Spectrometry using the PTB neutron multisphere spectrometer (NEMUS) at flight altitudes and at ground level

Bonner sphere measurements are presented for flights at altitudes of up to 12 km and geomagnetic latitudes between 26°N and 86°N and compared with results obtained by several survey meters. As an example of the natural neutron background near sea level, results from a recent longterm measurement campaign performed at the PTB site using an extended spectrometer are presented. The dependence of neutron fluence and ambient dose equivalent on the atmospheric pressure is demonstrated.