DeepCore and Beyond Toward Precision Physics with Neutrino Telescopes
Tyce DeYoung Department of Physics Pennsylvania State University
MANTS ’11 Uppsala, Sweden September 25, 2011 The Neutrino Detector Spectrum
Accelerator-based
Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV
Atmospheric/Astrophysical The Neutrino Detector Spectrum
Accelerator-based
Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV SNO, Borexino, Super-K, KamLAND, LBNE Double CHOOZ, Daya Bay, etc. Atmospheric/Astrophysical The Neutrino Detector Spectrum
NOνA OPERA Accelerator-based K2K, MINOS T2K MiniBooNE Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV SNO, Borexino, Super-K, KamLAND, LBNE Double CHOOZ, Daya Bay, etc. Atmospheric/Astrophysical The Neutrino Detector Spectrum
NOνA OPERA Accelerator-based K2K, MINOS T2K MiniBooNE Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV ANITA, SNO, Borexino, Super-K, AMANDA, Baikal, RICE, Auger, KamLAND, LBNE ANTARES IceCube, KM3NeT ARIANNA,... Double CHOOZ, Daya Bay, etc. Atmospheric/Astrophysical The Neutrino Detector Spectrum
NOνA OPERA Accelerator-based K2K, MINOS T2K MiniBooNE Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV ANITA, SNO, Borexino, Super-K, AMANDA, Baikal, RICE, Auger, KamLAND, LBNE ANTARES IceCube, KM3NeT ARIANNA,... Double CHOOZ, Gap Daya Bay, etc. Atmospheric/Astrophysical The Neutrino Detector Spectrum
NOνA OPERA Accelerator-based K2K, MINOS T2K MiniBooNE Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV ANITA, SNO, Borexino, Super-K, AMANDA, Baikal, RICE, Auger, KamLAND, LBNE ANTARES IceCube, KM3NeT ARIANNA,... Double CHOOZ, Gap Daya Bay, etc. Atmospheric/Astrophysical Gamma Ray Bursts Neutrino Oscillations Soft Galactic Dark Cosmic Ray Matter Accelerators The Neutrino Detector Spectrum
NOνA OPERA Accelerator-based K2K, MINOS T2K MiniBooNE Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV ANITA, SNO, Borexino, Super-K, AMANDA, Baikal, RICE, Auger, KamLAND, LBNE DeepCore ANTARES IceCube, KM3NeT ARIANNA,... Double CHOOZ, Daya Bay, etc. Atmospheric/Astrophysical Gamma Ray Bursts Neutrino Oscillations Soft Galactic Dark Cosmic Ray Matter Accelerators The Neutrino Detector Spectrum
NOνA OPERA Accelerator-based K2K, MINOS T2K MiniBooNE Energy ↔ Volume
10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 1 EeV ANITA, SNO, Borexino, Super-K, AMANDA, Baikal, RICE, Auger, KamLAND, LBNE DeepCore ANTARES IceCube, KM3NeT ARIANNA,... Double CHOOZ, PINGU & Beyond? Daya Bay, etc. Atmospheric/Astrophysical Gamma Ray Bursts Neutrino Oscillations Soft Galactic Dark Cosmic Ray Matter Accelerators IceCube DeepCore
• IceCube collaboration decided to augment “low” energy response with a densely instrumented infill array: DeepCore
• Significant improvement in capabilities from ~10 GeV to ~100 GeV (νμ)
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 IceCube DeepCore
• IceCube collaboration decided to augment “low” energy response with a densely instrumented infill array: DeepCore
• Significant improvement in capabilities from ~10 GeV to ~100 GeV (νμ)
• Primary scientific rationale was the indirect search for dark matter
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 IceCube DeepCore
• IceCube collaboration decided to augment “low” energy response with a densely instrumented infill array: DeepCore
• Significant improvement in capabilities from ~10 GeV to ~100 GeV (νμ)
• Primary scientific rationale was the indirect search for dark matter
• Particle physics using atmospheric neutrinos • Neutrino oscillations, including tau neutrino appearance
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 IceCube DeepCore
• IceCube collaboration decided to augment “low” energy response with a densely instrumented infill array: DeepCore
• Significant improvement in capabilities from ~10 GeV to ~100 GeV (νμ)
• Primary scientific rationale was the indirect search for dark matter
• Particle physics using atmospheric neutrinos • Neutrino oscillations, including tau neutrino appearance
• Neutrino sources in Southern Hemisphere? • Galactic cosmic ray accelerators, dark matter in the Galactic center
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 IceCube DeepCore
• IceCube collaboration decided to augment “low” energy response with a densely instrumented infill array: DeepCore
• Significant improvement in capabilities from ~10 GeV to ~100 GeV (νμ)
• Primary scientific rationale was the indirect search for dark matter
• Particle physics using atmospheric neutrinos • Neutrino oscillations, including tau neutrino appearance
• Neutrino sources in Southern Hemisphere? • Galactic cosmic ray accelerators, dark matter in the Galactic center
• Neutrino astronomy at low energies (e.g. GRBs)?
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 Overhead View 2010 configuration
IceCube DeepCore
DeepCore • DeepCore extends the reach of IceCube to lower energies • Denser module spacing scattering • Hamamatsu super-bialkali PMTs IceCube Strings HQE DeepCore Strings DeepCore Infill Strings (Mix of HQE and • Deployed in the clearest ice normal DOMs)
18 standard DOMs 16 HQE DOMs DOMs DeepCore strings have Side View 14 10 DOMs with a Std. DOM-to-DOM spacing 12 DOMs of 10 meters 10
Dust Layer 8 ~35% HQE 6 increase in DOMs 4 50 HQE DOMs with an quantum DOM-to-DOM spacing 2 efficiency of 7 meters 21 Normal DOMs with a 0 DOM-to-DOM spacing 5 10 15 20 25 30 35 40 of 17 meters Optical Efficiency (%)
Figure 1: Laboratory measurement of the relative optical e ciencies at 45 Cand405nm, near the peak PMT sensitivity. A standard reference 2-inch PMT was used for normalization purposes. The black dashed curve is for DOMs with standard PMTs, the red solid curve for HQE DOMs. Using the ratio of the mean relative e ciencies, the new PMTs have an e ciency 1.39 times higher than the standard PMTs.
140 standard DOMs
HQE DOMs DOMs 120
100
80
60
40
20
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Noise Rate (kHz)
Figure 2: Laboratory measurement of the HQE DOM noise rate for the DOM at 45 C. The black dashed curve is for DOMs with standard PMTs, the red solid curve for HQE DOMs.
Figure 4 shows the dark noise rates and Fig. 5 shows the relative occupancies for standard and HQE DOMs, measured in situ. The occupancy is defined as the fraction of events in which each DOM detected one or more photons and is on a string with at least seven other DOMs that also detected photons. Each DOM must also be in “hard local coincidence,” a condition that requires it to have at least one neighboring DOM registering a hit contemporaneously (see
6 Overhead View 2010final configurationconfiguration
IceCube DeepCore
DeepCore • DeepCore extends the reach of IceCube to lower energies • Denser module spacing scattering • Hamamatsu super-bialkali PMTs IceCube Strings HQE DeepCore Strings DeepCore Infill Strings (Mix of HQE and • Deployed in the clearest ice normal DOMs)
18 standard DOMs 16 HQE DOMs DOMs DeepCore strings have Side View 14 10 DOMs with a Std. DOM-to-DOM spacing 12 DOMs of 10 meters 10
Dust Layer 8 ~35% HQE 6 increase in DOMs 4 50 HQE DOMs with an quantum DOM-to-DOM spacing 2 efficiency of 7 meters 21 Normal DOMs with a 0 DOM-to-DOM spacing 5 10 15 20 25 30 35 40 of 17 meters Optical Efficiency (%)
Figure 1: Laboratory measurement of the relative optical e ciencies at 45 Cand405nm, near the peak PMT sensitivity. A standard reference 2-inch PMT was used for normalization purposes. The black dashed curve is for DOMs with standard PMTs, the red solid curve for HQE DOMs. Using the ratio of the mean relative e ciencies, the new PMTs have an e ciency 1.39 times higher than the standard PMTs.
140 standard DOMs
HQE DOMs DOMs 120
100
80
60
40
20
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Noise Rate (kHz)
Figure 2: Laboratory measurement of the HQE DOM noise rate for the DOM at 45 C. The black dashed curve is for DOMs with standard PMTs, the red solid curve for HQE DOMs.
Figure 4 shows the dark noise rates and Fig. 5 shows the relative occupancies for standard and HQE DOMs, measured in situ. The occupancy is defined as the fraction of events in which each DOM detected one or more photons and is on a string with at least seven other DOMs that also detected photons. Each DOM must also be in “hard local coincidence,” a condition that requires it to have at least one neighboring DOM registering a hit contemporaneously (see
6 Online Atmospheric Muon Veto
• Look for hits in veto region consistent with speed-of-light travel time to hits in DeepCore • Achieves 7 x 10-3 rejection of cosmic ray muon background with 99% efficiency for neutrinos interacting within DeepCore • More sophisticated versions used offline
1 simulatedspeed atm. of µ light (inward) simulated atm. ν µ
light 0.1 diffusing outward cosmic ray muons probability per event 0.01
neutrinos -1.0 -0.5 0.0 0.5 1.0 particle speed [m/ns]
Figure 11: Particle speed probabilities per event for simulated muons from cosmic-ray inter- actions (black dashed line) and simulated muons from atmospheric neutrinos inside DeepCore (red solid line). The speed is defined to be positive if the hit occurred before the COG time (see text) and negative if it appeared after. Hits in the veto region are generally expected to have a speed close to c +0.3m/ns.Smallerspeedsoccurforlightdelayedbyscattering. Larger speeds are in principle' acausal, but since the COG time represents the start of a Deep- Core event, whereas the COG position defines its center, the particle speeds for early hits are slightly overestimated. Events with a hit within a particle speed window between +0.25 and +0.4 m/ns are rejected.
1.00 0.25 m/ns 0.30 m/ns
0.99 0.35 m/ns 0.40 m/ns 0.45 m/ns Signal efficiency 0.98 0.55 m/ns
0.70 m/ns
0.97 1.00 m/ns
0.96 0.85 0.90 0.95 1.00 Background rejection
Figure 12: Signal e ciency as a function of background rejection for events having one or more hits with a particle speed (see text) between +0.25 m/ns and a variety of upper values, ranging from +0.35 m/ns to +1.0 m/ns, as indicated in the figure. Upper values higher than about +0.4 m/ns result in greater signal loss without significant additional background rejection.
17 DeepCore Lepton Effective Volume
200 200 DeepCore Trigger DeepCore Trigger DeepCore Online Filter DeepCore Online Filter IceCube Trigger w/o DC IceCube Trigger w/o DC Megaton Megaton 150 150 300 m
Physical 100
100 m Deep Core Volume 400 ~28 MT 50 50 νe νμ 0 0 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0 νe Energy (Log10 GeV) νµ Energy (Log10 GeV)
• Many DeepCore triggers are events occurring in the rest of IceCube • These events are rejected by the online veto algorithm • Online efficiency for neutrinos interacting in the DeepCore volume is >98% • Efficiency in final analysis will be significantly lower; losses to reconstruction efficiency, background rejection DeepCore Neutrino Effective Area ) ) 2 2 IceCube Trigger w/o DeepCore IceCube Trigger w/o DeepCore 10 DeepCore+IceCube Trigger 10 DeepCore+IceCube Trigger DeepCore Online Filter DeepCore Online Filter 1 1
10-1 10-1 Effective Area (m Effective Area (m DeepCore 10-2 DeepCore 10-2
10-3 10-3
10-4 10-4 without νe without νμ 10-5 10-5 DeepCore DeepCore 10-6 10-6 1.0 1.5 2.0 2.5 3.0 3.5 4.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Log (ν Energy - GeV) Log (ν Energy - GeV) 10 e 10 µ
• DeepCore dominates total response for Eν below ~100 GeV, depending on flavor • Improved trigger efficiency overcomes much smaller volume • Linear growth at high energies reflects neutrino interaction cross section, not detector efficiency Search for Solar Dark Matter M. Danninger, TAUP 2011
• Solar WIMP dark matter searchesQuick probe sensitivity Preliminary what to sensitivities expect SD scattering cross section • SI cross section constrained well by direct search experiments
• DeepCore is essential to low mass WIMPs
• For non-SUSY DM, even lower energies are of interest
Matthias Danninger Uppsala Meeting 15 Search for Solar Dark Matter M. Danninger, TAUP 2011
• Solar WIMP dark matter searchesQuick probe sensitivity Preliminary what to sensitivities expect SD scattering cross section • SI cross section constrained well by direct search experiments
• DeepCore is essential to low mass WIMPs
• For non-SUSY DM, even lower energies are of interest
Matthias Danninger Uppsala Meeting 15 Search for Solar Dark Matter M. Danninger, TAUP 2011
• Solar WIMP dark matter searchesQuick probe sensitivity Preliminary what to sensitivities expect SD scattering cross section • SI cross section constrained well by direct search experiments
• DeepCore is essential to low mass WIMPs
• For non-SUSY DM, even lower energies are of interest
Matthias Danninger Uppsala Meeting 15 MANDAL et al. PHYSICAL REVIEW D 81, 043508 (2010) dark matter, and dark energy densities divided by the The dashed green line (‘‘AMANDA-II diff.’’) is the critical density [1]. The isotropic diffuse flux from the constraint to 90% confidence from the AMANDA-II limit annihilations of cosmological dark matter is too small to on the isotropic diffuse flux of #", and the solid green line be relevant, since the density of dark matter on cosmologi- (‘‘IceCube casc. diff.’’) is the constraint to 90% confidence cal scales is very low, and the flux is suppressed by another from the projected IceCube limit on the isotropic diffuse power of &c=m. flux using cascade events. Since the flux from cosmologi- Because of the loss of signal due to event selection and cal dark matter is weak to begin with, contributing only 1% the presence of background fluxes, both the AMANDA-II of the total flux over the 2% facing the galactic center, we limit and the projected IceCube limit are only valid at see that it is quickly overwhelmed by the atmospheric flux energies greater than 20 TeV. Below these thresholds below 40 TeV. Nonetheless, due to the lower back- we add the atmospheric background flux to these limits, ground of atmospheric #e compared to #" at these high and use these total fluxes to calculate the constraints on the energies, using cascade events improves the constraint by a dark matter lifetime. factor of 5. The dashed blue line (‘‘DeepCore tr. 5yr’’) is the con- III. RESULTS straint to 2' from IceCube + DeepCore for tracklike events after five years of running, and the solid blue lines are the The results for dark matter decays are shown in Fig. 2; constraints to 2' for cascade events after one year the regions below the contours are excluded. The black (‘‘DeepCore casc. 1yr’’) and three years (‘‘DeepCore contour (‘‘Super-K up-"’’) is the Super-Kamiokande limit casc. 3yr’’) of running. We see that for the "þ"À final to 3' from up-going muons discussed in the Introduction. state, while tracklike events can only reduce the available The orange band is the preferred region to fit the PAMELA Fermi-preferred parameter space in five years, cascade MANDAL et al. PHYSICAL REVIEW D 81, 043508 (2010) eÆ anomaly, and the red ellipses are the preferred region to events can rule it out altogether in only three years. dark matter, and dark energy densities divided by the fit theThe Fermi dashedeÆ anomaly. green line These (‘‘AMANDA-II three regions are diff.’’) given is by the Similarly for the (þ(À final state, tracklike events can 27 critical density [1]. The isotropic diffuse flux from the Ref.constraint [27] up to to 90% mass confidence 30 TeV and from lifetime the AMANDA-II10 s. limit rule out the parameter space in less than five years, but annihilations of cosmological dark matter is too small to on the isotropic diffuse flux of #", and the solid green line be relevant, since the density of dark matter on cosmologi- (‘‘IceCube casc. diff.’’) is the constraint to 90% confidence cal scales is very low, and the flux is suppressed by another from the projected IceCube limit on the isotropic diffuse power of &c=m. flux using cascade events. Since the flux from cosmologi- Because of the loss of signal due to event selection and cal dark matter is weak to begin with, contributing only 1% Non-Standardthe presence of background Dark fluxes, both the AMANDA-II of the total flux over the 2% facing the galactic center, we limit and the projected IceCube limit are only valid at see that it is quickly overwhelmed by the atmospheric flux energies greater than 20 TeV. Below these thresholds below 40 TeV. Nonetheless, due to the lower back- Matterwe Searches add the atmospheric background flux to these limits, ground of atmospheric # compared to # at these high e " and use these total fluxes to calculate the constraints on the energies, using cascade events improves the constraint by a dark matter lifetime. factor of 5. The dashed blue line (‘‘DeepCore tr. 5yr’’) is the con- III. RESULTS straint to 2' from IceCube + DeepCore for tracklike events after five years of running, and the solid blue lines are the The results for dark matter decays are shown in Fig. 2; constraints to 2' for cascade events after one year the regions below the contours are excluded. The black • As a general-purpose detector, (‘‘DeepCore casc. 1yr’’) and three years (‘‘DeepCore , 043508 (2010) contour (‘‘Super-K up-"’’) is the Super-Kamiokande limit casc. 3yr’’) of running. We see that for the "þ"À final IceCube-DeepCoreto 3' from up-going will muons soon discussed inbe the Introduction. state, while tracklike events can only reduce the available 81 The orange band is the preferred region to fit the PAMELA Fermi-preferred parameter space in five years, cascade able to probeeÆ anomaly, new and the theories red ellipses are using the preferred region to events can rule it out altogether in only three years. fit the Fermi eÆ anomaly. These three regions are given by Similarly for the (þ(À final state, tracklike events can archival dataRef. [27 ]sets up to mass 30 TeV and lifetime 1027 s. rule out the parameter space in less than five years, but
FIG. 2 (color online). Constraints for decay to "þ"À (left) and (þ(À (right); the regions below the contours are excluded. The black • E.g., interpretations of PAMELA contour (‘‘Super-K up-"’’) is the Super-Kamiokande limit to 3' from up-going muons, the orange band is the PAMELA-preferred positron fraction in terms of region, and the red ellipses are the Fermi-preferred region; these three are given by Ref. [27]. The dashed green line (‘‘AMANDA-II diff.’’) is the constraint to 90% confidence from the AMANDA-II limit on the isotropic diffuse flux of #", and the solid green line decaying or boosted leptophilic (‘‘IceCube casc. diff.’’) is the constraint to 90% confidence from the projected IceCube limit on the isotropic diffuse flux using cascade events. The dashed blue line (‘‘DeepCore tr. 5yr’’) is the constraint to 2' from IceCube + DeepCore for #" tracklike events after five years of running, and the solid blue lines are the constraints to 2' for all-flavor cascade events after one year (‘‘DeepCore casc. 1yr’’) dark matter and three years (‘‘DeepCore casc. 3yr’’) of running.
• Will have the world’s largest 043508-4 neutrino set – many things we can use it for Mandal, Buckley, Freese, Spolyar, & Murayama, PRD
FIG. 2 (color online). Constraints for decay to "þ"À (left) and (þ(À (right); the regions below the contours are excluded. The black contour (‘‘Super-K up-"’’) is the Super-Kamiokande limit to 3' from up-going muons, the orange band is the PAMELA-preferred region, and the red ellipses are the Fermi-preferred region; these three are given by Ref. [27]. The dashed green line (‘‘AMANDA-II diff.’’) is the constraint to 90% confidence from the AMANDA-II limit on the isotropic diffuse flux of #", and the solid green line (‘‘IceCube casc. diff.’’) is the constraint to 90% confidence from the projected IceCube limit on the isotropic diffuse flux using cascade events. The dashed blue line (‘‘DeepCore tr. 5yr’’) is the constraint to 2' from IceCube + DeepCore for #" tracklike events after five years of running, and the solid blue lines are the constraints to 2' for all-flavor cascade events after one year (‘‘DeepCore casc. 1yr’’) and three years (‘‘DeepCore casc. 3yr’’) of running.
043508-4 Mena, Mocioiu & Razzaque, Phys. Rev. D78, 093003 (2008) Neutrino Oscillations
ντ appearance
• Atmospheric neutrinos from Northern Hemisphere oscillating νμ disappearance over one earth diameter have νμ oscillation minimum at ~25 GeV L = D • Higher energy region than accelerator-based experiments
• Plot of νμ disappearance shows Preliminary only simulated signal, rough 1400 Unoscillated energy estimator 1200 Oscillated No Reconstruction 1000 θ23 = π/2 • Analysis efficiencies not 2 -3 Δm23 = 2.4 × 10 eV 800 15σ included yet – work ongoing Events/NChannel/Year Cos(zenith) < -0.6 per bin • Promising work on a track 600 length reconstruction, zenith- 400
only reconstruction inspired by 200 ANTARES (J.-P. Yánez, J. 0 0 10 20 30 40 50 60 70 80 90 100 Brunner) NChannels [Hit DOMs] Observation of Neutrino Cascades (Preliminary)
• Disappearing νμ should appear in IceCube as ντ cascades • Effectively identical to neutral current or νe CC events
• Could observe ντ appearance as a distortion of the energy spectrum, if cascades can be separated from muon background
• We believe we see neutrino cascade events for the first time • The dominant background now Candidate cascade event is CC νμ events with short tracks Run 116020, Event 20788565, 2010/06/06
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 Beyond DeepCore: PINGU
• Developing a proposal to one possible geometry further increase density of New PINGU instrumentation in DC volume Strings • An additional 18-20 strings, 1000-1200 DOMs • Make use of well-established IceCube drilling technology • Might get to a threshold Existing standard of ~1 GeV in a ~10 MTon Existing IceCube DeepCore volume strings Strings • Also an R&D platform for future detectors on a ~decade timeline
• Price tag expected to be around $25M – $30M
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 PINGU Effective Volumes Preliminary
100 100 Megaton Megaton 10 10
1 1
0.1 IC2011 DC Contained 0.1 IC2011 DC Contained
PINGU Contained PINGU Contained
0.01 0.01 0.0 0.5 1.0 1.5 2.0 2.5 0.0 0.5 1.0 1.5 2.0 2.5 νe Energy (Log GeV) ν Energy (Log GeV) 10 µ 10
• Increased effective volume for energies below ~15 GeV • Nearly an order of magnitude increase at 1 GeV (100’s of kton) • Does not include analysis efficiencies, reconstruction precision • Absolute scale lower, but improvement over DeepCore likely >10x PINGU Neutrino Physics 5 Mena, Mocioiu, Razzaque, arXiv:0803.3044 0.5 • Lower mass WIMPs 1
2 2 sin 2 sin 2 θ13 = 0.1 (ΝΗ) θ13 = 0.1 (ΝΗ) 2 2 sin 2 sin 2 0.4 θ13 = 0.1 (ΙΗ) 0.8 θ13 = 0.1 (ΙΗ) • Increased sensitivity2 to 2 sin 2 sin 2 θ13 = 0.06 (ΝΗ) θ13 = 0.06 (ΝΗ) 2 2 supernova neutrinossin 2 sin 2 θ13 = 0.06 (ΙΗ) θ13 = 0.06 (ΙΗ) 0.3 0.6 ) ) µ µ ν ν
− −
nd e µ
ν • Sensitivity to 2 oscillation ν P( 0.2 peak/trough P( 0.4
0.1 • Possible sensitivity to neutrino 0.2 mass hierarchy via matter 0 0 5 effects10 if θ13 is 15large 20 25 5 10 15 20 25 E [GeV] E [GeV] ν ν • Exploit asymmetries in ν / ν̄ cross section, kinematics • Control of systematics crucial FIG. 2: left (right panel): Oscillation probabilities for νe → νµ, νµ → νµ transitions for cν = −1. • Plan for a robust calibration program to understand systematics channel and thereforeTyce DeYoung is in many ways complementaryMANTS ’11,falling Uppsala, Sweden spectrum, so one would expectSeptember this 25, 2011 tau-induced to the appearance experiments. While the matter effects muon background not to be very large. It is however sig- are a small correction in the νµ survival probability, they nificant ( 10%) due to the fact that, as seen in Figure 3, ∼ are sufficient to provide a difference between the differ- the first maximum in the νµ ντ oscillation probability → ent mass orderings because of the very large number of (minimum in the νµ νµ survival probability) falls ex- events. actly in the energy range→ of interest and for a large range Note that in Fig. 1 the difference between event rates the ντ flux can be significantly larger than the νµ flux. for the two hierarchies increases (although the overall These events significantly change the energy spectrum of rates decreases) for cν bins ( 0.9, 0.8) and ( 0.8, 0.7) the measured muon-like events and contain information − − − − compared to the ( 1, 0.9) bin. This is because the res- about the main oscillation parameters, ∆31 and θ23. onant matter density− − for neutrino energies in the first 3 1 energy bin
0.6 IV. BACKGROUNDS AND SYSTEMATIC
UNCERTAINTIES 0.4 Oscillation probabilities The main backgrounds to the signal we are exploiting 0.2 in the current study are atmospheric downward going muons from the interactions of cosmic rays in the atmo- sphere and tau (anti)neutrinos from νµ,e(¯νµ,e) ντ (¯ντ ) 0 5 10 15 20 25 30 35 40 45 50 → E [GeV] transitions. The cosmic muon background can be elimi- ν nated by angular cuts and in the Ice Cube deep core is significantly reduced compared to the IceCube detector. FIG. 3: νµ survival probability and νµ → ντ oscillation prob- − 2 The tau neutrino background can be included in the ability for cν = 1, sin 2θ13 =0.1 analysis as an additional source of µ-like events. Tau (anti)neutrinos resulting from atmospheric neutrino fla- The uncertainties in the atmospheric neutrino flux vor transitions will produce a τ lepton by CC interac- have been discussed in the previous section and they af- tions in the detector effective volume. The tau leptons fect the analysis. It is however possible to use the data produced have an 18% probability of decaying through itself to improve some of the errors introduced by these ∼ the τ − µ−ν¯µντ channel. effects, by considering energy and angular bins where os- → The secondary muons can mimic muons from νµ CC cillation effects are not important as a reference and thus interactions and must be included in the oscillated signal. canceling out some of these uncertainties in the analysis The energy of a ντ needs to be about 2.5 times higher (see also [26]). than a νµ to produce, via tau decay, a muon of the same The uncertainties in other oscillation parameters also energy. But the atmospheric neutrino flux has a steeply affect the possibility of determining the neutrino mass hi- PINGU HierarchyNeutrino Measurement? mass hierarchy - PINGU
• Simulations of 20-string PINGU for 5 years with large θ13 Very Preliminary !!!Normal!hierarchy! • Assumes perfect Inverted!hierarchy! background rejection, select events within 25º of vertical • 5 GeV muon energy bins – ~25 m length resolution
• Up to 20% (=10σ) effectsFresh in fromseveral the farm energy/angle - GENIE PINGU bins numu and numubar (thanks Jason!) processed. Events are SMT3 trigger level 20 string PINGU • Signal is potentially there,infill. if systematics can be controlled September, 2011 IceCube Collaboration Meeting - Uppsala Sweden Darren R. Grant - University of Alberta
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011 R&D: Multi-PMT Digital Optical Module
P. Kooijman & • Based on a KM3NeT design E. de Wolf
• Glass cylinder containing 64 3” PMTs and associated electronics Possible • Effective photocathode area >6x that of a design standard IceCube 10” PMT for future array: • Diameter similar to IceCube DOM, single 64 x 3” connector PMTs
• Might enable Cherenkov ring imaging in the ice • Feasible to build a multi-MTon detector in ice with an energy threshold of 10’s of MeV?
• R&D beginning (U. Katz/P. Kooijman) Possible design for future array: 64 x 3” PMTs Conclusions
• DeepCore has been running for 1 year, just commenced taking data in final configuration • Additional 8 strings, densely instrumenting the inner 30 MTon of IceCube • Reduces energy threshold to ~10 GeV
• Particle physics in the ice: significant improvement in sensitivity to dark matter, potential for measurements of neutrino oscillations • Initial progress is encouraging, but much remains to be done
• Thinking about a future upgrade of IceCube to further extend its particle physics capabilities – PINGU and possibly beyond • Potential for significant contributions to fundamental particle physics, but requires a level of precision better than we have achieved so far
Tyce DeYoung MANTS ’11, Uppsala, Sweden September 25, 2011