When was the proton discovered

There is no way to look directly at an atom and see its detailed structure. When a discovery is first made, there is often no language to use to tell others exactly what it is. This was the problem in talking about the atom and its structure. Research builds upon itself—one piece connects to another. Each finding gives a clearer picture of the whole and also raises new questions.

The detective work that led to the discovery of the proton was built upon finding pieces to the puzzle and putting them together in the right way. The electron was discovered using a cathode ray tube. An electric current was passed from the cathode the negative pole to the anode positive pole.

Several experiments showed that particles were emitted at the cathode and that these particles had a negative charge. These experiments demonstrated the presence of electrons. If cathode rays are electrons that are given off by the metal atoms of the cathode, then what remains of the atoms that have lost those electrons? He described the fundamental physical feature of the depth-dose curve for protons and heavy-charged particles in comparison with photons or X-rays.

He described the way the particle beams deposit their energy as the beam enters the body in route to the tumor: a smaller amount of energy is released first, and then a much larger amount of the beam energy is released at the end of its path Bragg peak and then completely stops Figure 3.

In addition to Wilson being a very accomplished sculptor and architect, he was later responsible for the development of Fermi Laboratory and became its founding director Figure 4. Figure 4 Dr. Schematic diagram for the experiment that led to the discovery of neutrons by Chadwick.

Various experiments showed that mass of the nucleus is approximately twice than the number of proton. What is the origin of this additional mass? Rutherford postulated the existence of some neutral particle having mass similar to proton but there was no direct experimental evidence. Several theories and experimental observations eventually led the discovery of neutron. One leading explanation was that there were electrons and additional protons in the nucleus as well -- the protons still contributed their mass but their positive charge was canceled out by the negatively charged electrons.

So in the helium example, there would be four protons and two electrons in the nucleus to yield a mass of 4 but a charge of only 2. Rutherford also put out the idea that there could be a particle with mass but no charge.

He called it a neutron, and imagined it as a paired proton and electron. There was no evidence for any of these ideas. Chadwick kept the problem in the back of his mind while working on other things.