A simple note on what is alpha decay

α-particle decay occurs when a parent nucleus releases an α particle (a nucleus of helium) with two neutrons and protons. The decay product’s charge on nucleus Z is two units minus the parent’s. Its nuclear mass A is four mass number units minus the parent’s because they expelled this quantity of nuclear charge, and mass is taken away by the alpha particle. 

Due to a loss of two units in charge of the nucleus between parent and product, the decay result will be a brand-new element that will be moved two units to the left. The ejected particle is known as the alpha particle. Alpha decay is a nuclei decay process. After alpha decay, the nucleus changes from one element to another.

Radium, for example, has a proton number of eighty-eight and is found in column two of the periodic chart. After releasing an α particle, the decay result is radon, an element with a proton number of 86. Because alpha radiation is the most destructive ionising radiation, it is rarely lethal unless the originator is consumed or inhaled. The ejected particle is known as the alpha particle. 

The principal α emitters of medical relevance were radon and radium in the past. Radium-223 dichloride is still used to treat osseous metastases. Other α emitters are currently investigated for therapeutic purposes, including the delivery of short-half-life alpha emitters to cancer cells via radiopharmaceuticals. 

Because of their short-range, α particles can transport a deadly dose of radiation to tiny metastatic cell clusters while the surrounding tissue is spared. All alpha emitter work must be done in a strictly controlled environment.

Geiger-Nuttall rule

Most known alpha-particle emitters have energy spectra in the 4–6 MeV region, with a few dipping as small as two MeV and reaching as high as ten MeV. The alpha emitter’s half-period and the kinetic energy of the released α particles have a predictable relationship. Short-lived nuclides emit the highest-energy alpha particles, while very long-lived alpha-particles emit the lowest-energy α particles. Physicists Hans Geiger and John Mitchell Nuttall established a linear link between log and the energy of the α particle.

Classical physics cannot account for the Geiger-Nuttall rule, but quantum mechanics or wave mechanics explains it. The transmittance through barriers of nuclear potential, a notion proposed in 1928, was shown to account for the decay data in an acceptable way, and it has only been modified in detail since then. The barrier-penetration equations are formulated so that log versus 1/E correlation plots give nearly straight lines.

Nuclear potential barrier

At large r distances compared to the radius of the nucleus, the potential energy of a 2e charged α particle in the field of a remnant nucleus with a charge (Ze) equals to 2(Z2)e2/r. 

Short-range, nuclear attractive forces oppose and overcome electrostatic repulsion at very close distances. The potential nuclear barrier is the net potential energy U as a function of the separation r between the alpha particle and its remnant nucleus.

One of the different operational meanings of the nuclear radius R is the range r = R at which the nucleus’s attracting forces just equal the electrostatic repulsive forces. The potential energy for classic examples of heavyweight, alpha-emitting nuclei is around 25–30 MeV at this range, known as the top of the nuclear obstruction.

In the nucleus, the α particle appears as a wave of de Broglie. According to wave mechanics, this wave has a very small but limited possibility of breaking through the nuclear potential energy barrier and escaping the nucleus as an alpha particle. 

Transference of a particle via an energy barrier in classical electrodynamics is impossible. However, it is conceivable in wave mechanics. This transference of a wave of matter through an energy barrier is similar to the very known phenomenon of visible light passing through metal like gold. If the gold is sufficiently thin, like a thin gold leaf, light passes through it.

Gamow’s Theory of alpha decay

An alpha particle might exist within a heavy nucleus as a different entity. A potential barrier keeps such a particle in the nucleus in constant motion, and there is a tiny but definite chance that the particles will cross through the barrier.

The decay chance per unit time, λ, can be expressed as

λ = ν T

ν: the quantity of instances an alpha particle in a nucleus hits the potential barrier in a second

T: the possibility that the particle will be pass through the barrier

Conclusion

To summarise, α-particle decay occurs when a parent nucleus releases an α particle (a nucleus of helium) with two neutrons and protons. Alpha decay is a nuclei decay process. The ejected particle is known as the alpha particle.

After alpha decay, the nucleus changes from one element to another. The decay product’s charge on nucleus Z is two units minus the parent’s, and its nuclear mass A is four mass number units minus the parent’s because they expelled this quantity of nuclear charge, and mass is taken away by the alpha particle. 

Due to a loss of two units in charge of the nucleus between parent and product, the decay result will be a brand-new element that will be moved two units to the left.