Lessons from Neutrinos in the IceCube Deep Core Array

Transcription

1 Lessons from Neutrinos in the IceCube Deep Core Array Irina Mocioiu Penn State TeV 2009, July

2 Point sources Diffuse fluxes from astrophysical objects from cosmic ray interactions from dark matter annihilation... Correlations with other observations: cosmic rays, gamma rays... Neutrino Telescopes - AMANDA/ICECUBE : Cerenkov light in ice (South Pole) - ANTARES, NEMO, NESTOR, etc. : Cerenkov light in water (Mediterranean) - RICE: radio Cerenkov in ice (South Pole) - ANITA: radio Cerenkov from ice (balloon at South Pole) - PIERRE AUGER: air showers (Argentina,...) -... What to look for?

3 Lessons for Particle Astrophysics Weak interactions - access to dense, violent envirenoments - test mechanism powering astrophysical sources - cosmic ray acceleration processes - cosmic ray propagation and intergalactic backgrounds -... Lessons for Particle Physics high energies, beyond those accessible in colliders, etc. weak interactions - neutrino interaction cross-sections (in Standard Model!) - neutrino properties - new interactions/particles - dark matter -...

4 How to do it? - measure all you can! - take into account everything you know/can think about! - identify the right observables! energy distributions angular distributtions flavour composition better detector techniques smart tricks, unique signatures, etc. very good simulations correlations with other observables: photons, protons, etc. can distinguish particle physics from astrophysics effects learn about both!

5 Deep Core Array motivation: galactic sources, dark matter annihilation galactic center above horizon at South Pole need to reduce large cosmic muon background dense phototube coverage region in the deep ceter region of IceCube

6 Doug Cowen, Nu2008 Deep Core Array

7 Deep Core Array greatly reduce large cosmic muon background 4π coverage look at downgoing events, galactic sources, galactic center low energy threshold open up the neutrino energy range from 10 Gev to 100 Gev overlap with Super-Kamiokande at low energy and IceCube at high energy

8 Atmospheric Neutinos Cosmic ray π + π 0 30km µ + e + ν e ν µ ν µ Underground ν e, ν e,, ν µ, ν µ,ν τ, ν τ detector background to many searches Lots of them!

9 Atmospheric Neutinos Super-Kamiokande: Expect: N(ν µ + ν µ ) N(ν e + ν e ) isotropic 2 at low energy used zenith angle distributin to prove neutrino oscillations IceCube Deep Core N(ν µ+ ν µ ) N(ν e + ν e ) 10 steep energy spectrum (E 3 ν ) ν e flux not measured at high energies

10 Neutrino oscillations: massive and mixed neutrinos ν e produced together with the electron in weak interactions does not have to be one of the definite mass particles ν 1 or ν 2 ( νe ν µ ) = ( cos θ sin θ sin θ cos θ ) ( ν1 ν 2 ) ( P(ν α ν β ) = sin 2 2θsin 2 m 2 ) ( ) L = sin 2 2θsin m2 L 4E E m 2 ji = m2 j m2 i [ m 2 ] : ev, [L] : km, [E] : GeV

11 Summary of Experimental Results Solar Neutrinos: ν e ν x, x = µ, τ + reactor antineutrinos m 2 sol ev 2 tan 2 θ sol 0.45 Atmospheric Neutrinos: ν µ ν x, x = τ + accelerator neutrinos m 2 atm ev 2 sin 2 2θ atm 1 Reactor antineutrinos: ν e ν e sin 2 2θ reactor < 0.1 for m ev 2

12 Three flavors neutrino oscillations c 12 c 13 s 12 c 13 s 13 e iδ s 12 c 23 c 12 s 23 s 13 e iδ c 12 c 23 s 12 s 23 s 13 e iδ s 23 c 13 s 12 s 23 c 12 c 23 s 13 e iδ c 12 s 23 s 12 c 23 s 13 e iδ c 23 c 13 We want to measure: θ 13 hierarchy (sign of m 2 atm ) CP violation (δ) m 2 21 = m2 sol, m2 32 = m2 atm θ 12 = θ sol, θ 13 = θ reactor, θ 23 = θ atm, δ large effort to build new accelerator experiments for this purpose use matter effetcs

13 Neutrino Oscillations in the IceCube Deep Core tracks: µ like fully contained events Angular distribution: cos θ (0,1) atmosperic flux normalization cos θ ( 0.9,0) + main oscillation signal ( m 2 32, θ 23) cos θ ( 1, 0.9) + matter effects (θ 13, hierarchy, CP) Energy distribution: E 40GeV: neutrino oscillations 50 GeV E 5 TeV atmospheric neutrino flux E 10 TeV: Earth density profile

14 Normal versus inverted mass hierarchy O. Mena, I. M., S. Razzaque, Phys.Rev.D78, (2008) cos θ ( 1, 0.9) cos θ ( 0.9, 0.8) cos θ ( 0.8, 0.7) Note E µ 0.5E ν

15 Normal versus inverted mass hierarchy χ 2 fit to discriminate between normal and inverted hierarchy Normal 100 Mt yr,θ 23 45, No systematics Inverted 100 Mt yr,θ 23 45, No systematics cp 0 cp sin 2 2Θ sin 2 2Θ 13

16 Normal versus inverted mass hierarchy χ 2 fit to discriminate between normal and inverted hierarchy Normal 100 Mt yr,θ 23 45, 10 systematics Inverted 100 Mt yr,θ 23 45, 10 systematics cp 0 cp sin 2 2Θ sin 2 2Θ 13

17 How about cascades? Electromagnetic cascades: Tau decay: τ e + ν e + ν τ ν e CC interactions: ν e + N e + X Hadronic cascades Tau decay: τ ν τ + X ν τ NC interactions: ν τ + N ν τ + X ν τ CC interactions: ν τ + N τ + X ν e,µ NC and CC interactions

18 ν τ 1 ν µ ν µ 0.8 ν µ ν τ Oscillation probabilities E ν [GeV] large number of ν τ

19 Number of shower events for sin 2 2θ 13 = 0.01 and δ = 0 in bin sizes of 5GeV and c ν (-1,-0.9) atm ν e and ν µ ->ν e ν τ ->ν e Number of events Shower Energy[GeV]

20 ν τ cascades with G. Giordano and O. Mena ν µ ν τ τ e or hadrons dominates present world sample of ν τ events: 9 (DONUT) high statistics ν τ interactions first direct evidence for ν µ ν τ appearance ν τ interaction cross-section non-standard interactions of ν τ experience with cascade detection

21 Outlook IceCube Deep Core galactic sources, dark matter annihilation atmospheric neutrinos high statistics, large energy range better understanding of background for other searches neutrino oscillations mass hierarchy ν τ : oscillations, ν τ interactions, cascade detection