21,380 research outputs found
How the minuscule can contribute to the big picture: the neutron electric dipole moment project at TRIUMF
A permanent electric dipole moment (EDM) of a fundamental particle violates
both parity (P) and time (T) reversal symmetry and combined charge and parity
(CP) reversal symmetry if the combined reversal of charge, parity \textit{and}
time (CPT) is preserved. It is a very promising place to search for physics
beyond the Standard Model. Ultracold neutrons (UCN) are the ideal tool to study
the neutron electric dipole moment since they can be observed for hundreds of
seconds. This article summarizes the current searches for the neutron EDM using
UCN and introduces the project to measure the neutron electric dipole moment at
TRIUMF using its unique accelerator driven spallation neutron and liquid helium
UCN source. The aim is to reach a sensitivity for the neutron EDM of around
cm.Comment: 12 pages, 6 figures, MENU 2016 Conference, Kyoto, Japa
Preparation of linear hydroxy substituted polyphosphazenes
The synthesis of partially hydroxy-substituted phosphazene prepolymers amenable to processing into cellular, flexible polyurethane foams was investigated. Factors determined include (1) the environment of the hydroxyl group; (2) the ease of the hexachlorocyclotriphosphazene polymerization; (3) the nature of the nonreactive substituents; and (4) the mode of introduction of the hydroxyl entity. The specific approaches taken, the rationale of the selections made, and the results are discussed
The NJL-jet model for quark fragmentation functions
A description of fragmentation functions which satisfy the momentum and
isospin sum rules is presented in an effective quark theory. Concentrating on
the pion fragmentation function, we first explain why the elementary (lowest
order) fragmentation process q --> q \pi is completely inadequate to describe
the empirical data, although the "crossed" process \pi --> q \bar{q} describes
the quark distribution functions in the pion reasonably well. Taking into
account cascade-like processes in a generalized jet-model approach, we then
show that the momentum and isospin sum rules can be satisfied naturally,
without the introduction of ad hoc parameters. We present results for the
Nambu--Jona-Lasinio (NJL) model in the invariant mass regularization scheme and
compare them with the empirical parametrizations. We argue that the NJL-jet
model, developed herein, provides a useful framework with which to calculate
the fragmentation functions in an effective chiral quark theory.Comment: 21 pages, 7 figure
The structure and possible origins of stacking faults in gamma-yttrium disilicate
Parallel stacking faults on (010) planes are frequently observed in hot-pressed Y2Si2O7. A combination of conventional dark-field imaging and high-resolution transmission electron microscopy was used to investigate the structure of these faults and it was found that they consist of the repeat of one layer of the two layer γ-Y2Si2O7 structure with an associated in-plane rigid body displacement. The resulting structure was confirmed by image simulation of high-resolution images from two perpendicular projections. A model for the formation of the stacking faults is proposed as a consequence of a transformation from β-Y2Si2O7 to γ-Y2Si2O7 in the hot pressing
Preparation of perfluorinated 1,2,4-oxadiazoles
Fluorinated alkyl or alkylether 1,2,4 oxadiazole compounds are prepared by cyclizing the corresponding alkyl or alkylether imidoyl amidoximes in vacuo or in an inert atmosphere at a temperature within the range of 40 C to 100 C. for a period of 8 to 144 hours in the presence of an acid compound which can accept ammonia to form a salt. The imidoyl amidoximes usable in this process are either polymeric or nonpolymeric. The products, when polymeric, have excellent heat, chemical and solvent resistance
Synthesis of perfluoroalkylene aromatic diamines
Analogues of methylene dianilines were synthesized, in which the methylene group between the two aromatic nuclei was replaced by various perfluoroalkylene linkage. The hydrolytic thermal, and thermal oxidative stabilities of PMR Polyimides derived from these diamines were determined. Three types of PMR Polyimide discs were fabricated from the dimethyl ester of 3,3', 4,4'-benzophenonetetracarboxylic acid, the methyl ester of 5-norbornene-2,3-dicarboxylic acid, and one of the following three diamines: methyl dianiline, 1,3-bis(4-aminophenyl)hexafluoropropane, and 2,2-bis(4-aminophenyl)hexafluoropropane. The polyimide based on 2,2-bis(4-aminophenyl)hexafluoropropane exhibited the best hydrolytic, thermal, and thermal oxidative stability as determined by moisture uptake and thermogravimetric analysis
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