Explain the radiation and radioactivity and early pioneers in radioactivity

1. TOPIC 1: History of Radiation

2. Learning Objectives
•Explain radiation and radioactivity
•Explain early pioneers in radioactivity

3. RADIATION
Radiation
Energy 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

4. Electromagnetic radiation
Imaging employs electromagnetic radiation

5. 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
rotations
transmitters

6. 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

7. 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

8. 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

9. 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

10. 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

11. VIDEO 1

12. 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

13. VIDEO 2

15. 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

17. 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

18. Ernest Rutherford
New 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

19. First Reports of Injury
Late 1896
Elihu Thomson - burns from
deliberate exposure of a finger to
X-rays
Edison’s assistant - hair fell
out & scalp became inflamed
& ulcerated

21. Mihran Kassabian (1870-1910)

22. Chronology of early nuclear
physics

23. 1895 - 1901

24. 1902 - 1908

25. 1909 - 1919

26. 1932 - 1938

27. 1939 - 1942