TY - JOUR
T1 - Water calibration measurements for neutron radiography
T2 - Application to water content quantification in porous media
AU - Kang, M.
AU - Bilheux, H. Z.
AU - Voisin, S.
AU - Cheng, C. L.
AU - Perfect, E.
AU - Horita, J.
AU - Warren, J. M.
N1 - Funding Information:
This research was supported by the Laboratory Directed Research and Development (LDRD) Program of Oak Ridge National Laboratory and the Joint Directed Research and Development (JDRD) Program of the University of Tennessee UT-ORNL Science Alliance . The authors are thankful for contributions from Lakeisha Walker, Keely Willis, and the HFIR support groups, especially the HFIR Machine Shop, Brent Taylor, Gary Lynn, Lisa Fagan, Jaimie Werner, and the Instrument Development Group. The detector set-up was developed in collaboration with Prof. Dayakar Penumadu in the Department of Civil and Environmental Engineering at the University of Tennessee–Knoxville. This research at Oak Ridge National Laboratory's High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy, which is managed by UT-Battelle, LLC.
PY - 2013
Y1 - 2013
N2 - Using neutron radiography, the measurement of water thickness was performed using aluminum (Al) water calibration cells at the High Flux Isotope Reactor (HFIR) Cold-Guide (CG) 1D neutron imaging facility at Oak Ridge National Laboratory, Oak Ridge, TN, USA. Calibration of water thickness is an important step to accurately measure water contents in samples of interest. Neutron attenuation by water does not vary linearly with thickness mainly due to beam hardening and scattering effects. Transmission measurements for known water thicknesses in water calibration cells allow proper correction of the underestimation of water content due to these effects. As anticipated, strong scattering effects were observed for water thicknesses greater than 0.2 cm when the water calibration cells were positioned close to the face of the detector/scintillator (0 and 2.4 cm away, respectively). The water calibration cells were also positioned 24 cm away from the detector face. These measurements resulted in less scattering and this position (designated as the sample position) was used for the subsequent experimental determination of the neutron attenuation coefficient for water. Neutron radiographic images of moist Flint sand in rectangular and cylindrical containers acquired at the sample position were used to demonstrate the applicability of the water calibration. Cumulative changes in the water volumes within the sand columns during monotonic drainage determined by neutron radiography were compared with those recorded by direct reading from a burette connected to a hanging water column. In general, the neutron radiography data showed very good agreement with those obtained volumetrically using the hanging water-column method. These results allow extension of the calibration equation to the quantification of unknown water contents within other samples of porous media.
AB - Using neutron radiography, the measurement of water thickness was performed using aluminum (Al) water calibration cells at the High Flux Isotope Reactor (HFIR) Cold-Guide (CG) 1D neutron imaging facility at Oak Ridge National Laboratory, Oak Ridge, TN, USA. Calibration of water thickness is an important step to accurately measure water contents in samples of interest. Neutron attenuation by water does not vary linearly with thickness mainly due to beam hardening and scattering effects. Transmission measurements for known water thicknesses in water calibration cells allow proper correction of the underestimation of water content due to these effects. As anticipated, strong scattering effects were observed for water thicknesses greater than 0.2 cm when the water calibration cells were positioned close to the face of the detector/scintillator (0 and 2.4 cm away, respectively). The water calibration cells were also positioned 24 cm away from the detector face. These measurements resulted in less scattering and this position (designated as the sample position) was used for the subsequent experimental determination of the neutron attenuation coefficient for water. Neutron radiographic images of moist Flint sand in rectangular and cylindrical containers acquired at the sample position were used to demonstrate the applicability of the water calibration. Cumulative changes in the water volumes within the sand columns during monotonic drainage determined by neutron radiography were compared with those recorded by direct reading from a burette connected to a hanging water column. In general, the neutron radiography data showed very good agreement with those obtained volumetrically using the hanging water-column method. These results allow extension of the calibration equation to the quantification of unknown water contents within other samples of porous media.
KW - Neutron radiography
KW - Porous media
KW - Quantification
KW - Water calibration
UR - http://www.scopus.com/inward/record.url?scp=84873640502&partnerID=8YFLogxK
U2 - 10.1016/j.nima.2012.12.112
DO - 10.1016/j.nima.2012.12.112
M3 - Article
AN - SCOPUS:84873640502
SN - 0168-9002
VL - 708
SP - 24
EP - 31
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
ER -