Evaluation of gamma ray buildup factor data in water with MCNP4C code

The exposure buildup factors for gamma and X-ray photons in water are computed using the MCNP4C code. The results are obtained for the energy range 0.04–6 MeV and penetration depths up to 10 mfp. The results are compared with the published buildup factor data during 1960–2010. Both agreements and discrepancies are observed between our results and the data appearing in the literature. It is concluded that at higher energies and deep penetration the existing data for photon buildup factor in water are still inadequate.