Particle Physics and Astrophysics with Large Neutrino Detectors

Pennsylvania State University

Irina Mocioiu

Experiments

• IceCube/DeepCore: Cherenkov light in ice (South Pole)PINGU

• Antares: Cherenkov light in water (Mediteraneen)

• Pierre Auger: air showers (Argentina)

• radio Cherenkov: higher energy

• large underground neutrino detectors …

Real data! + more to come

Sources• some “guaranteed” high energy neutrinos:

cosmic rays

CMB

GRB

AGNMaybe:• dark matter annihilation• topological defects• cosmic strings• …

Exactly how many?Where?What energies?

Lessons for particle astrophysics

• access to dense, violent environment • test mechanism powering astrophysical sources• cosmic ray acceleration processes• cosmic ray propagation and intergalactic backgrounds• …

weak interactions

Lessons for particle physicshigh energies, beyond those accessible in colliders, etc. weak interactions

• neutrino interaction cross-sections (in Standard Model!) • neutrino properties• new interactions/particles• dark matter• …

complementary to photons and charged particles

Sources

Propagation:

• flavor composition mostly decay

not always: neutron decay, energy thresholds, energy losses, matter effects, magnetic fieldsenergy dependent flavor ratios depend on neutrino and source properties

• neutrino oscillations over long distances decay + maximal mixing: different initial state: three flavor mixing important• non-standard neutrino properties: decay, additional interactions, extra neutrinos, …• change flavor composition/energy spectrumInteractions: • in SM: cross section extrapolations, energy losses, flavor • beyond SM: new interactions, LIV, new particles, dark matter, …

How to do it?

o measure all you cano take into account everything you know/can think abouto Identify the right observables

• energy distributions• angular distributions• flavor compositions• better detector techniques • smart tricks, unique signatures• very good simulations• correlations with other observables: photons, protons, etc.

can distinguish particle physics from astrophysics effects learn about both

Pastpr, Nu 2012

IC 59 diffuse

Sullivan, Nu 2012

diffuse limits

Cascades: 14 events; expected bkgd 11.6

highest energies, gamma horizon very limited

Ishihara, Nu 2012IceCube sensitivity greatly improved

Nature 484, 351 (2012)

Sullivan, Nu 2012IceCube GRB search

Excluded models?

Hummer, Baerwald, Winter (2012)He, Liu, Wang, Nagataki, Murase, Dai (2012)

Not yet! Probing interesting parameter space

• Detailed analysis • Energy dependence in spectra -> order of magnitude reduction in nrs

Outlook

• Neutrino telescopes now real: data!

• Getting better

• Just starting to get interesting now!

• High energy astrophysical neutrinos• smoking gun for hadronic processes

(few events for point source)• need detailed analysis for data interpretation

IceCube Deep Core

• initial motivation: look for neutrinos from galactic sources, dark matter annihilation galactic center is above horizon at South Pole

need to reduce large cosmic muon background

• coverage look at down-going events, study galactic sources, galactic center

• low energy threshold: opens the 10 -- 100 GeV neutrino energy range

• overlap with Super-Kamiokande at low energy and with IceCube at high energies

Atmospheric neutrinos

• Background to many searches• lots of them

• > 50,000 events per year!• somebody’s background is somebody else’s signal

• remember: solar neutrinos: solar physics, atmospheric neutrinos: proton decay

• expect: at low energies

Super-Kamiokande

IceCube Deep Core

•

• steep energy spectrum ( )

• flux hard to measure at high energies

Three-flavor neutrino oscillations• Three-flavor mixing matrix (in terms of Euler angles)

• We want to measure

hierarchy (sign of ) CP violating phase

Large effort to build new accelerator/reactor experiments beams: great control/precision; long time scales/high cost

octant

Neutrino oscillations in the IceCube Deep Coretracks: -like fully contained events

Angular distribution:

Energy distribution:

• atmospheric flux normalization• + main oscillation signal ( )• + matter effects ( , hierarchy, CP)

• neutrino oscillations• atmospheric neutrino flux• Earth density profile

ICDC physical mass: Effective mass in our analysis: (energy dependent)

E. Fernandez-Martinez, G. Giordano, O. Mena, I. M. (2010)G. Giordano, O. Mena, I. M. (2010)O. Mena, I. M., S. Razzaque (2008);

ICDC atmospheric neutrinos

Measure main oscillation parametersIceCube Deep Core:• very large statistics• contribution from multiple peaks

Present: : MINOS : Super-Kamiokande

E. Fernandez-Martinez, G. Giordano,O. Mena, I. M.(2010)

Observable energy:

Normal versus inverted mass hierarchy

• fit to discriminate between normal and inverted hierarchyO. Mena, I. M., S. Razzaque (2008)

• much better now, with known and large

E (GeV)5 10 15 20 250

1

0.4

0.8

0.2

0.6

(Super-Kamiokande)

(MINOS)Presently allowed values:

IceCube Deep Core: Observable energies of 5 to 50 GeV10 energy bins, 4 angular bins

vs.1st energy bin, 1 angular bin +9 energy bins, 4 angular bins vs.Exclude first 2 energy bins: 8 energy bins, 4 angular bins

vs

vs completely free

IceCube Deep Core

• Expected allowed regions depend on the true values of

the parameters and control of systematic

uncertainties

• Neutrino oscillations: now important physics goal of ICDC -> PINGU

• CC interactions:• NC interactions:• decay

How about cascades?

Earth diameter

high energy (tau threshold effects small)background low:oscillations

• Looking for helped by:

Tau cascade rates• or hadrons large

• present world sample of events:

5(9) DONUT + (2) (OPERA)

• Super-Kamiokande (after 15 years):

• high statistics interactions

• ICDC has already observed cascade events in the first small data sample

• direct evidence for appearance

• interaction cross-section

• non-standard interactions of

• experience with cascade detection

Mass Hierarchy in PINGU Akhmedov, Razzaque, Smirnov, 2012

in 5 years, depending on reconstruction

• systematics • very general analysis, no details • DIS only• full analysis: likely better outcome!

Mass Hierarchy in ICDC Agarwalla, Li, Mena, Palomares-Ruiz , 2012

PINGU- more physics than ICDC lower energy: better “shape” of first peak (precision) secondary peaks -> two mass scales contribute (CP violation+matter effect)

- analysis more involved than ICDC• better reconstruction/resolution • atmospheric flux: transition between mu+pi and pi:

-> flavor and energy dependence• cross-sections: many contributions

-> energy dependent uncertainties -> limited use of full kinematics: very useful with DIS in ICDC -> larger systematics/more work + outside input potentially very (cross section measurements, etc.)

• Input from reactors, etc.• Precision measurement of main oscillation parameters• Above 10 GeV – nu tau cascades• Matter effects – hierarchy• few GeV – interference of two mass scales – CP phase• theta_23 octant • non-standard interactions – matter effects• very useful information in combination with long baseline exp.

What physics?

What is needed:

• (Some) angular reconstruction: 3-4 bins sufficient• Energy measurement: important to have few GeV and > 10GeV• Flavor ID?

Atmospheric Neutrino Oscillations • Large energy range: 100 MeV - 100 GeV

• Many baselines: 15 km – 13000 km

cover large parameter space

• Complementary information• Consistency checks very important

Surprises? Is the three flavor oscillation picture the entire story?Are weak interactions the entire story?

Long Baseline Neutrino Oscillation Experiments• Fixed distance• Good energy measurement• Well known flux (near detector) good parameter determination

Sterile Neutrinos

• Model dependence: – 3+1 (6 angles), 3+2 (10 angles), 3+2+CP violation– angles: sterile mixing with , , – possible affect and differently

• If one present, expect the other• No one to one correspondence between

LSND/MiniBooNE (mu-e) and IceCube observations (mu-mu,mu-tau)

• Can constrain or discover oscillations at high mass scale for angles in the general range probed by MiniBooNE/LSND• Cannot directly confirm/rule out MiniBooNE/LSND sterile nu interpretation

Sterile Neutrinos

• Cannot directly confirm/rule out MiniBooNE/LSND sterile nu interpretation

except in specific/predictive models: 1205.5230Minimal 3+2 neutrino model - 4 massive mass eigenstates, 1 massless - 2 additional, right handed Weyl fields - 4 mixing angles + 3 phases Standard parameters+ 45angle+one extra phase

- distortion of spectrum - large tau appearance

D. Hollander, I.M.

Non-Standard Interactions (NSI)

Matter effects in neutrino oscillations

Very weak constraints in the sector

• Expected in connection with mass generation models, sterile neutrinos, etc. • Parameterize our ignorance by most general form and try to constrain from data

Preliminary

εeτ - εττ

Large correlations/degeneracy between parameters

W. Wright, I.M.

Remember some history• 1980’s: large detectors looking for proton decay, grand unification, etc.; atmospheric neutrinos are background

atmospheric neutrino problem

Atmospheric neutrinos: many uncertainties

Beamline Proposals: MINOS 1995 OPERA 1998 ICARUS 1993 (detector),

1996 (neutrino oscillations)

Super-Kamiokande (1998)

Long Baseline Neutrino Oscillation Experiments

• K2K (2000): confirmation of neutrino oscillations

• MINOS (2006): energy spectrum, best mass difference measurement

• OPERA: (2010) first tau candidate neutrino detection

• ICARUS: taking data

• T2K: taking data -> precision measurements, sub-dominant effects

• NOVA: under construction

Outlook• IceCube Deep Core detector already taking data !• built to look for galactic sources, dark matter

• someone’s background can be someone else’s signal

• experiments take a very long time to construct/operate

• atmospheric neutrinos: huge statistics, many energies/distances

• use the data we already have and get the most of it!

• PINGU: huge, cheap, fast

• long baseline experiments: fixed baseline, limited energy range

• atmospheric neutrinos: many baselines, large energy range

complementary information

• combined data: consistency checks

• expect SURPRISES!