Design of Active-Type Personal Dosemeter for High-Energy Neutrons
*In order to design an active-type personal dosemeter having sufficient sensitivity to high-energy neutrons up to 100 MeV, the characteristic response of several types of silicon (Si) semiconductor detectors has been investigated experimentally and theoretically. At first, the response of each detector has been checked to protons accelerated by a Van de Graff accelerator installed at Kobe University. A fully-depleted Si detector was selected as a promising detector element owing to a simple structure and comprehensive characteristics. In the next step, neutron irradiation experiments were carried out in a monoenergetic reference field in JAEA. On the other hand, theoretical distributions of the deposited energy were estimated in a simplified geometry consisting of Si and PE layers. An agreement in the relative shape was confirmed between the theoretical and experimental results. Applying this calculation procedure to other neutron energies and various thickness of sensitive layer, it was found that the energy dependence could be improved by the two-window technique by setting different discrimination levels on the pulse height. Another important characteristic of the angular dependence was also discussed for practical application of a personal dosemeter for high energy neutrons.
Radiator design for detecting high-energy neutrons with a nuclear track detector
Abstract Subsequent to the proposal of a two-layer structured radiator for more efficient detection of high-energy neutrons with a plastic nuclear track detector (PNTD), its availability has been investigated both experimentally and theoretically. An inner deuterized hydrocarbon (CD2) layer adjacent to PNTD should play the role of both a radiator of deuterons recoiled there and a degrader for energetic protons recoiled in the outer layer of a CH2 material. It was found that the energy dependence of the efficiency was changed sensitively by the thickness of the CD2 layer. A best combination of CH2 and CD2 thickness was estimated under a condition of a constant total thickness. For example, the sensitivity could be flattened within 20% between about 5 and 70 MeV by using 1 g / cm 2 - CD 2 and 2 g / cm 2 - CH 2 .
Application of infrared camera to bituminous concrete pavements: measuring vehicle
Infrared thermography (IR) has been used for decades in certain fields. However, the technological level of advancement of measuring devices has not been sufficient for some applications. Over the recent years, good quality thermal cameras with high resolution and very high thermal sensitivity have started to appear on the market. The development in the field of measuring technologies allowed the use of infrared thermography in new fields and for larger number of users. This article describes the research in progress in Transport Research Centre with a focus on the use of infrared thermography for diagnostics of bituminous road pavements. A measuring vehicle, equipped with a thermal camera, digital camera and GPS sensor, was designed for the diagnostics of pavements. New, highly sensitive, thermal cameras allow to measure very small temperature differences from the moving vehicle. This study shows the potential of a high-speed inspection without lane closures while using IR thermography.