Question

People who work around radioactivity wear film badges to monitor the amount of radiation that reaches their bodies. Each badge consists of a small piece of photographic film enclosed in a lightproof wrapper. What kind of radiation do these devices monitor, and how can they determine the amount of radiation the people receive?

Short answer

Film badges monitor ionizing radiation by darkening when exposed. The degree of darkness indicates radiation levels.

Step-by-step solution

Identify Radiation Types Monitored

Film badges are designed to monitor ionizing radiations, which include alpha particles, beta particles, gamma rays, X-rays, and neutron radiation. These types of radiation have the capability to affect the structure of atoms and molecules they interact with, necessitating monitoring.

Working of Film Badges

Film badges contain a photographic film that darkens when exposed to ionizing radiation. The level of darkening on the film correlates with the intensity and type of radiation exposure the badge has undergone.

Measuring Radiation

After a certain period, the film badge is developed in a controlled environment. The darkness of the film is measured and compared with a standard to quantify the amount of radiation exposure. The type of radiation and its energy level can also be deduced based on how much the film has darkened and which filters were included.

Key concepts

Ionizing Radiation

Ionizing radiation consists of particles or waves that have enough energy to remove tightly bound electrons from atoms, creating ions. This process can affect the atoms and molecules in living tissue, which is why it's crucial to monitor for safety reasons. Ionizing radiation includes:

• Alpha particles: Heavy and positively charged. They can be stopped by a sheet of paper and are not able to penetrate the skin.
• Beta particles: Lighter and less charged. They can pass through paper but are generally stopped by plastic, glass, or aluminum.
• Gamma rays and X-rays: High-energy electromagnetic waves. They can penetrate deeply into the body and require dense materials like lead or several inches of concrete for protection.
• Neutron radiation: Uncharged and can penetrate materials easily. Typically managed by substances rich in hydrogen, like water or paraffin.

Understanding these types helps determine the kind of protection needed for people working with radioactive materials. Different types of ionizing radiation require different shielding methods, and these need to be tailored to the work environment to ensure safety.

Film Badge Dosimeters

Film badge dosimeters are a simple yet effective means of monitoring cumulative radiation exposure for those working around ionizing radiation. They function similarly to a camera film by "capturing" radiation. The badge consists of:

• A piece of photographic film sensitive to ionizing radiation.
• A lightproof wrapper to ensure the film only reacts to radiation and not to visible light.
• Filters that help identify the type and energy of the radiation.

When ionizing radiation hits the film, it causes a chemical change that darkens the film, representative of the radiation dose received. These dosimeters are routinely processed in a lab to assess the exposure levels, ensuring that they remain within safe limits. Film badges are worn by radiation workers for specific periods, often from a week to several months, depending on the work environment and regulations.

Radiation Exposure Measurement

Measuring radiation exposure is crucial for assessing the safety and health risks for individuals working with or around radioactive materials. It helps in maintaining safe levels of exposure and prevents long-term health effects associated with ionizing radiation. The process of measuring exposure using film badge dosimeters involves several steps:

• Collection of exposed film badge dosimeter from the wearer.
• Development of the film in a controlled environment to reveal the level of darkening, which is proportional to the radiation dose received.
• Comparison of film darkness against a standard scale to determine the dose.
• Analysis with filters to differentiate between types of radiation and ascertain their respective energy levels.

This method allows organizations to assess individual exposure levels accurately and make informed decisions about occupational safety. By regularly checking radiation doses, it’s possible to adjust work practices and schedules to minimize exposure, adhering to regulatory limits and keeping the workforce safe.