Digitized neutron imaging with high spatial resolution at a low power research reactor: Applications to steel and rock samples

The influence of boron micro-inhomogeneities on neutron transmission

“…N s and N o are the count numbers behind the sample and in the open beam respectively, and N b represents the background [7,10]. Ideally, the background is determined by replacing the sample by an 'infinite' strong absorber with same dimensions (in practice 5 cm thick borolene is sufficient).…”

“…Such small absorber fluctuations are not visible in neutron images [7], but macroscopic boron inhomogeneities have been observed in boral (boron aluminum).…”

“…2. The read out noise depends on the readout speed of the CCD chip, where the best signal-to-noise ratio is obtained at lowest speed and an overall signal-to-noise ratio of 60 has been obtained [6,7]; the lowest detectable transmission level at our beam line when approaching the noise limit level is: T min P 5.0 Á 10 À5 ± 2.0 Á 10 À5 (see Fig. 3 at maximum thickness d = 2.3 cm).…”

“…The scope of this project is a comprehensive analysis of neutron transmission data for quality assurance, thereby considering energy distribution, detector response, beam hardening, background, and finally, as a new tool in the analysis, absorber inhomogeneities. The macroscopic absorber homogeneity can be directly verified by high-resolved neutron imaging [2][3][4][5][6][7], however, micro-structures reveal themselves only in strong absorbing materials, i.e., transmission probabilities of 10 À2 and below, which requires an efficient background shielding [6,7]. The main objective of this work is to investigate the effect of micro-inhomogeneities on neutron transmission, in order to obtain additional information about the absorber distribution beyond the detector resolution.…”

Implementation of Dynamic Neutron Radiography and Integrated X-Ray and Neutron Tomography in Porous Carbonate Reservoir Rocks

“…Neutrons with their peculiar properties (such as ability to penetrate metals) and sensitivity to hydrogen (Schillinger et al, 2000), offer a valuable tool for such studies related to flow problems like capillarity-driven (e.g., Cnudde et al, 2008) or pressure-driven flow (e.g., Yehya et al, 2018). Several studies have used Neutron radiation images to characterize the porosity, moisture, and water absorption in different materials such as concrete (De Beer et al, 2005;Kanematsu et al, 2009;Zhang et al, 2010Zhang et al, , 2011Yehya et al, 2018), steel (Zawisky et al, 2010), building stones (Hameed et al, 2006(Hameed et al, , 2009Cnudde et al, 2008;Zawisky et al, 2010;Dewanckele et al, 2014), porous asphalt (Lal et al, 2014), sandstones (De Beer and Middleton, 2006;Hall, 2013), clay-rock (Stavropoulou et al, 2019), dehydration of molding sand (Schillinger et al, 2011), and cultural heritage artifacts (Fedrigo et al, 2018;Schillinger et al, 2018).…”