Evaluation of gamma contribution in a neutron calibration field of Am-Be241 source.

The paper presents the evaluation of gamma contribution in a neutron calibration field of a 241Am-Be source. The characterization of gamma flux spectra and gamma ambient dose equivalent rates has been performed using a portable NaI(Tl) gamma spectrometer. For obtaining the gamma ambient dose equivalent rates from the measured spectra, two approaches were applied based on the applications of the G(E) function and the ICRP 74 conversion factors, respectively. Comparison of the gamma ambient dose equivalent rates obtained from the two approaches shows an agreement within 5%. The gamma contribution in the neutron calibration field is evaluated about 2.3-3.3% of the total neutron ambient dose equivalent rate in the distance range of 100-250cm.