Atmospheric Turbid Conditions due to Fine Particles in Recent Years at Nagasaki, Japan

Atmospheric turbid conditions caused by fine particles, which are defined as the particles in the size range between 0.3 and 1.0μμm in diameter, are occasionally significant in recent years over the Nagasaki area in Japan. These conditions make the horizontal visibility very low as 4-5 km despite of fair weather. We studied two significantly turbid cases rich with fine particles, which took place during 25-27 March 2003 and on 23 May 2005, from the viewpoint of a detailed understanding of their influences to visibility and the properties of fine aerosols. As a result of this study, the noticeably low visibility conditions due to fine particles are closely connected with the high concentration of sulfur which transported from the Asian continent. Fine particles sometimes make very turbid conditions in spring without the influence of yellow sand dust particles. This peculiarity should be paid further attention from the viewpoint of air quality conservation over East Asia

High detection efficiency scintillating fiber detector for time-resolved measurement of triton burnup 14 MeV neutron in deuterium plasma experiment

The behavior of the 1 MeV triton has been studied in order to understand the alpha particle confinement property in the deuterium operation of toroidal fusion devices. To obtain time evolution of the deuterium-tritium (D-T) neutron emission rate where the secondary DT neutron emission rate is approximately 1012 n/s, we designed two high detection efficiency scintillating fiber (Sci-Fi) detectors: a 1 mm-diameter scintillation fiber-based detector Sci-Fi1 and a 2 mm-diameter scintillation fiber-based detector Sci-Fi2. The test in an accelerator-based neutron generator was performed. The result shows that the directionality of each detector is 15° and 25°, respectively. It is found that detection efficiency for DT neutrons is around 0.23 counts/n cm2 for the Sci-Fi1 detector and is around 1.0 counts/n cm2 for the Sci-Fi2 detector

Neutron yield calculation of thin and thick d-D targets by using PHITS with frag data table

The D(d, n)3He reaction is one of the common monoenergetic neutron sources. We compile the Frag Data table of D(d, n)3He reaction from the literature as an external cross-section data for PHITS. We confirm the validity of the Frag Data table by the calculation of the total and angular neutron yield calculations for an ideal deuterium thin target. Finally, PHITS with the Frag Data table is applied to the angular neutron yield and spectrum calculations of the gas target and the deuterium-loaded titanium target of the Tohoku University Fast Neutron Laboratory