ﾊA Cloud Chamber Shows Tracks
from Cosmic Raysﾊ
and Natural Radioactivity
You'll be able to watch variety cases of cosmic rays through the videos here.
| You can see three interesting tracks in the upper right: labeled A, B and C that all originate at a point O. These three tracks were created at the same time by the an interaction at point O. In each track, the left part is thicker than right. This means the particles moved from right to left, because the tracks become thicker when the speed of the particle slows down. The appearance of the tracks has nothing to do with exposure time of the camera. | 
Video High-energy charged particles 3 |
| The three tracks, OP, QR, RS show a series of reactions but the details of the reactions are unknown. We can guess that tracks OP and QR were produced by high-energy charged particles. Then, the particle that produced QR decayed at point R to another less massive charged particle that leaves a thinner track RS. However, RS is thicker than an electron's track but thinner than an alpha's track. It may be produced by some kind of meson. | 
VideoSeries of reaction |
| The track HC was produced by a high-energy charged particle moving from the lower right. Notice that the track is thicker on the upper part. The track is thicker than an electron's track but thinner than an alpha's track. It may be produced by some kind of meson.ﾊ | 
Video High-energy charged particles |
| Since two tracks OA and OB appear simultaneously, an unknown reaction happened at O to make these tracks. Since the cloud chamber only shows charged particles it is possible that an unseen neutral particle deposited the energy to produce the two tracks. | 
Video Unknown trails mpg |
| Many thin parallel trails appear simultaneously at the upper part of this video image. This is an example of a "cascade shower". A cascade shower is a reaction where an energetic primary cosmic ray some distance away from the chamber produced a vast number of electron positron pairs which resulted in the parallel tracks. Photons were probably also produced but they would not be seen since they have no charge.ﾊ | 
Video Cascade shower 1 mpg |
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Video data
| The Large Scale Diffusion Cloud Chamber: was made by PHYWE
SYSTEME GMBH in Germany. Toshiaki Iwami, of the Niigata Science Museum staff took all the videoﾊ images with a SONY Digital Handycam DRC-PC100 video camera. The date the image was made is shown on lower left..(year, month, day)ﾊ |
This page was written by T.Iwami and producted by A.Nakamura
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Japan TEL: +81-25-283-3331 FAX: +81-25-283-3336 E-mail: nsm@coral.ocn.ne.jp |