Paul van Kampen

4d→5p transitions in the extreme ultraviolet photoabsorption spectra of Sn II and Sn III

The photoabsorption spectrum of a tin laser-produced plasma has been recorded in the 23-33 eV region using the dual laser plasma technique. 4d→5p transitions from the 4d105s25p ground state of Sn II and from the 4d105s2 ground and 4d105s5p excited states of Sn III were observed and new features identified with the aid of multiconfiguration Hartree-Fock calculations. The relative intensities of transitions in Sn III indicate a departure from local thermodynamic equilibrium conditions in the absorbing plasma.

Lorentz contraction and current-carrying wires

The force between two parallel current-carrying wires is investigated in the rest frames of the ions and the electrons. A straightforward Lorentz transformation shows that what appears as a purely magnetostatic force in the ion frame appears as a combined magnetostatic and electrostatic force in the electron frame. The derivation makes use of a reasonably well-known problem of a charged particle moving parallel to a current-carrying wire, which is often used to illustrate that what appears as a purely electrostatic force in one frame appears as a purely magnetostatic force in another. This paper, aimed at undergraduate electromagnetism and special relativity courses, serves to dispel the notion that this makes either the electrostatic or the magnetostatic force redundant.

EUV photoabsorption spectra of Cd II and Cd III

The photoabsorption spectrum of singly ionized cadmium has been measured in the 23.6–110 eV region using the dual laser plasma technique. We have observed many of the 4d105s → 4d95s np, mf transitions (7 ≤ n ≤ 9, 4 ≤ m ≤ 9) for the first time and identified them with the aid of Hartree–Fock and quantum defect calculations. We also report a number of window resonances in the 27–40 eV region whose origins have not been determined, and the overall shape of the 4d photoionization spectrum. Finally, we have determined four new 4d9nl levels of Cd2+.

A new science competition for secondary school students : the First European Union Science Olympiad

The first European Union Science Olympiad (EUSO2003) took place at Dublin City University in April 2003. In this paper we discuss the philosophy behind and implementation of this new competition, and the role third-level institutions can play in making science more attractive to second-level students via competitions of this nature. Emphasis is placed on the interdisciplinary nature of the experiments, the team-working skills required and the potential for stimulating the uptake of science at second and third levels. We use an experimental problem on photosynthesis, which has a strong physics component, to illustrate our ideas and methodology and assess the overall success of the first EUSO competition.

Extreme ultraviolet continuum emission from laser-generated plasmas and applications to spectroscopy

The application of extreme ultraviolet (XUV) radiation to studies of core excited atoms, ions, molecules, and solids has led to the demand for suitable XUV continuum light sources. An excellent, compact, reproducible source is the laser produced plasma, which for a suitable choice of target material can be used to generate a line-free continuum throughout the vacuum ultraviolet (VUV) and XUV from 4 to 200 nm. The characteristics and underlying physics of such sources are discussed and their application to inner shell photoexcitation studies of atoms and ions are briefly described.

Reply to ‘Comment on “Lorentz contraction and current-carrying wires”’

This reply answers the issues raised in the Comment on my paper (van Kampen 2008 Eur. J. Phys. 29 879–83). The error of applying a single Lorentz transformation to a wire segment is discussed in some detail.

The First EU ScienceOlympiad (EUSO): a modelfor science education

In April 2003 the first European Science Olympiad took place in Dublin City University in Ireland.In this competitionsecond level students were asked to carry out a number of tasks involving biology, physics and chemistry. Students had qualified initially in competitions in one of these subjects and were organised into integratedteams which worked together to complete the tasks. This paper examines the background to the competition,describes aspects of the biological input in developing the tasks and discusses the value of the approach andits potential benefits in improving both interest levels in science and the quality of science education.

Outcomes of a service teaching module on ODEs for physics students

ABSTRACT This paper reports on the first part of a multiphase research project that seeks to identify and address the difficulties encountered by physics students when studying differential equations. Differential equations are used extensively by undergraduate physics students, particularly in the advanced modules of their degree. It is, therefore, necessary that students develop conceptual understanding of differential equations in addition to procedural skills. We have investigated the difficulties encountered by third-year students at Dublin City University in an introductory differential equations module. We developed a survey to identify these difficulties and administered it to students who had recently completed the module. We found that students’ mathematical ability in relation to procedural competence is an issue in their study of differential equations, but not as severe an issue as their conceptual understanding. Mathematical competence alone is insufficient if we expect our students to be able to recognize the need for differential equations in a physical context and to be able to set up, solve and interpret the solutions of such equations. We discuss the implications of these results for the next stages of the research project.

Student thinking about the divergence and curl in mathematics and physics contexts

Undergraduate physics students are known to have difficulties with understanding mathematical tools, and with applying their knowledge of mathematics to physical contexts. Using survey statements based on student interviews and written responses to open-ended questions, we investigated the prevalence of correct and incorrect conceptions regarding the divergence and curl of vector fields, among both mathematics and physics students. We compare and contrast pre-instruction responses from intermediate-level E&M students at KU Leuven and the University of St Andrews, with post-instruction responses from St Andrews students enrolled in a vector calculus course. The differences between these student populations were primarily in areas having to do with physics-related concepts and graphical representations of vector fields. Our comparison of pre- and post-instruction responses from E&M students shows that their understanding of the divergence and curl improved significantly in most areas, though not as much as would be desired.

The evolution of 4D photoabsorption in tellurium with increasing ionisation

The photoabsorption spectra of Te I-Te IV have been recorded and analysed in the XUV spectral region using the dual laser produced plasma technique. Photoexcitation from the 4d subshell is the dominant process in the 35-150 eV energy region. For photon energies between 35-45 eV discrete structure corresponding to 4d-np (n>4) transitions were obtained. Above the 4d ionisation threshold the spectra of Te I-Te III were found to be dominated by a 4d-ef shape resonance, which peaks at ~88 eV in each case. A transfer of oscillator strength from the resonance to discrete 4d-nf (n>3) transitions with increasing ionisation is clearly evident, and the 4d-4f transitions are the strongest features in the Te IV spectrum. Hartee-Fock with configuration interaction and time dependent local density approximation calculations successfully account for this behaviour and permit identification of the discrete features. The use of a prepulse to maximise the brightness of a tungsten continuum emitting plasma was also investigated.