Neutron particles and The history of the discovery and uses

in StemSocial2 months ago (edited)

Neutrons are atomic particles that reside in the nucleus of atoms along with protons. Neutrons have no electrical charge. The mass of a neutron particle is greater than the mass of a proton particle. Proton and neutron mass is about one atomic mass unit 1 AMU. 1 AMU means 1.67377 x 10 '-27 kilogram .Neutron and proton particles together are called nucleons.


The atomic number of an atom is determined by the number of protons. It doesn't matter how many neutrons the atom has. But the atomic mass number is the number of protons and neutrons. We know that, an atom of carbon has 6 protons and 6 neutrons. So its atomic mass number is 12. However, the number of protons and neutrons in the nucleus of an atom is not always the same. For example, A typical gold atom has 118 neutrons and 79 protons. So its atomic mass number is 197. Hope that clears things up.

The number of neutrons in the nucleus of an atom is denoted by the letter N. Protons and neutrons are held together by the nuclear force. The atomic number defines the chemical properties of the atom, and is determined by the number of neutrons. The average radius of a neutron is about 0.8×10'−15m, which makes it easy to understand how small it is.

Protons have a positive electric charge, but neutrons do not have a measurable electric charge. Protons are affected by the electric field due to receiving a positive electric charge. Neutrons are not affected by electric fields because they have no charge. Neutrons have a magnetic moment, They do have a magnetic property called spin. The neutron's spin direction is affected by magnetism nicely.


Free neutrons decay into protons, electrons and antineutrinos. Neutrons have an average lifetime of less than 15 minutes. This is known as radioactivity or beta decay. This is due to the fact that the mass of the neutron is slightly greater than that of the proton.

When the neutron is free outside the nucleus it is variable and has an average lifetime of about 15 minutes. Protons have less mass than neutrons due to which neutrons decay. According to mass-energy equivalence, when the neutron thus decays to a proton it attains a lower energy state. Beta decay of neutrons is called radioactive decay which emits beta rays from the nucleus of an atom.The decay energy of this process for a free neutron is 0.782343 MeV. This process is mostly based on the masses of neutron, proton, and electron.

The history of the discovery of neutron particles

James Chadwick discovered the neutron in 1932. He was able to prove the existence of neutrons. Neutrons have since been used to initiate various types of nuclear fusion. Scientists then reasoned that if neutrons were produced in the fission process, each of these neutrons could cause further fission in a nuclear chain reaction. In 1938, nuclear fission was discovered. Scientists then reasoned that if neutrons were produced in the fission process, each of these neutrons would cause further fission in a nuclear chain reaction. They started working on this matter. As a result, science progressed towards the first self-sustaining nuclear reactors and the first nuclear weapons.

Photo of James Chadwick source

Rutherford had discovered the atomic nucleus in 1911. And 8 years after that he had observed the proton in 1919. Rutherford's atomic model which was discovered in 1911 said that the atom was a negatively charged, large nucleus with a small positive charge surrounded by a large cloud of electrons.

After the observing year 1919 , Rutherford stated that the nucleus consists of positively charged protons and neutrally charged particles in 1920. He believed that the electrons resided inside the nucleus.

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.source

W.D. Harkins correctly predicted the existence of the neutron particle in 1920. He was the first to use the term neutron with the atomic nucleus. Rutherford proposed that an electron and a proton combine to form a new particle which is neutral. He also named this particle Neutron. But the problem was there was no evidence behind it. Throughout the 1920s, physicists believed that the atomic nucleus was composed of protons and electrons. But the obvious problem was that it was difficult to reconcile the proton–electron model of the nucleus with Heisenberg's uncertainty principle of quantum mechanics.

In 1931, Walther Both and Herbert Becker discovered that alpha particle radiation from polonium, if incident on beryllium, boron, or lithium, produced unusually sharp radiation. Thus, the scientists continued to conduct various experiments and failed to match the results.

After that comes James Chadwick. He continued to conduct various experiments quickly. In 1932, James Chadwick did similar experiments. He proposed that the new radiation was coming from a neutral particle with the same mass as a proton called a neutron. Chadwick won the Nobel Prize in Physics in 1935 for the discovery of the neutron.

The extensive use of neutron particles

Neutrons are used in many nuclear reactions and play an important role. When atomic nuclei capture free neutrons then Neutron activation takes place. Then neutron radiation induces radioactivity in materials. After the discovery of neutrons, the contribution of neutrons is especially important in the development of nuclear reactors and nuclear weapons. Elements such as uranium-235 and plutonium-239 fission to accept their neutrons.

Neutrons excite delayed and fast gamma rays from materials. Neutron activation analysis (NAA) is often used to analyze small samples of materials in nuclear reactors, while fast gamma neutron activation analysis (PGNAA) is often used to analyze industrial bulk materials in sedimentary rocks around boreholes and in conveyor rings.

Another use of neutrons is nuclear detection in light. When a fast neutron collides with a light nucleus it loses a large part of its energy. By measuring the rate at which slow neutrons return to Earth after reflecting off hydrogen nuclei. A neutron beam can determine the amount of water in the soil.


Neutron radiation can be used for medical treatment because of both sharp and ionization. There are some problems. Unfortunate side-effects may occur to leave the influence of neutron radiation to leave radioactive. Therefore neutron tomography is not a side -effective device for a treatment. Yet to avoid any major danger, some small problems have to be accepted.

Since 1976, the Neutron Therapy Facility—one of only three such facilities in the United States, and one of only about a dozen worldwide—has treated more than 3100 patients. source

Neutrons are used to treat cancer. Quick neutron therapy uses more than 20 mev-rich neutrons to treat cancer. A neutron destroys a tumor cell by a nuclear reaction. If the radiation is excluded in small levels for the loss of cancer tissue, it gets time to recover itself in normal tissue. Short-powerful neutron beams are used in boron adoption therapy for cancer treatment. In boron receiving therapy, the patient is first given a boron drug. The boron tumor is desired. The tumor is then thrown in very low-powerful neutron which is captured by the boron-10 isotope. Which stimulates Boron -11, resulting in lithium -7 and an alpha particle. This process keeps enough energy to kill malignant cells. However, nearby cells can greatly damage. For cancer treatment, the neutron source that has the severity of this one thousand million neutrons is used per square centimeter per second.






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