I know of no reason to expect carbon-based anything to be effective for protection against anything except "slow" neutrons. The only thing I know of for protection against radiation in general is material with heavy nuclei such as lead. The only useI know of involving carbon to affect radiation is in the first nuclear reactor, in which graphite, consisting of amorphous compacted carbon, was used as s "moderator" to slow the neutrons emitted in that reactor because uranium 235 has a much higher nuclear cross section to "slow" neutrons than to the "fast" ones emitted in U-235 fission. I believe that carbon would be totally useless for shielding against any other type of radiation.