A Complex Detector Array at the Tibet Cosmic Ray Observatory Zhen Cao Institute of High Energy Physics, China, Beijing 100049 TeVPA08, Beijing, China, September, 2008

Outline Motivation and scientific goals Tentative design of the detector array Components and performance Tentative time schedule Cost estimates Conclusion

Motivation & Scientific goals TeVγray observation has an opportunity to find CR sources: 60+ sources discovered 50+ galactic: high energy (>30TeV) is crucial (high sensitivity and high energy resolution) Source population & temporal feature are important (full duty cycle and sufficient sensitivity) PeV CR spectra of individual composition Bridge at high altitude (4300m) between space/balloon borne measurements and ground based measurements Searching for Dark Matter galactic sub-structures

Aharonian et al., 2006 (astro-ph/0611813) RXJ1713.7-3946 at TeV energies SNR ~1600 years old, distance of 1kpc. TeV emission seen by CANGAROO (2000) HESS observation (since 2003) ~90h live 53 s resolved morphology (1st time at TeV energy): Shell structure Strong coincidence with X map (ASCA) Unambiguous proof of SNRs shocks as acceleration sites Aharonian et al., 2006 (astro-ph/0611813)

RXJ1713.7-3946 ASCA data: (synchrotron X rays) Leptonic model ASCA data: (synchrotron X rays) Fine structures in the radiation morphology points to B>100µG If leptonic, X/TeV ratio requires B~10µG (with sIC/sSync a B-2 ) Hadronic model favored Hadronic model Still pending: Hadronic model to be confirmed Occurence of such objects? (cf scan)

50+ are galactic without absorption Many SNRs, WRs and OB ass. E-spectra only up to 10TeV Many varying sources > 0.05ICrab 1.44x10-16ph/cm2s 1.35PeV Accurate measurements of spectra of γsources are crucial for finding CR sources

Mrk 421/501 Long term Variability Mrk 421 by ARGO Mrk 421 by ASM of RXTE

CR spectrum around “knee” Over 50 yrs, results are unsatisfactory The best location is at high altitude Solution is E-spectrum for individual composition

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

Tentative design of the complex detector array Two major components 1km2 complex array forγrays and CRs >30TeV 1 km2 scintillation detector array 40k m2 μdetector array 28 C-telescopes 1k m2 burst detector 90k m2 water Cerenkov detector for γ>100GeV

Future plan for a complex of CR+γdetectors WCD: 4x104m2 μ : 100x400m2 e : 2400x1m2 CT: 28 BD: 1000x1m2 AS+μ: ARGO: 104m2

γ/p discrimination γsurvival rate ~99% Angular resolution 0.5° Above 60TeV CR BG-free(10-5) γsurvival rate ~99% Angular resolution 0.5°

Sensitivities for 100TeV γsky E-resolution 60% Without reconstruction

Expectation: if HESS sources are in the field of view HESSJ 1614-518 1616-508 1632-478 1634-472 1702-420 1708-410 1713-381 1745-303 1804-216 1834-087 1837-069 Ec=1PeV Ec=100TeV YBJ 1km2

Should look for old SNRs (J.Fang&L.Zhang, arXiv:0711.4173 )

Sensitivities for γsources >500GeV wide FOV scanning for source population 5σper year (24%duty cycle) for sources like Crab in the whole field of view Important complementary to each other 5σper 50hrs for a single source like Crab

Resolution for light and heavy composition μ-content, Xmax and HE (>30TeV) shower particles

DICE-type C-telescope for Xmax (expect aΔXmax~50g/cm2) Very preliminary result without C-light emitting angle correction

Cost Free high energy (1EeV)extension Re-Configuration Tower CT: 16 μ : 100x400m2 Side Trigger CT: 2x4

Aperture of HEE Event rate ~25k/yr

knee Second knee We are here

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

Dark Matter g-rays from the sub-halos ARGO sensitivity LHAASO sensitivity Reed et al, MNRAS357,82(2004) source Then we get the gamma ray flux from the subhalos? The peaks represent the gamma ray flux from different subhalos at different directions. Psi is the angle between the source and the GC. y g-rays from smooth bkg sun GC

Tentative time schedule Phase I (a half of the full scale array) Detector R/D: (test run with small array) 1yr Detector Producing & deployment: 3yr Electronics R/D: 2yr Electronics production: 2yr DAQ for low energy γdetector array: 4yr Test operation for 1 year Phase II (complete the whole array for 3yr)

Cost estimates (MUSD) e detector： 3.4 + (2400m2) μdetector： 44.6 + (40k m2) = 48.0 C-telescopes： 4.0 (28 telescopes) Burst detector: 3.0 (1k m2) Water C-detector: 58.0 (90k m2) Data management: 4.3 subtotal： 117.3 Operational budget: 4.0/yr (for 10yrs)

Conclusion Plan to build a ground based large and complexγ/CR observatory at high altitude (4300m a.s.l.) within 10 years Complementary to CTA in γastronomy Unique for CR measurements at Knees Promising DM detection Tentative proposal submitted to CAS (review cycle will start next month) A separate proposal for R/D is approved (last month) Completely open to colleagues on collaborating and optimizing the instruments

Idea from Magic Coll.

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