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Nuclearite search with the ANTARES neutrino telescope + A short reminder on the magnetic monopoles

MANTS Meeting (Sep 24 - 25 -- Uppsala, Sweden ). Nuclearite search with the ANTARES neutrino telescope + A short reminder on the magnetic monopoles. Vlad Popa, for the ANTARES Collaboration Institute for Space Sciences, Bucharest – Magurele, Romania. Magnetic monopoles: MANTS 2010, ICRC 2011.

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Nuclearite search with the ANTARES neutrino telescope + A short reminder on the magnetic monopoles

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  1. MANTS Meeting (Sep 24 - 25 -- Uppsala, Sweden) Nuclearite search with the ANTARES neutrino telescope + A short reminder on the magnetic monopoles Vlad Popa, for the ANTARES Collaboration Institute for Space Sciences, Bucharest – Magurele, Romania

  2. Magnetic monopoles: MANTS 2010, ICRC 2011 • “Light” enough to be relativistic (M ≤ 1013 GeV, no proton decay catalysis) • Detectable trough Cherenkov light (direct or from δ e- ) • Search started with a blind analysis • Using the upgoing neutrino candidates (only upgoing MMs) • Based on the light yield and on β < 1 (β added as a free parameter in the reconstruction) • After unblinding the Dec. 2007 – Dec. 2008 data…

  3. Magnetic monopoles: MANTS 2010, ICRC 2011 • “Light” enough to be relativistic (M ≤ 1013 GeV, no proton decay catalysis) • Detectable trough Cherenkov light (direct or from δ e- ) • Search started with a blind analysis • Using the upgoing neutrino candidates (only upgoing MMs) • Based on the light yield and on β < 1 (β added as a free parameter in the reconstruction)

  4. Nuclearites: ICRC 2011 • “Light” enough to be relativistic (M ≤ 1013 GeV, no proton decay catalysis) • Detectable trough Cherenkov light (direct or from δ e- ) • Search started with a blind analysis • Using the upgoing neutrino candidates (only upgoing MMs) • Based on the light yield and on β < 1 (β added as a free parameter in the reconstruction)

  5. Nuclearites: ICRC 2011 • Slowly moving objects (NOT relativistic) • Detectable trough Cherenkov light (direct or from δ e- ) • Search started with a blind analysis • Using the upgoing neutrino candidates (only upgoing MMs) • Based on the light yield and on β < 1 (β added as a free parameter in the reconstruction)

  6. Nuclearites: ICRC 2011 • Slowly moving objects (NOT relativistic) • Detectable trough black body radiation • Search started with a blind analysis • Using the upgoing neutrino candidates (only upgoing MMs) • Based on the light yield and on β < 1 (β added as a free parameter in the reconstruction)

  7. Nuclearites: ICRC 2011 • Slowly moving objects (NOT relativistic) • Detectable trough black body radiation • Search started with a blind analysis • Using the upgoing neutrino candidates (only upgoing MMs) • Based on the light yield and on β < 1 (β added as a free parameter in the reconstruction)

  8. Nuclearites: ICRC 2011 • Slowly moving objects (NOT relativistic) • Detectable trough black body radiation • Search started with a blind analysis • Looking only for DOWNGOING nuclearites • Based on the light yield and on β < 1 (β added as a free parameter in the reconstruction)

  9. Nuclearites: ICRC 2011 • Slowly moving objects (NOT relativistic) • Detectable trough black body radiation • Search started with a blind analysis • Looking only for DOWNGOING nuclearites • Based on the event duration

  10. Nuclearites: basic propertiesE. Witten, Phys. Rev. D30 (1984) 272A. De Rujula, S. L. Glashow, Nature 312 (1984) 734 • Aggregates of u, d, s quarks + electrons,ne=2/3 nu –1/3 nd –1/3 ns • Ground state of QCD; stable for 300 < A < 1057 rN 3.5 x 1014 g cm-3 rnuclei 1014 g cm-3 Produced in Early Universe or in strange star collisions (J. Madsen, PRD71 (2005) 014026) Candidates for cold Dark Matter! Searched for in CR reaching the Earth

  11. Masses ~ TeV: “strangelets” Electronic cloud • External electronic cloud • Easy to ionize • May be relativistic • “Nuclear” cross sections • Interactions: accretion or fragmentation? Accretion “strongly disfavored” by SLIM → cannot reach ANTRES

  12. Masses ~ 1013 GeV: “nuclearites” • Most electrons inside SQM • Hard to ionize • Galactic velocities (~300 km/s) • “Atomic” cross sections • Elastic interactions with atoms Can reach ANTARES from above.

  13. Masses > 81014 GeV: “nuclearites” • All electrons inside SQM • Electrically neutral • Galactic velocities (~300 km/s) • Mass dependent cross sections • Elastic interactions with atoms Can reach ANTARES from above. For M > 1022 GeV, can traverse the Earth (isotropic flux)

  14. Typical galactic velocities   10-3 • Dominant interaction: elastic collisions with atoms in the medium • Dominant energy losses: • Phenomenological flux limit from the local density of DM:

  15. in the atmosphere: a = 1.2 10-3 g cm-3; b = 8.6 105 cm; H  50 km (T. Shibata, Prog. Theor. Phys. 57 (1977) 882.) in water: w  1 g cm-3 Arrival conditionsto the depth of ANTARES After a propagation path L in a medium, the velocity of a nuclearite of initial velocity v0 becomes:

  16. 2100 m 2274 m 2448 m Velocities in ANTARES Example for vertical incidence

  17. For M  8.4 1014 GeV it depends only on v2 The passage of a nuclearite in matter produces heat along its path In transparent media some of the energy dissipated could appear as visible light (black body radiation) The “optical efficiency” = the fraction of dE/dx appearing as light in water estimated to be  = 3  10-5 (lower bound) (A. De Ruhula, S.L. Glashow, Nature 312 (1984) 734) A little more on dE/dx…

  18.  starts to increase Light production / cm of path Example for vertical incidence

  19. General strategy in ANTARES: “all data to shore”. If the charge (amplitude) is above a pre-defined threshold, -> “L0” hit, buffered in a 2.2 s window. The basic info: the “hit”: time and charge information of a photon detected by a PMT

  20. General strategy in ANTARES: “all data to shore”. If the charge (amplitude) is above a pre-defined threshold, -> “L0” hit, buffered in a 2.2 s window. Local coincidence: “L1”. Two L0 hits in the same storey within 20 ns, or a single large amplitude hit (3 pe or more) The “directional trigger” (DT): at least 5 L1 hits anywhere in the detector, within a 2.2 s window and causally connected. “T3 cluster”: two “L1” hits in adjacent or next-to-adjacent storeys within 20 ns. The “cluster trigger” (CT): at least two T3 within 2.2 s.

  21. General strategy in ANTARES: “all data to shore”. All PMT pulses in a 2.2 s window conserved in a buffer, as well as the previous window. When a trigger occurs (DT or/and CT), all hits (above threshold) from the corresponding time window as well as the previous one are recorded for off-line analysis. The shortest duration of an “event” (“snapshot”) is thus 4.4 s; as triggers could occur in the next time window, snapshots could be longer (adjacent events are merged). Nuclearites are expected to be slowly moving: should be seen as anomalously long events, or as series of consequent snapshots. The typical crossing time about 1 ms!

  22. Nuclearite search in ANTARES, 2007 and 2008 data Various detector configurations (5, 9, 10 and 12 lines) Data recorded during ANTARES completion Variations in the operation conditions (e.g.. new lines added) Different threshold values Each configuration treated separately! Blind analysis: the search strategy defined trough Monte Carlo, validated using 15% of each data set, analysis on all data after unblinding maximized efficiency

  23. Monte Carlo simulations Nuclearites: Chose the mass and initial velocity, compute the velocity at the entry in the simulation hemisphere, propagate in the hemisphere with time resolution of 2 ns Geometrical acceptance Events, mixed with background and processed by DT and CT triggers Efficiencies Background: • Atmospheric muons: MUPAGE (M. Bazzoti et al., Comput. Phys. Commun, 181 (2010) 835) • Bioluminiscence, K, etc, extracted from real runs.

  24. Selection criterion: the duration of the events, dt = tlasttrigg. – tfirsttrigg. Triggers optimized for relativistic particles → most simulated events produce multiple adjacent snapshots! For single snapshot events we require dt > 2C1 (Cut “C2”) “C1” cut

  25. No event survived the C1 (+C2) cuts applied to 15% of the data collected during 2007 and 2008. Analysis sensitivities' obtained for all configurations.

  26. After unblinding, data from 2007 and 2008 were analyzed. Very few events survived the cuts. Each was carefuly analized: - check of the Event Display - study of the collected charge barycenter versus time. As the light emitted by the over-heated nuclearite path is isotropic, this should describe the event topology (a first step event reconstruction). No event compatible with the down-going nuclearite predictions. All events interpretable as bioluminescent phenomena. We could derive the 90% upper flux limit for down-going nuclearites,

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