Exploring the Cosmos with Neutrinos Aart Heijboer …all of them. nm vidi interview 14 mei 2008 nm

Why look for High Energy Cosmic Neutrinos? To study the universe at high energies, neutrinos are the ideal messenger particle, not absorbed in the source or on their way to Earth not deflected by magnetic fields: point back to the source proton (cosmic ray) Big, open questions: What is the physics of the most energetic objects in the universe? (Gamma Ray Bursts, Supernova remnants, Active Galactic Nuclei). What is the origin of high energy cosmic rays? What is the nature of the Dark Matter?

How to detect Cosmic Neutrinos? Proposed research will be carried out with two European projects: ANTARES: uses 200x200x400 m3 of Mediterranean Sea water – nearing completion. KM3NeT: will be at least 1x1x1 km3. In R&D phase.

Antares and its first neutrinos Upgoing muon detected (Atmospheric background) muon-neutrino

Neutrino flavour mixing Neutrinos come in three types (or flavours): nm, ne and nt Observations of atmospheric and Solar neutrinos have showed that neutrinos have a tiny mass and change flavour. Implication for neutrino telescopes: Even though the source produces (mostly) nm, on Earth all flavours are equally abundant nt ne nm proposal: Develop methods to detect ne and nt and use them to complement nm to maximize discovery potential of Antares and KM3NeT And use them to search for neutrino point sources.

nt Event signatures ne nm electron shower muon tau lepton decays Eµ=10 TeV electron shower muon tau lepton decays ne nm long track, not contained single localized 'shower' ‘double bang’ We will develop the data-analysis (reconstruction) software to exploit the information from all signatures.

nt Event signatures ne nm nm ne nt electron shower muon tau lepton Eµ=10 TeV electron shower muon tau lepton decays ne nm nm ne nt ne and nt have low background and great energy resolution energy resolution is crucial to study the spectra which convey the physics of the sources. direction resolution energy resolution detection rate background ++ - + -- - + + - ++ long track, not contained single localized 'shower' double bang ‘double bang’ We will develop the data-analysis (reconstruction) software to exploit the information from all signatures. 7

Looking for point sources Sky plot of one year of atmospheric muon neutrinos A neutrino source or a random cluster of atmospheric background neutrinos?

Looking for point sources + nm ne nt A neutrino source or a random cluster of atmospheric background neutrinos? Even a few ne and nt could resolve the question! Will develop the methods to classify events and combine them in a single events from different neutrino types

Summary Propose to exploit electron and tau neutrinos in addition to muon neutrinos New capabilities will benefit experiments as a whole (opportunities to collaborate) Enhanced study of the source spectra & enable n-mixing measurements My group will use these methods to perform the most sensitive search for cosmic sources of neutrinos with Antares Very high-profile measurement Optimal chance of discovering the first cosmic neutrino source! Relevant experience: Developed search method and reconstruction currently used in ANTARES. Still well known (and occasionally active) → flying start. Combining measurements & statistics: Bs-mixing at CDF Opening up new channels: Higgs search at CDF. Leadership, fruitful collaboration on large and small scales. Now is the time Antares will be completed in a few weeks! Crucial input needed soon to decide KM3NeT design. Thank you for your attention.

Added power and science potential Energy resolution is crucial: background has know, very steep spectrum spectra convey the physics!

Tau Neutrino Signatures in IceCube: Overview Cartoon Inverted lollipop but low-E tau decays quickly to ; Study ratio Esh/Etr Low E  Lollipop Double bang, w/cascades un- resolvable, but nearby DOM(s) see double pulsed waveform Double Pulse Tau created and decays inside, cascades well-separated Double Bang Tau created outside (un- detected), decaysmuon, see  in light level along track Sugardaddy (see talk by T. DeYoung)‏ Tau created insidecascade, decays outside (undetected)‏ Inverted Lollipop Tau created outside (un- detected), decayscascade Lollipop Description Signature            DOM Waveform    

Is the muon reconstruction working? To very good approximation: true fraction of upgoing events is zero. Let's use this fact to our advantage for a change => See how well reconstruction measures the number of up-going events here, just about half the events are reconstructed as up going: => reco is not doing anything useful (we're not even sure these events are muons at all... could be random k40)‏ will discuss these later here, (only) about 1% of events are reconstructed in wrong hemisphere. 5 string data