Résumé
We developed an integrated silicon detector to be embedded in a stratospheric balloon or a plane in order to investigate the radiative atmospheric environment. The key component of the detector is a commercial silicon diode from ORTEC in which incident protons from atmosphere interact. This leads to a charge collection on the electrodes due to the electric field in the diode (96 V). The active area of the diode is 4.5 cm² and its thickness is 150 µm. We developed a specific electronic system to measure the energy deposition. The power management is on a dedicated board that has three direct-current-to-direct-current convertors that create four voltages from a 12 V battery to supply the electronic devices. There are also 32 three-volt lithium button cells that provide 96 V for the reverse bias of the diode.The experiment board contains the plug for the silicon diode in parallel with a test input, a preamplifier/shaper, a comparator, a peak detector, a microcontroller, and some peripherals. The charges coming from the silicon diode are converted into a voltage signal by the preamplifier/shaper. This voltage is then used to trigger the microcontroller on an event with the comparator that allows an adjustment of the detection threshold. The amplitude of the same voltage signal is measured by the Analog-to-Digital Converter (ADC) of the microcontroller with the help of a peak detector. The experiment also measures the temperature and stores the data. A Real Time Clock timestamps the events in order to calculate the event rate as a function of the particle fluxes. Our detector was calibrated with a Californium source, and it was fully characterized under neutron beams from 25 MeV up to 180 MeV. Differential detection cross sections for different neutron beam energies were shown to be in good agreement with simulations performed with the MC-Oracle code. We performed four stratospheric balloon flights (with ESA and CNES) and confirmed the correlation between the count rate and the altitude. Moreover, we observed that the radiative environment is not isotropic and demonstrated the potential of our tool for investigating the radiative atmospheric environment. These results are useful for estimating the particle flux that affects electronic devices and onboard aircraft systems.