Development of an imaging plate as a heavy-nuclide detector

It is very important for the study of nucleo-synthesis in supernova explosion to be able to measure the abundance of heavy nuclides in cosmic rays. Though a large-area detector is necessary for measurements of the abundance, it takes very long time to analyze the data for large-area detectors such as emulsion chamber. To address this need, we are developing a new type of heavy nuclide detector using an imaging plate which is manufactured by Fuji Film Co. Ltd. This film has a position resolution of 25 /spl mu/m and a sensitivity 1000 times higher than X-ray film. Moreover it is easy to enlarge since the area of one plate can be 20/spl times/25 cm/sup 2/, and the accumulated cosmic-ray-interaction information can be read out in about 10 minutes. To measure the characteristics of the imaging plate for heavy nuclides, we irradiated it with several kinds of nuclides using an accelerator in the National Institute of Radiological Sciences. These tests demonstrated that using an imaging plate, carbon, silicon, and argon nuclides can be distinguished.