Study on the Observation of Radiation Using an S Cloud Chamber

—Education Activity in Lower Secondary School—

Abstract

The purpose of this research is to verify that the track of radiation can be easily observed by using an S cloud chamber in lower secondary school. Many practices to observe radiation have been carried out using various cloud chambers. However, these practices need dry ice or liquid nitrogen. Therefore, it was difficult to experiment on the cloud chamber at schools which could not get dry ice. We used an S cloud chamber, which is a high-performance cloud chamber that has a chemical freezing mixture such as snow melting agent (MgCl₂·6H₂O) instead of dry ice, etc., and which is easy for lower secondary school students to make. In addition, we used collected dust for the radiation source. It was shown that the dust collected in the room at the Hokkaido University of Education was mainly ²²²Rn of uranium series and its daughter nuclides, and it was shown to be sufficiently usable as a radiation source within 1 hour from being picked. In this study, the S cloud chamber was actually made in lower secondary school and the track of radiation of the dust was observed. As a result, we were able to observe the track of radiation by using only familiar material, and it was revealed that lower secondary school students could easily observe the track of beta rays, which had been quite difficult to observe. We found the student’s recognition of the radiation changed after the lesson. From these facts, it is clear that the lesson using the freezing mixture and the S cloud chamber is effective for lower secondary school students who have no dry ice.