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Discovery of Cosmic Rays. What are they? Where do they come from? Who cares?. Discovery of Radioactivity. In 1896 Antoine Becquerel accidentally discovered radioactivity. Left Uranium on a photographic plate inside a closed box. Decide to develop photograph expecting to see nothing

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discovery of cosmic rays

Discovery of Cosmic Rays

What are they?

Where do they come from?

Who cares?

discovery of radioactivity
Discovery of Radioactivity
  • In 1896 Antoine Becquerel accidentally discovered radioactivity.
  • Left Uranium on a photographic plate inside a closed box.
  • Decide to develop photograph expecting to see nothing
  • He saw an image of the Uranium crystal!!!
  • How can this happen if there was no light in the box??

discovery of radioactivity3
Discovery of Radioactivity

  • Pierre and Marie Currie became interested in Becquerel's discovery.
  • They coined the term “radioactivity”.
  • 1903 Becquerel and the Curie’s won Nobel prize.
  • In 1911 Marie Curie awarded Nobel prize for discovering new radioactive elements, Polonium and Radium.

The attention that English scientists paid to the Curies' work helped make them household names in that country, as in this famous caricature, “Radium,” from the popular British periodical Vanity Fair.


The spontaneous process of nuclei undergoing a change by emitting particles or rays is called radioactive decay.


Radioactive nuclei degenerate in three ways:

  • Alpha decay (He nucleus ejected)
  • Bata decay (e- ejected)
  • Gamma rays (high energy E-M radiation)
detection of radiation
Detection of Radiation
  • Geiger Counter
  • The device is named after the German physicist Hans Geiger.
  • Detects particles emitted by radioactive sources.
  • Makes an audible clicking noise when particles pass through chamber.

discovery of cosmic rays7
Discovery of Cosmic Rays
  • From 1911 to 1913 Victor Hess measured radiation levels at various altitudes (up to 17,500 ft) in the Earth’s atmosphere.
  • Radiation levels increased with altitude!
  • This radiation was called “Cosmic Radiation” later became “Cosmic Rays”.
  • Won Nobel Prize in 1936.

what are cosmic rays
What are Cosmic Rays?
  • Charged particles (protons, electrons, and other atomic nuclei) coming from outer space.
  • Traveling at near the speed of light,

186,000 miles per second, or 300,000 km per second.

Where do they come from?

How did they get accelerated to such high speeds?

what are cosmic rays9
What are Cosmic Rays?
  • High speed protons and electrons, primary particles, strike Earth’s upper atmosphere.
  • Nuclear collisions produce a shower of secondary particles, called muons.
  • It is mainly these muons that are observed on Earth’s surface.
possible origins of cosmic rays
Possible Origins of Cosmic Rays

The Sun

The Big Bang


Gamma Ray Bursts

the big bang
The Big Bang
  • Creation of universe is thought to have occurred about 15 billion years ago.
  • Gigantic explosion of something, possibly a black hole.

the big bang12
The Big Bang
  • Big Bang created a lot of high energy g-rays.
  • If two g-rays collide they create high energy particles.
  • Some these particles may have become what we now call cosmic rays
  • A massive star explodes.
  • Ejects protons, electrons and other atomic nuclei.
  • These particles may become cosmic rays.
  • The most likely origin for cosmic ray particles.
  • Crab nebula shows the remnant of a supernova explosion that occurred in 1054 AD.
  • Observed in the daytime by Chinese astronomers.
  • Pulsar is a rapidly rotating neutron star
  • If jets sweep past the Earth then we see a pulse.
  • Particles can be ejected out the jet.
  • These particles may be observed at the Earth as Cosmic Rays.
  • Crab Nebula shows this type of jet structure.
  • This is a combined image from visual and X-ray pictures.
  • When massive (>8 Suns) stars die they explode as supernovae.
  • They create a black hole.
  • Cygnus X-1 is an X-ray binary star.
  • An observable hot blue star appears to be orbiting nothing.
  • This nothing appears to have 10 solar masses and is thought to be a black hole.
active galaxies
Active Galaxies
  • Some galaxies have large radio jets.
  • These jets are emitting at all wavelengths.
  • They also are ejecting high energy particles.
active galaxies20
Active Galaxies
  • These galaxies have strong jets.
  • Thought to have super massive black holes in there nucleus.
  • 106 or 109 solar masses.
  • High energy particles emitted along jets.
gamma ray bursts
Gamma Ray Bursts
  • Intense Gamma Ray bursts detected by orbiting space telescopes.
  • Burst only last a few seconds.
  • Occur randomly over the entire sky
gamma ray bursts22
Gamma Ray Bursts
  • Thought to be caused by colliding neutron stars.
  • Probably emit high energy particles.
solar flares
Solar Flares

RHESSI spacecraft images of gamma-rays (blue) and X-rays (red) thrown off by the hottest part of the flare are shown with UV images from the TRACE spacecraft. The gamma rays are made by energetic protons at the Sun. Scientists were surprised that the gamma rays matched the energy spectrum of protons at Earth: the proton storm may have come directly from the Sun and not from the CME as anticipated.

RHESSI and TRACE View of

January 20, 2005 Solar Flare


Detecting Cosmic Ray Showers

what questions do you have
What questions do you have?

Take out a sheet of paper and write down any questions

you have concerning radiation from cosmic rays?

Yes we will collect them so everyone participates.

who cares
Who Cares
  • May affect weather and climate
  • May affect health
  • May be used for homeland security
  • Curiosity

Therefore, YOU should care because these particles are streaming though the air and passing through your body every second and may be affecting your life!


Detecting Cosmic RaysAcross Georgia

  • Are cosmic ray hits evenly distributed over a large area?
  • Want to place detectors in middle and secondary schools around the state and let students count muon incident rate.
scientific results
Scientific Results

Student observations that show changes in count rate

during the intense Solar Activity that occurred in the

Fall of 2003.

taking action we now will
Taking ActionWe now will
  • show you how to set up and use detectors here at your school
  • show you some possible experiments you can run to help GSU scientists learn about Cosmic Ray Showers.
  • show you how to submit your results to GSU scientists.

Chaisson and McMillian, (2005). Astronomy Today (5th Ed.)

Shipman, Wilson, and Todd, (2003). An Introduction to Physical

Science (10th Edition).