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Tibet Air Shower Arrayplus Muon Detector Array

for the 100 TeV Gamma-RayWide Sky Survey

K. Kawata

For the Tibet AS Collaboration

ICRR, University of Tokyo

Locating PeV Cosmic-Ray Accelerators: Future Detectors in Multi-TeV Gamma-Ray AstronomyAdelaide 6 - 8 December 2006

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M.Amenomori,1 S.Ayabe,2 X.J.Bi,3 D.Chen,4 S.W.Cui,5 Danzengluobu,6 L.K.Ding,3 X.H.Ding, 6

C.F.Feng,7 Zhaoyang Feng,3 Z.Y.Feng,8 X.Y.Gao,9 Q.X.Geng,9 H.W.Guo,6 H.H.He,3 M.He,7 K.Hibino,10

N.Hotta,11 HaibingHu,6 H.B.Hu,3 J.Huang,12 Q.Huang,8 H.Y.Jia,8 F.Kajino,13 K.Kasahara,14Y.Katayose,4

C.Kato,15 K.Kawata,12 Labaciren,6 G.M.Le,16 A.F. Li,7 J.Y.Li,7 Y.-Q. Lou,17 H.Lu,3 S.L.Lu,3 X.R.Meng,6

K.Mizutani,2,18 J.Mu,9 K.Munakata,15 A.Nagai,19 H.Nanjo,1 M.Nishizawa,20 M.Ohnishi,12 I.Ohta,21 H.Onuma,2

T.Ouchi,10 S.Ozawa,12 J.R.Ren,3 T.Saito,22 T.Y.Saito,23 M.Sakata,13 T.K.Sako,12 T.Sasaki,10 M.Shibata,4

A.Shiomi,12 T.Shirai,10 H.Sugimoto,24 M.Takita,12 Y.H.Tan,3 N.Tateyama,10 S.Torii,18 H.Tsuchiya,25

S.Udo,12 B. Wang,9 H.Wang,3 X.Wang,12 Y.G.Wang,7 H.R.Wu,3 L.Xue,7 Y.Yamamoto,13 C.T.Yan,12

X.C.Yang,9 S.Yasue,26 Z.H.Ye,16 G.C.Yu,8 A.F.Yuan,6 T.Yuda,10 H.M.Zhang,3 J.L.Zhang,3 N.J.Zhang,7

X.Y.Zhang,7 Y.Zhang,3 Yi Zhang,3 Zhaxisangzhu,6 and X.X.Zhou 8

(1) Dep. of Phys., Hirosaki Univ., Hirosaki, Japan(2) Dep. of Phys., Saitama Univ., Saitama, Japan(3) Key Lab. of Particle Astrophys., IHEP, CAS, Beijing, China(4) Fac. of Eng., Yokohama National Univ., Yokohama , Japan(5) Dep. of Phys., Hebei Normal Univ., Shijiazhuang, China(6) Dep. of Math. and Phys., Tibet Univ., Lhasa, China(7) Dep. of Phys., Shandong Univ., Jinan, China(8) Inst. of Modern Phys., South West Jiaotong Univ., Chengdu, China(9) Dep. of Phys., Yunnan Univ., Kunming, China(10) Fac. of Eng., Kanagawa Univ, Yokohama, Japan(11) Fac. f of Educ., Utsunomiya Univ., Utsunomiya, Japan(12) ICRR., Univ. of Tokyo, Kashiwa, Japan(13) Dep of Phys., Konan Univ., Kobe, Japan(14) Fac. of Systems Eng., Shibaura Inst. of Tech., Saitama, Japan

(15) Dep. of Phys., Shinshu Univ., Matsumoto, Japan(16) Center of Space Sci. and Application Research, CAS, Beijing, China(17) Phys. Dep. and Tsinghua Center for Astrophys., Tsinghua Univ., Beijing, China (18) Advanced Research Inst. for Sci. and Engin., Waseda Univ., Tokyo, Japan(19) Advanced Media Network Center, Utsunomiya University, Utsunomiya, Japan(20) National Inst. of Info., Tokyo, Japan(21) Tochigi Study Center, Univ. of the Air, Utsunomiya, Japan(22) Tokyo Metropolitan College of Industrial Tech., Tokyo, Japan(23) Max-Planck-Institut fuer Physik, Muenchen, Germany (24) Shonan Inst. of Tech., Fujisawa, Japan(25) RIKEN, Wako, Japan(26) School of General Educ.,Shinshu Univ., Matsumoto, Japan

The Tibet AS Collaboration

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Contents

1. Introduction2. Tibet Air Shower Array Tibet Muon Detector Array3. Sensitivity Simulation4. Outlook5. Costs6. Summary

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1. IntroductionCosmic ray Acceleration Origin

New 14 HESS sources

Hard spectral indices

Faint in other wavelengths

Theoretical

possibility

• 0 decay• IC*• …

• Old SNR• Asymmetric PWN• …

Key observation 100 TeV region Wide sky survey

Aharonian et al, ApJ, 636, 777 (2006)

* >100TeV IC is difficult due to sync. cooling & KN effect

200GeV-10TeV200GeV-10TeVNew 14 HESS sourcesNew 14 HESS sources

SuzakuSuzakuHESS J1616-508HESS J1616-508

Matsumoto et al, PASJ, in pressastro-ph/0608475

Yamazaki et al, MNRA,371, 1975 (2006)

Blondin et al, ApJ,563, 806 (2001)

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2. Tibet Air Shower (AS) Array

Tibet China (90.522oE, 30.102oN) 4300 m a.s.l.

Number of Scinti. Det. 0.5 m2 x 789 Effective Area for AS ~37,000 m2

~50,000 m2

Energy region~TeV - 100 PeV Angular Resolution ~0.4 @10 TeV (Gamma) ~0.2 @100 TeV Energy Resolution ~70% @10 TeV (Gamma) ~40% @100TeV F.O.V. ~2 sr

Tibet Muon Detectors (Image)

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Tibet Muon Detector (MD) Array7.2m x 7.2m x 1.5m depth 　 Water pool20”PMT x 2 　 (HAMAMATSU R3600)Underground 2.5m ( ~515g/cm2~19X0)

Material: Concrete pool White epoxy resin paint　　　　 184 detctors　　　　　　　　 Total 　 9540 m2

Counting the number of muons accompanying an air shower

Present AS ArrayFuture AS+MD Array (Type 1)Future AS+MD Array (Type 2)

Gamma/Hadron separation

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Milagro SK (Anti) Tibet MD

PMT 8”PMT 8”PMT 20”PMT

Detector Area80m ｘ 60m Depth8m

(Upper4800m2 /Lower2000m2)All Surface ~7400m2

Thickness ~2.5m 9540m2

Depth1.5m

Unit 1PMT@2.8m×2.8m 2PMTs@6m2 2PMTs@52m2

Photo- Coverage 0.4％ 0.52％ 0.75％

Number of PMTs

Upper: Depth 1.4m, 450Lower: Depth 6.0m, 273

1885 368

Already established technique High cost performance Easy to design long path length detector Cherenkov threshold (electron 750keV in the water)

Water Cherenkov Technique

High rejection power for low energy e+/- & Good technique for muon detection

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Future AS+MD Array (Type 2)

Air Shower Generation - Corsika Ver.6.204 CR: 0.3TeV-10PeV, Crab Orbit Chemical components　　　　　　　　　 Interaction model: QGSJET01c Gamma: 0.3TeV-10PeV, Crab Orbit 　　　　　　 E-2.6

Core position: Throw randomly within 300 ｍ radius

Scintillation det. (Tibet AS) - Epics UV8.00 Estimate energy, direction, core position, …

Soil + Cherenkov det. (Tibet MD) - GEANT4 8.0 Reflectance at walls 70% Att. length ~40m@400nm (Dependant on wave length)

Quantum Eff. ~20%@400nm (Dependant on wave length)

Accidental muons 300 Hz/m2 x 9540m2 x 200 ns 　 = ~0.57 muons/an air shower 　 (Poisson noise distribution)

AS

MD

MD (Type2)

AS

3. Sensitivity Simulation

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Air Shower Reconstruction by AS Array Energy - Sum of particle density by all scintillation detectors (we do not use the lateral function in this talk.)Direction - Relative timings at each detectors

~10 TeV Air Shower (Simulation)

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Energy & Angular Resolution (Simulation)

10 TeV ~+70%-40%100 TeV ~+40%-30%(Gamma rays)

10 TeV ~0.4 degrees100 TeV ~0.2 degrees(Gamma rays)

Energy Resolution Angular Resolution

two typical air-shower size bins

~10 TeV

~100 TeV

10TeV 100TeV 1000TeV

11NPE

~100TeV

NPE

~10TeV

Muon Number vs. Shower Size (Type2 Simulation)

( Shower Size)

NP

E(

Muo

n N

um

ber)

10TeV 100TeV 1000TeV

20%50%80%

: Sum of particle density by all scintillation det. Shower SizeNPE:Sum of photoelectrons by all muon det. Muon number　　　 G CR

G CR

0

0

10TeV:Cut value NPE=~40Background: ~99% 　 RejectionGamma rays: ~60% SurvivalSensitivity: ~6 times Improved

100TeV:Cut value NPE=~600Background: >99.8% RejectionGamma rays: ~100% SurvivalSensitivity: >20 times Improved

(gamma)

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Survival Efficiency (Type2 Simulation)

CR

Gamma

10TeV 100TeV 1000TeVE:10 TeV:Cut value NPE=~40Background: ~99% 　 RejectionGamma rays: ~60% SurvivalSensitivity: ~6 times Improved

100 TeV:Cut value NPE=~600Background: >99.8% 　 RejectionGamma rays: ~100% SurvivalSensitivity: >20 times Improved Almost background free!

1000 TeV:Cut value NPE=~8000Background: >>99.8% RejectionGamma rays: ~100% SurvivalSensitivity: Background free!

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Tibet AS Array 50,000m2

+Tibet MD Array

9,540m2

Crab orbit

Sensitivity to Point-like Gamma-ray Source

EGRET

GLASTMAGIC

VERITAS

HESS

Tibet AS

Tibet AS+MD (Type2)Tibet AS+MD (Type1)

Search window size0.3 degrees >50TeV,while angular resolution<0.3 degrees.

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4. Outlook

Tibet AS+MD~100 TeV

HESS~200 GeV

Location 30N-90E 23S-16E

F.O.V. ~1.5 sr ~0.02 sr

Duty Cycle ~90% ~10%

Angular Resol. ~0.2° ~0.1°

Energy Resol. ~40% ~20%

BackgroundRejection

>99% ~99%

Sensitivity(RX J1713 Unit PL Index = –2.19)

~5% RXJ1713(1 year 5σ)

~1% RXJ1713(50 hours 5σ)

Number of detections ？ >20

Tibet AS+MD ability will be close to HESS.How many sources can we detect in the 100 TeV Northern Sky?

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Known Galactic Sources in the Northern Sky

TeV J2032+4130 HESS J1837-069 HESS J1834-087

Cas A LS I +01 303

Large Zenith ~ 37o Large Zenith ~ 39o

Periodic objectMAGIC - Peak flux

MGRO J2019+37

Diffuse gammaflux is corresponding to(3.0 x 3.0 deg.)

Our sensitivityVery preliminary!

Type 1Type 2

VERITAS

Extrapolation

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How Many New Sources?

Induces are harder

Aharonian et al, ApJ, 636, 777 (2006)

(If it is constructed at southern hemisphere)Most of new HESS sources detectable by Tibet AS+MD

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Green, arXiv:astro-ph/0411083http://www.mrao.cam.ac.uk/surveys/snrs/index.html

Green’s SNR catalog

HESS survey region82 SNRs

Tibet F.O.V. region86 SNRs

~new 14 detected (SNR-like)~new 14 detectable?? (SNR-like)optimistic value?But, could not be 0?

Expectation of the number of SNR-like sources in the Northern Sky

Aharonian et al, ApJ, 636, 777 (2006)

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5. Costs

Items Remarks Unit price

(US $)

Quantity Total

(US $)

PMT 20” PMT 5,000 368 1.84M

ElectronicsADC, TDC, HV,

Cable, …800 184 0.147M

Water poolConstruction fee

(Waterproof paint, Concrete, … )

250/m2 9,540m2 2.39M

Water purification & circulation

MF filters, … 0.15M

Others +

Total (US $) 4.5M +

Total ~5M US$

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Tibet MD Project 50,000 m2 Tibet air shower array + 9,540 m2 Water cherenkov muon detector array

~5M US$ - 100 TeV gamma-ray wide sky survey.

Sensitivity simulation Detailed simulation was done (two configurations). 　 F(>100TeV) ~2 x 10-15 cm-2 s-1 (1 calender year, 5or 10 events). Improve sensitivity by an order of magnitude. Inner MDs are very important.

Candidates of 100 TeV sources in the northern sky Promising: Crab, TeV J2032+4130, HESS J1837-069, MGRO J2019+37 Interesting: Cas A, HESS J1834-089, LS I +61 303 (Need several years)

+ several new sources?

6. Summary

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Tibet AS+MD200?~

CASA-MIA1991~1996

Milagro2000~

KASCADE1996~

Grapes-III2001~

Location 30.102N 90.522E Tibet 4300m(606g/cm2)

40.2N 112.8WUtah1500m(870g/cm2)

35.9N 106.7W NewMexico 2650m (750g/ cm2)

49.1 N8.4E Karlsruhe 110m(1022 g/cm2)

11.4N 76.7EOoty 2200m(800 g/cm2)

EnergyETH75%

1-104.5TeV10TeV

50-104.5TeV60TeV

~0.1TeV-?10TeV

100-104.5TeV260TeV

10-104TeV?

Energy Resolution

40% (100TeV) 100%(100TeV) ? ? ?

AngularResolution

0.4° (>10TeV)0.2° (>100TeV)

2 °(>~100TeV)0.5°(>~700TeV)

1°(>~1TeV)0.55°(>~600TeV)

?

AS Eff Area(Particle coverage)

50,000m2

Scinti. (0.9%)230,000m2

Scinti. (0.7%) 4,800m2 Water (100%) (with Outrigger 34,000m2)

40,000m2

Scinti.(1.3%)10,000m2

Scinti.(1.2%)

μ Eff Area 9,540m2

Water2,500m2

Scinti.~2,000m2

Water622m2

Scinti.560m2 x4 layersProp. Counters

Absorber Soil 2m +Concrete 0.5m(515g/cm2)19X0

Soil 3m

(600g/ cm2)22X0

Water 6m

(600g/ cm2)16X0

Lead 10cm +Iron 4cm(145g/cm2)20X0

Concrete 2m

(460g/cm2)17X0

Muon Eth >1GeV >1GeV >1.2GeV >0.23GeV >1GeV