A Large High Altitude Air Shower Observatory LHAASO Project Zhen Cao Institute of High Energy Physics, China, Beijing TeVPA, SLAC,2009

Yangbajing Valley in Tibet

YBJ, Tibet 4300m a.s.l.

Outline Scientific Perspectives Tentative design of a detector array Performance Prototyping Conclusion

Scientific Problems and Possible Solutions TeVγray observation has an opportunity of finding CR origin: 80+ sources discovered –50+ galactic sources: γat high energy (>30TeV) is crucial (high sensitivity and high energy resolution) –All-sky survey forγsource population is necessary (full duty cycle, wide FOV and sufficient sensitivity) PeV CR spectra of individual composition –Bridge between space/balloon borne measurements and ground based UHECR measurements Searching for Dark Matter galactic sub-structures ？ Hadronic model Leptonic model

A Tentative Design of A Complex Detector Array Three major components 1km 2 complex array forγrays and CRs >30TeV –1 km 2 scintillation detector array –40k m 2 μ detector array –28 C-telescopes –1k m 2 burst detector 90k m 2 water Cerenkov detector for γ>100GeV Two MagicII telescopes

Large High Altitude Air Shower Observatory Charge Particle Array μdetector Array Water C Array LHAASO Project: γastronomy and origin of CR Wide FOV C-Telescope Array & Core Detector Array

Contribution of Magic Coll.

Water Cherenkov Detector

μdetector

Ground Charge Particle Detector 250mm 20mm 1.2m 1m scintillator PMT WS fiber Thick Iron Case 2.3cm

Wide FOV Cherenkov telescopes

Shower Core Detector YAC detector Pb(7r.l.)Fe(1cm) Plastic scinti.

Cost Free high energy (1EeV)extension Tower CT: 16 μ : 100x400m 2 Side Trigger CT: 2x4 Re-Configuration

Performance 1km 2 array for γ detection >50TeV Tibet site WCDA for source survey CR (30TeV ~ 1EeV): both knees & absolute energy scale

Forγastronomy ARGO ？

Resolution for light and heavy composition μ-content, Xmax and HE (>30TeV) shower particles ProtonIron For Proton and Helium: 1.5 m spacing Nb>100, any 5 (> 30 GeV) For Iron: 3.75m spacing Nb>100, any 21 ( > 30 GeV)

The keys are to lower threshold, making connections with direct measurements & measure spectra up to 100PeV

A bridge between balloon measurements and ground base UHECR experiment covering both “ knees ” with absolute energy scale

Dark Matter  -rays from the sub-halos Reed et al, MNRAS35 7,82(2004) LHAASO sensitivity LHAASO sensitivity  -rays from smooth bkg source sunGC  ARGO sensitivity

Prototyping R/D budget: ~$1M Detector unit IHEP

On Site Prototype Exp. 1% of the final configuration of LHAASO ARGO Hall

预先研究进展 1% 规模实验计划

From S. P. SWORDY, Space Science Reviews 99: 85–94, CR Energy Spectrum (160k events) resolution < 10% With bias<3% Core resolution <1m

Conclusion a ground based large and complex γ/CR observatory at high altitude (4300m a.s.l.) within 5~10 years –Complementary to CTA in γ astronomy –Unique for CR measurements at Knees –Perhaps useful for DM detection

Perspectives on γ Astronomy Survey the whole sky for γ sources above 100GeV (>90% of area is never surveyed at a sensitivity of 0.03I Crab ) Investigate detailed energy spectra for galactic sources above 30TeV, cosmic ray sources are expected to be identified Detailed morphologic investigation of discovered sources for acceleration mechanism. (>30GeV)

Domestic Collaboration(13 inst.) ARGO collaboration: –APC of IHEP (detector design, project organization) –Tibet Univ. （ FPM ） –SW Jiaotong Univ. （ FPM: construction at high altitude) –Yunnan Univ. (PMT calib., optics) –Shandong Univ. (PMT calib.. Computing & Simulation) –Hebei Normal Univ. (Simulation) New collaborators –EPC of IHEP (KM2A electronics, DAQ) –USTC (WCDA electronics, trigger and PMT calib.) –PKU (computing, UHE CRs) –IAP (high Altitude Atmospheric Phys. ) –CSSAR (Space weather monitoring and prediction) –NSMC (Space weather monitoring and prediction) –IMP (Biophys. & Environment ) Communication Members (potential collaborators): –Tsinghua Univ. –Shanghai Jiaotong Univ. –Eastern Institute of Science and Technology –Nanking Univ.

International Collaboration ARGO collaboration: –Rome II Univ. （ RPC, Simulation, Slow Control ） –Lecce Univ. （ CRs, electronics) –Napeli Univ. (DAQ) –Torino Univ. (ECAL, GRBs) –….. Magic collaboration: –Max Planck Institute (Germany) (electr., Simulation, analysis) –Padova Univ. (Italy) (Telescope, optics) –IFAE (Spain) (Telescope, analysis) –….. Heidelberg Univ. (phys. Analysis) Communication Members (future collaborators): –HAWC Coll. (WCDA)

You are invited to Lhaaso at Lhasa! Large High Altitude Air Shower Observatory