Cylindrical Neutron Spectrometer System: Design and Characterization

A multilayer cylindrical neutron spectrometer (CNS) system has been designed based on the similar principle of a commercial Bonner sphere spectrometer (BSS) system. The characteristics, e.g., spectral neutron fluence response functions and angular neutron fluence response functions, of the CNS system have been evaluated using MCNP6 simulations. The dosimetric quantities including neutron fluence rate (phi(E)), neutron ambient dose equivalent rate ((H) over dot*(10)), neutron ambient dose equivalent-averaged energy ((E) over tilde), neutron fluence-averaged energy ((E) over bar) and neutron fluence-to-ambient dose equivalent conversion coefficient ((h) over bar (phi)) of three neutron standard fields with Am-241-Be source were evaluated using the CNS system. The standard uncertainties of the dosimetric quantities were also estimated and discussed. Comparison of dosimetric quantities measured by the CNS and the BSS systems was made in order to verify the operation of the CNS system. The discrepancies in phi(E), (H) over dot*(10), (E) over tilde, (E) over bar and (h) over bar (phi) measured by the CNS and the BSS systems are 7%, 5%, 8%, 11% and 3%, respectively. This agreement indicates that the CNS system is reliable for neutron dosimetry and radiation safety assessment. The CNS system is advantageous due to its compactness, portability and simplicity in fabrication.