AIST Stories No2

21AIST in present day living! of the dosimeter is no more than 20 g. The battery is a single 3 V button battery. The dosimeter can work more than a year without changing this battery.The development team's Ryoichi Suzuki, Prime Senior Researcher of the Research Institute of Instrumentation Frontier, says "Such a small size and low power consumption was previously thought to be very difficult to achieve. However, we managed to do it by applying the development of battery-operated portable X-ray sources*1, AIST's own miniaturization and energy efficiency technologies cultivated in the development of equipment using microelectromechanical systems (MEMS) and wireless technology. This could be described as a crystallization of AIST's comprehensive capabilities."This dosimeter measures gamma ray radiation, which is associated with radionuclides with long half-lives and long-term effects. The lower limit of measurement and display is 0.1 µSv (microsieverts, µ = 10-6)*2. This is about a tenth of the lower limit of detection of the usual dosimeters used by professional staff dealing with radiation. A semiconductor sensor is employed for detection*3. This sensor sometimes misdetects electrical noise caused by physical impacts and the like as radiation. Therefore, an impact sensor is also incorporated and a function for removing noise is employed, further improving the detection accuracy. When a high dose is measured, a warning is given by a LED light and an alarm.Data from the dosimeter is transferred to a computer or the like without having to be physically connected, by an optical communication adapter or a wireless link. Hence, total amounts of exposure and variations in dose amounts can be checked by day, by hour, or by some other time interval. We anticipate that decontamination work will be conducted on the basis of these records, and that behaviors that avoid exposure will be adopted. Thus, the radiation exposure of residents can be minimized.Plans for distribution to returning residents; deployment in decontamination plantsWhen the development was announced, there were many enquiries both from interested businesses and from local government bodies, NPOs and the general public. Society in general showed great interest and enthusiasm. In partnership with Chiyoda Technol Corporation, a provider of radiation dosimetry services, AIST conducted research ▼‌‌The user can see the day's dose, aggregated dose up to a point in time, and which time period of the day exposure was highest (what the user was doing at that time).◦Food ◦Residential◦Disaster prevention◦Safety and security◦‌‌Medicine, welfare, caregiving◦‌‌Environment, resources, energy◦Electronics◦‌‌Medicine, chemistry, biotechnologyinto mass production of the dosimeters. After a demonstration experiment with the residents of Tsukuba City where AIST is located, the technology was transferred to Chiyoda Technol for commercial production. The manufactured dosimeter is the leading candidate for distribution by local governments planning for the return of evacuated residents. The technology is now being considered not only for returning residents, but also for radiation monitoring in decontamination plants and robots working inside nuclear power plants.Suzuki adds that "We are going to improve usability and reliability and expand the range of applications, by increasing data transfer speeds to improve ease of use as well as making it possible to measure low-energy X-rays in clinical locations, and so on."*1 Battery-operated portable X-ray source: AIST developed a practical portable X-ray source in 2009, using a carbon nanostructure cold cathode electron source. Among its other features, the X-ray source can capture over 300 high-precision X-ray transmission images with two AA-size batteries. It does not need to be warmed up, so X-ray examinations can be performed immediately when required. It can even take high-speed images at 1/1000 s.*2 Sv (sievert): A unit representing how much an organism is affected by exposure to radiation.*3 Semiconductor sensor: One method of detecting gamma rays. A tiny current that flows when radiation strikes a semiconductor PN junction is amplified to produce a signal representing the radiation. This enables a radiation detector that is smaller and cheaper than a detector that uses a Geiger-Müller tube (a so-called Geiger counter).Since yesterdaySince a week agoTotal measurement periodDose (µSv)3.817.2611.8Number of days17344.0Average dose rate (µSv/h) screen display exampleChanges in exposure over the total measurement periodChanges in exposure over the last 24 hoursAn illustration of uses of the compact dosimeter0.60100Days agoAverage dose rate (µSv/h) agoDose by hour (µSv/h)432101357911131517192123HomeSchool/workplaceTravel to school/workDaily‌lifePlaying in the park, driving, etc.The dosimeter is carriedImpact in the following fields! Community lifeIndustry