AMANDA observations constrain the ultrahigh energy neutrino flux

A number of experimental techniques are currently being deployed in an effort to make the first detection of ultrahigh energy cosmic neutrinos. To accomplish this goal, techniques using radio and acoustic detectors are being developed, which are optimally designed for studying neutrinos with energies in the PeV-EeV range and above. Data from the AMANDA experiment, in contrast, have been used to place limits on the cosmic neutrino flux at less extreme energies (up to approximately 10 PeV). In this Letter, we show that by adopting a different analysis strategy, optimized for much higher energy neutrinos, the same AMANDA data can be used to place a limit competitive with radio techniques at EeV energies. We also discuss the sensitivity of the IceCube experiment, in various stages of deployment, to ultrahigh energy neutrinos.     

Particle physics on ice: constraints on neutrino interactions far above the weak scale

Ultrahigh energy cosmic rays and neutrinos probe energies far above the weak scale. Their usefulness might appear to be limited by astrophysical uncertainties; however, by simultaneously considering up- and down-going events, one may disentangle particle physics from astrophysics. We show that present data from the AMANDA experiment in the South Pole ice already imply an upper bound on neutrino cross sections at energy scales that will likely never be probed at man-made accelerators. The existing data also place an upper limit on the neutrino flux valid for any neutrino cross section. In the future, similar analyses of IceCube data will constrain neutrino properties and fluxes at the theta(10%) level.     

Recent Highlights from IceCube

The ~1 km ³ IceCube neutrino observatory was completed in December, 2010 and is taking data on cosmic-ray muons and neutrinos, extraterrestrial neutrinos, and setting limits on a variety of exotic phenomena. This proceeding will cover recent IceCube results, with an emphasis on cosmic rays and on searches for extraterrestrial neutrinos, with a stress on results presented at the 2013 International Cosmic Ray Conference.     

Limits on neutrino emission from gamma-ray bursts with the 40 string IceCube detector

IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18) eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.     

IceCube Neutrinos: from Oscillations to PeV-Energy Events

With IceCube and its low-energy extension DeepCore, a neutrino detector with an energy reach from tens of gigaelectronvolt to exaelectronvolt has been commissioned. It measures the atmospheric neutrino spectrum from the lower energies where neutrinos oscillate to energies as large as 100 TeV with a statistic of more than 100,000 events per year. The initial results suggest that IceCube can measure the oscillation parameters in an energy range that exceeds existing observations by 1 order of magnitude, thus opening a new window on neutrino physics. We emphasize the search for sterile neutrinos particularly relevant to cosmology. We also discuss the first observation of (PEV) petaelectronvolt-Energy events that cannot be accommodated by the flux anticipated by extrapolation of the present atmospheric neutrino measurements.     

Radiography of Earth's core and mantle with atmospheric neutrinos

A measurement of the absorption of neutrinos with energies in excess of 10 TeV when traversing the Earth is capable of revealing its density distribution. Unfortunately, the existence of beams with sufficient luminosity for the task has been ruled out by the AMANDA South Pole neutrino telescope. In this Letter we point out that, with the advent of second-generation kilometer-scale neutrino detectors, the idea of studying the internal structure of Earth may be revived using atmospheric neutrinos instead.     

Astroparticle physics with high energy neutrinos: from AMANDA to IceCube

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 10²⁰ eV and 10¹³ eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the science reach of its extension, IceCube. Similar experiments are under construction in the Mediterranean. Neutrino astronomy is also expanding in new directions with efforts to detect air showers, acoustic and radio signals initiated by super-EeV neutrinos. The outline of this review is as follows:

Introduction

Why kilometer-scale detectors?

Cosmic neutrinos associated with the highest energy cosmic rays

High energy neutrino telescopes: methodologies of neutrino detection

High energy neutrino telescopes: status

     

Probing a supersymmetric model for neutrino masses at ultrahigh energy neutrino telescopes

A bilinear R-parity breaking SUSY model for neutrino mass and mixing predicts the lightest superparticle to decay mainly into a pair of tau leptons or b quarks along with a neutrino for relatively light SUSY spectra. This leads to a distinctive triple bang signature of SUSY events at ultrahigh energy neutrino telescopes like IceCube or Antares. While the expected signal size is only marginal at IceCube, it will be promising for a future multi-km³ size neutrino telescope.     

Neutrino astronomy: An update

Detecting neutrinos associated with the still enigmatic sources of cosmic rays has reached a new watershed with the completion of IceCube, the first detector with sensitivity to the anticipated fluxes. In this review, we will briefly revisit the rationale for constructing kilometer-scale neutrino detectors and summarize the status of the field.     

Status of the AMANDA experiment

The AMANDA high energy neutrino telescope has successfully been increased in size from four detector strings to ten detector springs during the 1996/1997 season. The first upward going muon-neutrino candidates have been reconstructed from the 1996 year's four-string data. Three new detector strings will be deployed during 1997/1998 to 2350 metres depth.     

Constraints and tests of the OPERA superluminal neutrinos

The superluminal neutrinos detected by OPERA indicate Lorentz invariance violation (LIV) of the neutrino sector at the order of 10(-5). We study the implications of the result in this work. We find that such a large LIV implied by OPERA data will make the neutrino production process π → μ + ν(μ) kinematically forbidden for a neutrino energy greater than about 5 GeV. The OPERA detection of neutrinos at 40 GeV can constrain the LIV parameter to be smaller than 3×10(-7). Furthermore, the neutrino decay in the LIV framework will modify the neutrino spectrum greatly. The atmospheric neutrino spectrum measured by the IceCube Collaboration can constrain the LIV parameter to the level of 10(-12). The future detection of astrophysical neutrinos of galactic sources is expected to be able to give an even stronger constraint on the LIV parameter of neutrinos.     

ANTARES, Physics potential, progress and status

Observational neutrino astronomy can bring information - also on particle physics - that can not be obtained in other ways. In general this concerns processes at extreme energy and distance scales. Particularly of interest are cosmic accelerators, GUT phase transition remnants and dark matter annihilation. After four years of R&D the ANTARES Collaboration begins the actual construction of a neutrino telescope to be deployed at 2400 m depth near Toulon in the Mediterranean sea. The telescope will be particularly sensitive to high-energy upward-going neutrinos. The physics case, measurements, the structure of the detector and recent progress are discussed.     

The Baikal Neutrino Telescope

We review the present status of the Baikal Neutrino Experiment and present results of a search for upward-going atmospheric neutrinos and magnetic monopoles obtained with the detector NT200. The results of a search for very high energy neutrinos are presented and an upper limit on the extraterrestrial diffuse neutrino flux is obtained. We describe the strategy of upgrading the NT200 to NT200+ and creating a detector on the Gigaton scale at Lake Baikal. The first results obtained with the new NT200+ detector as a basic cell of a future Gigaton detector are presented. The text was submitted by the authors in English.     

About the Earth density and the neutrino interaction

We visit again the problem to extract information about the mass distribution of the Earth using neutrino collisions with the Earth matter. The topic was addressed in several opportunities using different observable related with the neutrino flux arriving to a neutrino telescope like IceCube. In the present work we have used an observable that is weakly dependent of the initial flux. We check the homogeneity hypothesis and fit a simplified Earth model consistent with the observational value of the Earth mass and the inertia moment.     

Baikal neutrino telescope: Status, results, and prospects of development

The main physical results obtained with the Baikal neutrino telescope NT200 during the period 1998–2003 are reviewed: the limits for the diffuse flux of high-energy neutrinos, high-energy muons, and magnetic monopoles and the results of search for neutrinos from the center of the Earth due to annihilation of weakly interacting massive particles and from local neutrino sources. In April, 2005, the neutrino telescope NT200 was extended by introduction of three new strings, located at a distance of 100 m from the NT200 center. The new deep-water complex NT200+ has an effective volume for detecting cascades from high-energy neutrinos larger than that of NT200 by a factor of 4. At a cascade energy of 10 PeV, the effective volume of the new complex is 10⁷ m³. Further development of the Baikal neutrino experiment is related to the design and fabrication of a detector with a volume of about 1 km³. Original Russian Text ? K.V.Antipin, V.M. Ainutdinov, V.A. Balkanov, I.A. Belolaptikov, D.A. Borshchev, N.M. Budnev, R.V. Vasil’ev, R. Vishnevskii, I.A. Danil’chenko, G.V. Domogatskii, A.A. Doroshenko, A.P. D’yachok, Zh.-A.M. Dzhilkibaev, O.N. Gaponenko, K.V. Golubkov, O.A. Gress, T.I. Gress, O.I. Grishin, V.A. Zhukov, A.M. Klabukov, A.I. Klimov, A.A. Kochanov, K.V. Konishchev, A.P. Koshechkin, L.A. Kuz’michev, V.F. Kulepov, E. Middel, T. Mikokaiskii, M.B. Milenin, R.R. Mirgazov, S.P. Mikheev, E.A. Osipova, G.L. Pan’kov, L.V. Pan’kov, A.I. Panfilov, D.P. Petukhov, E.N. Pliskovskii, P.G. Pokhil, V.A. Poleshchuk, E.G. Popova, V.V. Prosin, M.I. Rozanov, V.Yu. Rubtsov, Yu.A. Semenei, B.A. Tarashchanskii, S.V. Fialkovskii, B.K. Shaibonov, A.A. Sheifler, A.V. Shirokov, K. Spiring, I.V. Yashin, 2007, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2007, Vol. 71, No. 4, pp. 597–601.     

Nonlinear increase in the energy input into a medium at the fusion of regularized femtosecond filaments

We consider dark matter consisting of long-living particles with masses 10⁷ GeV ? M ?10¹⁶ GeV decaying through hadronic channel as a source of high-energy neutrino. Using recent data on high-energy neutrino from IceCube and Pierre Auger experiments, we derive the upper-limits on neutrino flux from dark matter decay and constraints on dark matter parameter space. For the dark matter masses of order 10⁸ GeV the constraints derived are slightly stronger than those obtained for the same dark matter model using the highenergy gamma-ray limits.     

Status and first results of the ANTARES neutrino telescope

The ANTARES detector is the most sensitive neutrino telescope observing the southern sky and the world’s first particle detector operating in the deep sea. It is installed in the Mediterranean Sea at a depth of 2475 m. As example for the first results, the determination of the atmospheric muon flux is discussed; a fair agreement with previous measurements is found. Furthermore, the results of a search for high-energy events in excess of the atmospheric neutrino flux are reported and significant limits are set on the diffuse cosmic neutrino flux in the multi-TeV to PeV energy range. Using data taken during the construction phase, a first analysis searching for point-like excesses in the neutrino sky distribution has been performed. The resulting sensitivity of ANTARES is reported and compared to measurements of other detectors.     

Decay of high-energy astrophysical neutrinos

Existing limits on the nonradiative decay of one neutrino to another plus a massless particle (e.g., a singlet Majoron) are very weak. The best limits on the lifetime to mass ratio come from solar neutrino observations and are tau/m greater, similar 10(-4) s/eV for the relevant mass eigenstate(s). For lifetimes even several orders of magnitude longer, high-energy neutrinos from distant astrophysical sources would decay. This would strongly alter the flavor ratios from the phi(nu(e)):phi(nu(mu)):phi(nu(tau))=1:1:1 expected from oscillations alone and should be readily visible in the near future in detectors such as IceCube.     

50 TeV HEGRA sources and infrared radiation

The recent observations of 50 TeV gamma radiation by HEGRA have the potential of determining the extragalactic flux of infrared radiation. The fact that radiation is observed in the range between 30 and 100 TeV sets an upper limit on the infrared flux, while a cutoff at E_γ ≈ 50 TeV fixes this flux with a good accuracy. If the intrinsic radiation is produced due to interaction of high energy protons with gas or low-energy target photons, then an accompaning high-energy neutrino flux is unavoidable. We calculate this flux and underground muon flux produced by it. The muon flux is dominated by muons with energies about 1 TeV and can be marginally detected by a 1 km² detector like an expanded AMANDA.