title: Neutron emission and dose distribution from natural carbon irradiated with a 12 MeV amu-1 12C5+ion beam.
abstract: Measured neutron energy distribution emitted from a thick stopping target of natural carbon at 0°, 30°, 60° and 90° from nuclear reactions caused by 12 MeV amu-1incident12C5+ions were converted to energy differential and total neutron absorbed dose as well as ambient dose equivalent H*(10) using the fluence-to-dose conversion coefficients provided by the ICRP. Theoretical estimates were obtained using the Monte Carlo nuclear reaction model code PACE and a few existing empirical formulations for comparison. Results from the PACE code showed an underestimation of the high-energy part of energy differential dose distributions at forward angles whereas the empirical formulation by Clapier and Zaidins (1983 Nucl. Instrum. Methods 217 489-94) approximated the energy integrated angular distribution of H*(10) satisfactorily. Using the measured data, the neutron doses received by some vital human organs were estimated for anterior-posterior exposure. The estimated energy-averaged quality factors were found to vary for different organs from about 7 to about 13. Emitted neutrons having energies above 20 MeV were found to contribute about 20% of the total dose at 0° while at 90° the contribution was reduced to about 2%.
authors.affiliation: Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064, West Bengal, India.
authors.forename: Maitreyee
authors.initials: M
authors.lastname: Nandy
authors.forename: P K
authors.initials: PK
authors.lastname: Sarkar
authors.forename: T
authors.initials: T
authors.lastname: Sanami
authors.forename: M
authors.initials: M
authors.lastname: Takada
authors.forename: T
authors.initials: T
authors.lastname: Shibata
mesh_terms: D002244:Carbon / Q000737:chemistry*; D017357:Cyclotrons; D020450:Heavy Ions; D006801:Humans; D008962:Models, Theoretical; D009010:Monte Carlo Method; D009502:Neutrons; D009686:Nuclear Physics; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012542:Scattering, Radiation
chemical_list: D002244:Carbon