Neutron Spectrum Measured in Aberdeen Tunnel Underground Laboratory with a Multisphere Neutron Spectrometer

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Aithousa Mitropoulos

Aithousa Mitropoulos

Megaron, Athens - Greece

Speaker

Mr Hao Liu (Department of Physics, The University of Hong Kong, Hong Kong)

Description

Neutrons from natural radioactivity and spallation reactions initiated by cosmic ray muons represent a major source of background for underground neutrino experiments. A set of multisphere neutron spectrometer was developed. It consisted of 8 Bonner Spheres, made of high-density polyethylene, with diameter from 12.7 cm (5 in) to 30.84 cm (12 in). Lead shells with 1 cm and 2 cm thickness were added to the 15.24 cm (6 in) sphere to increase the detection efficiency of high-energy neutrons (E > 10 MeV). The response matrices of the detectors were calculated with Geant4 from 1 eV to 1 GeV. The neutron spectrum inside the Aberdeen Tunnel Underground Laboratory, with an overburden of ~660 m.w.e., was measured with the neutron spectrometer which was calibrated with an AmBe source. The neutron spectrum and flux were deduced by unfolding the measured count rates using a genetic algorithm.

Primary author

Mr Hao Liu (Department of Physics, The University of Hong Kong, Hong Kong)

Co-authors

Mr C.M. Wong (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Mr H.Y. Ngai (Department of Physics, The University of Hong Kong, Hong Kong) Dr J.C.S. Pun (Department of Physics, The University of Hong Kong, Hong Kong) Dr J.K.C. Leung (Department of Physics, The University of Hong Kong, Hong Kong) Prof. K.B. Luk (Department of Physics, University of California, Berkeley, USA) Mr K.K. Kwon (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Mr K.K. Wong (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Mr K.P. Tong (Department of Physics, The University of Hong Kong, Hong Kong) Prof. M.C. Chu (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Mr M.W. Kwok (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Mr S.Y. Ngan (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Mr T. Kwok (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Mr W.H. Luk (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Ms W.Y. Lai (Department of Physics, The University of Hong Kong, Hong Kong) Mr X.C. Chen (Department of Physics, The Chinese University of Hong Kong, Hong Kong) Dr Y.C. Lin (Department of Physics, The University of Hong Kong, Hong Kong)

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