114,058 research outputs found
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.
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
Nature of fault planes in solid neutron star matter
The properties of tectonic earthquake sources are compared with those deduced
here for fault planes in solid neutron-star matter. The conclusion that
neutron-star matter cannot exhibit brittle fracture at any temperature or
magnetic field is significant for current theories of pulsar glitches, and of
the anomalous X-ray pulsars and soft-gamma repeaters.Comment: 5 AAS LaTeX pages 1 eps figur
From Service to Experience: Understanding and Defining the Hospitality Business
Failure adequately to define or understand hospitality as a commercial phenomenon has created a fragmented academic environment and a schizophrenia in the industry that has the potential to limit its development as a global industry. This article suggests that, by redefining hospitality as behaviour and experience, a new perspective emerges that has exciting implications for the management of hospitality businesses. A framework to describe hospitality in the commercial domain is proposed. This framework suggests a focus on the host–guest relationship, generosity, theatre and performance, ‘lots of little surprises’, and the security of strangers – a focus that provides guests with experiences that are personal, memorable and add value to their lives
Does money matter in inflation forecasting?.
This paper provides the most fully comprehensive evidence to date on whether or not monetary aggregates are valuable for forecasting US inflation in the early to mid 2000s. We explore a wide range of different definitions of money, including different methods of aggregation and different collections of included monetary assets. In our forecasting experiment we use two non-linear techniques, namely, recurrent neural networks and kernel recursive least squares regression - techniques that are new to macroeconomics. Recurrent neural networks operate with potentially unbounded input memory, while the kernel regression technique is a finite memory predictor. The two methodologies compete to find the best fitting US inflation forecasting models and are then compared to forecasts from a naive random walk model. The best models were non-linear autoregressive models based on kernel methods. Our findings do not provide much support for the usefulness of monetary aggregates in forecasting inflation
Photodegradation Mechanisms of Tetraphenyl Butadiene Coatings for Liquid Argon Detectors
We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB)
coatings of the type used in neutrino and dark matter liquid argon experiments.
Using gas chromatography coupled to mass spectrometry we have detected the
ultraviolet-blocking impurity benzophenone (BP). We monitored the drop in
performance and increase of benzophenone concentration in TPB plates with
exposure to ultraviolet (UV) light, and demonstrate the correlation between
these two variables. Based on the presence and initially exponential increase
in the concentration of benzophenone observed, we propose that TPB degradation
is a free radical-mediated photooxidation reaction, which is subsequently
confirmed by displaying delayed degradation using a free radical inhibitor.
Finally we show that the performance of wavelength-shifting coatings of the
type envisioned for the LBNE experiment can be improved by 10-20%, with
significantly delayed UV degradation, by using a 20% admixture of
4-tert-Butylcatechol.Comment: 12 pages, 9 figures. Submitted to JINS
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