Introduction of Artificial Transmutation
The process of converting one element into another by bombarding it with fundamental particles is called artificial transmutation. The very first artificial element produced by the process of artificial transmutation was oxygen. Thus, in simple words, it is the process of transformation of one particular element into another by the making use of artificial means. For getting an element of oxygen, the nucleus of nitrogen was bombarded with an alpha particle. Normally, the element that is produced through the process usually exhibits radioactivity which results in induced radioactivity. The particles that you can use for bombardment are:
α-particle; Proton and Deuteron: 1H3, Neutron 0n1
Process of Artificial Transmutation
Now, as we read above, the new or artificial element that is produced by the process of artificial transmutation exhibits radioactivity, which results in induced radioactivity. Usually, the particles that are bombarded with the main element are, α-particle; Proton, and Deuteron, Neutron, Alpha particles, deuterons and protons, they all carry nuclei that are positively charged. They are not suitable projectiles because they all repel positively charged nuclei.
Neutrons, on the other hand, possess no charge at all, and hence considered the best projectile for the artificial transmutation process. When the main element or the targeted element is bombarded with a neutron, the resulting element or product shall depend upon the speed of the neutron with which it is bombarded. The bombardment is slow; the neutrons penetrate into the nucleus of the targeted element. When the bombardment speed is high the neutrons pass through the nucleus. The other name of a slow neutron is the thermal neutron. In producing a nuclear reaction, the slow neutrons are more effective than the high-speed neutrons.
Who Discovered Artificial Transmutation?
On June 2nd, under the guidance of the Junior Scientific Club, the annual Boyle lecture was delivered by Lord Rutherford who took the “Artificial Transmutation of the Elements” as his subject . He described the pioneer achievements of Messrs, Cockcroft, and Walton at the Cavendish Laboratory in applying the high voltage method of generating fast streams of protons for producing atomic transformation and detailed recent developments of method by which it was possible to obtain still greater results at a lower voltage. Further modifications have led to conclusions of high interest, and the new type of projectile results in extending the knowledge factor of types of possible transformation, most of which is now in use.
It was probable that further assaults would be made on the stability of the nucleus shown, and there was particular evidence of the appearance of a more positively charged particle of mass comparable with that of the negative electron. The bombarding projectiles are imparted with high energy before bombarding the target nucleus by the device called Particle accelerator, like linear accelerator, cyclotron, synchrotron, etc.
Ernest Rutherford was one of the pioneers who discovered artificial transmutation. He discovered the following by exposing the nitrogen atoms to alpha particles. He bombarded the said nitrogen nucleus with the present alpha particles in order to get oxygen.
Rutherford allowed α -particles to pass through different glasses. He studied the different processes that may happen. The apparatus consists of a thick glass chamber A provided with an adjustable rod, carrying a radioactive substance R. The side of the glass tube facing R is covered by a metal plate with a central hole which is closed by a thin silver foil. A screen S coated with a fluorescent material like zinc sulfide is arranged in front of the silver foil and the scintillations produced on it can be observed through the microscope M. The radioactive substances emit α -particles whose range in the air is roundabout 8cm. When the glass tube is filled with nitrogen gas, scintillations are observed even when R is at a distance of 40cm from the foil. These particles produce scintillations and it cannot be α -particles because they cannot have such a long range. A further analysis proved that each of these particles had a mass which was nearly equal to that of a hydrogen atom and carried a positive charge equal to that of an electron. The new particles were named as protons.
When a nitrogen nucleus is hit by an α (42He ) -particle, it disintegrates into an oxygen nucleus with a proton 11H . The nuclear reaction can be represented as
\[N_{7}^{14} + He_{2}^{4} \rightarrow O_{8}^{17} + H_{1}^{1}\]
The light elements from boron to potassium, with the exception of carbon and oxygen, will be transmuted by bombarding with α -particles ( 42He ).
In fact, the first nuclear transmutation was also witnessed and applied to the branch of modern physics by Frederick Soddy. He was working with Rutherford in the year 1901, and they both discovered that radioactive thorium could transform itself into radium. They were excited to witness that the process was transmutation and Soddy worked on it further to apply it to the branch of Physics.
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Some Prominent Examples of Artificial Transmutation
When an alpha particle is bombarded with the nucleus of a nitrogen element, oxygen as an artificial element is produced. As a part of transformation, one atom of hydrogen is also produced.
When an alpha particle is bombarded with the nucleus of an aluminum element, phosphorus as an artificial element is produced. As a part of the transformation, a neutron is produced.
When Uranium-28 is bombarded with neutrons, the resultant element is Uranium-239. Uranium-239 is very unstable; therefore, it decays to Neptunium. When it decays, it produces beta particles.
Conversion Laws Applied to Nuclear Reactions
While studying artificial transmutation, it is necessary to keep a note on “conversion laws” that are applied to a nuclear reaction.
The number of nucleons in a nuclear reaction stays the same or is conserved.
The mass–energy relation is conserved.
The charge is conserved, to understand it differently, the sum of charges on the left-hand side of the reaction is equal to the number of charges on the right-hand side.
Artificial Transmutation Equation
The artificial transmutation equation is based upon the conversion laws as noted above. It represents the conversion of one element into the other. The reaction is shown with the number of protons. The element which is to be converted by bombardment is kept at the left-hand side along with the fundamental particle that has to be bombarded, on the right-hand side comes the final element along with the subatomic particles. An example of this can be:
When you bombard Uranium-238 with a neutron, it will convert into Uranium -239, it is highly unstable and transmutes into Neptunium which can be seen emitting a beta participle.
Difference Between Artificial Transmutation and Artificial Radioactivity
In artificial transmutation, one element, which is a non-radioactive element, is converted into a final element by bombarding a fundamental particle through artificial means. While in artificial radioactivity, the radioactivity is induced in a stable element, and the whole process undergoes numerous nuclear reactions.
FAQs on Artificial Transmutation
1. What is the main Difference Between Artificial Transmutation and Nuclear Decay?
Well, the main difference between the two revolves around the process of the two. While artificial transmutation revolves around making use of a said generator such as a cyclotron in order to transmute elements, nuclear decay is actually the process of natural decaying of a said element resulting in constituent elements. While nuclear decay is a natural process that was initiated at the start of the universe, artificial transmutation is an artificial process.
2. What do you need for Artificial Transmutation?
The artificial transmutation can be achieved while using particle accelerators that strike the elements with the help of deuterons, small nuclei, or alpha particles. While using this process, you can lodge a few of the bombarding particles from protons into the target nucleus, resulting in transmutation into an entirely different element altogether.
3. What are nuclear fission reactors?
Nuclear fission reactors are not just a source of heat for power production. They are also an abundant source of neutrons. As neutrons have no charge in themselves, they have the ability to be inserted into the nuclei of a wide variety of elements. This usually makes the nucleus 'neutron rich' and makes the nucleus unstable. It, therefore, makes the material bombarded with neutrons into a radioactive isotope of the original material provided beforehand. The radioactive nuclei will then decay into the nuclei of another element. Canada is one of the primary sources of isotopes for medical and industrial use because the type of nuclear reactor they have built there makes nuclear transmutation easier to do. They, therefore, make the isotopes, and they sell them around the world.
4. What are transuranic elements?
These are elements with proton numbers greater than 92. Since the dawn of the nuclear age, the elements with proton numbers higher than 92 have existed on our planet. The transuranic elements have not occurred naturally, they are artificially created.
