The Large High Altitude Air Shower Observatory LHAASO

Science case for LHAASO – Survey of the γ-ray sky above 100 GeV – Wide FOV and high duty cycle – Observation of transient sources – Extended sources / diffuse emission / halos – Study cosmic accelerators and high-energy phenomena – Search for cosmic-ray origin among galactic gamma-ray sources – Gamma spectra at high energies – Visibility for hadronic origin and charged particle acceleration – Measurement of cosmic rays above 30 TeV – Bridge between direct and indirect measurements – Unprecedented statistics for anisotropy studies in the knee region – New Physics and other studies – Dark matter – Quantum gravity

HE γ-ray detection HESS, MAGIC, VERITAS, CTA 100 GeV- 30 TeV Good p-γ separation Good angular resolution BUT Low duty cycle and Limited fov (4°) MILAGRO, ARGO, HAWC TeV High duty cycle Large field of view BUT Lower rejection power and low angular resolution Fermi ( GeV) High duty cycle Large field of view BUT Limitated energy

Identification of hadronic emission To identify an hadronic emission: - Fermi: 100MeV-few GeV, difficult to interpret (low energy/space resolutions, geometry, jet composition, boost factors…) - Above TeV, leptonic emission suppressed by Klein-Nishina absorption => clear identification - Graal: detection of HE neutrino SNR IC443

Experimental strategy Gamma-ray source survey: Water Cherenkov Detector Array (WCDA) with a total active area of 90000m 2 High-energy end of the gamma spectra: Particle detector array with an effective area of 1km 2 (KM2A) including an array of 1200 muon detectors (MD) with m 2 active area and an array of 5000 scintillators (ED) (allows to reject hadronic shower background) Cosmic-ray spectra and composition: 24 wide FOV Cherenkov telescope array (WFCA) and high threshold core detector array (SCDA) with an effective area of 5000m 2. Accurate measurement of composition by combining information from KM2A

Survey of gamma sources Calculation is based on a one-year observation of the Crab for detection at 5 σ level. IACT for 50h exposure

ARGOAS+MDHAWCLHAASOCTA Area6,500m m m 2 1km 2 10km 2  θ (deg) BG rejection power / Duty Cycle>90% 10% FOV (sr) Sensitivity TeV0.55 TeV Energy resolution30% >50%30%15% Sky survey, extended, transientSED, morphology

Main drawbacks Located in the Northern hemisphere while CTA will be in the South (for the first phase) No so clear science case for extragalactic sources (strong attenuation with EBL). Very close horizon.

Prospects of CR Physics 30TeV - 10PeV – Energy scale – Knees for H,He,… – Anisotropy 10PeV - 100PeV – Composition – Energy spectrum: knee of Fe 100PeV - 2EeV – Spectrum bending and composition changing – Transition from galactic to extra-galactic

Back tracking of cosmic accelerators by CR At low energies, significant anisotropies in arrival direction (dipoles and higher order multipoles) have been observed At the highest energies, above 55 EeV, some correlations with nearby extragalactic matter have been found but no clear identification of sources Auger: Arrival direction compared to AGN catalogue VGV Origin of cosmic rays is still an open question! CEN A

Complementary to CTA LHAASO: Continuous, wide field of view survey (need only one year to detect all Fermi sources at TeVs and at 1%Crab) CTA: Detailed source morphology studies LHAASO: Study of extended sources LHAASO: Higher energies than CTA =>hadron processes LHAASO: Source variability monitoring

LHAASO layout 90 km 2 gamma ray survey telescope 1 Mm 2 surface EAS detector array Central detector array for cosmic rays

LHAASO Layout in 1 km 2 at 4300m a.s.l. 90km 2 Water Cherenkov Detector array. Each one has a size of HAWC 24 Wide FOV air Cherenkov image Telescopes. 400 burst detectors for high energy secondary particles near the core of air showers 6100 scintillator detectors and 1200 μ-detectors form an array covering 1 km 2 LHAASO observatory

Status LHAASO has been included in the roadmap of the infrastructure construction for basic science in a short term, (5 years). Total 16 projects are included. LHAASO is also mentioned in the European roadmap for Astroparticle Physics. Site selected Technology that used in LHAASO are currently tested with engineering arrays at scales of 1%-10% of the full project Steps ahead: environment impact evaluation, feasibility reviewing, TDR reviewing “Pre-LHAASO” project LAWCA consisting of one single water Cherenkov chamber of 220mx110m to be built side-by-side with the ARGO-YBJ RPC array is under construction.

The formal proposal is sent to CCDR, the review on the proposal is expected to be finished in 2014 and completed in 2018 Uncertain! could be 12m from now or earlier HAWC Construction

Collaboration ~80 Chinese scientists France: IPNO + OMEGA (Letter of Intend) Italia: mainly participants in ARGO Russia: collaborators from TUNKA

Conclusion A ground based large and complex γ/CR observatory at high altitude (4300m a.s.l.) within 5~6 years – γ astronomy: all sky survey and spectroscopy – Unique for CR measurements at the knees – Useful for exploring for new physics Site is decided Management structure is established The construction is scheduled to start in next year Forming the Collaboration