1 Neutrinos at the South Pole Particle Astrophysics at Maryland Neutrinos –Where they fit in the Standard Model Astrophysical Neutrino sources IceCube –Overview –Science Reach –Progress & Prospects

2 Particle Astrophysics –combines particle physics and astrophysics to address some of the most fundamental questions about our universe. –makes observations of high energy elementary particles from space to study both their basic properties and the properties of the objects which produce them. Examples –Atmospheric and Solar Neutrinos –Gamma-rays from Active Galactic Nuclei

3 Particle Astrophysics at Maryland Faculty –Greg Sullivan –Andrew Smith –Jordan Goodman Grad Students –Liz Hays –Dusan Turcan –Jon Pretz –Ralf Ehrlich Post-Docs –Erik Blaufuss –Ty DeYoung –Ulisse Bravar Visiting Professors –Robert Ellsworth –David Berley –Gene Loh

Particle Astrophysics at Maryland Two Current Experiments – –Milagro Gamma-Ray Astronomy Los Alamos –Super-Kamiokande Atmospheric Neutrinos Solar Neutrinos

Particle Astrophysics at Maryland Milagro

6

7 Milagro Outriggers

8 Milagro EGRET at 100 MeV Milagro at 1 TeV

9 Super-Kamiokande

The Department of Physics Super-K

11 Why do we care about neutrinos? Neutrinos –They only interact weakly –If they have mass at all – it is very small They may be small, but there sure are a lot of them! –300 million per cubic meter left over from the Big Bang –with even a small mass they could be most of the mass in the Universe!

12 Facts about Neutrinos Neutrinos are only weakly interacting 40 billion neutrinos continuously hit every cm 2 on earth from the Sun (24hrs/day) Interaction length is ~1 light-year of steel 1 out of 100 billion interact going through the Earth

13 How do we see neutrinos? muon   electron e e-

14 Cherenkov Radiation When a charged particle moves through transparent media faster than speed of light in that media. Cherenkov radiation Cone of light

1400 m 2400 m AMANDA South Pole IceTopRunway 80 Strings80 Strings 4800 PMT4800 PMT Instrumented volume: 1 km3 (1 Gton)Instrumented volume: 1 km3 (1 Gton) IceCube is designed to detect neutrinos of all flavors at energies from 10 7 eV (SN) to eVIceCube is designed to detect neutrinos of all flavors at energies from 10 7 eV (SN) to eV

16 neutrino muon Cherenkov light cone Detector interaction Infrequently, a cosmic neutrino is captured in the ice, i.e. the neutrino interacts with an ice nucleus In the crash a muon (or electron, or tau) is produced The muon radiates blue light in its wake Optical sensors capture (and map) the light

South Pole Dark sector AMANDA IceCube Dome Skiway

18 Atmospheric neutrinos

 +  CMB  e + + e - With 10 3 TeV energy, photons do not reach us from the edge of our galaxy because of their small mean free path in the microwave background.

20 Acceleration to eV? ~10 2 Joules ~ 0.01 M GUT dense regions with exceptional gravitational force creating relativistic flows of charged particles, e.g. coalescing black holes/neutron stars dense cores of exploding stars supermassive black holes

21 GammaRayBursts Photons and protons Photons and protons coexist in internal coexist in internal shocks resulting in shocks resulting in pion and neutrino pion and neutrino production production External shocks also External shocks also

22 Produces cosmic ray beam Radiation field: Radiation field:

23 Supernova shocks expanding in interstellar medium Crab nebula

24 Galactic Beam Beam Dump Dump

25 Modeling yields the same conclusion: Line-emitting quasars such as 3C279 Beam: blazar jet with equal power in electrons and protons Target: external quasi-isotropic radiation N events ~ 10 km -2 year -1 Supernova remnants such as RX (?) Beam: shock propagating in interstellar medium Target: molecular cloud

26 Irrespective of the cosmic-ray sources, some fraction will produce pions (and neutrinos) as they escape from the acceleration site pions (and neutrinos) as they escape from the acceleration site through hadronic collisions with gas through hadronic collisions with gas through photoproduction with ambient photons through photoproduction with ambient photons Cosmic rays interact with interstellar light/matter even if they escape the source escape the source Transparent:Transparent: protons (EeV cosmic-rays) ~ photons (TeV point sources) ~neutrinos Obscured sourcesObscured sources Hidden sourcesHidden sources Unlike gammas, neutrinos provide unambiguous evidence for cosmic ray acceleration! Sources:

27 GZK Cosmic Rays & Neutrinos Cosmogenic Neutrinos are guaranteed to exist if primaries are nucleons.Cosmogenic Neutrinos are guaranteed to exist if primaries are nucleons. May be much larger fluxes, for some models, such as topological defectsMay be much larger fluxes, for some models, such as topological defects p +  CMB   + ….

28 Neutralino capture and annihilation Sun  Earth Detector    velocity distribution  scatt  capture  annihilation interactions int.  int.

29 neutrino muon Cherenkov light cone Detector interaction Infrequently, a cosmic neutrino is captured in the ice, i.e. the neutrino interacts with an ice nucleus In the crash a muon (or electron, or tau) is produced The muon radiates blue light in its wake Optical sensors capture (and map) the light

AMANDA Event Signatures: Muons  + N   +  + N   + X CC muon neutrino Interaction  track  track

AMANDA Event Signatures: Cascades  CC electron and tau neutrino interaction: (e, ,) + N  (e,  ) + X (e, ,) + N  (e,  ) + X  NC neutrino interaction: x + N  x + X x + N  x + X Cascades

32 E µ =10 TeV ≈ 90 hitsE µ =6 PeV ≈ 1000 hits Energy Reconstruction Small detectors: Muon energy is difficult to measure because of fluctuations in dE/dx IceCube: Integration over large sampling+ scattering of light reduces the fluctutions energy loss.

33 Neutrino ID (solid) Energy and angle (shaded) Neutrino flavor Filled area: particle id, direction, energyFilled area: particle id, direction, energy Shaded area: energy onlyShaded area: energy only

34 E µ = 10 TeVE µ = 6 PeV Muon Events Measure energy by counting the number of fired PMT. (This is a very simple but robust method)

35   Double Bang  + N -->  - + X  + X (82%) E << 1PeV: Single cascade (2 cascades coincide) E ≈ 1PeV: Double bang E >> 1 PeV: partially contained (reconstruct incoming tau track and cascade from decay) Regeneration makes Earth quasi transparent for high energie  ; (Halzen, Salzberg 1998, …) Also enhanced muon flux due to Secondary µ, and µ (Beacom et al.., astro/ph ) Learned, Pakvasa, 1995

36 DAQ design: Digital Optical Module - PMT pulses are digitized in the Ice Design parameters: Time resolution:≤ 5 nsec (system level) Dynamic range: 200 photoelectrons/15 nsec (Integrated dynamic range: > 2000 photoelectrons) Digitization depth: 4 µsec. Noise rate in situ: ≤500 Hz 33 cm DOM For more information on the Digital Optical Module: see poster by R. Stokstad et al.

37