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Neutrons have the power to penetrate metals or heavy elements such as calcium, silicon, and iron. Neutrons also have high sensitivity, so they can be used to detect elements such as boron and chlorine. An accelerator-driven, compact neutron system has been developed in RIKEN for practical use on job sites.In this paper, a pixel imaging detector for fast neutrons with energy levels above 1 MeV is developed and used to produce images of an iron rod and air pockets through 30 cm of concrete. Also, the salt concentrations of 4 cm- and 5 cm-thick mortar blocks are measured, and a correlation diagram is obtained for up to 1 kg/m3.

This study concerns twist phenomena occurring in curved hat channel products and aims to clarify the causes of twist using physical quantities obtained by finite element analysis. Several drawing heights were examined. We evaluated the torque around the longitudinal axis, which can be regarded as the driving force of the twist. In addition, transitions of the torque during the process of tool removal were analyzed. After removing the die and blank holder, the twist torque in models with larger drawing heights became negative, accounting for the positive twist, which occurs after punch and pad removal. On the other hand, the twist torque in models with smaller drawing heights remained positive, accounting for the negative twist. Such analyses of the transition of twist torque provide useful information when considering measures for reducing twist.