What are the characteristics of alpha particles in nuclear experiments?

Alpha particles are positively charged particles consisting of two protons and two neutrons, emitted during radioactive decay.

Alpha particles are one of the three types of particles emitted during the process of radioactive decay, the other two being beta and gamma particles. They are relatively large in size and carry a positive charge, due to the presence of two protons. This makes them doubly positively charged particles. They are essentially helium nuclei, as they consist of two protons and two neutrons, the same as a helium atom but without the electrons.

In nuclear experiments, alpha particles are often used because of their unique characteristics. They have a relatively low penetration power, meaning they can't travel far or through dense materials. They can be stopped by a sheet of paper or a few centimetres of air. This is due to their large size and positive charge, which cause them to interact strongly with matter, ionising atoms and molecules in their path. This ionising property makes them potentially harmful to living tissues and cells, which is why safety precautions must be taken when working with alpha particles.

Despite their low penetration power, alpha particles have a high ionising power. This means they are very effective at knocking electrons off atoms, creating ions. This property is utilised in smoke detectors, where a small amount of a radioactive material that emits alpha particles is used. The ions produced by the alpha particles allow a current to flow. If smoke enters the detector, it disrupts this current, triggering the alarm.

In terms of their speed, alpha particles are slower than both beta and gamma particles. Their speed is typically around 10% the speed of light. This, combined with their large mass, gives them a significant amount of energy, making them useful in various applications, from medical treatments to power sources for space probes.