Design and development of the extended-range Bonner sphere spectrometer at Ciemat

The Neutron Standards Laboratory (LPN) at CIEMAT serves as the national reference for calibrating neutron measurement devices and conducts research on measuring different neutrons fields, arising the necessity of neutron spectrometry. There are different neutron fields which are attracting interest in the recent years, for example ambient neutron spectra, generated basically by cosmic rays in the atmosphere or secondary neutrons on the surroundings of accelerators, for instance in protontherapy centres. These neutrons spectra are characterized by having an important component of high energy neutrons up to hundreds MeV or even GeV. In order to do spectrometry in this kind of neutron fields, a Bonner Sphere Spectrometer extended range was designed, constructed and tested. •Response Matrix simulations for Bonner Sphere Spectrometer wit Monte Carlo code.•Digital electronics implementation to the extended Bonner Sphere Spectrometer.•Ambient neutron measurements with an extended range BSS.