HELAC: a package to compute electroweak helicity amplitudes

HELAC is a FORTRAN based package that is able to compute efficiently helicity amplitudes for arbitrary scattering processes within the standard electroweak theory. The algorithm exploits the virtues of the Dyson-Schwinger equations as compared to the traditional Feynman graph approach. All electroweak vertices are included in both the unitary and Feynman gauges, and computations including all mass effects are available. A version performing multi-precision computations with arbitrary - user defined - accuracy is also included, allowing access to any phase space point for arbitrary high energies.Comment: 14 page

‘Multilingual Mindset’:a New Perspective for Student Transition in Higher Education

Student Transition into and out of higher education (HE) is a theme where a lot has been written, explored and analysed. The aim of this opinion piece is to suggest a new pragmatic definition of ‘transition’, based on multilingual approaches to teaching and learning. It will also demonstrate some areas of relevance for this type of theory, providing a novel perspective in monoglot cultures. After reviewing some definitions of transition suggested by existing academic literature, the paper calls for the establishment of a ‘multilingual mindset’ in the field of HE. A ‘multilingual mindset’ could inform theoretical debate on transition, addressing the existing strong trends for the encouragement of Internationalisation in higher education. It recognises those challenges with transition which stem from cultural and linguistic difference and emphasises particularly those which are invisible, or difficult to approach, in monoglot cultures. Accounts of current practice within the scope of a ‘multilingual mindset’, along with personal reflections from a Scottish University perspective, are considered. The paper is written in the hope of providing food for thought, encouraging further experimentation and, perhaps, public exploration and enhancement of this culturally important perspective: that is dealing with Student Transition in Higher Education with a ‘multilingual mindset’

HELAC-PHEGAS: automatic computation of helicity amplitudes and cross sections

HELAC-PHEGAS is a FORTRAN based package that is able to compute automatically and efficiently tree-order helicity amplitudes and cross sections for arbitrary scattering processes within the standard electroweak theory and QCD. The algorithm for the amplitude computation, HELAC, exploits the virtues of the Dyson-Schwinger equations. The phase-space generation algorithm, PHEGAS, constructs all possible kinematical mappings dictated by the amplitude under consideration. Combined with mutichannel self-optimized Monte Carlo integration it results to efficient cross section evaluation.Comment: 4 pages, LaTeX, to appear in the proceedings of the VII International Workshop on Advanced Computing and Analysis Technics in Physics Research, ACAT 2000, Fermilab, October 16-20, 200

Artificial control of the bias-voltage dependence of tunnelling anisotropic magnetoresistance using quantization in a single-crystal ferromagnet

A major issue in the development of spintronic memory devices is the reduction of the power consumption for the magnetization reversal. For this purpose, the artificial control of the magnetic anisotropy of ferromagnetic materials is of great importance. Here, we demonstrate the control of the carrier-energy dependence of the magnetic anisotropy of the density of states (DOS) using the quantum size effect in a single-crystal ferromagnetic material, GaMnAs. We show that the mainly two-fold symmetry of the magnetic anisotropy of DOS, which is attributed to the impurity band, is changed to a four-fold symmetry by enhancing the quantum size effect in the valence band of the GaMnAs quantum wells. By combination with the gate-electric field control technique, our concept of the usage of the quantum size effect for the control of the magnetism will pave the way for the ultra-low-power manipulation of magnetization in future spintronic devices.Comment: 9 pages, 7 figure

Geant4 based simulations for novel neutron detector development

A Geant4-based Python/C++ simulation and coding framework, which has been developed and used in order to aid the R&D efforts for thermal neutron detectors at neutron scattering facilities, is described. Built upon configurable geometry and generator modules, it integrates a general purpose object oriented output file format with meta-data, developed in order to facilitate a faster turn-around time when setting up and analysing simulations. Also discussed are the extensions to Geant4 which have been implemented in order to include the effects of low-energy phenomena such as Bragg diffraction in the polycrystalline support materials of the detector. Finally, an example application of the framework is briefly shown.Comment: Proceedings for the 20th International Conference on Computing in High Energy and Nuclear Physics (CHEP

Suppression of intrinsic neutron background in the Multi-Grid detector

One of the key requirements for neutron scattering instruments is the Signal-to-Background ratio (SBR). This is as well a design driving requirement for many instruments at the European Spallation Source (ESS), which aspires to be the brightest neutron source of the world. The SBR can be effectively improved with background reduction. The Multi-Grid, a large-area thermal neutron detector with a solid boron carbide converter, is a novel solution for chopper spectrometers. This detector will be installed for the three prospective chopper spectrometers at the ESS. As the Multi-Grid detector is a large area detector with a complex structure, its intrinsic background and its suppression via advanced shielding design should be investigated in its complexity, as it cannot be naively calculated. The intrinsic scattered neutron background and its effect on the SBR is determined via a detailed Monte Carlo simulation for the Multi-Grid detector module, designed for the CSPEC instrument at the ESS. The impact of the detector vessel and the neutron entrance window on scattering is determined, revealing the importance of an optimised internal detector shielding. The background-reducing capacity of common shielding geometries, like side-shielding and end-shielding is determined by using perfect absorber as shielding material, and common shielding materials, like B$_{4}$C and Cd are also tested. On the basis of the comparison of the effectiveness of the different shielding topologies and materials, recommendations are given for a combined shielding of the Multi-Grid detector module, optimised for increased SBR.Comment: 26 pages, 18 figures, revise

Exploring language education in Scotland:multilingual aspiration in a monolingual perspective

Scotland attempts to dispel the hegemonic identity of a ‘monolingual country’. The aim of this paper is to explore the educational habitus in contemporary Scotland as articulated by two mechanisms. These are: efforts to promote linguistic vitality and language revitalization, with the development of new curricula and pedagogies; and the working of governing mechanisms and policy instruments, particularly the 1+ 2 Language Approach (Scottish Government 2012). With this in mind, specific policy documents such as 1+2 Language Policy (Scottish Government 2012), National Gaelic Language Plan 2012-2017 (Bòrd na Gàidhlig 2012), Consultation Paper of Gaelic Medium Education (GME) Bill (Scottish Government 2014) and their related documents were studied. A discursive analytic tool was used: Spolsky’s (2004, 2009, 2012) a three component model of language policy – practices, beliefs and management. According to Spolsky, practices “are the observable behaviors and choices” (2009, p. 4); beliefs “are the values or statuses assigned to named languages, varieties and features” (2009, p. 4) and management is the explicit and observable effort… to modify practices and beliefs” (2009, p. 4)