Abstract
Abstract
An Extended-range Bonner sphere spectrometer (EBSS) has been
developed to investigate the neutron spectra of the China initiative
Accelerator Driven System. This paper presents the design,
calibration, and validation measurements of the EBSS system using a
standard 241Am-Be neutron source and the cosmic ray
neutrons. The EBSS system was simulated using the PHITS code, and
the geometric structures were designed using the response functions
obtained by simulations. The EBSS system comprises of seven
polyethylene-only spheres and seven extended-range spheres encased
in lead, copper, or tungsten shells along with a bare 3He
proportional counter. To verify the accuracy of the simulated
response functions, the EBSS system was calibrated with
monoenergetic neutron beams of 565 keV at the China Institute of
Atomic Energy in Beijing. The EBSS system was used to measure
neutron count rates of the 241Am-Be neutron source and cosmic
ray neutrons. Subsequently, the measured neutron count rates were
converted into neutron spectra by the unfolding
software. Experimental findings demonstrate the precise capability
of the EBSS system to measure neutron spectra across a wide range of
neutron radiation fields.