Speaker
Dr
Cédric Cerna
(Centre d'Etudes Nucléaires de Bordeaux Gradignan)
Description
The SuperNEMO Demonstrator experiment aim to study the neutrino less double beta decay of 7kg of 82Se in order to reach a limit on the light Majorana neutrino mass mechanism T1/2(0nubb) > 6.5 . 10^24 years (90%CL) equivalent to a mass sensitivity m_bb < 0.20 - 0.40 eV (90%CL) in two years of data taking. The detector construction started in 2014 and the installation in the Laboratoire Souterrain de Modane (LSM) is expected during the course of 2015.
The remaining level of 226Ra (238U chain) in the detector components can lead to the emanation of 222Rn gas. This isotope should be controlled and reduced down to the level of a 150 µBq/m3 in the tracker chamber of the detector to achieve the physic goals.
Besides the HpGe selection of the detector materials for their radiopurity, the most critical materials have been tested and selected in a dedicated setup facility able to measure their 222Rn emanation level. The operating principle relies on a large emanation tank (0.7m^3) that allows to measure large material surfaces or large number of construction pieces. The emanation tank is coupled to an electrostatic chamber equipped with a silicon diode to perform the alpha spectroscopy of the gas and extract the 222Rn daughters. The transfer efficiency and the detector efficiency have been carefully calibrated through different methods. The intrinsic background of the system allows one to measure 222Rn activities down to 3mBq, leading to a typical emanation sensitivity of 20 µBq/m^2/day for a 30m^2 surface sample.
Several construction materials have been measured and selected, such as nylon and aluminized mylar films, photomultipliers and tracking chamber parts.
Primary author
Dr
Cédric Cerna
(Centre d'Etudes Nucléaires de Bordeaux Gradignan)
Co-authors
Mr
Benjamin Soule
(Centre d'Etudes Nucleaire de Bordeaux Gradignan)
Dr
Frédéric Perrot
(Centre d'Etudes Nucleaire de Bordeaux Gradignan)
