The 1st Workshop on Gamma Ray Astronomy at High Altitude

A large scale (~km^2) ground based cosmic ray experiment is now proposed in China. The project, named as Large High Altitude Air Shower Observatory (LHAASO) is located in Tibet, near the site of the ARGO and AS_gamma experiments at 4300m a.s.l. The scientific goals of the project includes: survey for gamma ray sources in energy range starting from ~100GeV, measure the gamma-ray energy spectra of sources above 30TeV for identifying cosmic ray sources, measure morphologic structure of sources for details of charged particle acceleration mechanism, measure cosmic ray spectra of individual composition starting from 30TeV where direct CR measurements provide absolute calibrations of both energy scale and composition. The CR measurement is expected to cover both "knees" around 1PeV and 100PeV by means of a multi-parameter investigation at a best altitude where air showers reach their maxima on the ground with all systematic uncertainties minimized. Many other issues associated with low threshold shower detection may be addressed by using detectors at the high altitude. In order to fulfill such an ambitious experiment, we plan to build large scale water Cherenkov detectors (~90,000m^2), ground scintillation counter arrays for detecting both muons and charged particles, fluorescence/Cherenkov telescope arrays and shower core detector array. It is very helpful to organize a workshop to discuss all the issues and ways to tackle those targets in experiments. We are organizing such a workshop near Beijing, in Hebei province China on April 28 29 and 30. You are welcome to join the discussion in the workshop.