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

A 51�� of the Effect of Molecular and Aerosol Conditions in the Atmosphere on Air Fluorescence Measurements at the Pierre Auger Observatory

ArXiv 1002.0366 (2010)

Abstract:

The air fluorescence detector of the Pierre Auger Observatory is designed to perform calorimetric measurements of extensive air showers created by cosmic rays of above 10^18 eV. To correct these measurements for the effects introduced by atmospheric fluctuations, the Observatory contains a group of monitoring instruments to record atmospheric conditions across the detector site, an area exceeding 3,000 km^2. The atmospheric data are used extensively in the reconstruction of air showers, and are particularly important for the correct determination of shower energies and the depths of shower maxima. This paper contains a summary of the molecular and aerosol conditions measured at the Pierre Auger Observatory since the start of regular operations in 2004, and includes a discussion of the impact of these measurements on air shower reconstructions. Between 10^18 and 10^20 eV, the systematic uncertainties due to all atmospheric effects increase from 4% to 8% in measurements of shower energy, and 4 g/cm^2 to 8 g/cm^2 in measurements of the shower maximum.

Erratum to "Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory" [Astroparticle Physics 32(2) (2009), 89-99] (DOI:10.1016/j.astropartphys.2009.06.004)

Astroparticle Physics 33:1 (2010) 65-67

Authors:

J Abraham, P Abreu, M Aglietta, C Aguirre, EJ Ahn, D Allard, I Allekotte, J Allen, P Allison, J Alvarez-Muñiz, M Ambrosio, L Anchordoqui, S Andringa, A Anzalone, C Aramo, E Arganda, S Argirò, K Arisaka, F Arneodo, F Arqueros, T Asch, H Asorey, P Assis, J Aublin, M Ave, G Avila, T Bäcker, D Badagnani, KB Barber, AF Barbosa, SLC Barroso, B Baughman, P Bauleo, JJ Beatty, T Beau, BR Becker, KH Becker, A Bellétoile, JA Bellido, S BenZvi, C Berat, P Bernardini, X Bertou, PL Biermann, P Billoir, O Blanch-Bigas, F Blanco, C Bleve, H Blümer, M Boháčová, 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, W Carvalho, A Castellina, O Catalano, L Cazon, R Cester, J Chauvin, A Chiavassa, JA Chinellato, A Chou, J Chudoba, J Chye, RW Clay, E Colombo, R Conceição, B Connolly, F Contreras, 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, JRT de Mello Neto

Erratum: Search for high-energy Muon neutrinos from the "naked-eye" GRB080319b with the icecube neutrino telescope (The Astrophysical Journal (2009) 701 (1721))

Astrophysical Journal 708:1 (2010) 911-912

Authors:

R Abbasi, Y Abdou, M Ackermann, J Adams, M Ahlers, K Andeen, J Auffenberg, X Bai, M Baker, SW Barwick, R Bay, JLB Alba, K Beattie, S Bechet, JK Becker, KH Becker, ML Benabderrahmane, J Berdermann, P Berghaus, D Berley, E Bernardini, D Bertrand, DZ Besson, M Bissok, E Blaufuss, DJ Boersma, C Bohm, J Bolmont, S Böser, O Botner, L Bradley, J Braun, D Breder, T Burgess, T Castermans, D Chirkin, B Christy, J Clem, S Cohen, DF Cowen, MV D'Agostino, M Danninger, CT Day, C De Clercq, L Demirörs, O Depaepe, F Descamps, P Desiati, G De Vries-Uiterweerd, T Deyoung, JC Diaz-Velez, J Dreyer, JP Dumm, MR Duvoort, WR Edwards, R Ehrlich, J Eisch, RW Ellsworth, O Engdegrd, S Euler, PA Evenson, O Fadiran, AR Fazely, T Feusels, K Filimonov, C Finley, MM Foerster, BD Fox, A Franckowiak, R Franke, TK Gaisser, J Gallagher, R Ganugapati, L Gerhardt, L Gladstone, A Goldschmidt, JA Goodman, R Gozzini, D Grant, T Griesel, A Gro, S Grullon, RM Gunasingha, M Gurtner, C Ha, A Hallgren, F Halzen, K Han, K Hanson, Y Hasegawa, J Heise, K Helbing, P Herquet, S Hickford, GC Hill, KD Hoffman, K Hoshina, D Hubert, W Huelsnitz, JP Hül

Light asymmetric dark matter

Proceedings of the 6th Patras Workshop on Axions, WIMPs and WISPs, PATRAS 2010 (2010) 158-163

Authors:

MT Frandsen, S Sarkar

Abstract:

Stable relic particles of mass around 5 GeV with an intrinsic matter-antimatter asymmetry would naturally provide the dark matter. They do not annihilate after being captured by the Sun and the capture rate is exponentially enhanced if they have self-interactions (of the right order to solve the excessive substructure problem of collisionless cold dark matter). Such particles can significantly affect heat transport in the Sun and may solve the 'Solar composition problem' - the predicted small changes in low energy neutrino fluxes are potentially measurable by Borexino and the proposed SNO+ and LENS experiments.

Measurement of sound speed vs. depth in South Pole ice for neutrino astronomy

Astroparticle Physics 33:5-6 (2010) 277-286

Authors:

R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, K Andeen, J Auffenberg, X Bai, M Baker, SW Barwick, R Bay, JL Bazo Alba, K Beattie, JJ Beatty, S Bechet, JK Becker, KH Becker, ML Benabderrahmane, J Berdermann, P Berghaus, D Berley, E Bernardini, D Bertrand, DZ Besson, M Bissok, E Blaufuss, DJ Boersma, C Bohm, J Bolmont, S Böser, O Botner, L Bradley, J Braun, D Breder, T Castermans, D Chirkin, B Christy, J Clem, S Cohen, DF Cowen, MV D'Agostino, M Danninger, CT Day, C De Clercq, L Demirörs, O Depaepe, F Descamps, P Desiati, G De Vries-Uiterweerd, T Deyoung, JC Diaz-Velez, J Dreyer, JP Dumm, MR Duvoort, WR Edwards, R Ehrlich, J Eisch, RW Ellsworth, O Engdegrd, S Euler, PA Evenson, O Fadiran, AR Fazely, T Feusels, K Filimonov, C Finley, MM Foerster, BD Fox, A Franckowiak, R Franke, TK Gaisser, J Gallagher, R Ganugapati, L Gerhardt, L Gladstone, A Goldschmidt, JA Goodman, R Gozzini, D Grant, T Griesel, A Groß, S Grullon, RM Gunasingha, M Gurtner, C Ha, A Hallgren, F Halzen, K Han, K Hanson, Y Hasegawa, J Heise, K Helbing, P Herquet, S Hickford, GC Hill, KD Hoffman, K Hoshina, D Hubert, W Huelsnitz

Abstract:

We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at ∼5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background. © 2010 Elsevier B.V. All rights reserved.

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