A Large High Altitude Air Shower Observatory LHAASO

A Large High Altitude Air Shower Observatory LHAASO Project Zhen Cao Institute of High Energy Physics, China, Beijing 100049 Te. VPA, SLAC, 2009

Yangbajing Valley in Tibet

YBJ, Tibet 4300 m a. s. l.

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

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

A Tentative Design of A Complex Detector Array Three major components • 1 km 2 complex array forγrays and CRs >30 Te. V – 1 km 2 scintillation detector array – 40 k m 2 μdetector array – 28 C-telescopes – 1 k m 2 burst detector • 90 k m 2 water Cerenkov detector for γ>100 Ge. V • Two Magic. II telescopes

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

Contribution of Magic Coll.

Water Cherenkov Detector

μdetector

Ground Charge Particle Detector 1. 2 m 250 mm m 250 m 1 m 20 mm Thick Iron Case scintillator 2. 3 cm PMT WS fiber

Wide FOV Cherenkov telescopes

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

Cost Free high energy (1 Ee. V)extension Tower CT: 16 μ : 100 x 400 m 2 Side Trigger CT: 2 x 4 Re-Configuration

Performance • • 1 km 2 array for γdetection >50 Te. V Magic. II @ Tibet site WCDA for source survey CR (30 Te. V ~ 1 Ee. V): both knees & absolute energy scale

Forγastronomy ARGO ？

Resolution for light and heavy composition μ-content, Xmax and HE (>30 Te. V) shower particles Proton Iron For Proton and Helium: l 1. 5 m spacing l. Nb>100 , any 5 (> 30 Ge. V) For Iron: l 3. 75 m spacing l. Nb>100 , any 21 ( > 30 Ge. V)

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

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

Dark Matter g-rays from the sub-halos ARGO sensitivity LHAASO sensitivity Reed et al, MNRAS 35 7, 82(2004) source y sun GC g-rays from smooth bkg

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

On Site Prototype Exp. • 1% of the final configuration of LHAASO all OH G R A

CR Energy Spectrum (160 k events) resolution < 10% With bias<3% Core resolution <1 m From S. P. SWORDY, Space Science Reviews 99: 85– 94, 2001.

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

Perspectives on γAstronomy • Survey the whole sky for γsources above 100 Ge. V (>90% of area is never surveyed at a sensitivity of 0. 03 ICrab) • Investigate detailed energy spectra for galactic sources above 30 Te. V, cosmic ray sources are expected to be identified • Detailed morphologic investigation of discovered sources for acceleration mechanism. (>30 Ge. V)

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 (KM 2 A 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)

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