Now let’s talk about some of the early pioneers who helped shape our understanding of radiation.

—

In 1896, Becquerel discovered that penetrating radiations were given off naturally by uranium. He found the radioactive salts of uranium spontaneously created a shadow on a photographic plate covered by black paper. These radiations were later classified as alpha, beta, and gamma rays.  This era was considered the formal beginning of the new field of the study of radioactive substances.

The Scientific International (SI) unit for radioactivity, the becquerel, was named after him.

—

In 1895 Wilhelm Roentgen experimented with electrons in a Crookes tubes and noticed images on a film that he couldn’t see with the naked eye.  The Crooke’s tube is a tube with a gas in it with a charge applied to it. His experiments showed that the emanations could pass through some materials easier than others.  The emanations were virtually unimpeded through things like fabric and tissue, but not through metal and bone. These emanations were so mysterious that Roentgen named them after an unknown variable in Algerbra, X. Hence the name “X-Rays.”

The measurement of exposure was named after Roentgen.

—

Roentgen was able to produce the very first image of bones using this newly discovered technology called X-rays.   The picture on the left is the first x-ray image of a hand.  It was Roentgen that convinced his wife to put her hand in front of the Crooke’s tube.  Her comment was “I think I’ve seen my death” because she could see her bones.  Back then, if one saw somebody’s bones, they were dead.

The picture on the right was very soon after Roentgen discovered x-rays.  A doctor brought a boy to him who was shot in the hand with buckshot while hunting.  Having the knowledge of the locations of the lead buckshot helped save the boy’s hand.  This was the first “diagnostic x-ray” picture taken.

Within one year, this new technology had spread throughout the world and was greatly improved.

—

In 1898 a major accomplishment came from the effort of Marie & Pierre Curie.  Pierre was Marie’s professor and they later married.

They developed an electrometer to quantify the electrons as a results of ionizations from radioactive substances.

Marie Curie was the first person and the only woman to win the Nobel Prize twice, and the only person to win the Nobel Prize in two scientific fields.

—

The Curies spent several years separating the elements of Pitchblend, a natural ore containing Uranium and Thorium.  They were successful in separating the two elements and quantifying the mass of each element.  However, upon counting the two elements for their radioactivity on an electrometer (measuring electrons that were free from the gamma interactions of the isotopes), the total activity of each did not total the activity of the sample before separation.

—

Marie measured some “residual” amount of mass that was crystallized on the bottom of the dish.  The reading on the electrometer made up the difference.  She was able to account for the mass through the amount of radiations.  She named this new crystalline material Radium. They isolated the Radium and determined that one gram of pure Radium would have 37,000,000,000 disintegrations per second.  This value soon became a standard of measurement which today we call the Curie.

Madam Curie coined the term “radioactive” which described the energy emanating from unstable elements.

—

Radium Therapy Craze

This is the tragic true story of the lives of girls who performed the task of painting radium mixed with phosphor onto dials of watches.  The practice of using the lips to make a tight brush, dip into the radium mixture, then paint the dials onto watches was performed to respond to the demand for these watches during WWI.  Unknowingly, this radioactive material was similar to calcium (chemically); thus, when touched to the lips, some went into the body and into their skeleton.    The girls suffered agonizing pain and died young.  The book THE RADIUM GIRLS is “their” story told by friends, doctors and lawyers who followed them.

The moral to this story is best told by the famous writer, George Bernard Shaw:

“The gods of old are constantly demanding human sacrifices”.  Enchantment (as what Radium was once thought) –in the tales of the past, and present– can also mean a curse.

—

This light was from the absorption of higher frequency emissions and the transmission of a visible spectrum light, commonly called fluorescence.  In 1897, J.J. Thomson hypothesized that this phenomenon was attributable to the high-speed and negatively charged particles which he called electrons.

Man’s first clues to radiation were in the latter part of the 19th century with experiments regarding electrical discharges in vacuum tubes.  The charges were produced by applying a high voltage across the electrodes in a tube.   The observations included a light from the gas in the tube, commonly called a Crookes tube.

—

In 1900 Max Planck formulated the concept with Albert Einstein that energy that we see (visible light) and that we don’t see (UV rays, gamma, and X-rays) are actually little bundles of energy called photons.  They move in waves with specific frequencies depending on the energy of the emission.

—

In 1905, Albert Einstein was able to take this concept to another level.  He hypothesized that mass and energy are interchangeable.  Thus, his famous equation:  E=mc2.  This equation was the beginning of the understanding of the energy that exists in the nucleus of an atom.  And, if it could be harnessed, it could create large amounts of energy from a small mass.  His theories were essential in the understanding of nuclear fission and finally the nuclear bomb.  Einstein was nominated as the “Man of the 20th Century” due to his contribution to the world.

In 1939 be told FDR that the Allies needed to start making the atomic bomb since Germany was already well on the way, thus initiating the Manhattan project

—

In 1911, Ernest Rutherford performed many experiments in which he bombarded elements with energetic particles from various naturally-occurring radioactive materials.  He discovered that the atom contains material with positive and negative charges.  Later he found that when he bombarded a nitrogen nucleus with alpha particles, energetic protons were released.  This was the first man-made nuclear transformation.  He had forced an alpha particle  which is two protons and two neutrons, into the nucleus of an atom.

—

This particle was the neutron.  The nucleus must contain two types of particles, the proton and the neutron.  Since the term “element” is defined by the number of protons and since adding neutrons does not change the element, the term “isotope” was developed to refer to differing number of neutrons.  This concept was discovered by Chadwick.