Muon Attenuation and Exposure Budgets for Void Detection in the Great Pyramid of Khufu

This paper computes the muon attenuation, exposure and resolution budget for imaging the Great Pyramid of Khufu with cosmic-ray muons. Sight lines through 110 metres of limestone at a density of 2.2 grams per cubic centimetre present an opacity of 2.42e+04 grams per square centimetre (242 metres of water equivalent), which sets a minimum muon energy of 50.51 GeV and a transmitted vertical intensity of 0.1315 per square metre per second per steradian. For a detector of 1 square metres with the stated acceptance and efficiency, divided among 900 image elements, the stated feature produces a flux contrast of 0.4052 and reaches five standard deviations in 23.65 days of counting, while the target precision of 0.05 per image element requires 62.14 days. A deployment of 180 days delivers a per-element precision of 0.02938, corresponding to a thickness sensitivity of 3.232 metres. The combined angular resolution is 10.4 milliradians, of which tracking contributes 1.768 milliradians and multiple scattering at the threshold momentum 10.24 milliradians. The budget is compared with published muography of the same class of target, for which the ScanPyramids collaboration reported a large void above the Grand Gallery in 2017 after exposures of several months with nuclear emulsion, scintillator and gas detectors. Every number is computed by the accompanying script from the stated inputs. Computed, not measured.