Short-term variation of cosmic radiation measured by aircraft under constant flight conditions

The temporal variations in cosmic radiation on aircraft under constant flight conditions were measured by a Liulin detector. Rather than a commercial long-distance aircraft, we used a military reconnaissance aircraft performing a circular flight at a constant altitude over the Korean Peninsula. At 9144 m (30,000 ft), the mean and standard deviation of the radiation dose rate (among 35 measurements) was 2.3 and 0.17 mu Sv/h, respectively. The experiment yielded two observational results. First, the dose rate changed over a flight time of 5-7h; second, no strong correlation was revealed between the cosmic rays observed from the ground-based neutron monitor and the radiation doses at aircraft altitude. These observations can provide insight into the short-term variation of cosmic radiation at aviation altitudes. When discarding various negligible factors, it is postulated that the changes in the geomagnetic field and the air density still could affect the variation of cosmic radiation at aircraft altitude. However, various factors are less known about the dependence on the cosmic radiation. Therefore, investigations of possible factors are also warranted at the monitoring points of space weather.