IceCube Sterile Neutrino Searches

Anomalies in short baseline experiments have been interpreted as evidence for additional neutrino mass states with large mass splittings from the known, active flavors. This explanation mandates a corresponding signature in the muon neutrino disappearance channel, which has yet to be observed. Searches for muon neutrino disappearance at the IceCube neutrino telescope presently provide the strongest limits in the space of mixing angles for eV-scale sterile neutrinos. This proceeding for the Very Large Volume Neutrino Telescopes (VLVnT) Workshop summarizes the IceCube analyses that have searched for sterile neutrinos and describes ongoing work toward enhanced, high-statistics sterile neutrino searches.Comment: Proceeding for the VLVNT2018 Conferenc

Dynamical Pion Collapse and the Coherence of Conventional Neutrino Beams

In this paper we consider the coherence properties of neutrinos produced by the decays of pions in conventional neutrino beams. Using a multi-particle density matrix formalism we derive the oscillation probability for neutrinos emitted by a decaying pion in an arbitrary quantum state. Then, using methods from decoherence theory we calculate the pion state which evolves through interaction with decay-pipe gases in a typical accelerator neutrino experiment. These two ingredients are used to obtain the distance scales for neutrino beam coherence loss. We find that for the known neutrino mass splittings, no non-standard oscillation effects are expected on terrestrial baselines. Heavy sterile neutrinos may experience terrestrial loss of coherence, and we calculate both the distance over which this occurs and the energy resolution required to observe the effect. By treating the pion-muon-neutrino-environment system quantum mechanically, neutrino beam coherence properties are obtained without assuming arbitrary spatial or temporal scales at the neutrino production vertex.Comment: 13 pages, 10 figures. v2: Minor typographical corrections v3: Accepted for publication in Phys.Rev.

New meanings from old buildings

The three modest house projects described here are by three fellow travellers — the two authors and David Lea — interested in the Organic side of Modernism. Conversational partners who have worked together in various capacities over many years, they share a common conviction about ‘working with the given

Vibrational transfer functions for base excited systems

Computer program GD203 develops transfer functions to compute governing vibration environment for complex structures subjected to a base motion

Surface brightness measurements for APM galaxies

This paper considers some simple surface brightness (SB) estimates for galaxies in the Automated Plate Measuring Machine (APM) catalogue in order to derive homogeneous SB data for a very large sample of faint galaxies. The isophotal magnitude and area are used to estimate the central surface brightness and total magnitude based on the assumption of an exponential SB profile. The surface brightness measurements are corrected for field effects on each UK Schmidt plate and the zero-point of each plate is adjusted to give a uniform sample of SB and total magnitude estimates over the whole survey. Results are obtained for 2.4 million galaxies with blue photographic magnitudes brighter than b_J = 20.5 covering 4300 deg^2 in the region of the south galactic cap. Almost all galaxies in our sample have central surface brightness in the range 20 to 24 b_J mag per arcsec^2. The SB measurements we obtain are compared to previous SB measurements and we find an acceptable level of error of +/- 0.2 b_J mag per arcsec^2. The distribution of SB profiles is considered for different galaxy morphologies for the bright APM galaxies. We find that early-type galaxies have more centrally concentrated profiles.Comment: 14 pages, 17 figures, accepted for publication in MNRA