The x-rays

quite a discovery!

by Jesús Morales Rodriguez and Rafael Alencar de Paula

Jesús Morales Rodriguez is PhD Candidate at Polytechnique School of Montreal in Electrical Engineering

Jesús Morales Rodriguez is PhD Candidate at Polytechnique School of Montreal in Electrical Engineering

Rafael Alencar de Paula is PhD Candidate at Polytechnique School of Montreal in Industrial Engineering

Rafael Alencar de Paula is PhD Candidate at Polytechnique School of Montreal in Industrial Engineering

Wilhelm Roentgen was already working on the effects of cathode rays during 1895, before he actually discovered X-rays. His experiments involved the passing of electric current through gases at extremely low pressure. On November 8, 1895 while he was experimenting, he observed that certain rays were emitted during the passing of the current through discharge tube. His experiment that involved working in a totally dark room with a well covered discharge tube resulted in the emission of rays which illuminated a barium platinocyanide covered screen. The screen became fluorescent even though it was placed in the path of the rays, two meters away from discharge tube.

The German professor of physics, discovered the x rays when he applied a high voltage electrical energy at the ends of a glass tube filled of a special gas. The experiment produced a fluorescent glow able to pass throughout some solid bodies. He continued experimenting until he realized that it was possible to capture shadows of some objects in film sheets, for instance, the human skeleton, using photographic plate to capture the image of various objects of random thickness placed in the path of the rays. He generated the very first "roentgenogram" by developing the image of his wife's hand and analyzed the variable transparency as showed by her bones, flesh and her wedding ring. Based on his subsequent research and experiments, he declared that X-ray beams are produced by the impact of cathode rays on material objects.

Professor Roentgen won the first Nobel Prize in physics in 1901 [1]. He chose the x letter to name his discovery because it is used in mathematics to represent unknown variables. Since 1986 until our days, x rays have been used in the medicine, even though, many people died experimenting with x rays until the radiation became completely controlled throughout the years [2]. 

Some gases used to produce high energy x rays are Xenon and Krypton, while neon is selected for low energy ones. Also it is possible to use mixture of gases, depending on the application [3].

In addition to the medicine, x rays are used in the industry for diagnosis and nondestructive testing of products, normally, the manufacturers look for defects in their products. 

Which previous works made it possible?

A few of the many important people who have been involved in the research and study of X-rays are listed below:

  • Johan Hittorf - 1824 - 1914 - A German physicist who co-invented the Crookes tube.
  • Ivan Pulyui - 1845 - 1918 - A Ukrainian physicist & lecturer who assembled several designs of vacuum discharge tube.
  • Nikola Tesla - 1856 - 1943 - He studied X-rays using specially designed single-electrode tube (Bremsstrahlung process)
  • Fernando Sanford - 1854 - 1948 - A Professor of Physics who generated and detected X-rays in vacuum tubes.
  • Philipp Lenard - 1862 - 1947. He won the Nobel Prize for Physics for discovering many properties of the cathode rays.
  • Wilhelm Röntgen - 1845 - 1923 - The first person who discovered and systematically studied X-rays.
  • Thomas Edison - 1847 - 1931 -He examined calcium tungstate against X-rays & developed medically effective fluoroscope.

Special fact:

On 2009, London science museum did a contest about the top scientific invention. The X-ray was the winner with 1/5 votes.

The results: 

1st place - X-ray machines
2nd place - Penicillin
3rd place - DNA double helix
4th place - Apollo 10 capsule
5th place - V2 Rocket Engine
6th place - Stephenson's Rocket
7th place - Pilot ACE Computer
8th place - Steam Engine
9th place - Model T Ford
10th place - Electric Telegraph


[1] http://www.medicaldiscoverynews.com/shows/xray.html
[2] http://www.the-scientist.com/?articles.view/articleNo/30693/title/The-First-X-ray--1895/
[3] http://www.canberra.com/literature/fundamental-principles/pdf/Gamma-Xray-Detection.pdf
[4] http://www.infoplease.com/encyclopedia/science/x-ray-applications-x-rays.html
[5] http://images.radiopaedia.org/images/133697/86c1f2821cf7b547d33ecd2f55f94e_jumbo.jpg