Search results for "Secondary"
showing 10 items of 1765 documents
Search for decays of the Z0 into a photon and a pseudoscalar meson
1990
Abstract A search is reported for decays of the Z 0 into π 0 γ , ηγ and η ′ (958) γ in e + e − collisions using data collected during a scan around the Z 0 mass. In order to search for π 0 γ final states, in which the two photons from the π 0 decay are unresolved, the production of pairs of high-energy electromagnetic clusters is studied. The data are compared with the expectations from the pure QED process e + e − → γγ , and a 95% confidence level upper limit on the branching ratio of the Z 0 into π 0 γ of 4.9 × 10 −4 is derived. For η′γ, the decay modes of the mesons that contain two charged particles are largely free from QED background. These modes are used to place upper limits of 4.6 …
An experiment on wind energy
2012
We discuss an experiment on wind energy performed with home-made apparatus. The experiment reproduces a laboratory windmill, which can pump water from a lower level to a higher one. By measuring the gain of the gravitational potential energy of the pumped water, one can determine the power extracted from the wind. The activity was carried out with high-school students, in the framework of the Italian National Plan for Scientific Degrees-Physics. The proposed experiment allows teachers to discuss renewable energy sources with students whose knowledge of physics is limited to mechanics. It gives students the possibility to gain experience with energy and to increase their awareness of this re…
Exploring Gravitational Lensing
2019
In this article, we discuss the idea of gravitational lensing, from a systematic, historical and didactic point of view. We show how the basic lensing equation together with the concepts of geometrical optics opens a space of implications that can be explored along different dimensions. We argue that Einstein explored the idea along different pathways in this space of implication, and that these explorations are documented by different calculational manuscripts. The conceptualization of the idea of gravitational lensing as a space of exploration also shows the feasibility of discussing the idea in the classroom using some of Einstein's manuscripts.
Combining Knowledge of Physics and Chemistry in Teaching: The Behaviour of a Narrow Jet of Water in the Presence of Charged Insulators
2001
In this study the aim was to find out how student teachers applied their knowledge, in physics and chemistry, in an upper secondary science topic. The first stage consisted of an analysis of the upper secondary students’ interpretations of an experiment in which a charged rod is brought near another charged rod and a narrow jet of water. The second stage of the study was based on these results. The main research question was: How do the student teachers apply their knowledge to their explanations? The main finding was that the student teachers’ answers bore a strong resemblance to those of the upper secondary students. The earlier learning situation influenced the student teachers’ interpre…
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2021
Resumen basado en el de la publicación Resumen en inglés El tema de la energía es una parte muy importante de un curso de física, ya que proporciona un vínculo claro entre las diferentes secciones de física. Se analiza la enseñanza y el aprendizaje de la energía en el nivel secundario y se demuestra que los métodos tradicionales para enseñar energía: a) no consideran las ideas erróneas de los estudiantes, b) introducen la conservación de energía en mecánicas y termodinámicas, pero no aclaran si es un teorema o un principio, y c) no presentan la conservación de la energía como principio general de toda la física. Finalmente, se muestra un nuevo enfoque para la enseñanza de la energía. ESP
A Coupled Solid-Fluid Method for Modeling Subduction
2007
International audience; We present a novel dynamic approach for solid/fluid coupling by joining two different numerical methods: Boundary Element Method (BEM) and Finite Element Method (FEM). FEM results describe the thermo-mechanical evolution of the solid while the fluid is solved with the BEM. The bidirectional feedback between the two domains evolves along a Lagrangian interface where the FEM domain is embedded inside the BEM domain. The feedback between the two codes is based on the calculation of a specific drag tensor for each boundary/finite element. The approach is presented here to solve the complex problem of the descent of a cold subducting oceanic plate into a hot fluid like ma…
Non-cooperative Equilibria of Fermi Systems With Long Range Interactions
2019
We define a Banach space $\mathcal{M}_{1}$ of models for fermions or quantum spins in the lattice with long range interactions and explicit the structure of (generalized) equilibrium states for any $\mathfrak{m}\in \mathcal{M}_{1}$. In particular, we give a first answer to an old open problem in mathematical physics - first addressed by Ginibre in 1968 within a different context - about the validity of the so-called Bogoliubov approximation on the level of states. Depending on the model $\mathfrak{m}\in \mathcal{M}_{1}$, our method provides a systematic way to study all its correlation functions and can thus be used to analyze the physics of long range interactions. Furthermore, we show tha…
Secondary electron flight times and tracks in the carbon foil time pick-up detector
2014
Carbon foil time pick-up detectors used in the time-of-flight measurements of MeV energy ions have been studied in connection to time-of-flight-energy spectrometer used for heavy ion elastic recoil detection analysis. In experimental coincident TOF-E data characteristic halos are observed around light element isobars, and the origin of these halos were studied. The experimental data indicated that these halos originate from single electron events occurring before the electron multiplication in the microchannel plate. By means of electron trajectory simulations, this halo effect is explained to originate from single electron, emitted from the carbon foil, hitting the non-active area of the m…
Source of Polarized Electrons for MAMI B
1991
A source of polarized electrons has been set up in order to inject polarized electrons into the 855 MeV c.w. electron accelerator MAMI B at the Mainz nuclear physics institute. It is based on photoemission of the 3/5 semiconductor GaAsP and will provide a d.c. current of 100 µA with a beam emittance of 1π mm mrad, and a polarization of about 40%.
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2021
Resumen. La conservación de la energía es uno de los conceptos más importantes de la física porque unifi ca todos los fenómenos. En este artículo presentamos algunos resultados de una investigación sobre el proceso de enseñanza-aprendizaje del concepto de energía y su conservación realizado en el nivel de la educación secundaria española. El análisis de los datos pone de manifiesto que la conservación de la energía se introduce en mecánica y termodinámica pero no en todos los campos de la física. Los resultados experimentales se han utilizado para desarrollar un nuevo enfoque de la enseñanza de la energía. Palabras clave. Energía, educación en física, actividades de enseñanza. Summary. The …