1 Astro-Particle Physics 3 Acceleration mechanisms Manfred Jeitler

2 man-made accelerators: inside of an Alvarez-type accelerating structure

3 Cyclotron r orbit radius p particle momentum e particle charge B magnetic field revolution frequency must be independent of the particle‘s momentum ! man-made accelerators: operating principle of the cyclotron stable magnetic field to keep particles on track alternating electric field for acceleration

4 betatron: acceleration not by alternating electric field but by time- dependent magnetic field used for small-scale medical accelerators

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reflection of particles from magnetic clouds 7 collision not with individual particles but with the cloud as a whole

second-order Fermi acceleration 8 c v v

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injection problem 10

11 crab nebula remnant of supernova observed in 1054 shock front of expanding matter may accelerate particles (first-order Fermi acceleration)

12 pulsars neutron stars, remnants of supernova explosions radius ~10 km angular momentum conserved during collapse  very high rotational speed magnetic flux conserved during collapse  very high magnetic flux density spin and magnetic axis not aligned (just like on Earth)  moving magnetic field creates high electric field: E = v × B

13 accretion disk (binary system) matter from bigger partner is sucked into disk around massive (compact) partner (neutron star, black hole) relativistic effect gravitational energy of particles is transformed into kinetic energy (friction, transport of conserved angular momentum to the outside; supposed to be strong source of X-rays; exact mechanisms not yet completely understood)

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15 Hillas criterion: E < q B R R ~ 3.3 * p / B for: singly charged particle (Z=1) R in meters p in GeV/c B in Tesla

A Toy Model of magnetic fields Source Milky way Halo B ~  G  0.1 Mpc weak deflection (Extra-galactic B ~nG) Larmor radius: r L = 110 kpc Z -1 (E / eV) (B / 1  G) -1 Deflection angle for protons ~ few degrees 16

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