Photodisintegration of Carbon-12 by 330-Mev Bremsstrahlung

The excitation function for the reaction ${\mathrm{C}}^{12}(\gamma , 3\alpha )$ from 330-Mev bremsstrahlung has been measured. Ilford C2 600μ emulsions were irradiated and scanned for three-prong stars which satisfied conservation of momentum for the disintegration. Of the forty-six stars found, none were from quanta bigger than 42 Mev and so an upper limit for the cross section was estimated up to 100 Mev. From this it can be seen that there are no prominent resonances up to 100 Mev other than those already known.