Imaging of fast neutrons and gamma rays from 252 Cf in a heavily shielded environment

Abstract

A 75 MBq 252 Cf neutron source stored inside a steel water tank was characterised using a compact fast-neutron and gamma-ray imaging system based on a passive slot modulation imaging technique. Radiation fields were imaged from a variety of positions with the source in the stored position (located in the center of the water tank: high shielding) and in the exposed position (located at the edge of the water tank: low shielding). It was possible to locate the 252 Cf source in each image and gain additional information of the neutron and gamma-ray fields in the local environment including scatter contributions from the steel shield, floor and walls in proximity to the source. A long exposure image of the stored source, taken over thirty days, identified the location of the radiation source from the low dose (<1µSv/h) field penetrating through 46 cm of water in the storage tank.

Investigation into a suitable scintillator and coded-aperture material for a mixed-field radiation imaging system

“…Many of the mixed-field characterisation systems utilise a sensitive detector in a form of an organic scintillator [6,[12][13][14]. These can be found in collimated single pinhole cameras utilised in many branches of nuclear instrumentation engineering to facilitate radiation imaging requirements.…”

Investigation of instabilities of photomultiplier tubes for multi-element detector systems

“…Multi-element scintillator systems are used increasingly in a broad range of applications such as neutron spectrometry [1], nuclear security [2][3][4], fundamental studies of nuclear reactions [5][6][7], and in medical imaging for positron emission tomography (PET), single-photon emission computed tomography (SPECT) or X-ray imaging [8]; in such applications it is usually required that the response of each detector across an array is as consistent as possible. Non-destructive active interrogation techniques utilising neutrons and photons operate in environments where the incoming radiation flux can change by a few orders of magnitude in an instant, thus requiring detection systems to have a characterised drift of response [9].…”