ABSTRACT
With the use of an in situ and static method for gamma-ray measurements, levels of radioactive cesium 137 on shallow rugged reefs which lie between 37.3° N and 37.4° N, from the coastline of Fukushima to 141.06° E, at a depth of around 10â¯m were surveyed for the first time from May 2016 to December 2017. To confirm the contact between the detector and a surface of rock, we used a fact that potassium containing minerals are abundant and uniformly distributed in the area, and thus the strength of the photoelectric peak of natural radioactive potassium 40 is nearly constant over the area. We have found that the levels of radioactive cesium 137 varied from point to point within a range from 1â¯×â¯104â¯Bq/m2 to 6â¯×â¯104â¯Bq/m2.
Subject(s)
Cesium Radioisotopes/analysis , Water Pollutants, Radioactive/analysis , Environmental Monitoring/instrumentation , Environmental Monitoring/methods , Fukushima Nuclear Accident , Japan , Potassium Radioisotopes/analysis , Radiation Monitoring/instrumentation , Radiation Monitoring/methodsABSTRACT
A cosmic dust detector for use onboard a satellite is currently being developed by using piezoelectric lead zirconate titanate (PZT). The characteristics of the PZT detector have been studied by bombarding it with hypervelocity iron (Fe) particles supplied by a Van de Graaff accelerator. One central electrode and four peripheral electrodes were placed on the front surface of the PZT detector to measure the impact positions of the incident Fe particles. It was demonstrated that the point of impact on the PZT detector could be identified by using information on the time at which the first peak of the output signal obtained from each electrode appeared.