Description

Introduction to Cosmic Rays

  Last UPDATE : April 2019

Cosmic rays include protons and also larger nuclei, are very energetic particules that continually bombard the earth. Speed of cosmic rays nearly speed of light – c -.

OUTLINE of this COURSE

I. BACKGROUND of COSMIC RAYS

  What are Cosmic Rays?
  Where do they come from?
  History of Cosmic Rays
  Energy Level of Cosmic Rays
  How many Cosmic Ray strike the ground?

II. Muon Physics

  Life Time of Muon

III. Observation of Cosmic Rays

  Pierre Auger Observatory
  CROP
  The Berkeley Detector(*)

IV. References

The Berkeley detector is a highly portable coincidence muon detector is easy to use and easy to understand.

Energetic particles, traditionally called Cosmic Rays, were discovered nearly a hundred years ago, and their origin is still uncertain. Their main constituents are the normal nuclei as in the standard cosmic abundances of matter, with some enhancements for the heavier elements; there are also electrons, positrons and anti-protons, but no anti-nuclei.

Today we also have information on isotopic abundances, which show some anomalies, as compared with the interstellar medium. The known spectrum extends over energies from a few hundred MeV to 3*10^{20} eV and shows few clear spectral signatures: There is a small spectral break near 5*10^{15} eV, the “knee”, where the spectrum turns down; there is another spectral break near 3*10^{18} eV, the “ankle”, where the spectrum turns up again. Up to the ankle the cosmic rays are usually interpreted as originating from Galactic supernova explosions; however, we do not know what the origin of the knee is.

The particles beyond the ankle have to be extragalactic, it is usually assumed, because the Larmor radii in the Galactic magnetic field are too large; this argument could be overcome if those particles were very heavy nuclei as Fe, an idea which appears to be inconsistent, however, with the airshower data immediately above the energy of the ankle. Due to interaction with the cosmic microwave background there is a strong cut-off expected near 5*10^{19} eV, which is, however, not seen; The high energy cosmic rays beyond this “GZK-cutoff” (after its discoverers Greisen, Zatsepin and Kuzmin) are the challenge to interpret. We will describe the various approaches to understand the origin and physics of cosmic rays (abridged). (Cornell University, arXiv)
Who this course is for:

  Any high school physics student should take this course.
  Any college physics student should take this course.
  Any university physics student should take this course.
  Anyone who want to learn about Berkeley Detector
  Anyone who want to learn about Muon Physics
  Anyone who want to learn about Cosmic Rays

Requirements

  This course does not have any prerequisites.
  Interesting Physics enough

Last updated 4/2019