Prof Subir Sarkar: Publications

IceCube

IceCube at Oxford

I am a member since 2004 of the IceCube collaboration which discovered cosmic high energy neutrinos and identified some of their astrophysical sources.

IceCube @ Oxford

Asymmetric dark matter and the Sun

(2010)

Authors:

Mads T Frandsen, Subir Sarkar

Measurement of the energy spectrum of cosmic rays above 1018 eV using the Pierre Auger Observatory

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 685:4-5 (2010) 239-246

Authors:

J Abraham, P Abreu, M Aglietta, EJ Ahn, D Allard, J Allen, J Alvarez-Muñiz, M Ambrosio, L Anchordoqui, S Andringa, T Antičić, A Anzalone, C Aramo, E Arganda, K Arisaka, F Arqueros, H Asorey, P Assis, J Aublin, M Ave, G Avila, T Bäcker, D Badagnani, M Balzer, KB Barber, AF Barbosa, SLC Barroso, B Baughman, P Bauleo, JJ Beatty, BR Becker, KH Becker, A Bellétoile, JA Bellido, S BenZvi, C Berat, T Bergmann, X Bertou, PL Biermann, P Billoir, O Blanch-Bigas, F Blanco, M Blanco, C Bleve, H Blümer, M Boháčová, D Boncioli, C Bonifazi, R Bonino, N Borodai, J Brack, P Brogueira, WC Brown, R Bruijn, P Buchholz, A Bueno, RE Burton, NG Busca, KS Caballero-Mora, L Caramete, R Caruso, A Castellina, O Catalano, G Cataldi, L Cazon, R Cester, J Chauvin, A Chiavassa, JA Chinellato, A Chou, J Chudoba, RW Clay, E Colombo, MR Coluccia, R Conceição, F Contreras, H Cook, MJ Cooper, J Coppens, A Cordier, U Cotti, S Coutu, CE Covault, A Creusot, A Criss, J Cronin, A Curutiu, S Dagoret-Campagne, R Dallier, K Daumiller, BR Dawson, RM de Almeida, M De Domenico, C De Donato, SJ de Jong, G De La Vega, WJM de Mello Junior, JRT de Mello Neto, I De Mitri, V de Souza

Abstract:

We report a measurement of the flux of cosmic rays with unprecedented precision and statistics using the Pierre Auger Observatory. Based on fluorescence observations in coincidence with at least one surface detector we derive a spectrum for energies above 10¹⁸ eV. We also update the previously published energy spectrum obtained with the surface detector array. The two spectra are combined addressing the systematic uncertainties and, in particular, the influence of the energy resolution on the spectral shape. The spectrum can be described by a broken power law E^{- γ} with index γ = 3.3 below the ankle which is measured at log10 (Eankle / eV) = 18.6. Above the ankle the spectrum is described by a power law with index 2.6 followed by a flux suppression, above about log10 (E / eV) = 19.5, detected with high statistical significance. © 2010 Elsevier B.V. All rights reserved.

Measurement of the depth of maximum of extensive air showers above 10{18} eV.

Phys Rev Lett 104:9 (2010) 091101

Authors:

J Abraham, P Abreu, M Aglietta, EJ Ahn, D Allard, I Allekotte, J Allen, J Alvarez-Muñiz, M Ambrosio, L Anchordoqui, S Andringa, T Anticić, A Anzalone, C Aramo, E Arganda, K Arisaka, F Arqueros, H Asorey, P Assis, J Aublin, M Ave, G Avila, T Bäcker, D Badagnani, M Balzer, KB Barber, AF Barbosa, SLC Barroso, B Baughman, P Bauleo, JJ Beatty, BR Becker, KH Becker, A Bellétoile, JA Bellido, S Benzvi, C Berat, T Bergmann, X Bertou, PL Biermann, P Billoir, O Blanch-Bigas, F Blanco, M Blanco, C Bleve, H Blümer, M Bohácová, D Boncioli, C Bonifazi, R Bonino, N Borodai, J Brack, P Brogueira, WC Brown, R Bruijn, P Buchholz, A Bueno, RE Burton, NG Busca, KS Caballero-Mora, L Caramete, R Caruso, A Castellina, O Catalano, G Cataldi, L Cazon, R Cester, J Chauvin, A Chiavassa, JA Chinellato, A Chou, J Chudoba, RW Clay, E Colombo, MR Coluccia, R Conceição, F Contreras, H Cook, MJ Cooper, J Coppens, A Cordier, U Cotti, S Coutu, CE Covault, A Creusot, A Criss, J Cronin, A Curutiu, S Dagoret-Campagne, R Dallier, K Daumiller, BR Dawson, RM de Almeida, M De Domenico, C De Donato, SJ de Jong, G De La Vega, WJM de Mello Junior, JRT de Mello Neto, I De Mitri, V de Souza, KD de Vries, G Decerprit, L Del Peral, O Deligny, A Della Selva, C Delle Fratte, H Dembinski, C Di Giulio, JC Diaz, ML Díaz Castro, PN Diep, C Dobrigkeit, JC D'Olivo, PN Dong, A Dorofeev, JC Dos Anjos, MT Dova, D D'Urso, I Dutan, MA Duvernois, J Ebr, R Engel, M Erdmann, CO Escobar, A Etchegoyen, P Facal San Luis, H Falcke, G Farrar, AC Fauth, N Fazzini, A Ferrero, B Fick, A Filevich, A Filipcic, I Fleck, S Fliescher, CE Fracchiolla, ED Fraenkel, U Fröhlich, W Fulgione, RF Gamarra, S Gambetta, B García, D García Gámez, D Garcia-Pinto, X Garrido, G Gelmini, H Gemmeke, PL Ghia, U Giaccari, M Giller, H Glass, LM Goggin, MS Gold, G Golup, F Gomez Albarracin, M Gómez Berisso, P Gonçalves, D Gonzalez, JG Gonzalez, D Góra, A Gorgi, P Gouffon, SR Gozzini, E Grashorn, S Grebe, M Grigat, AF Grillo, Y Guardincerri, F Guarino, GP Guedes, JD Hague, V Halenka, P Hansen, D Harari, S Harmsma, JL Harton, A Haungs, T Hebbeker, D Heck, AE Herve, C Hojvat, VC Holmes, P Homola, JR Hörandel, A Horneffer, M Hrabovský, T Huege, M Hussain, M Iarlori, A Insolia, F Ionita, A Italiano, S Jiraskova, K Kadija, M Kaducak, KH Kampert, T Karova, P Kasper, B Kégl, B Keilhauer, A Keivani, J Kelley, E Kemp, RM Kieckhafer, HO Klages, M Kleifges, J Kleinfeller, R Knapik, J Knapp, D-H Koang, A Krieger, O Krömer, D Kruppke-Hansen, F Kuehn, D Kuempel, K Kulbartz, N Kunka, A Kusenko, G La Rosa, C Lachaud, BL Lago, P Lautridou, MSAB Leão, D Lebrun, P Lebrun, J Lee, MA Leigui de Oliveira, A Lemiere, A Letessier-Selvon, I Lhenry-Yvon, R López, A Lopez Agüera, K Louedec, J Lozano Bahilo, A Lucero, M Ludwig, H Lyberis, MC Maccarone, C Macolino, S Maldera, D Mandat, P Mantsch, AG Mariazzi, V Marin, IC Maris, HR Marquez Falcon, G Marsella, D Martello, O Martínez Bravo, HJ Mathes, J Matthews, JAJ Matthews, G Matthiae, D Maurizio, PO Mazur, M McEwen, G Medina-Tanco, M Melissas, D Melo, E Menichetti, A Menshikov, C Meurer, S Micanović, MI Micheletti, W Miller, L Miramonti, S Mollerach, M Monasor, D Monnier Ragaigne, F Montanet, B Morales, C Morello, E Moreno, JC Moreno, C Morris, M Mostafá, S Mueller, MA Muller, R Mussa, G Navarra, JL Navarro, S Navas, P Necesal, L Nellen, PT Nhung, N Nierstenhoefer, D Nitz, D Nosek, L Nozka, M Nyklicek, J Oehlschläger, A Olinto, P Oliva, VM Olmos-Gilbaja, M Ortiz, N Pacheco, D Pakk Selmi-Dei, M Palatka, J Pallotta, N Palmieri, G Parente, E Parizot, S Parlati, A Parra, J Parrisius, RD Parsons, S Pastor, T Paul, V Pavlidou, K Payet, M Pech, J Pekala, R Pelayo, IM Pepe, L Perrone, R Pesce, E Petermann, S Petrera, P Petrinca, A Petrolini, Y Petrov, J Petrovic, C Pfendner, R Piegaia, T Pierog, M Pimenta, V Pirronello, M Platino, VH Ponce, M Pontz, P Privitera, M Prouza, EJ Quel, J Rautenberg, O Ravel, D Ravignani, A Redondo, B Revenu, FAS Rezende, J Ridky, S Riggi, M Risse, P Ristori, C Rivière, V Rizi, C Robledo, G Rodriguez, J Rodriguez Martino, J Rodriguez Rojo, I Rodriguez-Cabo, MD Rodríguez-Frías, G Ros, J Rosado, T Rossler, M Roth, B Rouillé-d'Orfeuil, E Roulet, AC Rovero, F Salamida, H Salazar, G Salina, F Sánchez, M Santander, CE Santo, E Santos, EM Santos, F Sarazin, S Sarkar, R Sato, N Scharf, V Scherini, H Schieler, P Schiffer, A Schmidt, F Schmidt, T Schmidt, O Scholten, H Schoorlemmer, J Schovancova, P Schovánek, F Schroeder, S Schulte, F Schüssler, D Schuster, SJ Sciutto, M Scuderi, A Segreto, D Semikoz, M Settimo, A Shadkam, RC Shellard, I Sidelnik, BB Siffert, G Sigl, A Smiałkowski, R Smída, GR Snow, P Sommers, J Sorokin, H Spinka, R Squartini, J Stasielak, M Stephan, E Strazzeri, A Stutz, F Suarez, T Suomijärvi, AD Supanitsky, T Susa, MS Sutherland, J Swain, Z Szadkowski, A Tamashiro, A Tamburro, A Tapia, T Tarutina, O Taşcău, R Tcaciuc, D Tcherniakhovski, D Tegolo, NT Thao, D Thomas, J Tiffenberg, C Timmermans, W Tkaczyk, CJ Todero Peixoto, B Tomé, A Tonachini, P Travnicek, DB Tridapalli, G Tristram, E Trovato, M Tueros, R Ulrich, M Unger, M Urban, JF Valdés Galicia, I Valiño, L Valore, AM van den Berg, JR Vázquez, RA Vázquez, D Veberic, T Venters, V Verzi, M Videla, L Villaseñor, S Vorobiov, L Voyvodic, H Wahlberg, P Wahrlich, O Wainberg, D Warner, AA Watson, S Westerhoff, BJ Whelan, G Wieczorek, L Wiencke, B Wilczyńska, H Wilczyński, C Williams, T Winchen, MG Winnick, B Wundheiler, T Yamamoto, P Younk, G Yuan, A Yushkov, E Zas, D Zavrtanik, M Zavrtanik, I Zaw, A Zepeda, M Ziolkowski, Pierre Auger Collaboration

Abstract:

We describe the measurement of the depth of maximum, X{max}, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 10;{18} eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106{-21}{+35}) g/cm{2}/decade below 10{18.24+/-0.05} eV, and (24+/-3) g/cm{2}/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm{2}. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.

The northern site of the Pierre Auger Observatory

New Journal of Physics IOP Publishing 12:3 (2010) 035001

Trigger and aperture of the surface detector array of the Pierre Auger Observatory

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 613:1 (2010) 29-39

Authors:

J Abraham, P Abreu, M Aglietta, EJ Ahn, D Allard, I Allekotte, J Allen, J Alvarez-Muñiz, M Ambrosio, L Anchordoqui, S Andringa, T Antičić, A Anzalone, C Aramo, E Arganda, K Arisaka, F Arqueros, H Asorey, P Assis, J Aublin, M Ave, G Avila, T Bäcker, D Badagnani, M Balzer, KB Barber, AF Barbosa, SLC Barroso, B Baughman, P Bauleo, JJ Beatty, BR Becker, KH Becker, A Bellétoile, JA Bellido, S BenZvi, C Berat, T Bergmann, X Bertou, PL Biermann, P Billoir, O Blanch-Bigas, F Blanco, M Blanco, C Bleve, H Blümer, M Boháčová, D Boncioli, C Bonifazi, R Bonino, N Borodai, J Brack, P Brogueira, WC Brown, R Bruijn, P Buchholz, A Bueno, RE Burton, NG Busca, KS Caballero-Mora, L Caramete, R Caruso, A Castellina, O Catalano, G Cataldi, L Cazon, R Cester, J Chauvin, A Chiavassa, JA Chinellato, A Chou, J Chudoba, RW Clay, E Colombo, MR Coluccia, R Conceição, F Contreras, H Cook, MJ Cooper, J Coppens, A Cordier, U Cotti, S Coutu, CE Covault, A Creusot, A Criss, J Cronin, A Curutiu, S Dagoret-Campagne, R Dallier, K Daumiller, BR Dawson, RM de Almeida, M De Domenico, C De Donato, SJ de Jong, G De La Vega, WJM de Mello Junior, JRT de Mello Neto, I De Mitri

Abstract:

The surface detector array of the Pierre Auger Observatory consists of 1600 water-Cherenkov detectors, for the study of extensive air showers (EAS) generated by ultra-high-energy cosmic rays. We describe the trigger hierarchy, from the identification of candidate showers at the level of a single detector, amongst a large background (mainly random single cosmic ray muons), up to the selection of real events and the rejection of random coincidences. Such trigger makes the surface detector array fully efficient for the detection of EAS with energy above 3 × 10¹⁸ eV, for all zenith angles between 0^{{ring operator}} and 60^{{ring operator}}, independently of the position of the impact point and of the mass of the primary particle. In these range of energies and angles, the exposure of the surface array can be determined purely on the basis of the geometrical acceptance. © 2009 Elsevier B.V. All rights reserved.

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