3 resultados para Reactions in Polar Aprotic Media
Resumo:
The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher–catcher scenario, anisotropy in neutron emission was studied for the deuterium–deuterium fusion reaction. Simulation results are consistent with the narrow-divergence ( ∼ 70 ° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.
Resumo:
The capability to respond critically to science in the news is recognised as one aspect of science literacy. Consequently, science-related news reports are an essential resource for science teachers wishing to promote critical reading as the foundation of a critical response to media reported science. Consequently Science education in schools should prepare students to engage with informal sources of science, including news media, in the world beyond formal science education. An interest in science news media is not limited to the science specialist. Science news provides an authentic context for teachers of science and English to collaborate in promoting interdisciplinary learning. The challenges of using science related news, as a context for cross-curricular collaboration, highlight the professional development needs of both science and English teachers working in this context. This qualitative study with over 150 pupils involved secondary school science and English teachers working collaboratively using media reported science resources and collated data from interviews, pre and post intervention tasks, pupils’ classwork and teacher notes. The outcomes of the project showed pupil engagement and greater capacity to carry knowledge and skills across traditional subject boundaries. Teachers reported increased understanding of the pedagogy of the alternative subject specialist and increased confidence to move outside their subject in order to facilitate pupil learning. This study would suggest that adopting an interdisciplinary approach could enhance learning for pupils and increase the confidence and capability of teachers. Additionally teachers’ engagement in professional conversations focusing on pupil progress was noteworthy.