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Naito, Susumu*; Sano, Akira*; Izumi, Mikio*; Noda, Etsuo*; Hayashi, Kazuo*; Sato, Mitsuyoshi*; Suto, Osamu; Miyamoto, Yasuaki; Kondo, Shinichi*; Iinuma, Koichi*; et al.
Nuclear Science Symposium Conference Record, 2005 IEEE, Vol.1, p.495 - 499, 2005/10
An alpha radioactivity monitor (alpha-clearance monitor) is being developed to measure alpha radioactivity of uranium contaminated waste with large and complex surfaces. It uses an alpha radioactivity measurement method by collecting the air ionized by alpha particles using an air stream and by measuring its ion current. One of the major problems of the alpha-clearance monitor is the background ion current mainly by radon in atmosphere (
700 fA), which is much larger than ion current of an alpha particle (several fA). It strongly influences on the detection limit of alpha radioactivity. In order to improve the detection limit, we developed a method to monitor the radon concentration inside the monitor without the additional radon detector. In addition, the influencing factors on the detection limit: ion mobility and ion recombination coefficient were measured and evaluated on various environmental conditions (temperature, humidity and aerosol density).
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Matsufuji, Naruhiro*; Sato, Shinji*; Takada, Masashi*; Ishibashi, Kenji*
Nuclear Science Symposium Conference Record, 2005 IEEE, Vol.3, p.1288 - 1290, 2005/10
The response functions of a BC501A liquid organic scintillator have been measured for incidence of various charged particles to investigate the relationship between the kinetic energy of the charged particles and the light output of BC501A. The experiment was performed at Heavy-Ion Medical Accelerator in Chiba (HIMAC) utilizing spallation reactions by heavy ion bombardment on a graphite target. Charged particles incidental on BC501A were identified with the two-dimensional scatter plot of the time-of-flight and the light output. The light output of the BC501A scintillator was deduced as a function of the kinetic energy of the charged particles, and was compared with the semi-empirical formula. While the experimental data showed a good agreement with the formula for proton and deuteron, the data gave slightly larger values compared with the systematic trend for alpha particle.
Kawachi, Naoki; Sakamoto, Koichi*; Ishii, Satomi; Fujimaki, Shu; Suzui, Nobuo; Ishioka, Noriko; Matsuhashi, Shimpei
Nuclear Science Symposium Conference Record, 2005 IEEE, Vol.5, p.2908 - 2911, 2005/10
no abstracts in English
Kimura, Atsushi; Koizumi, Mitsuo; Toh, Yosuke; Oshima, Masumi; Mizumoto, Motoharu; Goto, Jun*; Arai, Yasuo*; Sagara, Masahiro*; Iri, Shinichi*; Kobayashi, Hirotsugu*; et al.
no journal, ,
To measure neutron cross-section data of minor actinides, we construct a Ge-spectrometer utilizing multiple 
-ray detection method. This spectrometer consists of 30 Ge crystals (40 detector outputs) and 128 BGO anti-Compton shields. Generally, a data acquisition system for such a big Ge spectrometer consists of many NIM modules; it requires large space and huge cost. To overcome these problems, we developed a new data acquisition system with digital signal processing techniques. We reported the conceptual design (and cost) in NSS 2004. In this NSS 2005, we report basic performance of this system (energy resolution, dead time and so on) and results of experiments with the Ge-spectrometer. We measured the energy resolution with a Eurisys clover detector, which is one component of the Ge-spectrometer. Obtained FWHMs (2.5 - 2.8 keV at 1.33 MeV) show good performances as normal MCA even with short shaping time and much higher channel density. The dead time of this system is only 3.2 micro sec per event.
Kawachi, Naoki; Ishii, Satomi; Sakamoto, Koichi; Fujimaki, Shu; Suzui, Nobuo; Ishioka, Noriko; Matsuhashi, Shimpei
no journal, ,
Positron Emitting Tracer Imaging System (PETIS) and Caron-11-labeled carbon dioxide (
CO
) could image photosynthesis in plant leaf, and C kinetics made it possible to estimate physiological function parameter in photosynthesis. With an exposure CO-gas to a leaf, together with air containing an ambient concentration of non-radioactive carrier CO gas, PETIS experiments were performed with four light conditions on a single leaf. In order to estimate the rate constant of photosynthesis parameters, time activity curves of CO gas input and leaf response were fitted to an appropriate compartmental tracer kinetic model, which applies of influx and efflux for photoassimilation and photosynthate delivery rate constants respectively. These results of photosynthesis parameters are consistent under light conditions.