CYSP-BEAM: A multi-detector directional spectrometer for in-beam neutron spectrometry

Abstract

CYSP-BEAM is a directional neutron spectrometer formed by a thick polyethylene cylindrical collimator followed by a sensitive capsule that contains several active thermal neutron detectors located at different depths along the cylindrical axis. Due to a thick lateral shield made of polyethylene and borated rubber, only neutrons from the direction identified by the collimating aperture can reach the internal detectors. As the response function of the internal detectors tend to peak at increasing energies as the detector depth increases, the device has spectrometric properties. This type of moderated spectrometer, whose prototype was the CYSP (CYlindrical SPectrometer), is capable to combine the functionalities of Bonner Spheres in a single device, thus requiring only one exposure to measure all the energy components of the incident beam, from thermal up to GeV neutrons. The neutron spectrum is obtained via few-channel unfolding methods. With respect to the original CYSP, the new CYSP-BEAM device is optimized to operate in the direct intense beam of neutron producing installations, such as large scale neutron science facilities. Compared with CYSP, CYSP-BEAM has narrower collimating aperture and the internal detectors have sensibility a factor 100 lower. Its response matrix was simulated using MCNPX. This paper describes the new device focusing on the internal detectors, the response matrix and the test measurement performed using the 14 MeV beam produced at the ENEA Frascati Neutron Generator (FNG).

NCT-WES: A new single moderator directional neutron spectrometer for neutron capture therapy. Experimental validation

“…-Comparison with existing single moderator neutron spectrometers. Another cylindrical single moderator spectrometer, called CYSP [5][6][7][8][9], was developed in the past to cover the energy range from thermal up to GeV neutrons. Compared to CYSP, NCT-WES is much more compact and light (40 kg against 120 kg) as the energy range of interest is considerably reduced.…”

“…NCT-WES belongs to the family of the single moderator neutron spectrometers [5][6][7][8][9]. Such devices were conceived to condense the functionality of Bonner Spheres in a single moderator with specific geometry, embedding multiple thermal neutron detectors in previously optimized positions.…”

Measuring the near-target neutron field of a D–D fusion facility with the novel NCT-WES spectrometer

“…Figure 5 shows the starting spectrum as well as the unfolded one. Both fluence spectra are normalised to one count in the 3 He monitor and refer to a conventional distance of 100 cm, corresponding to the point where the Bonner spheres were exposed in the experiment of Ref. [18].…”

“…The directional spectrometer NCT-WES (Neutron Capture Therapy Wide Energy Spectrometer) was developed within the INFN project ENTER_BNCT to operate rapid neutron spectrum measurements over the energy range from thermal up to 20 MeV neutrons. As the other single moderator neutron spectrometers created by the same collaboration [2][3][4][5], NCT-WES [6] offers the advantages of a Bonner sphere spectrometer (BSS) [5] in terms of high sensitivity, easy operation and wide energy range, but it requires only one exposure to examine all energy components of the field. The spectrum is obtained by processing the data from these detectors, together with the response matrix and the uncertainties, with a traditional few-channel unfolding code.…”

Thermal to GeV neutron spectrometry of the INES beam line at ISIS using the CYSP-BEAM spectrometer

“…CYSP-BEAM spectrometer [1] belongs to a class of "single moderator neutron spectrometers" [2,3] that condense the functionality of a Bonner spheres spectrometer in a single moderator embedding multiple thermal neutron detectors. In these instruments the neutron spectrum is obtained via few-channel unfolding [4].…”