Several measurements have been performed on the cosmic radiation field from the surface of the Earth up to the maximum altitudes of research aeroplanes. However, there is only limited information about that between 15 and 30 km altitudes. In order to study the radiation environment in the stratosphere, an experiment was built by students from Hungarian universities that flew on board the BEXUS (Balloon Experiments for University Students) stratospheric balloon in Northern Sweden, from the ESRANGE Space Center. The main technical goals of the experiment were to test at the first time the TRITEL 3D silicon detector telescope system in close to space conditions and to develop a balloon technology platform for advanced cosmic radiation and dosimetric measurements. The main scientific goals were to give an assessment of the cosmic radiation field at the altitude of the BEXUS balloons, to use the TRITEL system to determine dosimetric and radiation quantities during the balloon flight and to intercompare the TRITEL and Pille results to provide a correction factor for the Pille measurements. To fulfil the scientific and technological objectives, several different dosimeter systems were included in the experiment: an advanced version of the TRITEL silicon detector telescope, Geiger-Müller (GM) counters and Pille thermoluminescent dosimeters. The float altitude of the BEXUS balloon was ∼28.6 km; the total flight time was ∼4 h. Measurement data from the active instruments were received in real time by the ground team during the mission. There were no failures in the operation of the system; everything worked as expected. This article presents the scientific goals and results in detail. From the TRITEL measurements, the linear energy transfer spectra, the average quality factor of the cosmic radiation as well as the absorbed dose and the dose equivalent were determined. Estimations for the uncertainty in the TRITEL measurements were given. The deposited energy spectra measured with the TRITEL instrument were compared with the count rates measured with the GM counters. The experiences and results gained in the frame of the project will be used in the evaluation of TRITEL data from measurements on board the International Space Station. As an outlook a short overview is given of the planned rocket radiation experiments based on the system used in the BEXUS programme.

Aims:The sounding rocket experiment REM-RED was developed to operate on board the REXUS-17 rocket in order to measure the intensity of cosmic rays. The experiment was launched from the ESRANGE Space Center (68°N, 21°E) on the 17th of March 2015 at the beginning of the most intense geomagnetic storm within the preceding 10 years. The experiment provided the opportunity to measure the intensity of cosmic rays in the Polar Region up to an altitude of 88 km above sea level. Methods: The experiment employed Geiger-Müller (GM) counters oriented with their axes perpendicular to each other in order to measure the cosmic ray intensity during the flight of the rocket. This measurement setup allowed performing direction-sensitive measurements as well. During the ascent phase the rocket was spinning and hence stabilized along its longitudinal axis looking close to the zenith direction. This phase of the flight was used for studying the direction dependence of the charged particle component of the cosmic rays. Results: In comparison with earlier, similar rocket experiments performed with GM tubes at lower geomagnetic latitudes, significantly higher cosmic radiation flux was measured above 50 km. A non-isotropic behavior was found below 50 km and described in detail for the first time in the Polar Region. This behavior is in good agreement with the results of the TECHDOSE experiment that used the same type of GM tubes on board the BEXUS-14 stratospheric balloon.

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