The fortifications of Xi’an are an archaeological marvel and one of UNESCO ’s World Heritage Sites . The fortress was built during the 14th century by Zhu Yuanzhang , the first Emperor of the Ming dynasty , and it has been kept and refurbished several times since its construction . But to see the area that might need interventions , researchers today have utilise a cutting - boundary technique that requires heavenly help . Using cosmic ray , they have found some peculiarity within the walls .
The approach is called muography , or muon tomography . It apply a subatomic particle , called amuon , that is make in great abundance by cosmic ray . you could picture a mu-meson as the heavy cousin of the electron . They have the same electric charge , but muons are 200 times heavier . When cosmic light beam ( normally protons or atoms ) hit the atmosphere at high speed , they can create showers of muon .
Even though they last for just 2.2 microsecond , about 10,000 negative muon reach the land per bit before dilapidate into an electron and two kind ofneutrinos . That ’s roughly like pose one through your handwriting every secondment . When they get through solid object , they scatter due to the interactions with atoms , and by measure these scattered negative muon it is potential to map out the internal three - dimensional body structure of satisfying objects .
This technique has been use to volcanoes , including the three most famous Italian ones : Stromboli , Etna , andMount Vesuvius . It has been used to studyglaciers , and even assess damage to theFukushimanuclear power plant stick to the 2011 Tōhoku earthquake and tsunami . It has also had intriguing program in archaeology , notably the find of a null insidethe Great Pyramid of Giza .
“ Due to the natural presence and bass penetration of cosmic re muon , scientists have do various pioneer study in fields , such as impost security , the inner mental imagery of volcano , scientific archaeology , and others , ” the authors wrote in theirpaper . “ With unique advantages , muography has gained increase attention from archaeologists as a novel and innovative tool to investigate large - scale archaeological site . ”
When it come to the City Walls of Xi’an , investigator focused on a specific bulwark and discovered tightness anomalies within the wall . They believe that these are safety hazards for the structure and that they ought to be eliminated to keep the walls fend .
The study from the team intimate that muography can be an priceless peter , not just to meditate archeological land site , but also to preserve them .
The findings are reported in theJournal of Applied Physics .
