TOPIC 1: HISTORY OF RADIATION
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Transcript of TOPIC 1: HISTORY OF RADIATION
TOPIC 1: History of Radiation
Learning Objectives
•Explain radiation and radioactivity•Explain early pioneers in radioactivity
RADIATION
RadiationEnergy in transit in the form of high speed particles and electromagnetic waves.
Ionizing radiation-radiation with enough energy-during an interaction with an atom, it can remove electrons from orbital causing the atom to become charged or ionized -examples: gamma rays, neutrons
Non-ionizing radiation-radiation without enough energy to remove electrons from atoms-Examples: visible light, radio and television waves, ultra violet (UV), and microwaves with a large spectrum of energies
Electromagnetic radiation
Imaging employs electromagnetic radiation
l (m)->
10-12 10-10 10-8 10-7 10-6 10-5 10-2 1
gamma
radiation
X-rays far UV UV Visible
IR micro-
wave
radio
Nuclear
events
innner core
electron
high E
outer
elelctron
outer
electron
low E outer
electrons
molecular
vibrations
molecular
rotationstransmitters
RADIOACTIVITY
Radioactivity
The spontaneous transformation of an unstable atom and often results in the emission of
radiation
Radioactive Material
Any material that contains radioactive
atoms.
Radioactive Contamination
Radioactive material distributed over some
area, equipment or person
Before X-Rays were discoveredBefore X-ray were discovered…
Rumor has said that an Italian Surgeon, Guido Lanfranc used to check for breaks in a skull by placing a string between patients teeth and plucking it out. If it made a musical note the skull was in tact. If was dim or of toned it showed a broken bone
This could be very painful for patients. Think
about somebody just squeezing
your broken leg until they could find the place of
the break
When doctor’s diagnosed
broken bones, tumors, and
bullet locations it was all based on their best guess,
and physical examinations
Science Park HS -- Honors Chemistry
Roentgen:
Discoverer of X-rays 1895
Becquerel:
Discoverer of Radioactivity
1896
The Curies:
Discoverers of Radium and
Polonium 1900-1908
Rutherford:
Discoverer Alpha and Beta rays
1897
Early Pioneers in Radioactivity
Brief Background (x-rays)
Discovered accidentally by Wilhelm
Conrad Röntgen in
1895
He discovered that these new
invisible rays could pass
through most objects that
casted shadows including
human tissue but not human
bones and metals
How They Were Discovered
Röntgen discovered the new ray while working with a cathode
tube in his laboratory
The tube was a glass bulb that had positive and negative
electrodes inside
When the air was removed from the tube, and a high voltage was applied it produced a florescent
glow
VIDEO 1
How They Were Discovered
He did not know what kind of rays were responsible for this phenomenon so he
called them X-rays
He made a phosphorescent screen and was shocked when he put his hand in front of the screen – he
could see the outline of his bones
Working with cathode ray tubes he noticed a phosphorescent material in his lab glowing several meters away
VIDEO 2
Discovery of Radioactivity
Henri Becquerel French Physicist
Brief Background (Radioactivity)
He put different elements in the sun and placed
them on photographic plates in dark
drawers to study
phosphorescence
One day in 1896 there was no sun
and he put Uranium on a photographic plate in a dark
drawer. The next day the plate was cloudy! Energy
was coming from Uranium itself
Marie and Pierre Curie Poland and France
Brief Background (Radium & Polonium)
Both died because they were exposed to radioactivity which caused toxicity in their body
They discovered new radioactive elements Radium
and Polonium in1898
Marie and Pierre Curie spent years purifying radioactive
elements
Ernest RutherfordNew Zealand
Brief Background (Three types particle radiation)
Rutherford found three
different types of particles
were emitted
He called them
alpha(), beta()
and gamma(γ) particles
First Reports of InjuryLate 1896
Elihu Thomson - burns from deliberate exposure of a finger to X-rays
Edison’s assistant - hair fell out & scalp became inflamed & ulcerated
Mihran Kassabian (1870-1910)
Chronology of early nuclear physics
1895 - 1901
1902 - 1908
1909 - 1919
1932 - 1938
1939 - 1942