The response of large NaI(Tl) detectors to fast neutrons

Abstract The response of NaI(Tl) scintillators of three different sizes to neutrons is measured as a function of neutron energy in the 0.17MeV n range. Various processes contributing to the neutron induced pulse-height spectra are discussed. The importance of multiple inelastic and elastic scattering events is emphasized. The experimental results are presented in the form of nomograms which make it possible to reconstruct the NaI(Tl) pulse-height distribution for any given neutron spectrum within the energy range studied. Applications are considered to studies of single photon energy spectra as well as to sum-energy spectra of multiple photon cascades measured in the presence of intense neutron radiation. An example of such applications is described for the case of the 150 Nd( 12 C,xnγ) 162−x Dy reaction at E( 12 C) = 95MeV .