Cosmic-ray flux detected by an IR bolometer operated on board of a stratospheric aircraft

A bolometer was flown as an infrared detector on a stratospheric aircraft at altitudes of approximately 19 km during the APE campaign, which took place in Rovaniemi (Finland) in the period December 1996-January 1997. The signal impulses produced in the bolometer by the thermalisation of the ionisation induced by cosmic charged particles in the sensitive layer of the detector have been analysed. A statistics of approximately 4000 cosmic-ray events was recorded during four flights. In the period of the observations the solar activity was near its minimum. The observations from a stratospheric aircraft has made possible the collection of a first sampling of cosmic-ray flux variation with latitude and altitude. A comparison is made with previous balloon observations at the same altitudes. Model calculations are compared to the observed cosmic-ray energy loss distribution in the bolometer. The results are useful for the understanding of cosmic-ray background effects occurring in applications of high sensitivity bolometers in aircraft-borne measurements. (C) 1999 Elsevier Science B.V. All rights reserved.