Determination of dE/dx for heavy nuclides with the imaging plate

We are investigating the basic characteristics of an Imaging Plate (IP) as a detector for ultra-heavy cosmic rays. Irradiating the IPs with argon and iron particles from several incident angles, the images on the IP were measured. We confirmed that the images due to particles extend along the incident direction and that the information is useful for the determination of the incident angle. Moreover, we found a certain relation between the incident angle and the Photo-Stimulated Luminescence (PSL) value on the IP due to the deposited energy. Using the relation, we can find out the PSL value at which the particle would be injected perpendicular to the IP. From the normalized PSL value, the dE/dx of the particle can be determined. As the relation is held independently of the nuclide and the energy of the incident particle, it is useful to measure the dE/dx.