Evaluation of target photon dose mixed in mono-energetic neutron fields using Li(p,n)Be reaction

Tanimura, Yoshihiko   ; Tsutsumi, Masahiro; Saegusa, Jun; Shikaze, Yoshiaki ; Yoshizawa, Michio  

Mono-energetic neutron calibration fields have been developed at the Facility of Radiation Standards of Japan Atomic Energy Agency using a 4MV Pelletron accelerator. The fields of 8, 27, 144, 250, 565 keV and 1.2, 2.5, 5.0, 14.8 MeV neutrons were established using scandium, lithium, deuterium and tritium targets. The nuclear reactions between the accelerated particles and the target materials produce not only the mono-energetic neutrons but also unwanted photons. As the photons can affect the readings of dosemeters, their effects should be evaluated. In this work the photons in the 144, 250 and 565 keV neutron fields from a lithium fluoride target were measured using a cylindrical NaI(Tl) detector with 7.62 cm both in diameter and in length. The ambient dose equivalent H*(10) for the photons was evaluated by applying the "G(E) function" to the measured pulse height spectrum.