Ultra low energy results and their impact to dark matter and low energy neutrino physics

Understand

We present ultra low energy results taken with the novel Spherical Proportional Counter.

• The energy threshold has been pushed down to about 25 eV and single electrons are clearly collected and detected.
• To reach such performance low energy calibration systems have been successfully developed: - A pulsed UV lamp extracting photoelectrons from the inner surface of the detector - Various radioactive sources allowing low energy peaks through fluorescence processes.
• The bench mark result is the observation of a well resolved peak at 270 eV due to carbon fluorescence which is unique performance for such large-massive detector.