48,946 research outputs found
Comparisons of results obtained with several proton penetration codes, part 2
Penetration codes for solar flare proton spectrum incident on semi-infinite slabs of aluminum and of tissu
Fully Constrained Majorana Neutrino Mass Matrices Using
In 2002, two neutrino mixing ansatze having trimaximally-mixed middle
() columns, namely tri-chi-maximal mixing () and
tri-phi-maximal mixing (), were proposed. In 2012, it was
shown that with as well as
with leads to the solution,
, consistent with the
latest measurements of the reactor mixing angle, . To obtain
and
, the type~I see-saw
framework with fully constrained Majorana neutrino mass matrices was utilised.
These mass matrices also resulted in the neutrino mass ratios,
.
In this paper we construct a flavour model based on the discrete group
and obtain the aforementioned results. A Majorana neutrino
mass matrix (a symmetric matrix with 6 complex degrees of freedom)
is conveniently mapped into a flavon field transforming as the complex 6
dimensional representation of . Specific vacuum alignments
of the flavons are used to arrive at the desired mass matrices.Comment: 20 pages, 1 figure. arXiv admin note: substantial text overlap with
arXiv:1402.085
Deviations from Tribimaximal Neutrino Mixing using a Model with Symmetry
We present a model of neutrino mixing based on the flavour group
in order to account for the observation of a non-zero reactor mixing angle
(). The model provides a common flavour structure for the
charged-lepton and the neutrino sectors, giving their mass matrices a
`circulant-plus-diagonal' form. Mass matrices of this form readily lead to
mixing patterns with realistic deviations from tribimaximal mixing, including
non-zero . With the parameters constrained by existing
measurements, our model predicts an inverted neutrino mass hierarchy. We obtain
two distinct sets of solutions in which the atmospheric mixing angle lies in
the first and the second octants. The first (second) octant solution predicts
the lightest neutrino mass, ()
and the phase, (), offering the possibility of large observable violating
effects in future experiments.Comment: 9 pages, 3 figure
Incoherence of Bose-Einstein condensates at supersonic speeds due to quantum noise
We calculate the effect of quantum noise in supersonic transport of
Bose-Einstein condensates. When an obstacle obstructs the flow of atoms,
quantum fluctuations cause atoms to be scattered incoherently into random
directions. This suppresses the propagation of Cherenkov radiation, creating
quantum turbulence and a crescent of incoherent atoms around the obstacle. We
observe similar dynamics if the BEC is stirred by a laser beam: crescents of
incoherent atoms are emitted from the laser's turning-points. Finally, we
investigate supersonic flow through a disordered potential, and find that the
quantum fluctuations generate an accumulation of incoherent atoms as the
condensate enters the disorder.Comment: 6 pages, 5 figure
Teacher and student perceptions of the development of learner autonomy : a case study in the biological sciences
Biology teachers in a UK university expressed a majority view that student learning autonomy increases with progression through university. A minority suggested that pre-existing diversity in learning autonomy was more important and that individuals not cohorts differ in their learning autonomy. They suggested that personal experience prior to university and age were important and that mature students are more autonomous than 18-20 year olds. Our application of an autonomous learning scale (ALS) to four year-groups of biology students confirmed that the learning autonomy of students increases through their time at university but not that mature students are necessarily more autonomous than their younger peers. It was evident however that year of study explained relatively little
Multi-timer for milking studies
Recent research into milking machine operation has proved that the belief of old-time hand-milkers that fast milking was good milking was soundly based.
In current practice the emphasis is on convenient shed and yard design and systematic routine in handling the cows. This permits a high throughput of cows and a high output of milk per labour unit.
The multi-timer designed and built by Mr. G. W. R. Scott and described in this article will prove most valuable for pinpointing where time is lost
Spontaneous creation of non-zero angular momentum modes in tunnel-coupled two-dimensional degenerate Bose gases
We investigate the dynamics of two tunnel-coupled two-dimensional degenerate
Bose gases. The reduced dimensionality of the clouds enables us to excite
specific angular momentum modes by tuning the coupling strength, thereby
creating striking patterns in the atom density profile. The extreme sensitivity
of the system to the coupling and initial phase difference results in a rich
variety of subsequent dynamics, including vortex production, complex
oscillations in relative atom number and chiral symmetry breaking due to
counter-rotation of the two clouds.Comment: 7 pages, 5 figure
Charged particle radiation damage in semiconductors, 15 - Study and determination of an optimum design for space utilized lithium doped solar cells, part 1 Interim final report
Hall coefficient measurements of irradiated lithium doped solar cell
Quantifying Finite Temperature Effects in Atom Chip Interferometry of Bose-Einstein Condensates
We quantify the effect of phase fluctuations on atom chip interferometry of
Bose-Einstein condensates. At very low temperatures, we observe small phase
fluctuations, created by mean-field depletion, and a resonant production of
vortices when the two clouds are initially in anti-phase. At higher
temperatures, we show that the thermal occupation of Bogoliubov modes makes
vortex production vary smoothly with the initial relative phase difference
between the two atom clouds. We also propose a technique to observe vortex
formation directly by creating a weak link between the two clouds. The position
and direction of circulation of the vortices is subsequently revealed by kinks
in the interference fringes produced when the two clouds expand into one
another. This procedure may be exploited for precise force measurement or
motion detection.Comment: 7 pages, 5 figure
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