Chamber-Search Budgets for Muon Imaging Inside the Pyramid of the Sun at Teotihuacan

This paper computes the muon attenuation, exposure and resolution budget for imaging the Pyramid of the Sun at Teotihuacan with cosmic-ray muons. Sight lines through 65 metres of volcanic fill and adobe at a density of 1.9 grams per cubic centimetre present an opacity of 1.235e+04 grams per square centimetre (123.5 metres of water equivalent), which sets a minimum muon energy of 25.24 GeV and a transmitted vertical intensity of 0.413 per square metre per second per steradian. For a detector of 0.5 square metres with the stated acceptance and efficiency, divided among 250 image elements, the stated feature produces a flux contrast of 0.8208 and reaches five standard deviations in 1.112 days of counting, while the target precision of 0.05 per image element requires 11.99 days. A deployment of 240 days delivers a per-element precision of 0.01118, corresponding to a thickness sensitivity of 0.7264 metres. The combined angular resolution is 14.55 milliradians, of which tracking contributes 2.424 milliradians and multiple scattering at the threshold momentum 14.35 milliradians. The budget is compared with published muography of the same class of target, for which a muon detector operated for an extended period inside the Pyramid of the Sun searching for undiscovered chambers, following the earlier muon survey of the Pyramid of Quetzalcoatl precinct. Every number is computed by the accompanying script from the stated inputs. Computed, not measured.