nal background of CsI(Tl) crystal detec for dark matter search Tae Yeon Kim Seoul National University For the KIMS Collaboration Seoul National Univ. : J.M.Choi, R.K.Jain, S.C.Kim, S.K.Kim, S. Y. Kim , T.Y.Kim*, H.S.Lee, H.S.Park, I.H.Park, E.I.Won, H.S .Won, H.Y.Yang, M.S.Yang Sejong Univ. : W.K.Kang, J.I. Lee, D.S.Lim, Y.D.Kim Yonsei Univ. : J.Hwang, H.J.Kim, J.H.Lee, Y.J.Kwon Iwha Womans Univ. : I.S.Han, E.K.Lee SeongKyunKwan Univ. : I.S.Cho, D.H.Choi, S.H.Noh, I.T.Yu Chonbuk National Univ. : S.Y.Choi KAIST : P.Ko Univ. of Maryland : M.H.Lee, E.S.Seo National Taiwan Univ., :H.B.Li, C.H.Tang, M.Z.Wang Academia Cinica :W.P.Lai, H.T. Wong Inst. Of High Energy Physics : J.Li, Y.Liu, Q.Yue Inst. Of Atomic Energy : B.Xin, Z.Y.Zhou Tsing Hua University, China : J.J.Zhu (Korean Invisible Mass Search)
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Internal background of CsI(Tl) crystal detectors for dark matter search Tae Yeon Kim Seoul National University For the KIMS Collaboration Seoul National.
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Internal background of CsI(Tl) crystal detectors for dark matter search
Tae Yeon Kim
Seoul National University
For the KIMS Collaboration
Seoul National Univ. : J.M.Choi, R.K.Jain, S.C.Kim, S.K.Kim, S. Y. Kim, T.Y.Kim*, H.S.Lee, H.S.Park, I.H.Park, E.I.Won, H.S.Won, H.Y.Yang, M.S.YangSejong Univ. : W.K.Kang, J.I. Lee, D.S.Lim, Y.D.Kim Yonsei Univ. : J.Hwang, H.J.Kim, J.H.Lee, Y.J.Kwon Iwha Womans Univ. : I.S.Han, E.K.Lee SeongKyunKwan Univ. : I.S.Cho, D.H.Choi, S.H.Noh, I.T.Yu Chonbuk National Univ. : S.Y.Choi KAIST : P.Ko Univ. of Maryland : M.H.Lee, E.S.Seo National Taiwan Univ., :H.B.Li, C.H.Tang, M.Z.Wang Academia Cinica :W.P.Lai, H.T. Wong Inst. Of High Energy Physics : J.Li, Y.Liu, Q.Yue Inst. Of Atomic Energy : B.Xin, Z.Y.Zhou Tsing Hua University, China : J.J.Zhu
(Korean Invisible Mass Search)
- Location
• Underground Pumped Storage Power Plant of Korea South Electric Company
• 80 km northeast from Seoul • 2 hours from Seoul by car
- Depth
• Minimum : 350 m • Access tunnel : 1.4 km
• Temperature : 11 - 16 oC• Relative humidity : more than 90 %
- Experimental hall
1. Underground laboratory
2. External background- Cosmic rays
Measured with 3 plastic scintillation(BC408) counters of 1 cm thickness in coincidence.
A B
A : spectrum at sea level for 1 dayB : spectrum at underground lab. for 2 weeks
Count rate B / count rate A = (1.4±0.15)x10-4
- NeutronMeasured with 0.5 liter BC501A liquid scintillator for 13 days
3675 counts/13days
Fast neutron flux = 4x10-5 /cm2/sec in the energy range between 1.5 MeV and 6.0 MeV.
- Gamma ray
The rock composition (ICP-Mass analysis) :238U = 9 ppm 232Th = 3 ppm can be controlled < 0.005 cpd40K = 4 ppm in the above shielding.
GEANT4 simulation :The shieilding of (Pb 15 cm + Cu 10 cm) can reducegamma ray background of 1.5 MeV by a factor of 106 .