11,402 research outputs found
Manipulating a Neutrino Spectrum to Maximize the Physics Potential from a Low Energy Beta Beam
Proposed low energy beta beam facilities would be capable of producing
intense beams of neutrinos (anti-neutrinos) with well defined spectra. We
present analytic expressions and numerical results which accurately show how
the total neutrino flux reaching the detector depends on the geometry of the
source and the detector. Several authors have proposed measurements which
require using different flux shapes. We show that detectors of different sizes
and shapes will receive neutrino fluxes with different spectral shapes, and
that the spectral shape will also be different in different regions of the same
detector. Our findings also show that for certain measurements systematic
uncertainties and run time can be reduced.Comment: 18 pages, 10 figure
Oscillation Effects and Time Variation of the Supernova Neutrino Signal
The neutrinos detected from the next Galactic core-collapse supernova will
contain valuable information on the internal dynamics of the explosion. One
mechanism leading to a temporal evolution of the neutrino signal is the
variation of the induced neutrino flavor mixing driven by changes in the
density profile. With one and two dimensional hydrodynamical simulations we
identify the behavior and properties of prominent features of the explosion.
Using these results we demonstrate the time variation of the neutrino crossing
probabilities due to changes in the MSW neutrino transformations as the star
explodes by using the S-matrix - Monte Carlo - approach to neutrino
propagation. After adopting spectra for the neutrinos emitted from the
proto-neutron star we calculate for a Galactic supernova the evolution of the
positron spectra within a water Cerenkov detector and the ratio of charged
current to neutral current event rates for a heavy water - SNO like - detector
and find that these detector signals are feasible probes of a number of
explosion features
Neutrino Capture and r-Process Nucleosynthesis
We explore neutrino capture during r-process nucleosynthesis in
neutrino-driven ejecta from nascent neutron stars. We focus on the interplay
between charged-current weak interactions and element synthesis, and we
delineate the important role of equilibrium nuclear dynamics. During the period
of coexistence of free nucleons and light and/or heavy nuclei, electron
neutrino capture inhibits the r-process. At all stages, capture on free
neutrons has a larger impact than capture on nuclei. However, neutrino capture
on heavey nuclei by itself, if it is very strong, is also detrimental to the
r-process until large nuclear equilibrium clusters break down and the classical
neutron-capture phase of the r-process begins. The sensitivity of the r-process
to neutrino irradiation means that neutrino-capture effects can strongly
constrain the r-process site, neutrino physics, or both. These results apply
also to r-process scenarios other than neutrino-heated winds.Comment: 20 pages, 17 figures, Submitted to Physical Review
Induced antiferromagnetism and large magnetoresistances in RuSr2(Nd,Y,Ce)2Cu2O10-d ruthenocuprates
RuSr2(Nd,Y,Ce)2Cu2O10-d ruthenocuprates have been studied by neutron
diffraction, magnetotransport and magnetisation measurements and the electronic
phase diagram is reported. Separate Ru and Cu spin ordering transitions are
observed, with spontaneous Cu antiferromagnetic order for low hole doping
levels p, and a distinct, induced-antiferromagnetic Cu spin phase in the 0.02 <
p < 0.06 pseudogap region. This ordering gives rise to large negative
magnetoresistances which vary systematically with p in the
RuSr2Nd1.8-xY0.2CexCu2O10-d series. A collapse of the magnetoresistance (MR)
and magnetisation in the pre-superconducting region may signify the onset of
superconducting fluctuations.Comment: 22 pages, 11 figure
A method of determining attitude from magnetometer data only
Presented here is a new algorithm to determine attitude using only magnetometer data under the following conditions: (1) internal torques are known and (2) external torques are negligible. Torque-free rotation of a spacecraft in thruster firing acquisition phase and its magnetic despin in the B-dot mode give typical examples of such situations. A simple analytical formula has been derived in the limiting case of a spacecraft rotating with constant angular velocity. The formula has been tested using low-frequency telemetry data for the Earth Radiation Budget Satellite (ERBS) under normal conditions. Observed small oscillation of body-fixed components of the angular velocity vector near their mean values result in relatively minor errors of approximately 5 degrees. More significant errors come from processing digital magnetometer data. Higher resolution of digitized magnetometer measurements would significantly improve the accuracy of this deterministic scheme. Tests of the general version of the developed algorithm for a free-rotating spacecraft and for the B-dot mode are in progress
How might your staff react to news of an institutional merger? - A psychological contract approach
Purpose: To understand the nature of staff/ employee (i.e. learning and teaching, curriculum support, and administrative staff) perceptions, anxieties and worries about early merger change in the UK further education (FE) sector.
Design/methodology/approach: Survey data was collected from 128 out of 562 employees to examine perceptions of psychological contract (post-merger announcement) on an FE college in England. Paired t-tests were used to analyse quantitative data. Additionally, a content analysis of open-ended questions was incorporated as part of a combined methods survey evaluation approach for discussion and triangulation purposes.
Findings: Quantitative results from t-tests showed there had been a decrease in the perception of fulfilled obligations in nine of the ten areas of the psychological contract. Qualitative results indicated that communications, job security and uncertainty were common negative outcomes post-merger announcement. Implications for education managers from the case study include: a need for improved organizational communication; developing trust and mentorship for greater employee support, as well as; promoting further employee training and new opportunities for teamwork.
Research limitations/implications: Psychological contract theories for evaluating organizational change are useful given the recent interest in sharing public services and institutional mergers in the UK. This research demonstrates the benefits of using psychological contract, as well as how to apply such an evaluation for understanding staff concerns.
Originality/value: The article demonstrates a usable (psychological contract) survey evaluation approach for studying the impact of early merger change on staff in the FE, or higher (HE) education sectors in the UK (or elsewhere)
K-shell x-ray spectroscopy of atomic nitrogen
Absolute {\it K}-shell photoionization cross sections for atomic nitrogen
have been obtained from both experiment and state-of-the-art theoretical
techniques. Due to the difficulty of creating a target of neutral atomic
nitrogen, no high-resolution {\it K}-edge spectroscopy measurements have been
reported for this important atom. Interplay between theory and experiment
enabled identification and characterization of the strong
resonance features throughout the threshold region. An experimental value
of 409.64 0.02 eV was determined for the {\it K}-shell binding energy.Comment: 4 pages, 2 graphs, 1 tabl
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