Evaluation of positioning and density profiling accuracy of muon radiography by utilizing a 15-ton steel block

Abstract

A model experiment was performed in order to evaluate the spatial resolution and accuracy of determining density by utilizing steel blocks whose density (7.8 g cm⁻³) and geometrical structure (5 m in length and 40 cm in width) were both well known. By comparing the experimental result with simulations, a density and a width of the steel block were measured as 7.3 ± 1.0 g cm⁻³ and 37 ± 15 cm, respectively

Development of stroboscopic muography

“…The minimum resolvable distance (spatial resolution) at a target object is then defined by the minimum resolvable angle (RMS angular resolution) and the distance between the object and the detection system (R m) is ± 0.014 ± R m. "Forward-directed" muon trails can be distinguished from "backward-directed" ones by choosing positive or negative angles, respectively, because muons arriving from below (neutrino-induced muons) are negligible to those arriving from above. The combination of high angular resolution, relatively large active area, and the cosmic ray muon intensity allows stroboscopic imaging with acquisition frames as short as 400 h with a density resolution of 13 % for a target with a size of 30 m water equivalent (mwe) (Tanaka, 2012). The resolution of a similar type of the detection system was also verified using cosmic ray muon radiography of a large steel block (Tanaka, 2012).…”

“…The combination of high angular resolution, relatively large active area, and the cosmic ray muon intensity allows stroboscopic imaging with acquisition frames as short as 400 h with a density resolution of 13 % for a target with a size of 30 m water equivalent (mwe) (Tanaka, 2012). The resolution of a similar type of the detection system was also verified using cosmic ray muon radiography of a large steel block (Tanaka, 2012). These images and the results of our previous calibrations of spatial resolution of the transmission images confirm that the spatial resolution is limited only by the angular resolutions and intervals of the detection system.…”

Experiments on muon radiography with emulsion track detectors

“…In the world practice, studies of the internal structure of large objects by the muon radiography method is carried out either with electronic instrument, [21][22][23][24], or with track detectors on base of nuclear emulsions [25][26][27] (see Fig. 4).…”