Download Measuring Radon Levels using CR39 Detectors: A Laboratory Experiment - Prof. Samuel A. Abr and more Lab Reports Chemistry in PDF only on Docsity! Experiment 21: Measurement of Radon in Air – Prelab for assembly of Radon Detectors What is the purpose of this experiment? The purpose of this experiment is to measure the levels of Radon in a location of your choice. Why are we interested in Radon levels? Radon is a radioactive inert gas. It is a decay product from Uranium. Uranium is present in trace quantities in granite that may lie beneath the foundations of many houses. It can pass from cracks in granite through soil into houses. Radon became a serious concern in the 80’s in the first fuel crisis, when many people began insulating their households more tightly. Ironically a by product of the insulation was that Radon, which had been previously kept at low levels because of regular circulation and replacement of the air in a house, was able to build up to unacceptable levels. Why does it matter that Radon builds up? While radon is a decay produce of uranium, radon itself is subject to radioactive decay, emitting high energy alpha particles. These alpha particles represent a health hazard. What are alpha particles? Alpha particles are helium nuclei, with a mass of 4 atomic mass units (AMU) and a charge of +2. They are a class of radiation called ionizing radiation. They tend to strongly damage matter (and tissue) that they pass through. How do we detect radon? Because radon is one of the inert gases, we can’t use chemical reactivity to detect it, so we instead we’ll detect it’s alpha radiation. How do we detect alpha radiation? We use two facts about it. First, it damages matter it passes through. Second, because the alpha particles are fast moving, they tend to penetrate far into matter they strike. Thus, if the matter they pass through is sufficiently rigid alpha particles will leave tracks in the material. What material will we be using? A polymer called CR39. This is the most common material used in making eyeglass lenses. Will we be able to see the tracks as they are made? No, for three reasons. First, they are too small, so a microscope is required. Second, they need to be developed by soaking the CR39 in the proper solution. Third, the alpha emission is so rare in most locations, that a long period of exposure is necessary to observe a detectable number of tracks. How long is a long exposure? Four weeks. FOUR WEEKS? Yep, four weeks. So what’s the plan for today? Make the detectors according to the directions in your manual. Record what you do in your notebook. Put your detectors in a place you want to investigate. Are there especially good places to put the detectors? Basements and rooms with poor ventilation are good places. Anything I need to worry about? Yes. If a janitor finds your detector and doesn’t know what it’s for he or she might throw it out. So what do I do to prevent that?
