High-precision muography in archaeogeophysics: A case study on Xi’an defensive walls

Abstract

Muography is a rapidly developing and non-destructive tomographic technology that uses cosmic ray muons. Due to the natural presence and deeper penetration of cosmic ray muons, scientists have performed various pioneer studies in fields, such as customs security, the internal imaging of volcanoes, scientific archaeology, and others. With unique advantages, muography has gained increasing attention from archaeologists as a novel and innovative tool to investigate large-scale archaeological sites. This approach may be especially helpful for identifying endangered cultural relics and monuments. In the work, we employ a compact, rugged, and portable muon imaging system, CORMIS (COsmic Ray Muon Imaging System), deployed at up to six measurement locations to perform a case study of three-dimensional muography in Xi’an city, China. Cultural cities, such as Xi’an, have long histories and could benefit from innovative techniques used to investigate, conserve, and protect large historical sites. In this paper, we present in detail a high resolution survey on a rampart of a Xi’an defensive wall in demand of urgent protection. The survey data are carefully processed with advanced statistical methods newly introduced in muography, and the results indicate density anomalies inside the rampart with unprecedented levels of precision. The density anomalies are potential safety hazards and need to be eliminated as soon as possible. The successful implementation of this survey significantly encourages more engagement on the tangible application of high-precision 3D muography in archaeological investigations and protection projects around the world.

Laser scanner and UAV digital photogrammetry as support tools for cosmic-ray muon radiography applications: an archaeological case study from Italy

“…The virtual environment must be as robust as possible because of the affordability of muography survey outputs (transmission and density maps) strictly lie on it. Several studies have confirmed this statement 34,36,37,40,63 . Indeed, to preliminarily characterize the whole study area at a regional scale, and to perform preventive feasibility muon transmission simulations, a detailed digital elevation model (DTM) is warranted.…”

“…Only a few studies have highlighted the constraints of RS methods within the muon imaging workflow. In fact, the creation of a three-dimensional environment is a fundamental step for the achievement of a real muon radiography application when simulations are needed to assign directional relative transmission values and then convert them into directional average density values 26,41,55,63 .…”

Cosmic coding and transfer storage (COSMOCATS) for invincible key storage

“…(2) COSMOCAT can deliver the same numerical sequences of TRNs between the aboveground facility and a concealed underground vault. Cosmic-ray muons are penetrative, and they have been applied to imaging gigantic objects such as volcanoes 30 , ocean 31 , cyclones 32 , tectonics 33 , earthquake retrodiction 34 , Egyptian pyramids 35 , the Great Wall of China 36 as well as underground/underwater positioning 37 and navigation 38 , and precise time synchronization 39 .…”

Muography

“…Some of these works have been dedicated to searching for interior structural anomalies such as large voids 44,104,105,106 . An elongated void inside Khufu's pyramid in Egypt was first reported in 2017 by a muography team 44 and additional data have been collected since then to characterize the void, leading to the recent announcement that its shape is consistent with a corridor-like structure of about 9 m length with a transverse section of about 2 m by 2 m 79 .…”