Ronald Bruijn – 10 th APP Symposium Antares results and status Ronald Bruijn

Ronald Bruijn – 10 th APP Symposium Outline Antares Status/Timeline Line 1 – selected results Multiple lines – selected results Conclusion

Ronald Bruijn – 10 th APP Symposium Neutrino Astronomy γ γ ν p Neutrino detection : Muon created in CC interaction of muon-neutrino Muon emits Cherenkov light Photomultiplier tubes register photons Neutrinos are weakly interacting neutral particles : Traverse large distances without being absorbed Point back to their source water earth

17-12-'07 Ronald Bruijn – 10 th APP Symposium 4 Status/Timeline September 06 March 06 – 1st line ! December 06 January 07 December 07 Currently 10 lines operational ! ~ Summer 08

Ronald Bruijn – 10 th APP Symposium Line 1 – 1 st full detector line March Same day Reconstructed tracks ! Position along line (2500m depth )‏ Time of detected photon [ns] + Triggered Used in Fit Snapshot

Ronald Bruijn – 10 th APP Symposium Line 1 – 1 st full detector line March Same day Reconstructed tracks ! Position along line (2500m depth )‏ Time of detected photon [ns] + Triggered Used in Fit Snapshot

Ronald Bruijn – 10 th APP Symposium How do you get those tracks ? Arrival time of photon, assuming direct Cherenkov light : ρ: chi-squared function or probability density function Photon arrival times depend non-linearly on track parameters Iterative approach ! Muon ( : track parameters: position (3) and direction (2))‏ Hit time residual : Given N photon hits on the optical modules, optimize for

Ronald Bruijn – 10 th APP Symposium Line 1 Reconstruction Rotational symmetry around line axis, azimuthal angle undetermined

Ronald Bruijn – 10 th APP Symposium Line 1 : Angular resolution - data |Δθ| [degrees] Zenith angle resolution reaches 0.5 degrees when at least 10 floors are hit !

Ronald Bruijn – 10 th APP Symposium EM Showers Z In addition to continuous energy loss, a muon loses energy through stochastic processes (Bremsstrahlung, pair-production). An E.M. shower produces a signal that resembles a horizontal muon Time [ns] Position [m] shower muon ~ m ~ cm 450 m

Ronald Bruijn – 10 th APP Symposium Line 1 : Zenith angle distribution downward upward e.m. showers and ghost solutions Neutrinos ? Relative acceptance Points : data Bands : Monte-Carlo

Ronald Bruijn – 10 th APP Symposium Line 1 : Depth-intensity relation Use detector acceptance to determine muon flux Zenith angle corresponds to depth First comparison of Antares data ! Reasonable agreement with other experiments (figure from PDG, Antares points superimposed) Vertical muon intensity vs. depth

Ronald Bruijn – 10 th APP Symposium Line 1 : Neutrino Candidate(s) ‏ Consider upward going events (suppresses atmospheric muon background), apply increasingly harder quality criteria and compare with Monte-Carlo Remaining events Hits required in reconstruction Atm. muon Atm. Neutrinos Points are data At >= 10 hits, one event remains Time [ns] Position [m]

Ronald Bruijn – 10 th APP Symposium

Detector Performance New reconstruction method improves the effective area of the detector Neutrino energy [GeV] Effective area [m^2] old New Effective area * flux = detection rate

Ronald Bruijn – 10 th APP Symposium

EM Showers

Ronald Bruijn – 10 th APP Symposium EM Showers EM Showers along muon tracks can be identified and counted Work by S. Mangano (NIKHEF) ‏ (Plot normalized to data)‏

Ronald Bruijn – 10 th APP Symposium Neutrinos Zenith angle distribution after likelihood based quality cut Upgoing neutrino candidates

Ronald Bruijn – 10 th APP Symposium Neutrino Astronomy in the Mediterranean Sea has started !