NESCOFI@BTF started in 2011 with the aim of developing innovative neutron sensitive instruments for the spectrometric and dosimetric characterization of neutron fields, intentionally produced or present as parasitic effects, in particle accelerators used in industry, research and medical fields. Neutron spectra in these fields range from thermal (1E-8 MeV) to tens or hundreds MeV, thus spanning over more than 10 decades in energy.
To date, the multi-sphere spectrometer (or Bonner Sphere spectrometer) is the only existing device having the capability to simultaneously determine all energy components over such a large energy interval. The main disadvantage of this spectrometer is the need to sequentially expose a considerable number (usually more than 10) of detector+moderator configurations, thus leading to time-consuming irradiation sessions.
The idea behind NESCOFI is to provide real-time spectrometers able to simultaneously provide all energy components in a single irradiation. These could be employed for:
(1) Monitoring the neutron fields in terms of energy-integrated neutron flux and spectral neutron flux in energy intervals of interest.
(2) Active real-time control of possible deviations from nominal field properties and of possible modifications induced by materials introduced in the radiation field (samples, materials to be irradiated, patients to be treated).
The final users of the NESCOFI products will be a variety of facilities interested to monitor not only the intensity of a neutron beam, but also –and simultaneously- its energy and/or direction distribution (chip-irradiation, material science neutron beam-lines, reference neutron fields, research and cancer therapy facilities).

The basic idea behind the project is to exploit the moderation of neutrons in hydrogenated materials, as extensively done in Bonner Sphere spectrometers, but new designs and computational methods have been introduced. Particularly, instead of estimating the neutron energy distribution by exposing different detector+moderator configurations, this project aims at a single moderator embedding several "direct reading" thermal neutron detectors at different positions. The energy or angle distribution of the neutron field will be obtained using unfolding algorithms relying on the device response matrix and on the reading of the different detectors. This "unfolding" problem has a number of analogies with the spectrum reconstruction with Bonner Sphere spectrometers, for which a special code called FRUIT (FRascati Unfolding Interactive Tools) was developed at LNF.
The NESCOFI project planned to be completed in three years (2011-2013), organized as follows:
2011:
(1) optimization (via Monte Carlo simulation) of the spectrometer geometry and development of a prototype working with passive detectors
(2) establishment of reference neutron fields for testing purposes:
- the photo-neutron beam from the n@BTF facility at the LNF.
- neutron fields in medical field.

2012: Development of suitable "direct reading" (or active) thermal neutron detectors to be embedded in the final spectrometers

2013: Establishment and calibration of the final spectrometers