Fig. 3: Results of the analysis of the nuclear emulsion films installed in the descending corridor.

a The left figure shows the 3D model of Chevron and its origin. Center panels show the definition of the coordinate system and the origin of the rectangular cuboid which was defined as its North extremity along x, its center along y, and its bottom along z. Right panels show the set up of the main structure (MS) and sub-structures designated A (SSA), B (SSB). CH denotes the Chevron. b Two-dimensional angular distribution for EM1 to EM4. From left to right: observed muon flux (tracks/cm²/day/sr), 3D model, ratio of muon flux of the observed data to simulation, with MS, with MS and SSA, with MS and SSB, and path length with difference between the data and simulation. The resolution is \(\tan \theta\) = 0.025. c Histograms of path length with difference between the data and simulation in the range of 0.000 ≦ \(\tan {\theta }_{x}\) < 0.025 in the axial direction of \(\tan {\theta }_{y}\) corresponding to the North-South direction. d Region of existence of the NFC based on path length. e χ² analysis for the evaluation of parameters presenting location and shape of the NFC. The horizontal axis shows the values of evaluated parameters. The vertical axis is the value of reduced χ² obtained by the comparison of the data and simulation. f Histograms of muon flux in the range of −0.250 ≦ \(\tan {\theta }_{y}\) < −0.225 for EM1 and EM2, 0.200 ≦ \(\tan {\theta }_{y}\) < 0.225 for EM3 and EM4, respectively. The data with statistical error of 1 σ (standard deviation) are shown in red. The gray dashed line is the simulation without the inner structures, the black solid line is the simulation with the DC and MS, and the blue solid line is the simulation with the DC, MS, and SSA. g Results of the χ² analysis for the case where the MS and sub-structures are added to known structures. A, B, and C denote the case where MS, MS and SSA, MS and SSB are added, respectively.