30 Years of High-Energy Neutrino Astronomy: What have we achieved? A brief Review of the Past and some Thoughts for the Future. Peter K. F. Grieder University of Bern Switzerland Vulcano Workshop 2010 May 24-29 Frontier Objects in Astrophysics and Particle Physics 1
Overview • Motivation • Link between Cosmic Ray and Neutrino Physics • Summary of Historic Events, Relevant Years • Neutrino Detection: Methods and Telescopes • Present Results: Predictions and Measurements • Experimental Aspects, Sites, Problems of Past and Present in View of KM3 • Comments on Supplementary Auxiliary Detector Systems, Fall-back Projects 2
Why Neutrino Astronomy Find the Sources of UHE Cosmic Rays Astrophysical, Cosmological, Particle Physics Aspects Today’s astronomy is based on EM radiation: Optical Radio Infrared X-Rays Gamma Rays It yields a rich but single-sided picture of the Universe Much remains obscure, invisible. New alternative approaches, techniques are required. Neutrino astronomy is such an approach. It opens a new non-EM window into the Universe. 3
A Specific Problem Presents the UHE Primary Cosmic Radiation (Spectral uncertainties at UHE, GZK cutoff?) Compressed Double-Logarithmic Spectrum 4
Primary Cosmic Ray Spectrum (Akeno, AGASA, EAS-TOP and Yakutsk data excluded) 5
Questions concerning UHE CR • Where ends the primary spectrum * • Nature and composition of primaries * • Is there a GZK cutoff * • Where are the sources • What is the nature of the sources, mechanisms • Classical accelerators, cutoffs • Top-down hypothesis, mechanisms * Answers are in sight 6
How to Locate UHE CR Sources: Methods and Techniques • Anisotropy studies of arrival direction of UHE CR air showers Hadron astronomy (magnetic fields, GZK cutoff) Gamma-ray astronomy (CMBR) • Search for, locate Cosmic Powerhouses Gamma-ray astronomy Neutrino astronomy 7
Likely / Suspected Sources of UHE-CR, Neutrinos • Point Sources: • Supernova Remnants (E ≤ 10**16 eV) • AGNs • Blazars • Gamma Ray Bursters • Diffuse Sources: • GZK Neutrinos • Topological Defects, Supermassive Particles • Z-Bursts 8
Important Developments, Landmarks (Back to the Roots: How it all Began) • The energy crisis of the late 1920s (energy conservation in beta decay) prompted Pauli’s neutrino hypothesis as solution (1930). • Reines & Cowan’s experiment verified existence of neutrino (1956), (Reines, Nobel Price 1995). • Discovery of >10**18 eV showers by Clark et al. (1957) raises questions concerning nature and origin of primaries (extragalactic?). • Frank, Tamm and Cherenkov (1937/1938) get Nobel Price (1958), triggers development of Cherenkov detectors (Ginzburg, 1941/2003) • Cocconi (ICRC Moscow, 1959) proposed search for UHE gamma ray showers to locate CR sources (CMBR was not yet established). • Markov (Rochester Conf., 1960). proposed UHE neutrino detection in ocean, using Cherenkov light to locate CR sources. 9
Developments, Landmarks (cont.) • Askaryan developed acoustic shock (1957) and Cherenkov radio theory (1961). • Lederman et al. (1962) prove existence of electron and muon neutrino (Nobel Price 1988). • Penzias and Wilson (1964) discover CMBR (Nobel Prive 1978). • Greisen, Zatsepin and Kuzmin (1966) predict GZK Cutoff. • Perl et al. (1975) discover tau lepton (Nobel Price 1995), tau neutrino awaits discovery. • Neutrino oscillations (Theory: Pontecorvo et al., 1957, 1967; observations ~1993, ratio of ratios) (Koshiba, Nobel Price 2002). 10
Comment The evolution of Neutrino Physics has strongly affected neutrino astronomy in general, and in particular the scientific goals, but also the experimental concepts and techniques (electron-, muon- and tau neutrinos, and neutrino oscillations). 11
Neutrino Detection Via Neutrino Reactions only Characteristics of neutrino reactions and reaction products are neutrino flavor specific . 12
Effects of Neutrino Reactions in Target Acoustic Shock, Optical and Radio Cherenkov Emission 13
Detector Requirements Small neutrino cross sections require large target mass / volume, large detector surface / volume Suitable target / detector media are large bodies of water, ice, salt, air or rock, the Moon 14
Astrophysical Neutrino Telescopes Concepts, Detection Principles (Site and Energy Range Specific) Type Medium Detection Deep-water water optical Cherenkov, acoustic shock Deep-ice ice optical, radio Cherenkov, acoustic Surface air, rock EAS particles, fluorescence, radio Balloon ice radio Cherenkov emission Satellite air, ice, fluorescence, radio Cherenkov, rock reflected optical Cherenkov light Typical Design Concepts 15
3-D DUMAND Type Water / Ice Optical Cherenkov and Acoustic Detector Arrays AMANDA, ANTARES, Baikal, IceCube, NEMO, NESTOR, KM3 Hawaii 16
Surface based Particle, Fluorescence and Radio Detectors: Auger, GLUE, LOFAR (Tokyo INS) Young, Inclined (Horizontal) Air Shower 17
Balloon based Radio Detectors ANITA (Antarctic Impulsive Transient Antenna) Antarctica 18
Satellite based Cherenkov Radio Detectors LORD Project (Lunar Orbiting Detector) Horn Antennas 19
Satellite based Fluorescence Detectors JEM-EUSO Project Observes CR and Neutrino Induced Showers Sakaki et 20 al., 2008
Site, Medium and Concept Specific Problems, Advantages Ocean: instrumentation, long-range deployment from ship, platform, (ice), remote operations, background. Detector is serviceable. ANTARES, (Baikal), NEMO, NESTOR, KM3 Ice sheet: access, drilling (melting) of holes to site, detector is irreparable, homogeneity, background. Comparatively easy deployment. AMANDA, IceCube Surface: background, event identification. Easy instrumentation, access. Auger, GLUE, LOFAR (Tokyo INS) 21
Site, Medium and Concept Specific Problems, Advantages (cont.) Balloon: launch, radio background, short run time, difficult analysis and interpretation. Large target area, volume; high threshold energy. ANITA Satellite: launch, optical, radio background. Very high threshold energy, huge target volume, area . FORTE, JEM-EUSO, LORD 22
Relevant Target / Detector Medium Specific Properties, Parameters Composition (water, ice, air, salt, rock) Density, Homogeneity (Temperature) Optical properties, parameters (scattering, attenuation, refraction) Acoustic properties (sound propagation) Electromagnetic properties, parameters (radio propagation) (dielectric constant, conductivity) 23
Neutrino Fluxes: Model Predictions 24
Sensitivities of different Detectors: Anticipated and Determined Sensitivities of Different Experiments Saltzberg (2005) 25
Measured Neutrino Flux Limits: Results from Different Experiments Barwick et al., 2006 Gorham et al. 2004 26
Deep-Water Cherenkov Arrays: Site Relevant Properties Geographic location Depth Sky exposure Water properties Environment Background 27
Detector Site Relevant Parameters, Properties Geographic Location Sky Visibility, Background Muons DUMAND Neutrinos Near Equator 28
Depth (Altitude): Sky Visibility, Background: an Example 29
Skymap of Detected Neutrinos by AMANDA II at South Pole (can only observe northern hemisphere) 30
Sea / Ocean Parameters NESTOR Site DUMAND Site 31
Sea / Ocean Parameters (cont.) NESTOR Site DUMAND Site 32
Background, Environmental Considerations: (Site Specific) optical cosmic rays bioluminescence, chemo-luminescence natural radioactivity, 40K acoustic noise (radio noise) bio-fowling (stops at > 800 m b.s.l.) sedimentation (e.g., Sahara sand, Rivers) sea, ocean currents lightning storms 33
Muon Depth-Intensity Relation In Standard Rock In Water 34
Muon Depth-Intensity Relation (cont.) Sea water NESTOR site Depth 3338 m ANTARES NESTOR 3697 m NEMO, KM3 4108 m 35
Bioluminescence, Hawaii Site Depth 3000 m (tethered) Calibration Pulses 36
Bioluminescence (cont.) 1500 m Ocean currents and turbulence can 1 M cause stimulated bioluminescence of bacteria. 2500 m Effect is geographic location and depth dependent. cps 3500 m Fish, animals are irrelevant sources 4500 m of bioluminescence. Nearby rivers, cities increase effect. C dark noise, 3°C F bottom tethered (100 m a.g.) 100 0 100 Channel Number 37
Bioluminescence, Hawaii Site (cont.) 3000 m 4300 m 4300 m at start ascent 38
DUMAND Site Optical Background v/s Depth in Pacific near Hawaii Descent, Ascent ~40 – 80 cm/s (facing down) 39
Deep-Water Cherenkov Arrays: Important Elements, Topics • Optical (Acoustic) Sensor Modules, Clusters. • Array Design, Structure, Layout (mechanical). • Data Acquisition, Transmission and Processing Strategy, associated Electronics. • Event Reconstruction and Analysis. • System and Event Simulation. • Array and Environmental Monitoring System, Housekeeping. • Deployment and Installation. • Support and Maintenance. • Auxiliary Systems, (Shallow Muon Array etc.) • Fall-Back Projects. 40
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