A pixelated silicon telescope for solid state microdosimetry

Abstract A solid state microdosimeter consisting of a matrix of cylindrical Δ E elements of micrometric size implanted on a single E stage is discussed in this work. This detector was constructed in order to minimize some discrepancies found when comparing the distribution of energy imparted per event of a single Δ E -stage telescope with the one measured by a cylindrical tissue-equivalent proportional counter (TEPC). These discrepancies were ascribed to geometrical effects related to the wide sensitive area (1 mm2) of the single Δ E -stage telescope. Preliminary irradiations with mono-energetic neutrons showed a better agreement between the spectra measured with the new telescope and the TEPC. The improvement of the procedures adopted for correcting the spectra for tissue equivalence and for the effects due to the track distribution is also discussed

A telescope detection system for direct and high resolution spectrometry of intense neutron fields

A high energy- and spatial-resolution telescope detector was designed and constructed for neutron spectrometry of intense neutron fields. The detector is constituted by a plastic scintillator coupled to a monolithic silicon telescope (MST), in turn consisting of a DE and an E stage. The scintillator behaves as an “active” recoil-proton converter, since it measures the deposited energy of the recoil-protons generated across. The MST measures the residual energy of recoil-protons downstream of the converter and also discriminates recoil-protons from photons associated to the neutron field. The lay-out of the scintillator/MST system was optimized through an analytical model for selecting the angular range of the scattered protons. The use of unfolding techniques for reconstructing the neutron energy distribution was thus avoided with reasonable uncertainty (about 1.6% in neutron energy) and efficiency (of the order of 106 counts per unit neutron fluence). A semi-empirical procedure was also developed for correcting the non-linearity in light emission from the organic scintillator. The spectrometer was characterized with quasi-monoenergetic and continuous fields of neutrons generated at the CN Van De Graaff accelerator of the INFN-Legnaro National Laboratory, Italy, showing satisfactory agreement with literature data

Compact thermal neutron sensors for moderator-based neutron spectrometers

In the framework of the NESCOFI@BTF project of the Italian Institute of Nuclear Physics, different types of active thermal neutron sensors were studied by coupling semiconductor devices with a suitable radiator. The objective was to develop a detector of small dimensions with a proper sensitivity to use at different positions in a novel moderating assembly for neutron spectrometry. This work discusses the experimental activity carried out in the framework of the ERINDA program (PAC 3/9 2012) to characterise the performance of a thermal neutron pulse detector based on (6)Li

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

Improvement of the minimum detectable energy of a recoil-proton spectrometer based on a silicon telescope

A recoil-proton spectrometer based on a monolithic silicon telescope coupled to a polyethylene converter was recently proposed and discussed in the literature. The device consists of a DE and an E-stage detector (about 2 microns and 500 microns in thickness, respectively) made out of a single silicon wafer and separated by a highly-doped layer acting as a common electrode. The detection system allowed continuous neutron spectra to be measured down to about 400 keV by discriminating against the contribution of low-LET radiation generated by photons from the distribution of the energy deposited in the E stage. This discrimination was carried out by selecting detected particles, event-by-event, with a DE- E correlation. At neutron energies lower than 400 keV recoil-protons cannot reach the E stage owing to the thickness of the DE stage and therefore the discrimination failed. In order to further reduce the minimum detectable energy, an improved detection system, which also accounts for the energy deposited by recoil-protons in the DE stage, was studied and tested. The new setup permits the total energy deposited in the telescope to be measured directly by collecting the charge carriers, generated in both stages, at the deep common electrode. The capability of reproducing continuous neutron spectrawas also verified by irradiating the improved set-up with neutrons generated by protons striking a thick beryllium target at INFN e Laboratori Nazionali di Legnaro (Legnaro, Italy). The agreement of the unfolded spectra with literature data was satisfactory at energies higher than about 200 keV