero A, Machado Payeras A, Malacari M, Mancarella G, Mandat D, Manning BC, Manshanden J, Mantsch P, Marafico S, Mariazzi AG, Mariş IC, Marsella G, Martello D, Martinez H, Martínez Bravo O, Mastrodicasa M, Mathes HJ, Matthews J, Matthiae G, Mayotte E, Mazur PO, Medina-Tanco G, Melo D, Menshikov A, Merenda KD, Michal S, Micheletti MI, Miramonti L, Mockler D, Mollerach S, Montanet F, Morello C, Mostafá M, Müller AL, Muller MA, Mulrey K, Mussa R, Muzio M, Namasaka WM, Nellen L, Nguyen PH, Niculescu-Oglinzanu M, Niechciol M, Nitz D, Nosek D, Novotny V, Nožka L, Nucita A, Núñez LA, Palatka M, Pallotta J, Panetta MP, Papenbreer P, Parente G, Parra A, Pech M, Pedreira F, Pȩkala J, Pelayo R, Peña-Rodriguez J, Perez Armand J, Perlin M, Perrone L, Peters C, 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 Fernandez G, Rodriguez Rojo J, Roncoroni MJ, Roth M, Roulet E, Rovero AC, Ruehl P, Saffi SJ, Saftoiu A, Salamida F, Salazar H, Salina G, Sanabria Gomez JD, Sánchez F, Santos EM, Santos E, Sarazin F, Sarmento R, Sarmiento-Cano C, Sato R, Savina P, Schäfer C, Scherini V, Schieler H, Schimassek M, Schimp M, Schlüter F, Schmidt D, Scholten O, Schovánek P, Schröder FG, Schröder S, Schulz A, Sciutto SJ, Scornavacche M, Shellard RC, Sigl G, Silli G, Sima O, Šmída R, Sommers P, Soriano JF, Souchard J, Squartini R, Stadelmaier M, Stanca D, Stanič S, Stasielak J, Stassi P, Streich A, Suárez-Durán M, Sudholz T, Suomijärvi T, Supanitsky AD, Šupík J, Szadkowski Z, Taboada A, Tapia A, Timmermans C, Tkachenko O, Tobiska P, Todero Peixoto CJ, Tomé B, Torralba Elipe G, Travaini A, Travnicek P, Trimarelli C, Trini M, Tueros M, Ulrich R, Unger M, Urban M, Vaclavek L, Vacula M, Valdés Galicia JF, Valiño I, Valore L, van Vliet A, Varela E, Vargas Cárdenas B, Vásquez-Ramírez A, Veberič D, Ventura C, Vergara Quispe ID, Verzi V, Vicha J, Villaseñor L, Vink J, Vorobiov S, Wahlberg H, Watson AA, Weber M, Weindl A, Wiencke L, Wilczyński H, Winchen T, Wirtz M, Wittkowski D, Wundheiler B, Yushkov A, Zapparrata O, Zas E, Zavrtanik D, Zavrtanik M, Zehrer L, Zepeda A, Ziolkowski M, and Zuccarello F

Abstract

We report a measurement of the energy spectrum of cosmic rays above 2.5×10^{18}  eV based on 215 030 events. New results are presented: at about 1.3×10^{19}  eV, the spectral index changes from 2.51±0.03(stat)±0.05(syst) to 3.05±0.05(stat)±0.10(syst), evolving to 5.1±0.3(stat)±0.1(syst) beyond 5×10^{19}  eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5×10^{18}  eV is [5.66±0.03(stat)±1.40(syst)]×10^{53}  erg Mpc^{-3}.

Published
2020
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