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Type:
Educational Exhibit
Keywords:
Radiation physics, Radioprotection / Radiation dose, Experimental, Radiation effects, Education and training
Authors:
H. Hayashi, N. Kimoto, H. Okino, K. Takegami, I. Maehata, Y. Kanazawa; Tokushima/JP
DOI:
10.1594/ecr2016/C-0083
Learning objectives
A textbook about radiation physics may begin with an explanation of “ionization”,
and the understanding of ionization is important for freshmen entered in a training radiology course (Fig.
1). Commonly known,
the phenomena of ionization occurs due to interactions between X-rays and atoms,
and in higher learning students obtain the knowledge that photoelectric and Compton scattering effects,
play an important role in understanding ionization [1-3]. But actually,
there are no proper educational experimental apparatuses to demonstrate ionization. The aim of our study is to fabricate a new experimental apparatus.
Our experimental apparatus is based on a leaf electroscope,
which can detect the existence of charges. In the early stages of developmental radiation physics,
the leaf electroscope was used to derive the phenomena of ionization.
In recent years,
the leaf electroscope is used as a basic experimental educational tool in the high school. The feature of this apparatus is,
it is easy to understand,
because it clearly demonstrates the existence of charges through visualized information (conditions of leaves).
If the apparatus can explain ionization,
we think that the leaf electroscope is still a valuable experimental tool for the education of radiation physics.
The main idea of our experimental apparatus was proposed by Matsuura et al [4]. They fabricated the original leaf electroscope which consisted of two spaces; the lower space was used to irradiate X-rays,
and the upper space,
where charged leaves were placed.
First of all,
positive charges are induced to the leaves and the two leaves are opened by repulsion force. When X-rays were introduced to the lower space,
ions were produced through the phenomena of ionization. Then,
produced electrons are transported to the leaves and recombined with positive charges on the leaves. Because no charges appear on the leaves,
they are finally closed. The students can understand that the difference of “Open” and “Close” leaves is due to the irradiation caused by X-rays. This is basic concept of the educational experiment.
In this study,
we improved the apparatus for a more convenient use. Moreover,
we attempted to create a vacuum in the X-ray irradiation space. In an ideal condition,
one can understand that the ionization is caused by air through a comparison between the two experimental conditions of normal (standard temperature and pressure,
dry) and under a vacuum.