Jodi Lamoureux, LBNLNERSCCalor 2002 Cal Tech', Pasadena, CA

1
Calorimetry (GeV-EeV) in AMANDA and IceCube
Neutrino Telescopes

• Neutrino Astronomy Exotic Physics
• New Measurements from AMANDA
• Predictions for IceCube
• Conclusions
• Punch line Energy determination is critical to
  doing Neutrino Astronomy.

2
Neutrino Astronomy

• Stable particles p, g, e, n
• p X ? hadrons
• p ? nm m
• Astrophysical Sources
• AGN, GRB, Galaxy/Sag-A
• GZK ( p CMB g)
• Topological defects
• Cosmic-Rays
• Atmospheric Muons
• Atmospheric Neutrinos

3
Neutrino Astronomy

• Upper bounds to Neutrino Fluxes already exist
  from cosmic rays.

Waxman Bachall (WB) PRD,64,023002 Manheim
, Protheroe Rachen (MPR) PRD, 63,
023003
1 particle per m2-second
Gaiser, astro-ph/0011525
Knee 1 particle per m2-year
Cosmic Ray Flux
Ankle 1 particle per km2-year
GeV TeV PeV EeV
4
Neutrino Astronomy
Albuquerque, Lamoureux, Smoot, hep-ph/0109177

• Diffuse flux
• WB, MPR, GZK, galaxy
• Atmospheric nm
• Point sources
• AGN, Sgr-A, galactic center
• Background 1 deg/40,000 deg
• Variable sources
• GRB
• Background 1 deg/40,000 deg time coincidence
  factor.

En dFn/dEn (km-2 yr-1 sr-1)
TeV PeV EeV
5
Exotic Physics

• Dark matter clumps at the center of galaxies,
  stars and planets.
• Primary WIMP candidate is the neutralino
  lightest super symmetric particle in MSSM.
• c c ? n n, W W, Z Z, H H, W H, Z
  H, q q

6
Neutrino Rates 101

• Deep Inelastic Scattering
• Charge current
• nm p ? m X
• ne p ? e X
• Neutral current
• p ? n X

• Neutrino flux is attenuated as it passes through
  the earth.

Albuquerque, Lamoureux, Smoot, hep-ph/0109177
COS(qz) 0
COS(qz) 1
COS(qz)
7
Muon Calorimetry 101
Albuquerque, Lamoureux, Smoot, hep-ph/0109177

• Muons radiate energy as they travel through ice.
• Cerenkov light is a small fraction of the
  ionization component described by Bethe-Bloch
  equation.
• Above 1 TeV other processes dominate
• Bremstraahlung Photons
• Electron Pairs
• Photo-nuclear
• Radiation deposited in the detector depends
  on the energy of the muon as it passes near the
  detector

8
Photon Transport 101

• Cerenkov Light
• PMTs are sensitive to 300 nm to 600 nm
  wavelengths
• Muons and secondaries radiate Cerenkov light.
• Cascades tracks radiate Cerenkov light.
  Hadronic component is 0.8ltEMgt.
• Scattering is depth dependent
• See Kael Hansons talk in the calibration
  session.
• Calorimetry in AMANDA IceCube depends on the
  relation between photons detected and muon or
  cascade energy.

J. Ahrends, et. al, submitted PRD
9
Calorimetry in Ice

• Absorption length 100 m
• Scattering length 25 m
• Light is isotropized well before it is absorbed.
  
• To first order, sampling is insensitive to
  geometric position or PMT orientation.
• Current arrays sample a very small fraction of
  the total Cerenkov light
• Total PMT area/ detector surface area
• 10-5 for AMANDA and IceCube.
• PMTs on a string 20 m spacing between PMTs
• String spacing 100 m spacing between strings.
• String spacing determines energy threshold.

10
Atmospheric Neutrinos in AMADNA
J. Ahrends, et. al, submitted PRD
11
Atmospheric Neutrinos in AMANDA
J. Ahrends, et. al, submitted PRD

• Primary quality cuts
• Likelihood of track fit high
• High fraction of unscattered hits
• Long track length
• Hits spread smoothly along track
• Hits arent spherically distributed
• Low prob of being down-going

12
Atmospheric Neutrinos in AMANDA
J. Ahrends, et. al, submitted PRD

• Angular distributions of events are consistent
  with Atmospheric Neutrinos.
• 204 candidates with 10 background
• Rate is 0.65 (0.65 0.3) times the predicted
  rate.

Vertical Up-going
Horizon
J. Ahrends, et. al, submitted PRD
13
Atmospheric Neutrino Spectrum in AMANDA
J. Ahrends, et. al, submitted PRD
AMANDA measures flux in the energy range 66
GeV lt En lt 3.4 TeV
En 50 GeV
Simulated Energy Thresholds
Em (center) 20 GeV
14
Atmospheric Neutrino Spectrumin AMANDA
Predrag Miocinovic, PhD Thesis
Reconstructed E Generated E
PRELIMINARY

• Energy resolution is estimated by a gaussian s
  0.4log(Egen)

PRELIMINARY
15
Atmospheric Neutrino Spectrumin AMANDA
PRELIMINARY
Predrag Miocinovic, PhD Thesis

• At low cut levels, misreconstructed background is
  evident.
• Above cut level 7, normalization of data is 65
  as before.
• Spectrum shape is in good agreement with
  prediction.

Cut levels 1-3 Cut levels 4-6 Cut levels 7-9
TeV
16
SPASE-AMANDA Cosmic Ray Composition

• Lateral shower distribution is sensitive to the
  cosmic ray energy and composition.

• Spase array is 15 deg. From AMANDA

17
SPASE-AMANDA Cosmic Ray Composition

• Radiated light is multiplied by the number of
  muons in the bundle at the shower core.
• K50 N photons 50 m from core.
• Spase array at the Pole measures the lateral
  distribution of the shower.
• S30 N electrons 30 m from core.
• Comparison of muons in the core to the electrons
  30 m from the core.

18
SPASE-AMADNA Cosmic Ray Composition

• SIBYLL MC predicts a shift in the muon abundance
  vs electron abundance.
• Differences between SIBYLL and QGSJET Are taken
  as a systematic uncertainty.
• Smaller systematics
• Muon propogation
• Ice properties
• Electronics

Katherine Rawlins, PhD Thesis
PRELIMINARY
19
SPASE-AMANDACosmic Ray Composition

• A is the mean nucleon mass number of the cosmic
  ray spectrum.
• Composition above the knee is constent with
  higher mass cosmic rays.
• Energy resolution is better for bundles than
  single muons.
• PeV energies measured.

PRELIMINARY
Katherine Rawlins, PhD Thesis
65 proton / 35 iron 90 proton / 10 iron
PeV
20
WIMP Search in AMANDA
J. Ahrens et al. Submitted PRD astro-ph/0202370

• Neutralino Mass is 5 times average muon energy.
• Muon threshold is 50 GeV.

21
The Future IceCube

• IceCube
• 80 strings
• 60 PMTs/string
• Depth 1.4-2.4 Km

22
IceCube Concept

• IceTop
• 2 PMTs in a
• pool at the top
• of each string.
• 3D air-shower detector

23
Simulated IceCube Events
10 TeV Muon
375 TeV Electron
PeV Tau
6 PeV Muon
24
IceCube Sensitivity (gt10 GeV)

• WIMPs from the center of the earth and the sun.

25
IceCube Sensitivity (gtTeV)
Albuquerque, Lamoureux, Smoot, hep-ph/0109177

• Diffuse flux as a function of energy deposited in
  the detector.
• IceCube sensitive to
• 1/3rd of WB limit after 1 yr.
• 1/5th of WB limit after 2-3 yrs
• If diffuse flux is comes from lt10 sources,
  IceCube will identify them.
• GRB
• Atm flux/(20000DT) back-free
• 15 events/year
• Sagittarius A East
• Center of the Galaxy is above the horizon at the
  South Pole.
• 0 to 40 events/year at Mediterranean latitudes.

26
IceCube Sensitivity(gtEeV)
Engel, Stanev, astro-ph/0101216

• GZK n have Ultra High Energy
• Above the horizon at EeV.
• Radiated energy is enormous.
• Without reconstructing tracks number of photons
  in the detector gives lower limit to muon energy.
• Effective volume grows with energy
• 1 km2 _at_ E1015 GeV
• 8 km2 _at_ E1020 GeV
• Fewer than 2.5 events/(km2 yr) expected from GZK.

EeV
27
Conclusions

• First analyses of AMANDA-B10 calorimetry are
  encouraging.
• Atmospheric neutrino rate and spectrum are
  consistent within systematic uncertainties of
  theoretical predictions.
• Cosmic ray composition is consistent with higher
  mass cosmic rays above the knee.
• WIMP limit confirms other direct measurement
  results.
• IceCube is a discovery instrument
• Astrophysical fluxes are small but detectable if
  experiment is efficient. (no descoping, need
  near 100 duty cycle)
• WIMPS will provide a good cross check of Direct
  Detection limits.
• Source detection depends on understanding the
  energy resolution well.
• Trigger cut thresholds
• Spectrum measurement.
• Real physical insight comes from the energetics
  of the neutrino spectrum.