1. 1 Tibet Air Shower Array Results and Future Plan - Gamma Ray Observation - K. Kawata For the Tibet AS  Collaboration ICRR, University of Tokyo International Conference on Topics in Astroparticle and Underground Physics (TAUP) 2007 Sendai, Japan, September 11-15, 2007

2. 2 Contents  Tibet Air Shower Array  Recent Results Crab Nebula MGRO J2019+37 (Cygnus Region) MGRO J1908+06  Future Plan (Tibet muon detector project) Simulation Sensitivity Expected Results Prototype MD  Summary

3. 3 The Tibet AS  Collaboration M.Amenomori 1, X.J.Bi 2, D.Chen 3, S.W.Cui 4, Danzengluobu 5, L.K.Ding 2, X.H.Ding 5, C.Fan 6,C.F.Feng 6, Zhaoyang Feng 2, Z.Y.Feng 7, X.Y.Gao 8, Q.X.Geng 8, H.W.Guo 5, H.H.He 2, M.He 6, K.Hibino 9, N.Hotta 10, Haibing Hu 5, H.B.Hu 2, J.Huang 11, Q.Huang 7, H.Y.Jia 7, F.Kajino 12, K.Kasahara 13, Y.Katayose 3, C.Kato 14, K.Kawata 11, Labaciren 5, G.M.Le 15, A.F.Li 6, J.Y.Li 6, Y.-Q.Lou 16, H.Lu 2, S.L.Lu 2, X.R.Meng 5, K.Mizutani 13,17, J.Mu 8, K.Munakata 14, A.Nagai 18, H.Nanjo 1, M.Nishizawa 19, M.Ohnishi 11, I.Ohta 20, H.Onuma 17, T.Ouchi 9, S.Ozawa 11, J.R.Ren 2, T.Saito 21, T.Y.Saito 22, M.Sakata 12, T.K.Sako 11, M.Shibata 3, A.Shiomi 9,11, T.Shirai 9, H.Sugimoto 23, M.Takita 11, Y.H.Tan 2, N.Tateyama 9, S.Torii 13, H.Tsuchiya 24, S.Udo 11, B.Wang 8, H.Wang 2, X.Wang 11, Y.Wang 2, Y.G.Wang 6, H.R.Wu 2, L.Xue 6, Y.Yamamoto 12, C.T.Yan 11, X.C.Yang 8, S.Yasue 25, Z.H.Ye 15, G.C.Yu 7, A.F.Yuan 5, T.Yuda 9, H.M.Zhang 2, J.L.Zhang 2, N.J.Zhang 6, X.Y.Zhang 6, Y.Zhang 2, Yi Zhang 2, Zhaxisangzhu 5 and X.X.Zhou 7 (1) Department of Physics, Hirosaki University, Hirosaki 036-8561, Japan. (2) Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. (3) Faculty of Engineering, Yokohama National University, Yokohama 240-8501, Japan. (4) Department of Physics, Hebei Normal University, Shijiazhuang 050016, China. (5) Department of Mathematics and Physics, Tibet University, Lhasa 850000, China. (6) Department of Physics, Shandong University, Jinan 250100, China. (7) Institute of Modern Physics, SouthWest Jiaotong University, Chengdu 610031, China. (8) Department of Physics, Yunnan University, Kunming 650091, China. (9) Faculty of Engineering, Kanagawa University, Yokohama 221-8686, Japan. (10) Faculty of Education, Utsunomiya University, Utsunomiya 321-8505, Japan. (11) Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582, Japan. (12) Department of Physics, Konan University, Kobe 658-8501, Japan. (13) Research Institute for Science and Engineering, Waseda University, Tokyo 169- 8555, Japan. (14) Department of Physics, Shinshu University, Matsumoto 390-8621, Japan. (15) Center of Space Science and Application Research, Chinese Academy of Sciences, Beijing 100080, China. (16) Physics Department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084, China. (17) Department of Physics, Saitama University, Saitama 338-8570, Japan. (18) Advanced Media Network Center, Utsunomiya University, Utsunomiya 321- 8585, Japan. (19) National Institute of Informatics, Tokyo 101-8430, Japan. (20) Tochigi Study Center, University of the Air, Utsunomiya 321-0943, Japan. (21) Tokyo Metropolitan College of Industrial Technology, Tokyo 116-8523, Japan. (22) Max-Planck-Institut für Physik, München D-80805, Deutschland. (23) Shonan Institute of Technology, Fujisawa 251-8511, Japan. (24) RIKEN, Wako 351-0198, Japan. (25) School of General Education, Shinshu University, Matsumoto 390-8621, Japan.

4. 4 Tibet-III Air Shower (AS) Array  Number of Scinti. Det.0.5 m 2 x 789  Effective Area for AS~37,000 m 2  Energy region~TeV - 100 PeV  Angular Resolution~0.4 @10 TeV (Gamma rays) ~0.2 @100 TeV  Energy Resolution~70% @10 TeV (Gamma rays)~40% @100TeV  F.O.V.~2 sr Tibet Muon Detectors (Future Image) Yangbajing, Tibet, CHINA, 4300m a.s.l. 2 nd particles Timing & Energy deposit

5. 5 30 th ICRC 2007, Merida, Mexico Consistent with other observations using IACT Preliminary Energy Spectrum of Gamma rays from the Crab Nebula Centered at Crab position

6. 6 Moon Shadow Constant fitting -0.0034 o 0.011 o + Systematic pointing error < 0.01 o Absolute Energy Scale error –4.4% +- 7.9%stat +- 8%sys Energy dependence of Displacements Caused by Geomagnetic field Verification  Absolute energy scale  Angular resolution  Pointing error

7. 7 Northern Sky Survey & Cygnus Region Red --without Crab and Mrk421and Cygnus region Preliminary result  smooth radius 1.5° MGRO J2019+37 Tibet: 5.8  30 th ICRC 2007, Merida, Mexico

8. 8 MGRO J2019+37 Energy Spectrum 100% gamma-rays assumed  Milagro flux is E 2 dN/dE=(3.49±0.47stat ±1.05sys)x10 -12 TeVcm -2 s -1 from 3x3 square degree bin centered on the location of Hotspot (304.83 o,36.83 o ) at 12TeV, assuming a differential source spectrum of E -2.6 (reference : ApJ658:2007). Preliminary 30 th ICRC 2007, Merida, Mexico Tibet AS has no ability for Gamma/Hadron separation Assuming 100% of the excess is caused by gamma rays Not inconsistent with Milagro flux Milagro

9. 9 MGRO J1908+06 Tibet AS: In 2003, marginal excess ~4.4σ (pre-trial) Subsequently Milagro: clear excess (MGRO J1908+06) J.L. Zhang for the Tibet ASγ Collaboration, 28th ICRC, vol. 4, pp 2405 - 2408 (2003) Amenomori et al., 29th ICRC, vol. 4, pp 93 - 96 (2005) Amenomori et.al, ApJ 633,1005 (2005) MGRO J1908+06 Milagro error circle (stat.+sys.) G40.5-0.5 G39.2-0.3 GeV J1907+0557 Tibet error circle

10. 10 Tibet Muon Detector (MD) Array 7.2m x 7.2m x 1.5m depth Water pool 20”  PMT x 2 (HAMAMATSU R3600) Underground 2.5m ( ~515g/cm 2 ~19X 0 ) Material:  Concrete pool  White paint 192 detctors Total ~10,000 m 2 Counting the number of muons accompanying an air shower Gamma/Hadron separation extends AS to ~83,000m 2 MD ~10,000m 2

11. 11 Muon Number vs. Shower Size (Simulation)  : Sum of particle density by all scintillation det. Shower Size  N PE :Sum of photoelectrons by all muon det. Muon number  ( Shower Size)  N PE  ( Muon Number)  10TeV100TeV1000TeV 20% 50% 80% (gamma) 0 (~10TeV) 0 (~100TeV) Gamma CR 99.8% Rejection

12. 12 Tibet AS Array 83,000m 2 + Tibet MD Array 10,000m 2 Crab orbit Sensitivity to Point-like Gamma-ray Source Search window size 0.3 degrees >50TeV, while angular resolution <0.3 degrees. F.O.V. ~2 sr

13. 13 Above10 TeV cosmic/gamma ray wide sky survey  Measurement of cut-off energy in gamma ray spectrum Search for Pevatron Cosmic ray origin & acceleration mechanism  Diffuse gamma rays from Galactic plane (including Cygnus) Cosmic ray propagation  Monitoring time variable sources (AGN, GRB…) Measure column density of IR photons  Extragalactic background radiation UHCR cascading  Cosmic ray chemical composition around the Knee region Separate chemical composition by the number of muons Physics Motivation

14. 14  0 decay Protons E<1000TeV Gamma rays in the 100 TeV region Aharonian et al, A&A, 431, 197 (2005) Hard spectral index at TeV energies Faint in other wavelengths TeV J2032+4130 (~5% Crab) 10-1000TeV Inverse Compton

15. 15 Tibet AS+MD 1year, 5σ Epmax=100TeV 1000TeV 10000TeV VERITAS   decay model Aharonian et al. A&A, 464, 235(2007) Kelner et al., PRD 74, 034018 (2006) TeV J2032+4130 Crab -2.62 Aharonian et al, A&A, 431, 197 (2005) TeV J2032+4130 Unidentified source Cyg X-3 in Cyg OB2 HEGRA obs.~158 hours Extended ~6.2′   decay?

16. 16 MGRO J2019+37 Cygnus diffuse gamma rays Beacom et al. astro-ph/070175 (2007) Integral flux in 3 o ×3 o region Abdo et al. astro-ph/0611691 (2006)

17. 17 Diffuse Gamma Rays from Galactic Plane 0° 60°120° 180° 240° 300° -10° 10° 0° EGRET data Electron model Electron model  0 model

18. 18 Known Gamma-Ray Sources in the Northern Sky HESS J1837-069HESS J1834-087 Cas ALS I +01 303 Large Zenith ~ 37 o Large Zenith ~ 39 o Periodic object MAGIC - Peak flux VERITAS Mrk 421 Mrk 501 Tibet AS+MD 1year M87

19. 19 Prototype MD 52 m 2 x 2 units Constructionstart 1 st September 2007 complete end of November 2007 Feasibility study of construction Compare with simulation Search for 1000 TeV Gamma rays

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21. 21 Summary Performance of Tibet Air Shower Array: Angular Resolution0.2 o @100TeV Energy Resolution~40% @100TeV Systematic Pointing Error< 0.01 o Absolute Energy Error~10% Verification by the Moon Shadow Crab Nebula: Energy spectrum observed by Tibet AS is consistent with other observations using IACTs. MGRO J2019+37: Tibet flux is not inconsistent with Milagro results, if we assume 100% of the excess is caused by gamma rays. MGRO J1908+06: Marginal excess was found. Tibet AS+MD: 10000 m 2 Water Cherenkov Muon Detector (~5M US$) Sensitivity is 5-15% Crab @ 10-100 TeV. Construction of test MD (52 m 2 x 2) started 1 st September 2007.

22. 22 Thank you!