Continuous monitoring of cosmic-ray induced neutrons at the summit of Mt. Fuji


Kazuaki YAJIMA

National Institute of Radiological Sciences


Measurement of cosmic-ray induced neutrons with the rem-counter based radiation monitoring system using a long-distance wireless LAN constructed in the Mt. Fuji Weather Station has been carried out. In this year, setting location of the rem counter was changed to reduce the shielding effect by neighboring structures, and the continuous monitoring using the battery power supply was started on August 21. The counting rate of the rem counter in count per hour (cph) from August 27 to September 27 changed relatively calmly and so-called atmospheric pressure effect (negative correlation between the neutron counting rate and the atmospheric pressure) appeared as in previous year. The average of the counting rate of the period was about 132 ± 14 (cph). The continuous monitoring is going to continue until the next summer.