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

1

(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

2

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

3

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

4

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)

5

Tibet AS+MD Project

6

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

7

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

7

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

7

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

7

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

8

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

9

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

10

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.

Thanks！

11

16

Schematic view of the pool

Design of the large Tyvek bag

17

An inflated bag during testing

The pulse shape of one Muon events

Self-Trigger Result

18

A peak of charge distribution is defined as one muon.

Test for Different Site

19

A B

C

D

planform

pool

Soil

Scintillation counts

side view of the test system

2m