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