A molecular dynamics study of the thermal properties of thorium oxide

There is growing interest in the exploitation of the thorium nuclear fuel cycle as an alternative to that of uranium. As part of a wider study of the suitability of thorium dioxide (thoria) as a nuclear fuel, we have used molecular dynamics to investigate the thermal expansion, oxygen diffusion, and heat capacity of pure thoria and uranium doped (1-10%) thoria between 1500K and 3600 K. Our results indicate that the thermal performance of the thoria matrix, even when doped with 10%U, is comparable to, and possibly better than, that of UO2

Spin transference and magnetoresistance amplification in a transistor

A current problem in semiconductor spin-based electronics is the difficulty of experimentally expressing the effect of spin-polarized current in electrical circuit measurements. We present a theoretical solution with the principle of transference of the spin diffusion effects in the semiconductor channel of a system with three magnetic terminals. A notable result of technological consequences is the room temperature amplification of the magneto-resistive effect, integrable with electronics circuits, demonstrated by computation of current dependence on magnetization configuration in such a system with currently achievable parameters.Comment: 4 pages, 3 figures, revised version, changed title, new figure

GEANT4 Target Simulations for Low Energy Medical Applications

The GEANT4 code offers an extensive set of hadronic models for various projectiles and energy ranges. These models include theoretical, parameterized and, for low energy neutrons, data driven models. Theoretical or semi-empirical models sometimes cannot reproduce experimental data at low energies(<100MeV), especially for low Z elements, and therefore recent GEANT4 developments included a new particle\hp package which uses evaluated nuclear databases for proton interactions below 200 MeV. These recent developments have been used to study target designs for low energy proton accelerators, as replacements of research reactors, for medical applications. Presented in this paper are results of benchmarking of these new models for a range of targets, from lithium neutron production targets to molybdenum isotope production targets, with experimental data. Also included is a discussion of the most promising target designs that have currently been studied

A Study of Sir Philip Sidney\u27s Astrophel and Stella

The general purpose of this thesis is to determine the literary value of Sir Philip Sidney\u27s Astrophel and Stella. First of all, an analysis of the sonnet cycle as such is undertaken to evaluate these lyrics with respect to the unity and logical development of theme. Secondly, a close study of the content material is proposed with the aim of reflecting the poet\u27s ability to personalize and adapt conventionalized modes of expression and of portraying his excellence as a poet-courtier and literary craftsman. Thirdly, two research problems are projected--one, relating to the identity of the lady of the sonnets, the other, relating to the date of the composition of the sonnets--so that an acceptable solution of these controversial problems can be proffered. Finally, an attempt is made to make manifest Sidney\u27s originality in order to offset the common criticism that the sonnet sequence is a conventional imitation

5MW Power Upgrade Studies of the ISIS TS1 Target

The increasing demand for neutron production at the ISIS neutron spallation source has motivated a study of an upgrade of the production target TS1. This study focuses on a 5 MW power upgrade and complete redesign of the ISIS TS1 spallation target, reflector and neutron moderators. The optimisation of the target-moderator arrangement was done in order to obtain the maximum neutron output per unit input power. In addition, at each step of this optimisation study, the heat load and thermal stresses were calculated to ensure the target can sustain the increase in the beam power