Atmospheric neutrinos with Deep Core In the context

Atmospheric neutrinos with Deep Core In the context of atmospheric neutrinos in Ice. Cube

Outline • Atmospheric n in Ice. Cube – Zenith-angle dependence measured √ – Spectrum of atmospheric nm TBD • km 3 extends reach to E(nm) ~ Te. V • Look for new physics – What about electron neutrinos? – Deep core opens lower-energy window • Neutrino oscillation studies • Hierarchy? • Some comments on signal and background for both low and high energy

Atmospheric n spectrum Comment on charm models • RQPM model shown here: (Bugaev et al. , 1998) • ne crossover at 3 Te. V • nm crossover at 100 Te. V • • • p Calculation of Enberg, Reno, Sarcevic (ar. Xiv: 0806. 0418): nm, ne intensities factor 10 lower crossovers factor of two higher p m e Neutrino spectrum summed over all directions from below the horizon ( TKG & M Honda, Ann Revs 52, 153, 2002) nm ne nm

Muons in Ice. Cube-22 (2007) Downward atmospheric muons Upward neutrino-induced muons Patrick Berghaus et al. , Cosmo-08 and ISVHECRI-08

Muon neutrinos in IC 22 6000 /yr expected with point-source cuts

Oscillations + Deep Core = new opportunities < 100 Ge. V q 13 = 0 From Carsten at Utrecht If sin 22 q 13 = 0. 1 nm survival probability nm nt oscillation probability Mena, Mocioiu & Razzaque ar. Xiv: 0803. 3044 v 2

Expected in IC 80 With deep core Standard Ice. Cube 3. 2 E 5 / yr – 2. 7 E 5 / yr = 50 K/yr At trigger level

What about electron neutrinos? They might look like this: Kotoyo Hoshina IC 22 But it can also be a muon with a large radiative energy loss

On the other hand muon energy loss is stochastic • Strange things can happen – For example, here’s the energy loss history of the first Te. V random muon simulated with the Lipari-Stanev code: 2 photo-nuclear interactions One low-energy brem

Naïve expectations for rates of atmospheric n • Assumptions: – Muon neutrinos: full efficiency for m range > 0. 5 km (En > 150 Ge. V) – Electron neutrinos: Efficiency for ne from PDD is 0 for En < Te. V • Note advantage of lowering Eth for ne – ~800 ne interactions per km 3 yr Spectrum of ne events per km 3 yr (perfect eff)

Differential and integral spectrum of atmospheric muons Differential Integral Energy loss: Em (surface) = exp{ b X } · ( Em +e ) - e Set Em = e { exp[ b X ] - 1 } in Integral flux to get depth – intensity curve

High-energy atmospheric neutrinos Primary cosmic-ray spectrum (nucleons) Nucleons produce pions kaons Kaons produce most nm for 100 Ge. V < En < 100 Te. V charmed hadrons that decay to neutrinos Eventually “prompt n” from charm decay dominate, …. but what energy?

Importance of kaons at high E • Importance of kaons – main source of n > 100 Ge. V – p K+ + L important – Charmed analog important for prompt leptons at higher energy vertical 60 degrees

Neutrinos from kaons Critical energies determine where spectrum changes, but AKn / Apn and ACn / AKn determine magnitudes New information from MINOS relevant to nm with E > Te. V

Electron neutrinos K+ p 0 ne e± ( B. R. 5% ) KL 0 p± ne e ( B. R. 41% ) Kaons important for ne down to ~10 Ge. V

Te. V m+/m- with MINOS far detector • 100 to 400 Ge. V at depth > Te. V at production • Increase in charge ratio shows – p K+ L is important – Forward process – s-quark recombines with leading di-quark – Similar process for Lc? x 1. 37 1. 27 x Increased contribution from kaons at high energy

MINOS fit ratios of Z-factors • Z-factors assumed constant for E > 10 Ge. V • Energy dependence of charge ratio comes from increasing contribution of kaons in Te. V range coupled with fact that charge asymmetry is larger for kaon production than for pion production • Same effect larger for nm / nm because kaons dominate

Muon veto of atmospheric n

Vertical neutrino flux: comparison M. Honda et al. , PR D 70 (2004) 043008 G. D. Barr et al. (Bartol flux) PR D 70 (2004) 023006 http: //www-pnp. physics. ox. ac. uk/~barr/fluxfiles/ M. Honda et al. PR D 75 (2007) 043006

Unfolding SK measurements Gonzalez-Garcia, Maltoni, Rojo JHEP 2007

Atmospheric neutrino spectrum x 1. 37 1. 27 AMANDA atmospheric neutrino ar. Xiv: 0902. 0675 v 1 x increased m+/m- charge ratio in MINOS far detector suggests corresponding increase in Te. V neutrino flux from contribution of p K+ L

Neutrinos from charm • Main source of atmospheric n for En > ? ? • ? ? > 20 Te. V • Large uncertainty! Gelmini, Gondolo, Varieschi PRD 67, 017301 (2003)

Angular dependence For e. K < E cos(q) < ec , conventional neutrinos ~ sec(q) , but “prompt” neutrinos independent of angle Uncertain charm component most important near the vertical

Muon multiplicity at depth protons Iron Total energy per nucleus

Some comments on m background Atmospheric muons (shape only)

Muon energy spectrum at depth Invariant shape for slant depth > ~ 2 km. w. e. Nm= 7 5. 5 4. 4 2. 0 0. 2 0. 1 Nm=40 32 25 11 1. 2 0. 7

Muon energy spectrum at depth Nm=230 180 145 64 7. 1 0. 4 Nm=1300 1000 830 370 41 2

Energy deposit per 17 m Todor’s plot: --a single event ~ 300 muons A B

New Geometries Slightly better performance for highest energy muons coming sideways Best for both highest and intermediate (0. 1 -10 Pe. V) energy muons (probably preferred) Drilling of 9 holes in the last season inside a circle with radius of 423 m is possible. The most ambitious geometries possible in the last season are presented above.