Astroparticle Physics

16 Glossary 313Particle detector for the measurement of large extensive air showersbased on the measurement of the emitted scintillation light in theatmosphere.Vector with four components comprising energy and the three momentumcomponents.Vector with four components mostly comprising time in the firstcompoment and three additional spatial components.Break-up of a heavy nucleus into a number of lighter nuclei in thecourse of a collision.A differential equation that expresses the evolution of the universedepending on its energy density. This equation can be derived fromEinstein’s field equations of general relativity. Surprisingly, a classicaltreatment leads to the same result.Standard Big Bang models with negative (Ω 1), or flat (Ω = 1) space curvature.A particle with no observable inner structure. In the StandardModel of elementary particles quarks, leptons, photons, gluons,W + , W − bosons, and Z bosons are fundamental. All other objectsare composites of fundamental particles.In fusion lighter elements are combined into heavier ones. Fusionis the way how stars produce energy.Aggregation of galaxies in a spatially limited region.A spherical region mainly consisting of old stars surrounding thecenter of a galaxy.Magnetic field in our Milky Way with an average strength of3 µG = 3 × 10 −10 Tesla.Coordinate transformation for frames of reference in which forcefreebodies move in straight lines with constant speed without considerationof the fact that there exists a limiting velocity (velocity oflight). This theorem of the addition of velocities leads to conflictswith experience, in particular, for velocities close to the velocity oflight.Gallium experiment in the Gran Sasso laboratory for the detectionof solar neutrinos from the pp cycle.Fly’s Eyefour-momentumfour-vectorfragmentationFriedmann equationFriedmann–Lemaître universesfundamental particlefusionGgalactic clustergalactic halogalactic magnetic fieldGalilei transformationGALLEX experiment