Long-term measurements of cosmic ray neutrons by means of a Bonner spectrometer at mountain altitudes - first results.

A Bonner multi-sphere spectrometer has been installed in 2005 at the Environmental Research Station 'Schneefernerhaus' (2660 m above sea level) on the Zugspitze mountain, Germany, to measure the energy spectrum of cosmic-ray neutrons at high altitudes continuously. The system can be used to investigate small temporal variations in the cosmic radiation intensity. For example, measurements were done during periods of 2 Forbush decreases of the cosmic radiation intensity in July and September 2005, respectively. The results were compared with those obtained by using neutron monitors, and neutron fluence spectra measured during these events are presented and discussed.