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Study of the large Tyvek bag technique for the water Cherenkov detector in TIBET AS+MD ——status report
LIU ChengInstitute of High Energy Physics, CAS, China
(For the Tibet AS Collaboration)
ICRC2011@BEIJING ( 2011.8.11-18)
M.Amenomori(1), X.J.Bi(2), D.Chen(3), Y.Chen(2), S.W.Cui(4), Danzengluobu(5), L.K.Ding(2), X.H.Ding(5), C.F.Feng(6), Zhaoyang Feng(2), Z.Y.Feng(7), Q.B.Gou(2), H.W.Guo(5), H.H.He(2), Z.T.He(4,2), K.Hibino(8), N.Hotta(9), Haibing Hu(5), H.B.Hu(2), J.Huang(2), W.J.Li(2,7), H.Y.Jia(7), L.Jiang(2), F.Kajino(10), K.Kasahara(11), Y.Katayose(12),
C.Kato(13), K.Kawata(3), Labaciren(5), G.M.Le(2), A.F.Li(14,6,2), C.Liu(2), J.S.Liu(2), H.Lu(2), X.R.Meng(5), K.Mizutani(11,15), K.Munakata(13), H.Nanjo(1), M.Nishizawa(16), M.Ohnishi(3), I.Ohta(17), S.Ozawa(11), X.L.Qian(6,2), X.B.Qu(2), T.Saito(18), T .Y.Saito(19), M.Sakata(10), T.K.Sako(12), J.Shao(2,6), M.Shibata(12), A.Shiomi(20), T.Shirai(8), H.Sugimoto(21), M.Takita(3), Y.H.Tan(2), N.Tateyama(8), S.Torii(11), H.Tsuchiya(22), S.Udo(8), H.Wang(2), H.R.Wu(2), L.Xue(6), Y.Yamamoto(10), Z.Yang(2), S.Yasue(23), A.F.Yuan(5), T.Yuda(3), L.M.Zhai(2), H.M.Zhang(2), J.L.Zhang(2),
X.Y.Zhang(6), Y.Zhang(2), Yi Zhang(2), Ying Zhang(2), Zhaxisangzhu(5) and X.X.Zhou(7)
The Tibet ASγ Collaboration
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(13)Department of Physics, Shinshu University, Japan.
(14)School of Information Science and Engineering, Shandong Agriculture University, China.
(15)Saitama University, Japan.
(16)National Institute of Informatics, Japan.
(17)Sakushin Gakuin University, Japan.
(18)Tokyo Metropolitan College of Industrial Technology, Japan.
(19)Max-Planck-Institut fur Physik, Deutschland.
(20)College of Industrial Technology, Nihon University, Japan.
(21)Shonan Institute of Technology, Japan.
(22)RIKEN, Japan.
(23)School of General Education, Shinshu University, Japan.
(1)Department of Physics, Hirosaki University, Japan.
(2)Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, China.
(3)Institute for Cosmic Ray Research, University of Tokyo, Japan.
(4)Department of Physics, Hebei Normal University, China.
(5)Department of Mathematics and Physics, Tibet University, China.
(6)Department of Physics, Shandong University, China.
(7)Institute of Modern Physics, SouthWest Jiaotong University, China.
(8)Faculty of Engineering, Kanagawa University, Japan.
(9)Faculty of Education, Utsunomiya University, Japan.
(10)Department of Physics, Konan University, Japan.
(11)Research Institute for Science and Engineering, Waseda University, Japan.
(12)Faculty of Engineering, Yokohama National University, Japan.
OutlineIntroduction
Design of TIBET AS + MDTibet Air Shower ExperimentMuon DetectorRecent Results
Summary
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Crab nebulaWhipple (1989)
H.E.S.S.(since 2004)
1) Twenty years ago, Crab nebula was the only TeV γ source;
2) With the development of IACTs, more than 100 sources of TeV γ have been discovered;
3) Fermi detected 1873 sources in GeV range in its first two year operation.
Gamma-ray astronomy
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Where do gammas come from?
(1) Electromagnetic processes:
-Synchrotron, -Inverse Compton, -Bremsstrahlung
(2) Hadronic processes:
P + P π±+ π0 +… e± + ν + γ + … IC
Aharonian et al, A&A, 431, 197 (2005)
10-1000TeV
0 decay
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Example – Crab nebula
Search for 100TeV γ sources is one way to findthe origin, acceleration of CRs.
Scintillation Counters: 0.5 m2 x 789 Effective area ~ 37,000 m2
Energy region ~ TeV - 100 PeV Angular Resolution ~ 0.2 @100 TeV Energy Resolution ~ 40% @100TeV F.O.V. ~ 2 sr
Tibet ASγArray
90.522oE, 30.102oN, 4300 m a.s.l.(606g/cm2)
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Tibet AS+MD Project
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Muon Detector Array:
Underground 2.5m ( ~ 19X0)
Consists with 12 modules (each module has 16 pools)
concrete pool size is 7.2m wide х 7.2m long
With 20”PMT
MD-I (5 Pools) have been constructed
at the end of 2010
MD ~10,000m2
MD-A
Ensure long term stability of water quality Closed container technique
The large Tyvek bag technique using in MD-A optimized for the Tibet MD array
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water-recycling system technique
Milagro
Super-Kamiokande
closed container technique
Auger Surface Detector
HAWC
Ensure long term stability of water quality Closed container techniques
Outstanding diffuse reflectivityTyvek || LDPE ( λ>350nm, reflectivity > 90%)
The large Tyvek bag technique using in MD-A optimized for the Tibet MD array
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LDPE film bonded to Tyvek 1082D Weld membranes with welding machine
Ensure long term stability of water quality Closed container techniques
Outstanding diffuse reflectivityTyvek || LDPE ( λ>350nm, reflectivity > 90%)
More Cherenkov light Change the bag depth
from 1.5m to 1.9m
The large Tyvek bag technique using in MD-A optimized for the Tibet MD array
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1.9m7.2m
The Large Tyvek Bag (7.2 m × 7.2 m × 1.9 m)
Weld to a large bag in laboratory
Ensure long term stability of water quality Closed container techniques
Outstanding diffuse reflectivityTyvek || LDPE ( λ>350nm, reflectivity > 90%)
More Cherenkov lightChange the bag deep from 1.5m to 1.9m
Better water transparency Water purification system(five stages purification)
The large Tyvek bag technique using in MD-A optimized for the Tibet MD array
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1) Pre-processing
2) Reverse Osmosis
3) Ultraviolet purification
4) Electro-deionization
5) Ultra Filter
The output water resistivity > 10 MΩ*cm
Schematic view of the pool
MD-A Construction Scene
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Simulation installed of the bag in laboratory
The Water purification system
The MD-A been constructed in 2010
The TIBET AS array is recovering
The scene of the installation
The signal of the pool
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pool
Soil
Scintillation counts
Schematic view of the test system
1) central muons are selected if two scintillation counts are fired;
2) a clear single muon peak can be observed;
3) Future study of the data analysis and Monte Carlo (MC) simulation of the MD-A is in progress…
0.5m
Preliminary
Summary
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1) Five MD modules have been constructed in 2010;
2) The large Tyvek bag technique is used in MD-A;
3) In MD-A, 3 of the bags have be successfully installed and other pools are in installation;
4) Data analysis and MC simulation of the MD-A are under study.
The pulse shape of one Muon events
Self-Trigger Result
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A peak of charge distribution is defined as one muon.