Gamma Decay

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Gamma Decay

This lesson aligns with NGSS PS1.C

Introduction

Gamma decay is a fascinating phenomenon within the realm of nuclear physics, representing the release of high-energy gamma rays from an atomic nucleus. This process plays a pivotal role in understanding the stability and transformation of atomic nuclei, contributing to the broader comprehension of nuclear reactions and radioactive decay. In this article, we delve into the intricacies of gamma decay, exploring its mechanisms, significance, and providing real-world examples.

What is Radioactivity?

Radioactivity can be defined as a phenomenon wherein nuclei emit particles due to nuclear reactivity. Quantum theory states that predicting the exact moment when a specific atom will undergo decay is challenging.

Various types of radioactive decay exist, including:

Alpha Decay:

In this type of decay, a helium nucleus is emitted.

Beta Decay:

This decay involves the emission of electrons.

Gamma Decay:

High-energy photons are emitted in this form of decay.

Understanding Gamma Decay:

Gamma decay is one of the three primary types of radioactive decay, alongside alpha and beta decay. While alpha and beta decay involve the emission of particles, gamma decay is the emission of electromagnetic radiation in the form of gamma rays. These gamma rays are extremely high-energy photons, akin to X-rays, but with even greater energy levels.

Mechanism of Gamma Decay:

The mechanism behind gamma decay lies in the rearrangement of the internal structure of the nucleus to reach a more energetically favorable state. In simple terms, when a nucleus is in an excited state, one or more of its protons or neutrons may rearrange themselves to achieve a more stable configuration. During this rearrangement, excess energy is emitted in the form of gamma rays.

The energy of gamma rays can vary widely, ranging from a few keV (kilo-electron volts) to several MeV (mega-electron volts).

In contrast to alpha and beta decay, the process of gamma decay does not induce any physical change in the parent nucleus; both the daughter and parent nuclei remain unchanged. Typically, gamma decay follows alpha or beta decay in radioactive nuclei. The preceding alpha or beta decays leave the daughter nuclei in an excited state. To return to the ground state, the excited daughter nuclei emit one or more high-energy gamma rays. An illustrative example will aid in better understanding this process:

The above image illustrates the trajectory of Cobalt-60 transitioning from an excited state to a non-excited state. In this process, beta decay can result in the nucleus occupying one of two distinct energy levels. The percentages provided alongside the beta symbol denote the likelihood of nuclei opting for either of these pathways. The subsequent sequence involves beta decay, followed by gamma decay.

Gamma Rays and X-rays

Due to their energy levels, both x-rays and gamma rays possess significant penetration capabilities, posing potential hazards to biological life forms.

It is crucial to differentiate between x-rays and gamma rays. X-rays are generated by electrons, whether in atomic orbits or external applications like particle accelerators and synchrotrons radiation. On the other hand, gamma rays are emitted from the nucleus, particle decay, or annihilation reactions.

Examples of Gamma Decay:

To illustrate the concept of gamma decay, let's explore a few real-world examples:

Cobalt-60 Decay:

Cobalt-60 (Co-60) is a commonly cited example of gamma decay. This isotope undergoes beta decay, transforming a neutron into a proton and releasing a beta particle. The resulting nucleus, which is often in an excited state, subsequently undergoes gamma decay to achieve a more stable configuration. The emitted gamma rays from Co-60 are extensively used in medical and industrial applications, such as cancer treatment and sterilization.

Technetium-99m Decay:

Technetium-99m (Tc-99m) is widely utilized in nuclear medicine for diagnostic imaging. It undergoes gamma decay to reach a more stable state. The emitted gamma rays, with specific energy levels, are captured by detectors to create detailed images of internal body structures, aiding in the diagnosis of various medical conditions.

Summary

Radioactivity can be defined as a phenomenon wherein nuclei emit particles due to nuclear reactivity.
Gamma decay is the emission of electromagnetic radiation in the form of gamma rays.
When a nucleus is in an excited state, one or more of its protons or neutrons may rearrange themselves to achieve a more stable configuration. During this rearrangement, excess energy is emitted in the form of gamma rays.

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