Who is chadwick and what did he discover

Some scientists thought there were additional protons in the nucleus, along with an equal number of electrons to cancel out the additional charge. In , Rutherford proposed that an electron and a proton could actually combine to form a new, neutral particle, but there was no real evidence for this, and the proposed neutral particle would be difficult to detect. Chadwick went on to work on other projects, but kept thinking about the problem.

Around , several researchers, including German physicist Walter Bothe and his student Becker had begun bombarding beryllium with alpha particles from a polonium source and studying the radiation emitted by the beryllium as a result.

Some scientists thought this highly penetrating radiation emitted by the beryllium consisted of high energy photons. Chadwick had noticed some odd features of this radiation, and began to think it might instead consist of neutral particles such as those Rutherford had proposed. They found that this radiation knocked loose protons from hydrogen atoms in that target, and those protons recoiled with very high velocity.

In , he tried similar experiments himself, and became convinced that the radiation ejected by the beryllium was in fact a neutral particle about the mass of a proton.

He also tried other targets in addition to the paraffin wax, including helium, nitrogen, and lithium, which helped him determine that the mass of the new particle was just slightly more than the mass of the proton.

Chadwick also noted that because the neutrons had no charge, they penetrated much further into a target than protons would. By it had been established that the newly discovered neutron was in fact a new fundamental particle, not a proton and an electron bound together as Rutherford had originally suggested. Scientists soon realized that the newly discovered neutron, as an uncharged but fairly massive particle, could be used to probe other nuclei.

Chadwick, whose discovery of the neutron had paved the way for the atomic bomb, worked on the Manhattan Project during WWII. He died in Chadwick in this way prepared the way towards the fission of uranium and towards the creation of the atomic bomb. For this epoch-making discovery he was awarded the Hughes Medal of the Royal Society in , and subsequently the Nobel Prize for Physics in From to he worked in the United States as Head of the British Mission attached to the Manhattan Project for the development of the atomic bomb.

He returned to England and, in , retired from active physics and his position at Liverpool on his election as Master of Gonville and Caius College, Cambridge. He retired from this Mastership in Chadwick has had many papers published on the topic of radioactivity and connected problems and, with Lord Rutherford and C. Ellis, he is co-author of the book Radiations from Radioactive substances Sir James was knighted in In , he married Aileen Stewart-Brown of Liverpool.

They thought, and so announced, that this radiation was gamma radiation, similar to that produced by the newly discovered cosmic rays. When Chadwick saw the Joliot-Curie publications, he knew that there was something wrong with their interpretation — the energies were not right. Having just acquired some polonium of his own, he redid the Joliot-Curie experiments, this time sending the radiation into chambers containing various light elements, and he measured how much they rebounded from the radiation.

He discovered that the energy they picked up was considerable and could best be accounted for by a nuclear particle with about the mass of a proton, but no charge. The long-sought neutron had been discovered, and named. These are the marks of a great experimental physicist. But since his predicted particle had not yet been discovered, the name had not yet been used, and so Chadwick snatched it for his neutral particle. For they received their own Nobel Prize in the very same year in Chemistry , for their discovery of artificial radioactivity.