High spatial resolution fast-neutron imaging detectors for Pulsed Fast-Neutron Transmission Spectroscopy

Abstract

Two generations of a novel detector for high-resolution transmission imaging and spectrometry of fast-neutrons are presented. These devices are based on a hydrogenous fiber scintillator screen and single-or multiple-gated intensified camera systems (ICCD). This detector is designed for energy-selective neutron radiography with nanosecond-pulsed broad-energy (1-10 MeV) neutron beams. Utilizing the Time-of-Flight (TOF) method, such a detector is capable of simultaneously capturing several images, each at a different neutron energy (TOF). In addition, a gamma-ray image can also be simultaneously registered, allowing combined neutron/gamma inspection of objects. This permits combining the sensitivity of the fast-neutron resonance method to low-Z elements with that of gamma radiography to high-Z materials. KEYWORDS: Instrumentation and methods for time-of-flight (TOF) spectroscopy; Detection of contraband and drugs; Detection of explosives; Neutron radiography

Performance of the Commercial PP/ZnS:Cu and PP/ZnS:Ag Scintillation Screens for Fast Neutron Imaging

“…Consequently, different materials must be used for converting fission neutrons in visible light. Different types of scintillators for fast neutrons are investigated and proposed in the literature, e.g., plastic fiber screens used in [24,25], wavelength-shifting fiber (WSF) converters [26,27] and others [28]. This work focuses on the results of a characterization of different screens based on polypropylene (PP) mixed with zinc sulfide (ZnS) phosphor rather than on alternative detection systems [20,22].…”

Potential and status in imaging with fast neutrons

“…While in the previous examples the material composition is mainly obtained by analysing the neutron induced gamma radiation, work in [2][3][4] is focussed on Fast Neutron Resonance (FNR) imaging for contraband detection. The main difference between the various concepts in FNR is the method to determine the energy of the transmitted neutrons.…”

“…These unique properties of fast neutrons were exploited for various applications, foremost in civil security, like the detection of explosives and drugs in luggage and freight [1][2][3][4][5]. In [1] pulsed mono-energetic and collimated neutron beams from an accelerator are used for neutron induced gamma analysis of containers.…”

A novel fast-neutron detector concept for energy-selective imaging and imaging spectroscopy

“…The photo-sensor can be either a CCD camera, with limited field of view, 2 or a complicated and expensive position-sensitive gaseous photomultiplier. 6 Energy determination by time of flight (TOF) measurements 7 can be also achieved for fast neutrons by using a pulsed neutron generator: 8 however, in this approach the high cost are often prohibitive due to low turnaround in most of the industrial applications, and the available neutron flux is exceedingly reduced due to the low duty cycles of the beam.…”