Diapositiva 1 - Dipartimento di Fisica e Astronomia
Transcript
Diapositiva 1 - Dipartimento di Fisica e Astronomia
The Physics of MAGIC - INTRO Elisa Prandini for the MAGIC-D Team Padova, 2 November 2010 For your students light is… …what we observe with our eyes… …and our telescopes… Optical Observation: the “old” technique The oldest technique… why? Telescopes: lenses or mirrors? Telescopes from Earth or Satellites Very good angular resolution! In physics, light is a wave… and a particle: the photon! Collisions with ENERGY TRANSFER Molecules, Atoms and Nuclei have something in common “discrete” structure discrete emission! Nella transizione da una shell all’altra, l’elettrone emette pacchetti discreti di energia e.m. And is part of the electromagnetic spectrum 1 Km 700 nm 1m 1 cm 1 mm 100 nm 1 nm 0,1 nm 400 nm The Electromagnetic Spectrum WAVELENGTH FREQUENCY ENERGY E=hn=hc/l Now, let’s enter in the electromagnetic spectrum starting from the so-called “low-energy” The Radio Waves World ~10-8 eV the signal is emitted and observed by antennas (oscillating dipoles) It is the world of distant communications Even if it is not visible with our eyes, it is an “everyday world”: - mobile phone - radio - television - microwave owen The IR World ~1 eV Before the RED in the e.m. spectrum It is the world of HEAT It is light typically emitted by warm objects ~3 eV The Optical World… Our World! It is the world of objects emitting and absorbing visible light The X and g World keV – MeV – GeV - TeV The X and g World keV – MeV – GeV - TeV The X-rays world is not very bright: high energies! Man can produce artificially X-rays (atom and nucleus). The human body doesn’t emit X-rays, the bones simply stop them! Hence…: What we call “light” is part of the electromagnetic spectrum: it has the same origin and properties of radio, microwave, X-rays and gamma-rays. What is different is their ENERGY. An object can emit one ore more different waves When we study astrophysical objects we have to consider ALL the physical phenomena that happen -> that’s why we observe (or we try to observe) the same target in different wavelenghts The Milky Way emission The atmospheric extinction PROPOSTA ATTIVITA’ DI LABORATORIO EFFETTO FOTOELETTRICO: • Passaggio dalla fisica classica alla fisica moderna • Misure sperimentali e discussione teorica • L’evoluzione dell’effetto fotoelettrico: il Fotomoltiplicatore SEDE DI LAVORO: Polo Didattico (Via Loredan)