All About Who Discovered Neutrons

In the year 1932, British physicist Sir James Chadwick conducted an experiment that led to the discovery of neutrons. He bombarded beryllium with alpha particles from the natural radioactive decay of polonium. This resulted in radiation that showed high penetration through a lead shield. Unfortunately, this could not be explained with the help of known particles at the time.

James Chadwick was unable to explain his results with the existing laws back then, which were similar to energy and momentum conservation. Hence, the discovery of neutrons could not be proved. Therefore, Chadwick’s assumption of an uncharged neutral particle with the same weight as that of a proton disappeared eventually.

The Discovery of Neutrons

In 1930 Charlottenberg, Bothe and Becker showed that beryllium, boron and fluorine atoms produce high energy radiation when bombarded by alpha particles emitted from polonium. These three scientists associated it with y rays which were considered highly penetrating radiation.

One year later. Irene Curie studied the absorption of this secondary radiation from Be and Li. She found that its penetration was faster than what was said by Bothe. After two years, Irene and Fredrick Joliet Curie found that the ionisation generated by secondary Be radiation in a chamber is much higher when they placed a matter of hydrogen in front of it. This effect appeared due to the presence of protons in hydrogen. The increase in ionisation energy was due to the ejection of proton particles at a velocity of about 10% of the speed of light.

James Chadwick

In 1932, having been searching Rutherford’s neutron for almost a decade, James Chadwick had an idea to solve this contradiction. After a month, he published a book of his experiments and repetitions, demonstrating his results that resonated with momentum and energy conservation. For this, he used the quanta hypothesis. He argued that if beryllium emits y rays, then a mass defect of carbon will occur in the reaction. This defect is enough to prove that the energy of photons emitted in the process can not be greater than 14 x 10⁶ volts.

Chadwick concluded his observations till this point in the book. However, these difficulties disappear when it is assumed that the radiation consists of particles of mass 1 and charge 0, and these particles are neutrons.

Contradictions by Other Scientists

The discovery of neutrons caused many contradictions among other scientists. The Joliot-Curies were not convinced and went on to conduct additional experiments to provide new support for the neutron hypothesis. They focused on a nuclear reaction that produced nitrogen and found that the maximum neutron energy calculated is in accordance with the measured energy of protons ejected when they have been hit by neutrons.

Additionally, the emission of secondary electrons of high energy was in accordance with the neutron hypothesis. They also added that even though the radiation was complicated, y rays were present along with neutrons. This was also noted by another scientist Pierre Auger. The placement of hydrogen material in front of a neutron detector is used even now to quickly estimate the energy of incoming neutrons. However, neutrons thermalise in thick H-containing materials. This increases the chances of their interactions with the detector which in turn ejects protons from hydrogen. These thermalised neutrons cause a nuclear reaction and they eject protons along with other particles.

Neutral Radiation Confounded Scientists

The discovery of neutrons and neutral radiation confounded the scientists. Even today, scientists have not been able to come to any conclusions regarding the life of a neutron. Any particle revolving around the nucleus gets exhausted after a certain time and eventually falls inside the nucleus. Similarly, the neutron also, after its set life cycle, is bound to get exhausted and fall into the nucleus.

However, scientists have not been able to conclude the life period of a neutron yet. A neutron is said to be the building block of matter and its counterpart is the proton. Like other subatomic particles, neutrons do not last long outside the nucleus. Over time, it breaks into a proton, an electron and an antineutrino – which is a tiny particle. The real-time that is taken by a neutron to fall inside the nucleus is still unknown and its possibilities for the difference are some unknown kind of physics. This would be something associated with neutron decay or beyond standard methods used by scientists to explain these phenomena.

Conclusion

A particle that has high penetration power and the capability to eject electrons with a huge speed is referred to as a neutron. It consists of mass 1 and charge 0. Before Chadwick, several scientists claimed the presence of a neutral particle that has a high penetration power and bombards electrons at a very high speed when placed in front of a matter that has hydrogen in it. But the existence and lifetime of a neutron particle are still unknown and neutral radiation confounds scientists still. Though there are many studies regarding this, it is believed that the theory may be something beyond the standard methods used by scientists to explain these phenomena.