The basic definition and characteristics of beta rays

introduction

When exploring the complex world of radioactive materials, beta rays, also known as beta rays, are an indispensable part. As a high-energy electron stream released during radioactive decay, beta rays have demonstrated their unique properties and application value in various fields such as physics, chemistry, biology, and medicine. This article aims to comprehensively explain the basic definition, physical properties, biological effects, and practical applications of beta rays, in order to provide readers with a comprehensive and in-depth understanding.



1、 The basic definition of beta rays

Beta rays, also known as beta rays, are high-speed electron flows released by radioactive materials during beta decay. These electrons have a speed close to 99% of the speed of light and possess significant kinetic energy and penetration power. During beta decay, the protons or neutrons inside the nucleus undergo changes, releasing electrons and neutrinos, which are called beta particles or beta rays.
According to the different types of decay, beta rays can be divided into two types: positive beta decay and negative beta decay. In positive beta decay, a proton in the nucleus transforms into a neutron, while releasing a positron (i.e. a positive beta particle); In negative beta decay, a neutron transforms into a proton and releases a negatively charged electron (i.e., a negative beta particle or what we commonly refer to as a beta particle). These two decay processes together constitute the mechanism of beta ray production.

2、 The physical properties of beta rays

1. Penetration and ionization ability

The penetration and ionization ability of beta rays are between alpha and gamma rays. Compared to alpha rays, beta rays have stronger penetration power and can penetrate thinner material layers such as paper and fabric. However, compared to gamma rays, beta rays have weaker penetration and cannot penetrate thicker material layers, such as aluminum plates.

In terms of ionization ability, the ionization effect of beta rays is relatively weak. Ionization refers to the process in which charged particles ionize atoms or molecules in a substance, forming ion pairs. Due to the small mass of beta particles, their ionization ability is relatively weak and their destructive effect on substances is also relatively small.


2. Scattering and backscattering

When beta particles move in matter, they interact with the Coulomb field of the atomic nucleus, resulting in scattering phenomena. Due to the small mass of electrons, the scattering angle can be large, and even multiple scattering can occur, ultimately deviating from the original direction of motion. This scattering process is called elastic scattering. In some cases, beta particles may also undergo backscattering, which is a phenomenon where the scattering angle is greater than 90 °.

In addition, when beta particles move in matter, if their energy is depleted and they fail to penetrate the material, they may be bound by the material atoms and become members of the electrons outside the nucleus of the medium atom. This process is called absorption.

3. Bremsstrahlung and Cherenkov radiation

When beta particles move in matter, if their velocity approaches or exceeds the propagation speed of electromagnetic waves in the medium, radiation phenomena will occur. Among them, when electrons pass near the atomic nucleus and are accelerated by the Coulomb field, they will emit electromagnetic waves, known as bremsstrahlung. The loss rate of bremsstrahlung is directly proportional to the square of the atomic number, which means that bremsstrahlung is more likely to occur when electrons hit heavy elements.

Another type of radiation phenomenon is Cherenkov radiation. When the velocity of electrons in a medium exceeds the propagation speed of electromagnetic waves in the medium (i.e. v>c/n, where n is the refractive index of the medium), they will emit electromagnetic waves in a specific direction, known as Cherenkov radiation. This radiation phenomenon is of great significance in particle physics and accelerator technology.

3、 The biological effects of beta rays

1. Radiation damage

Due to the penetrating power and ionization ability of beta rays, when the human body is exposed to beta rays, it can cause a certain degree of damage to cells and tissues. This kind of damage is mainly manifested as a change in the chemical balance of cells, which in turn triggers a series of biological effects. In some cases, these biological effects may lead to cellular carcinogenesis or genetic material mutations.

2. Dose effect relationship

The degree of damage caused by beta rays to organisms is closely related to their irradiation dose. Generally speaking, the higher the irradiation dose, the greater the damage to the organism. Therefore, when evaluating the biological effects of beta rays, factors such as their irradiation dose and duration must be considered.

3. Protective measures

In order to reduce the damage of beta rays to organisms, a series of protective measures need to be taken. Firstly, direct contact with contaminated items and surfaces should be avoided as much as possible to prevent skin surface contamination and radiation hazards. Secondly, it is necessary to prevent inhaling contaminated air and consuming contaminated food to reduce the risk of internal exposure. In addition, for wounds or sensitive areas that may be exposed to beta radiation, appropriate shielding measures should be taken to reduce radiation dose.


4、 The practical application of beta rays

1. Medical field

In the field of medicine, beta rays are widely used in radiation therapy, radioactive isotope labeling, and drug development. By utilizing the ionization and penetration of beta rays, precise irradiation of tumor cells can be achieved to achieve therapeutic goals. Meanwhile, radioactive isotope labeling technology also provides strong support for drug development.

2. Industrial sector

Beta rays have high penetration power and can penetrate some thinner metal materials. In industry, this characteristic is used for material testing, such as measuring the thickness, density, and analyzing the composition of materials. By detecting the penetration ability of beta rays, the physical properties and quality of materials can be evaluated, providing important basis for material selection and use.