SeDiNe (Spherical Detection of Neutrons) is an SPC located at the « Laboratoire Souterrain de Modane » (LSM), a horizontal access lab in France, in the Alps, along the Frejus road tunnel between France in Italy.
Sedine is the first detector of its kind to be operated to detect low counting rates, thanks to the use of low radioactivity building materials and the copper/lead/polyethylene shieldings. The detector was implemented to measure the very low neutron (thermal and fast) flux within the lab.
Very sensitive measurements of thermal neutron flux have indeed been performed with 3He, and results in flux compatible with previous measurements, ie around 0.6 10-6 n/cm2/s.
The detector has also been operated with Ne/CH4 mixtures at pressure up to 3 bars to study residual radioactive background and evaluate sensitivity to low mass WIMPs. Recent data taking has been completed together with 37Ar and neutron calibration runs. Data are currently being analyzed (June 2015).
The 60 cm low activity copper detector is contained in 5 cm of copper, 10 cm of lead, 30 cm of polethylene shieldings to provide protection against environment radioactivity. Internal surface backgound from daughters of Radon decays have been significantly reduced thanks to several chemical attacks. Origin of the residual radioactive background is being investigated.