  We are investigating the total charge changing cross-section of 12C by using
the CR39 nuclear track detector. Target sandwiched with CR39 of 5 cm x 5 cm
area was irradiated with $^{12}$C ion at 55 MeV/n and 135 MeV/n at the Wakasa
wan Energy Research Center (WERC) and Heavy Ion Medical Accelerator in Chiba
(HIMAC), Japan, respectively. Exposed CR39s were etched in $^7$N NaOH solution
at 70$^\circ$C to visualize the tracks produced by the primary ion beam and its
fragmentations. The etching time was chosen between 15 and 25 hours according
to exposed densities of $^{12}$C ions. The SEIKO FSP 1000 imaging microscope
was used to get the image of the front and back surface etch pit
simultaneously. Then by counting the projectile track before and after the
target, the total charge changing cross-section has been measured. Since there
are no previous experimental data to compare, PHITS and Glauber model
calculated theoretical values were compared with the previous and this
experimental result. From that, the measured data were found in good agreement
with the previous and calculated value except for two points at energy 95.7 and
98.6 MeV/n. These two points need more analysis which will be done in the next
phase. Measured data in this study will be the first experimental TCC data for
$^{12}$C+Al interactions in the energy 100 MeV/n. These measured data will be
useful to verify the models, optimize shielding in space radiation
circumstances, and also to improve treatment planning on therapy, as well.
