Neutron photon and electron response functions of CAF{sub 2} and LIF TLD chips

TLD material of CaF{sub 2} with various doping has been considered insensitive to neutron radiation for a long time. It is true for low energy neutrons. However neutron interaction cross section data of calcium and fluorine both show significant cross sections for (n, p), (n, {alpha}), and (n, {gamma}) reactions with neutron energy of 1 MeV and above. The Monte Carlo code MCNP was used to calculate CaF{sub 2} and LiF energy response functions for photons, electrons, and neutrons as incident radiations. The calculations were performed for a TLD free in the air and with a water phantom. In photon and electron cases, the energy deposition, referred to as the *F8 tally, was used. Detailed transport of both primary and secondary particles are included in the calculations. For neutrons, charged particle production and interaction with the TLD material, in form of a neutron heating tally, F6, is the main contribution of energy deposition. We also tallied the energy deposition due to capture gamma rays and secondary electrons. The results show that, for low energy neutrons, {sup 6}LiF, {sup 7}LiF, and CaF{sub 2}, responses differ in several order of magnitudes, but for neutron energy above 5 MeV, the responses are withinmore » a factor of two. CaF{sub 2} TLD chips show higher sensitivity to high energy neutrons than to high energy photons. LiF has higher sensitivity than CaF{sub 2} for electrons With energies less than 5 MeV and lower sensitivity for higher energy electrons. For photons, CaF{sub 2} has a higher sensitivity than LiF for energies above 25 keV.« less