Neutron Scintillators for Cosmic Ray Detection in High Altitude Ballooning

Cosmic rays are high-energy particles originating from astrophysical phenomena such as supernovae. Upon reaching Earth's atmosphere, they interact with atmospheric molecules, producing secondary particles, including fast neutrons, that ionize the atmosphere and can potentially affect satellite electronics and climate models. Understanding cosmic ray flux in the upper atmosphere and its correlation with solar activity is a topic of ongoing research. This study employs an open-source, low-cost neutron scintillator platform carried by a high-altitude latex sounding balloon, capable of reaching altitudes of up to 35 kilometers, and its utility in measuring this cosmic ray flux. The scintillating radiation detector utilizes a silicon photomultiplier (SiPM) coupled with a scintillating material that emits short pulses of light upon radiation interaction. By analyzing the intensity and duration of the light pulses, the energy levels of incident particles are quantified. This modular setup allows the scintillating material to be swapped, optimizing detection efficiency for different types of radiation. In this case, the goal was to identify the neutrons that result from cosmic ray collisions. However, detecting fast neutrons is challenging, as fast neutrons interact weakly with scintillating materials and often require moderators to slow them for effective detection. A NaI(Tl) scintillator was employed, commonly used for radiation detection on the ground, but its effectiveness for high-energy neutron detection at altitude presents limitations requiring further investigation.