A Bonner Sphere Spectrometer for Pulsed Fields

Abstract

The use of conventional Bonner Sphere Spectrometers (BSS) in pulsed neutron fields (PNF) is limited by the fact that proportional counters, usually employed as the thermal neutron detectors, suffer from dead time losses and show severe underestimation of the neutron interaction rate, which leads to strong distortion of the calculated spectrum. In order to avoid these limitations, an innovative BSS, called BSS-LUPIN, has been developed for measuring in PNF. This paper describes the physical characteristics of the device and its working principle, together with the results of Monte Carlo simulations of its response matrix. The BSS-LUPIN has been tested in the stray neutron field at the CERN Proton Synchrotron, by comparing the spectra obtained with the new device, the conventional CERN BSS and via Monte Carlo simulations.

A feasibility study of a H2O-moderated 252Cf source for metrology

“…The spheres can be made of other materials; however, they are not so usual. Thus, the BSS can provide information over a broad energy range, making it valuable for characterizing complex radiation fields [8].…”

“…Neutron radiation can come from different directions, and the BSS is designed to measure the neutron fluence equally from all directions, around the instrument. Overall, the BSS offers several significant advantages, such as comprehensive energy characterization, isotropic response, and operational simplicity, making it a widely used and reliable technique for assessing neutron spectra and fluence in diverse applications [7,8].…”

Study of the responses and calibration procedures of neutron and gamma area and environmental detectors for use in proton therapy

“…and from the dead time losses when used in pulsed radiation fields(Aza et al 2013, Caresana et al 2014, Aza et al 2015, which were not primarily addressed in this work. As regards the energy response, besides the development of new detectors with extended responses (>20 MeV), relatively little technical advances have been done in this field over the years, and the problem remains essentially the same.…”

SpectroGEM

“…The polyethylene layer thickness needs to be large enough to thermalize the neutrons without absorbing them, as shown in Table 1.3. The response functions of these regions resemble those of the BSS [76], in which each sphere shows maximum response for a specific neutron energy depending on the amount of polyethylene employed.…”

“…In order to compare the performance of the BSS-LUPIN with the conventional CERN BSS, a series of measurements were performed with both systems [76] at the beginning of the access tunnel to the beam extraction area of the CERN Proton Synchrotron (PS).…”