Alpha decay is a type of radioactive decay that typically tends to alter or change the fixed number of protons and neutrons contained by an atom. Alpha decay is the process of nuclear decay in which an unstable nucleus tends to shoot out a particle that consists of two protons and two neutrons and gets converted into another element. The original atom gets transformed into another element due to the change in the number of protons and neutrons. Here, the ejected particle is known as the alpha particle. The alpha particle is basically a helium atom that has an atomic number or the number of protons equal to 2 and a mass number or the total number of protons and neutrons equal to four. The alpha particle is positively charged and has a relatively large mass. The huge mass of the alpha particle means that such particles can not penetrate deep into solid surfaces or travel long distances through the air. The alpha decay was initially distinguished from the other forms of radioactive decay by New Zealand-born British physicist Earnest Rutherford while he was observing the deflection of radiations through a magnetic field. In simple words, alpha decay causes unstable nuclei to lose an alpha particle. An alpha decay generally occurs when the proton to neutron ratio is considerably large. This means that the process of alpha decay is restricted to heavy elements.
Examples of Alpha Decay
There are a number of applications of alpha decay in real life. Some of them are listed below:
1. Smoke Detectors
One of the prominent applications of alpha decay can be observed in the smoke detectors installed in buildings. Smoke detectors typically make use of a radioactive element known as americium-241. The internal circuitry of the smoke alarm contains two charged plates, a battery, a detector circuit, and an alarming mechanism. The connections are made in such a way that one terminal of the battery is connected to the positive plate of the smoke detector, while the other terminal is connected to a detector of current. The detector of current is further connected to an alarm. The circuit gets completed by connecting the alarming system to the negative plate of the smoke detector. Americium-241 placed in the middle of the charged plates is capable of exhibiting alpha decay by releasing alpha particles into the surroundings. These alpha particles can be used to ionize the air molecules present in the surroundings. The ionisation of air molecules causes a significant amount of current to develop between the plates of the smoke detector. The magnitude of the current is quite high when ionization exists in the surroundings; therefore, the detector of the current does not ring the alarm. In case of fire, the smoke enters between the two charged plates of the smoke alarm and slows down the movement of ions between the plates, thereby decreasing the current. The detector of current detects the decrease in the magnitude of current and activates the alarming system.
2. Nature’s Helium Production
The alpha decay of radioactive elements such as uranium and thorium produce a helium nucleus in the environment. This process is known as nature’s helium production. The helium produced as a result can be used in multiple applications such as in the arc welding process, to create an inert atmosphere to facilitate the fabrication of semiconductor devices and optical fibres by avoiding contamination of the components, inflating the car airbags, and many more.
3. Alpha Particle X-Ray Spectroscopy
The alpha particles are typically used in alpha particle x-ray spectroscopy. The alpha particle x-ray spectroscopy is typically used to study the structural and elemental composition of rocks present on the surface of earth or other planets. This means that alpha decay plays an important role in astronomy and planetary sciences.
4. Medical Equipment
Alpha decay is used in a number of medical equipment for the diagnosis and treatment of various lethal diseases such as tumours, cancer, etc. Targeted alpha therapy, abbreviated as TAT, makes use of alpha particles and is generally used to kill cancerous cells. Likewise, to treat tumours the patient is made to ingest the lead-212 element, which is highly radioactive in nature. The element reaches the tumour site and tends to release alpha radiations into the surroundings, thereby killing the infected cells.
5. Static Eliminator
The alpha radiations produced by the alpha decay of the radioactive element polonium-210 are typically used to eliminate static electricity. The positive charge of the alpha particles tends to attract the free electrons, thereby reducing the impact of the static electricity developed in the surroundings. The static eliminators are usually used in industries such as in paper mills.
6. Spacecraft Power Source
Various radioisotope thermoelectric generators are used to supply power to a number of satellites and spacecraft. These type of generators make use of radioactive elements such as plutonium-238 that undergoes alpha decay and produces alpha radiations. The alpha radiations are further used to generate heat, which finally gets converted into electrical energy that can be used to power an array of satellites and spacecraft. The operation of such devices is quite similar to that of a battery. The advantage of using radioisotope thermoelectric generators is the high capacity and long life span.
7. Pacemaker Battery
Pacemakers make use of the radioactive element plutonium-238 as an energy source that undergoes alpha decay and emits alpha radiations. Radioactive elements are preferred to be used as a fuel source for pacemaker batteries because the half-life of such elements is nearly equal to 88 years and can be used to power the equipment for a relatively long time duration. The disadvantages of such fuel sources include inconvenience caused to the patients while travelling, problems to dispose of the gadget, and toxicity.
8. Remote Sensing Stations
Alpha radiations play an important role in supplying power to the remote sensing stations. For this purpose, strontium-90 is usually used. The alpha decay of strontium-90 supplies enough power to carry on the unmanned operations of the station. The use of radioactive power sources that make use of alpha decay is generally preferred over traditional diesel-solar hybrid generators as such sources operate for a relatively large duration of time and require minimum repair and maintenance.
9. Heating Devices
The heating devices used in the spacecraft normally make use of alpha radiations produced by the alpha decay of certain radioactive elements. The working of such heating devices is quite similar to radioactive thermal generators except for the fact that in this case the heat generated due to alpha decay is not converted into electrical energy, but is used directly.
10. Coast Guard Buoys
A buoy is a device that is placed in the middle of seas and oceans and is allowed to float on the surface or drift with the flow of water. The purpose of such devices is to mark the warning points for the ships and boats. To power coast guard buoys, the alpha decay of radioactive elements such as strontium-90 is typically used.
11. Oil Well Equipment
The oil industry consists of certain remote regions that are unsafe and have limited or no access to the workers and staff. In such places, alpha radiations and alpha decay of elements are typically used as a source of energy because the power generated by such radioactive elements is long-lasting and reliable in nature.
12. Seismic and Oceanographic Devices
Seismometers are devices that are located on the seafloor and are used to record the movement of the ground to predict the occurrence of an earthquake. Likewise, oceanographic devices are used to monitor the characteristics of the water and record important data regarding the current nature of tides and ocean current to predict the bad weather conditions and the probability of occurrence of natural disasters such as hurricanes, tsunamis, etc. Such unmanned devices are generally supplied with power by the alpha decay of certain radioactive elements.