Search

The Large High Altitude Air Shower Observatory (LHAASO) (Fig. 1) is located at Mt. Haizi (4410 m a.s.l., 600 g/cm2, 29° 21’ 27.56” N, 100° 08’ 19.66” E) in Daocheng, Sichuan province, P.R. China. LHAASO consists of 1.3 km2 array (KM2A) of electromagnetic particle detectors (ED) and muon detectors (MD), a water Cherenkov detector array (WCDA) with a total active area of 78,000 m2, 18 wide field-of-view air Cherenkov telescopes (WFCTA) and a newly proposed electron-neutron detector array (ENDA) covering 10,000 m2. Each detector is synchronized with all the other through a clock synchronization network based on the White Rabbit protocol. The observatory includes an IT center which comprises the data acquisition system and trigger system, the data analysis facility. In this Chapter, all the above-mentioned components of LHAASO as well as infrastructure are described.

Since the science white paper of the Large High Altitude Air Shower Observatory (LHAASO) published on arXiv in 2019 [e-Print: 1905.02773 (astro-ph.HE)], LHAASO has completed the transition from a project to an operational gamma-ray astronomical observatory LHAASO is a new generation multi-component facility located in Daocheng, Sichuan province of China, at an altitude of 4410 meters. It aims at measuring with unprecedented sensitivity the spectrum, composition, and anisotropy of cosmic rays in the energy range between 10$^{12}$ and 10$^{18}$~eV, and acting simultaneously as a wide aperture (one stereoradiant) continuously operating gamma-ray telescope in the energy range between 10$^{11}$ and $10^{15}$~eV with the designed sensitivity of 1.3\% of the Crab Unit (CU) above 100 TeV. LHAASO's capability of measuring simultaneously different shower components (electrons, muons, and Cherenkov/fluorescence light), will allow it to investigate the origin, acceleration, and propagation of CR through measurement of the energy spectrum, elemental composition, and anisotropy with unprecedented resolution. The remarkable sensitivity of LHAASO will play a key role in CR physics and gamma-ray astronomy for a general and comprehensive exploration of the high energy universe and will allow important studies of fundamental physics (such as indirect dark matter search, Lorentz invariance violation, quantum gravity) and solar and heliospheric physics. The LHAASO Collaboration organized an editorial working group and finished all editorial work of this science book, to summarize the instrumental features and outline the prospects of scientific researches with the LHAASO experiment., Comment: This document is a collaborative effort, 185 pages, 110 figures

Measuring radon-due neutron flux at various altitude (100, 1000, 1700, 4300 m above sea level) we found an evidence of significant increase of radon concentration with altitude. It was also conirmed by direct radon measurements at high altitude. This allowed us to assume cosmic rays could take part in process of soil activation: they transform long-lived nuclei of uranium and thorium to nuclei with shorter life-time through specific nuclear reactions. If the resulting nuclei belong to the U-238 radioactive chain they can lead to producion of Ra-226 and then to Rn-222, thus significantly increasing its production at high altitudes where cosmic ray flux is high.