Alpha Decay

Alpha decay, also referred as ɑ-decay, is a type of radioactive decay where an atomic nucleus produces an alpha particle (helium nucleus) and therefore converts or ‘decays’ into a new atomic nucleus with a mass number of four and an atomic number of two. The nucleus of a helium-4 atom, that consists of two protons and two neutrons, is identical to an alpha particle. 

Whenever the alpha-particle energies are measured spectroscopically, the emission of helium ions produces crisp line spectra. The most intense alpha group or line for even–even alpha emitters is always the one leading to the daughter’s ground state. Weaker, lower-energy lines lead to excited states, and there are typically many lines visible.

Alpha Decay

Alpha decay is a type of radioactive disintegration where certain unstable atomic nuclei spontaneously release an alpha particle to dissipate excess energy. Since alpha particles have two positive charges and a mass of four units, they form offspring nuclei with a positive nuclear charge or atomic number two units lower and a mass four units lower than their parents. As a result, polonium-210 (mass number 210  and atomic number 84, that is a nucleus with 84 protons) decays to lead-206 through alpha emission (atomic number 82).

The speed, and thus the energy, of an alpha particle expelled from a certain nucleus is a parameter of the parent nucleus which determines the alpha particle’s characteristic range or distance. Alpha particles, despite being released at a speed of about one-tenth that of light, are not very penetrating. They have only a few centimeters of range in the air (corresponding to an energy range of about 4 million to 10 million electron volts).

The major alpha emitters are elements heavier than bismuth (atomic number 83 and rare-earth elements ranging from neodymium (atomic number 60) to lutetium (atomic number 83). (atomic number 71). Alpha decay half-lives range from roughly a microsecond 106) to about 1017 seconds (over 3 billion years).

Ernest Rutherford first separated alpha decay from other types of radiation by observing the deflection of the radiation through a magnetic field. Because alpha particles carry a charge, they deflect in the same way as positive particles do.

The heaviest nuclides are most likely to undergo alpha decay. It can theoretically only happen in nuclei somewhat heavier than nickel (element 28), in which the overall binding energy per nucleon is no longer a maximum, making the nuclides unstable to spontaneous fission-type processes. This mode of decay has only been detected in nuclides far heavier than nickel, with the lightest known alpha emitters being the lightest tellurium isotopes.. Beryllium-8, on the other hand, decays to two alpha particles. 

The most common type of cluster decay is alpha decay, in which the parent atom ejects a specified daughter collection of nucleons and leaves another determined product behind. Due to the obviously extraordinarily high nuclear binding energy and the alpha particle’s comparatively modest mass, it is the most common form. Alpha decay, like some other cluster decays, is essentially a quantum tunnelling phenomenon. It is governed by the interaction of both the strong nuclear force and the electromagnetic force, with the exception of beta decay.

Safety

Although not particularly penetrating, ingesting a chemical which undergoes alpha decay is dangerous because the released alpha particles can rapidly injure inside tissues due to their small range. Interaction with membranes and live cells causes this harm.  Figure depicts a diagram depicting the various levels of penetration for various types of radiation.

The health consequences of alpha particles differ depending on how they are exposed. There can be long-term health effects whenever the alpha emitter is inhaled, eaten, or absorbed into the bloodstream. This harm raises a person’s cancer risk. When an alpha emitter is inhaled, it is proven to cause lung cancer in humans. One of the most common causes of alpha decay-related sickness in humans is the inhalation of radon, an alpha emitter.

Applications and Importance

In smoke detectors, radioactive materials which undergo alpha decay are employed . Alpha particles are emitted inside the smoke deterrent. The air inside the detector becomes ionised as a result. As smoke in the detector absorbs this alpha radiation, the ionisation is changed, and if smoke is present, the alarm is triggered. Alpha particles are also employed in a technique called Alpha Particle X-Ray Spectroscopy (APXS). The elemental composition of rocks and soil is examined using this method. 

Conclusion

Alpha decay is a type of radioactive disintegration in which certain unstable atomic nuclei release an alpha particle spontaneously to disperse surplus energy. Whenever the alpha-particle energies are measured spectroscopically, the emission of helium ions produces crisp line spectra. The most intense alpha group or line for even–even alpha emitters is always the one leading to the daughter’s ground state.