Showing papers on "Neutrino detector published in 2004"

Measurement of the total active B-8 solar neutrino flux at the Sudbury Neutrino Observatory with enhanced neutral current sensitivity

Abstract: The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) B-8 solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21+/-0.27(stat)+/-0.38(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Deltam(2)=7.1(-0.6)(+1.2)x10(-5) eV(2) and theta= 32.5(-2.3)(+2.4) degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.

Search for dark matter WIMPs using upward through-going muons in Super-Kamiokande

Abstract: We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs), with 1679.6 live days of data from the Super-Kamiokande detector using neutrino-induced upward through-going muons. The search is performed by looking for an excess of high energy muon neutrinos from WIMP annihilations in the Sun, the core of the Earth, and the Galactic Center, as compared to the number expected from the atmospheric neutrino background. No statistically significant excess was seen. We calculate the flux limits in various angular cones around each of the above celestial objects. We obtain conservative model-independent upper limits on the WIMP-nucleon cross section as a function of WIMP mass, and compare these results with the corresponding results from direct dark matter detection experiments.

Sensitivity of the icecube detector to astrophysical sources of high energy muon neutrinos

Abstract: We present the results of a Monte-Carlo study of the sensitivity of the planned IceCube detector to predicted fluxes of muon neutrinos at TeV to PeV energies. A complete simulation of the detector and data analysis is used to study the detector's capability to search for muon neutrinos from sources such as active galaxies and gamma-ray bursts. We study the effective area and the angular resolution of the detector as a function of muon energy and angle of incidence. We present detailed calculations of the sensitivity of the detector to both diffuse and pointlike neutrino emissions, including an assessment of the sensitivity to neutrinos detected in coincidence with gamma-ray burst observations. After three years of datataking, IceCube will have been able to detect a point source flux of E2*dN/dE = 7*10^-9 cm^-2s^-1GeV at a 5-sigma significance, or, in the absence of a signal, place a 90 percent c.l. limit at a level E2*dN/dE = 2*10^-9 cm^-2s^-1GeV. A diffuse E-2 flux would be detectable at a minimum strength of E2*dN/dE = 1*10^-8 cm^-2s^-1sr^-1GeV. A gamma-ray burst model following the formulation of Waxman and Bahcall would result in a 5-sigma effect after the observation of 200 bursts in coincidence with satellite observations of the gamma-rays.

Muon Track Reconstruction and Data Selection Techniques in AMANDA

Abstract: The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ice between 1500 and 2000 m. The primary goal of this detector is to discover astrophysical sources of high-energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector. The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2° accuracy. © 2004 Elsevier B.V. All rights reserved.

Combined analysis of short-baseline neutrino experiments in the (3 + 1) and (3 + 2) sterile neutrino oscillation hypotheses

Abstract: We investigate adding two sterile neutrinos to resolve the apparent tension existing between short-baseline neutrino oscillation results and CPT-conserving, four-neutrino oscillation models. For both $(3+1)$ and $(3+2)$ models, the level of statistical compatibility between the combined dataset from the null short-baseline experiments Bugey, CHOOZ, CCFR84, CDHS, KARMEN, and NOMAD, on the one hand; and the LSND dataset, on the other, is computed. A combined analysis of all seven short-baseline experiments, including LSND, is also performed, to obtain the favored regions in neutrino mass and mixing parameter space for both models. Finally, four statistical tests to compare the $(3+1)$ and the $(3+2)$ hypotheses are discussed. All tests show that $(3+2)$ models fit the existing short-baseline data significantly better than $(3+1)$ models.

Solar models and solar neutrino oscillations

Abstract: We provide a summary of the current knowledge, theoretical and experimental, of solar neutrino fluxes and of the masses and mixing angles that characterize solar neutrino oscillations. We also summarize the principal reasons for performing new solar neutrino experiments and what we anticipate from future studies.

Are solar neutrino oscillations robust

Abstract: The robustness of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar neutrino data is considered in a more general framework where non-standard neutrino interactions (NSI) are present. Such interactions may be regarded as a generic feature of models of neutrino mass. The 766.3 ton-yr data sample of the KamLAND collaboration are included in the analysis, paying attention to the background from the reaction ^13C(\alpha,n) ^16O. Similarly, the latest solar neutrino fluxes from the SNO collaboration are included. In addition to the solution which holds in the absence of NSI (LMA-I) there is a 'dark-side' solution (LMA-D) with sin^2 theta_Sol = 0.70, essentially degenerate with the former, and another light-side solution (LMA-0) allowed only at 97% CL. More precise KamLAND reactor measurements will not resolve the ambiguity in the determination of the solar neutrino mixing angle theta_Sol, as they are expected to constrain mainly Delta m^2. We comment on the complementary role of atmospheric, laboratory (e.g. CHARM) and future solar neutrino experiments in lifting the degeneracy between the LMA-I and LMA-D solutions. In particular, we show how the LMA-D solution induced by the simplest NSI between neutrinos and down-type-quarks-only is in conflict with the combination of current atmospheric data and data of the CHARM experiment. We also mention that establishing the issue of robustness of the oscillation picture in the most general case will require further experiments, such as those involving low energy solar neutrinos.

Prospects of accelerator and reactor neutrino oscillation experiments for the coming ten years

Abstract: We analyze the physics potential of long baseline neutrino oscillation experiments planned for the coming ten years, where the main focus is the sensitivity limit to the small mixing angle �13. The discussed experiments include the conventional beam experiments MINOS, ICARUS, and OPERA, which are under construction, the planned superbeam experiments J-PARC to Super-Kamiokande and NuMI off-axis, as well as new reactor experiments with near and far detectors, represented by the Double-Chooz project. We perform a complete numerical simulation including systematics, correlations, and degeneracies on an equal footing for all experiments using the GLoBES software. After discussing the improvement of our knowledge on the atmospheric pa

Two-phase emission detector for measuring coherent neutrino-nucleus scattering

Abstract: Coherent scattering is a flavor-blind, high-rate, as yet undetected neutrino interaction predicted by the Standard Model. We propose to use a compact (kg-scale), two-phase (liquid-gas) argon ionization detector to measure coherent neutrino scattering off nuclei. In our approach, neutrino-induced nuclear recoils in the liquid produce a weak ionization signal, which is transported into a gas under the influence of an electric field, amplified via electroluminescence, and detected by phototubes or avalanche diodes. This paper describes the features of the detector, and estimates signal and background rates for a reactor neutrino source. Relatively compact detectors of this type, capable of detecting coherent scattering, offer a new approach to flavor-blind detection of man-made and astronomical neutrinos, and may allow development of compact neutrino detectors capable of nonintrusive real-time monitoring of fissile material in reactors.

Experiments For CP-Violation: A Giant Liquid Argon Scintillation, Cerenkov And Charge Imaging Experiment ?

Abstract: In this paper we address a class of ``ultimate'' generation experiments for the search of CP-violation in neutrino oscillations. Neutrino factories require large magnetized detectors. New generation superbeams or beta-beams need giant detectors. The liquid Argon TPC technology has great potentials for both applications. Although the ICARUS program has demonstrated that this technology is mature, the possibility to built a giant liquid argon TPC is viewed by many as a technically impossible and unsafe task. We argue that a giant liquid argon Cerenkov and charge Imaging experiment would be an ideal match for a superbeam or a betabeam. Such a detector would in addition cover a broad physics program, including the observation of atmospheric neutrinos, solar neutrinos, supernova neutrinos, and search for proton decays, in addition to the accelerator physics program. We show a potential implementation of such a giant LAr detector and argue that it could be technically feasible. The possibility to host such a detector in an underground cavern is under study.

Ultra-high energy neutrino fluxes: new constraints and implications

Abstract: We apply new upper limits on neutrino fluxes and the diffuse extragalactic component of the GeV γ-ray flux to various scenarios for ultra-high energy cosmic rays and neutrinos. As a result we find that extragalactic top-down sources cannot contribute significantly to the observed flux of highest energy cosmic rays, except if the AGASA flux normalization is too high by at least a factor of two. The explanation of the observed ultra-high energy cosmic ray flux by the decay products of Z bosons produced in ultra-high energy neutrino interaction with relic neutrino background is ruled out by recent data from GLUE and FORTE experiments, provided cosmological limits on neutrino mass and clustering apply.

Tau Air Showers from Earth

Abstract: We estimate the rate of observable horizontal and upward ? air showers (HORTAUs and UPTAUs, respectively) considering both the Earth's opacity and the contribution of the terrestrial atmosphere. Our result applies to most neutrino telescope projects, especially to the Extreme Universe Space Observatory (EUSO). Using a compact analytical formula, we calculate the effective target volumes and masses for ? air showers emerging from the Earth. The resulting model-independent effective masses for EUSO may encompass?at E 1019 eV?a huge average volume (1020 km3) compared to current neutrino experiments. Adopting simple power-law neutrino fluxes, dN?/dE? E-2 and E-1, calibrated to Greisen-Zapetin-Kuzmin (GZK) like and Z-burst-like models, we estimate that at E 1019 eV, nearly half a dozen horizontal shower events should be detected by EUSO in 3 yr of data collection, considering the 10% duty cycle efficiency and a minimal ? neutrino energy fluence ?E? 50 eV cm-2 s-1 sr-1. The detection of HORTAUs may test the guaranteed GZK neutrino flux (secondaries of photopion production due to ultra-high-energy cosmic-ray [UHECR] scattering onto 2.75 K cosmic background radiation). We also find that the equivalent mass for an outer layer made of rock is larger than the water mass, contrary to simplified all-rock/all-water Earth models and previous studies. Therefore, we expect an enhancement of neutrino detection along continental shelves near the highest mountain ranges, because of the better geometrical acceptance of Earth-skimming neutrinos. In this picture, the Auger experiment might reveal such an increase at E? 1018 eV (with 26 events in 3 yr) if the angular resolution (both in azimuth and zenith) reaches an accuracy of nearly 1? (or below); the angular accuracy depends on the the morphology of the Andes, the distance of each element of the array from the mountain range, and the local terrestrial magnetic fields. Such a high angular resolution is necessary to disentangle ? air showers from more abundant downward horizontal UHECRs. Finally, we show that the number of UHE-induced ? air-shower events is larger at energies lower than E? ~ 1020 or E? ~ 1019 eV; therefore we suggest an extension of the EUSO sensitivity at the lowest possible energy.

A Strong Test of Electroweak Theory Using Pulsating DB White Dwarf Stars as Plasmon Neutrino Detectors

Abstract: We demonstrate that plasmon neutrinos are the dominant form of energy loss in model white dwarf stars down to Teff ~ 25,000 K, depending on the stellar mass. The lower end of this range overlaps the observed temperatures for the V777 Her star (DBV) instability strip. The evolution of white dwarfs at these temperatures is driven predominantly by cooling, so this directly affects the stellar evolutionary timescale in proportion to the ratio of the neutrino energy loss to the photon energy loss. This evolutionary timescale is observable through the time rate of change of the pulsation periods. Although the unified electroweak theory of lepton interactions that is crucial for understanding neutrino production has been well tested in the high-energy regime, the approach presented here should result in an interesting low-energy test of the theory. We discuss observational strategies to achieve this goal.

Search for extraterrestrial point sources of neutrinos with AMANDA-II.

Abstract: The results of a search for point sources of high energy neutrinos in the northern hemisphere were presented using AMANDA-II data collected in the year 2000. The results included the flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic ray induced atmospheric neutrinos and misreconstructed downgoing cosmic-rays muons, which revealed no statistically significant neutrino point sources was also presented. It was shown that AMANDA-II had achieved the sensitivity required to probe known TeV γ-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and γ-ray fluxes were equal.

Relic neutrino absorption spectroscopy

Abstract: Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino.more » With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.« less

A Rotating Collapsar and Possible Interpretation of the LSD Neutrino Signal from SN 1987A

Abstract: We consider an improved rotational mechanism of the explosion of a collapsing supernova. We show that this mechanism leads to two-stage collapse with a phase difference of \sim 5 h. Based on this model, we attempt a new interpretation of the events in underground neutrino detectors on February 23, 1987, related to the supernova SN 1987A.

Signatures of supernova neutrino oscillations in the Earth mantle and core

Abstract: The Earth matter effects on supernova (SN) neutrinos can be identified at a single detector through peaks in the Fourier transform of their `inverse-energy' spectrum. The positions of these peaks are independent of the SN models and therefore the peaks can be used as a robust signature of the Earth matter effects, which in turn can distinguish between different neutrino mixing scenarios. Whereas only one genuine peak is observable when the neutrinos traverse only the Earth mantle, traversing also the core gives rise to multiple peaks. We calculate the strengths and positions of these peaks analytically and explore their features at a large scintillation detector as well as at a megaton water Cherenkov detector through Monte Carlo simulations. We propose a simple algorithm to identify the peaks in the actual data and quantify the chances of a peak identification as a function of the location of the SN in the sky.

Supernova relic neutrinos in liquid argon detectors

Abstract: We study the possibility of detecting the background of supernova relic neutrinos (SRN) with liquid argon time projection chamber (TPC) detectors. As far as this study is concerned, these experimental devices are mainly sensitive to electron neutrino signals, and could provide further information on both the supernova explosion mechanism and the star formation rate at redshifts . We study in detail the main contributions to background in the relevant energy range from 8B and hep solar neutrinos as well as from low energy atmospheric neutrino fluxes. Depending on the theoretical prediction for the SRN flux we find that for a 3 kton and a 100 kton liquid argon TPC detector the signal may be observed at the 1σ and 4σ level, respectively, with five years of data taking.

Experimental Study of Acoustic Ultra-High-Energy Neutrino Detection

Abstract: An existing array of underwater, large-bandwidth acoustic sensors has been used to study the detection of ultra-high-energy neutrinos in cosmic rays. Acoustic data from a subset of 7 hydrophones located at a depth of $\sim 1600$ m have been acquired for a total live time of 195 days. For the first time, a large sample of acoustic background events has been studied for the purpose of extracting signals from super-EeV showers. As a test of the technique, an upper limit for the flux of ultra-high-energy neutrinos is presented along with considerations relevant to the design of an acoustic array optimized for neutrino detection.

White paper report on using nuclear reactors to search for a value of theta13

Abstract: There has been superb progress in understanding the neutrino sector of elementary particle physics in the past few years. It is now widely recognized that the possibility exists for a rich program of measuring CP violation and matter effects in future accelerator {nu} experiments, which has led to intense efforts to consider new programs at neutrino superbeams, off-axis detectors, neutrino factories and beta beams. However, the possibility of measuring CP violation can be fulfilled only if the value of the neutrino mixing parameter {theta}{sub 13} is such that sin{sup 2} (2{theta}{sub 13}) greater than or equal to on the order of 0.01. The authors of this white paper are an International Working Group of physicists who believe that a timely new experiment at a nuclear reactor sensitive to the neutrino mixing parameter {theta}{sub 13} in this range has a great opportunity for an exciting discovery, a non-zero value to {theta}{sub 13}. This would be a compelling next step of this program. We are studying possible new reactor experiments at a variety of sites around the world, and we have collaborated to prepare this document to advocate this idea and describe some of the issues that are involved.

Decoherent neutrino mixing, dark energy and matter-antimatter asymmetry

Abstract: A CPT violating decoherence scenario can easily account for all the experimental evidence in the neutrino sector including Liquid Scincillator Neutrino Detector. In this work it is argued that this framework can also accommodate the dark energy content of the Universe, as well as the observed matter-antimatter asymmetry.

Shower power: isolating the prompt atmospheric neutrino flux using electron neutrinos

Abstract: At high energies, the very steep decrease of the conventional atmospheric component of the neutrino spectrum should allow the emergence of even small and isotropic components of the total spectrum, indicative of new physics, provided that they are less steeply decreasing, as generically expected One candidate is the prompt atmospheric neutrino flux, a probe of cosmic ray composition in the region of the knee as well as small-x QCD, below the reach of collider experiments A second is the diffuse extragalactic background due to distant and unresolved AGNs and GRBs, a key test of the nature of the highest-energy sources in the universe Separating these new physics components from the conventional atmospheric neutrino flux, as well as from each other, will be very challenging We show that the charged-current electron neutrino 'shower' channel should be particularly effective for isolating the prompt atmospheric neutrino flux, and that it is more generally an important complement to the usually considered charged-current muon neutrino 'track' channel These conclusions remain true even for the low prompt atmospheric neutrino flux predicted in a realistic cosmic ray scenario with heavy and varying composition across the knee (Candia and Roulet, 2003 J Cosmol Astropart Phys JCAP09(2003)005) We also improve the corresponding calculation of the neutrino flux induced by cosmic ray collisions with the interstellar medium

Neutrino signatures of the supernova - gamma-ray burst relationship

Abstract: We calculate the TeV-PeV neutrino fluxes of gamma-ray bursts associated with supernovae, based on the observed association between GRB 030329 and supernova SN 2003dh. The neutrino spectral flux distributions can test for possible delays between the supernova and gamma-ray burst events down to much shorter time scales than what can be resolved with photons. As an illustrative example, we calculate the probability of neutrino induced muon and electron cascade events in a km scale under-ice detector at the South Pole, from the GRB 030329. Our calculations demonstrate that km scale neutrino telescopes are expected to detect signals that will allow us to constrain supernova-GRB models.

A rotating collapsar and possible interpretation of the LSD neutrino signal from SN 1987A

Abstract: We consider an improved rotational mechanism of the explosion of a collapsing supernova. We show that this mechanism leads to two-stage collapse with a phase difference of ∼5 h. Based on this model, we attempt a new interpretation of the events in underground neutrino detectors on February 23, 1987, related to the supernova SN 1987A.

Neutrino properties studied with a triton source and a large spherical TPC

Abstract: The purpose of the present paper is to study the neutrino properties as they may appear in the low-energy neutrinos emitted in triton decay: 1 3 H → 2 3 He +e − + ν e with maximum neutrino energy of 18.6 keV . The technical challenges to this end can be summarized as building a very large Time Projection Counters (TPC) capable of detecting low-energy recoils, down to 100 eV , within the required low background constraints. More specifically we propose the development of a spherical gaseous TPC of about 10-m in radius and a 200 Mcurie triton source in the center of curvature. One can list a number of exciting studies, concerning fundamental physics issues, that could be made using a large-volume TPC and low-energy antineutrinos: (1) The oscillation length involving the small angle δ= sin θ 13 , directly measured in our ν e disappearance experiment, is fully contained inside the detector. Measuring the counting rate of neutrino–electron elastic scattering as function of the distance of the source will give a precise and unambiguous measurement of the oscillation parameters free of systematic errors. In fact first estimations show that even with a year's of data taking a sensitivity of a few percent for the measurement of the above angle will be achieved. (2) The low-energy detection threshold offers a unique sensitivity for the neutrino magnetic moment which is about two orders of magnitude beyond the current experimental limit of 10 −10 μ B . (3) Scattering at such low neutrino energies has never been studied and any departure from the expected behavior may be an indication of new physics beyond the standard model. We present a summary of various theoretical studies and possible measurements, including a precise measurement of the Weinberg angle at very low momentum transfer.

Decoupling supernova and neutrino oscillation physics with LAr TPC detectors

Abstract: Core collapse supernovae are a huge source of all flavour neutrinos. The flavour composition, energy spectrum and time structure of the neutrino burst from a galactic supernova can provide information about the explosion mechanism and the mechanisms of proto neutron star cooling. Such data can also give information about the intrinsic properties of the neutrino such as flavour oscillations. One important question is to understand to what extent the supernova and the neutrino physics can be decoupled in the observation of a single supernova. On one hand, the understanding of the supernova explosion mechanism is still plagued by uncertainties which have an impact on the precision with which one can predict time-, energy-?and flavour-dependent neutrino fluxes. On the other hand, the neutrino mixing properties are not fully known, since the type of mass hierarchy and the value of the ?13 angle are unknown, and in fact large uncertainty still exists on the prediction of the actual effect of neutrino oscillations in the event of a supernova explosion. In this paper we discuss the possibility of probing the neutrino mixing angle ?13 and the type of mass hierarchy from the detection of supernova neutrinos with a liquid argon TPC detector. Moreover, describing the supernova neutrino emission by a set of five parameters (average energy of the different neutrino flavours, their relative luminosity and the total supernova binding energy), we quantitatively study how it is possible to constrain these parameters. A characteristic feature of the liquid argon TPC is the accessibility to four independent detection channels ((1) elastic scattering off electrons, (2) charged neutrino and (3) antineutrino and (4) neutral currents on argon nuclei) which have different sensitivities to electron neutrino, anti-electron neutrino and other neutrino flavours (muon and tau (anti)neutrinos). This allows us to over-constrain the five supernova and the flavour mixing parameters and to some extent disentangle neutrino from supernova physics. Numerically, we find that a very massive liquid argon detector (O(100?kton)) is needed to perform accurate measurements of these parameters, specially in supernova scenarios where the average energies of electron and non-electron neutrinos are similar (almost degenerate neutrinos) or if no information about the ?13 mixing angle and type of mass hierarchy is available.

The supernova relic neutrino backgrounds at KamLAND and Super-Kamiokande

Abstract: We calculate the supernova relic neutrino (SRN) background flux for the KamLAND and Super-Kamiokande (Super-K) detectors, motivated by the reduction in background at Super-K and new results for the star formation history (e.g., from the Sloan digital sky survey (SDSS)). Our best estimate for the flux at Super-K is slightly below, but very close to, the current Super-K upper limit. The Super-K upper limit is already inconsistent with a range of star formation histories allowed by the SDSS data. We estimate that the SRN background should be detected (at 1σ) at Super-K in a total of about 9 years (including the existing 4 years) of data. While KamLAND is a much smaller detector compared to Super-K, it profits from being practically background free and from its sensitivity to the lower energy supernova neutrinos. KamLAND could make a 1σ detection of the SRNs with a total of about 5 years of data. Given the small expected SRN event rate, we also consider the detection of the SRNs in a modified Super-K detector with a lower threshold and reduced background where the time to detection can be reduced by a factor of ten relative to the existing Super-K estimate.

Neutrino interferometry in curved spacetime

Abstract: Gravitational lensing introduces the possibility of multiple (macroscopic) paths from an astrophysical neutrino source to a detector. Such a multiplicity of paths can allow for quantum mechanical interference to take place that is qualitatively different from neutrino oscillations in flat space. After an illustrative example clarifying some underappreciated subtleties of the phase calculation, we derive the form of the quantum mechanical phase for a neutrino mass eigenstate propagating nonradially through a Schwarzschild metric. We subsequently determine the form of the interference pattern seen at a detector. We show that the neutrino signal from a supernova could exhibit the interference effects we discuss were it lensed by an object in a suitable mass range. We finally conclude, however, that---given current neutrino detector technology---the probability of such lensing occurring for a (neutrino-detectable) supernova is tiny in the immediate future.