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Title: Muons from the Moon
Speaker: Prof. Daniele Fargion (Rome University)
Host: Dr. Quanbu Gou
Time: 20:00 (Beijing Time), Wednesday, 2021-06-16
Zoom meeting URL：https://ihep-ac-cn.zoom.com.cn/j/83636684140?pwd=dHNNUTVUbHpoOGNZbURUMFZ1c2RvUT09
Meeting ID: 83636684140
LHAASO opens the pioneering windows to PeV gamma astronomy in recent months. PeV gamma rays are very probably of hadronic nature: They are originated by nucleon-nucleon scattering, leading to neutral pions and their consequent PeV gamma decays. A similar correlated signal should also rise by the twin charged pions, whose decays into muons and neutrinos may let them hit in km^3 IceCube leading to TeV up to PeV leptons track signals.
Such signals arose in last decade at IceCube. Neutrinos are weak particles and because of it they are usually been observed in very large underground detector with cosmic rays screened, while the surrounding ice is the calorimeter where the neutrinos interact.
However PeV-EeV tau neutrinos in 1999 and 2002 have been also suggested to be a different source of rare tau air showers: a first interaction of PeV tau neutrinos inside a mountain or Earth, a tau track and its escape in air, leading to tau decay in air flight, forming huge spread upward tau air showers. Several experiments such as Auger are looking for them since a decade ago.
More abundant TeV or PeV muons and their decay in flight are too long time to decay and to be detected in short Earth distances. However TeV - 0.1 PeV muons may be originated by tens TeV neutrinos inside lunar crust, escaping from the Moon, and the muons may decay while flying from Moon to Earth, and they may reach us as a source of air showering made by electron on Earth, while being inside Moon shadow.
The tens TeV electron air shower will be identical to a rare gamma air shower. Therefore inside the Moon Shadows in LHAASO, rarely, one should expect to discover several TeV gamma signal due to hundred TeV muon born in the Moon Shadow originated from hundred TeV neutrinos.
About the speaker:
Daniele Fargion is a Research Professor in theoretical astroparticle physics in Rome University. He has been the first proponent of tau air shower neutrino astronomy in 1999, of the solar flare neutrino astronomy during 2003-2006, and of muons from the Moon since 2017.