[en] The need for accurate core depletion calculations in Experimental Breeder Reactor No. 2 (EBR-2) is discussed. Because of the unique physics characteristics of EBR-2, it is difficult to obtain accurate and computationally efficient multigroup flux predictions. This paper describes the effect of various conventional and higher order schemes for group constant generation and for flux computations; results indicate that higher-order methods are required, particularly in the outer regions (i.e. the radial blanket). A methodology based on Nodal Equivalence Theory (N.E.T.) is developed which allows retention of the accuracy of a higher order solution with the computational efficiency of a few group nodal diffusion solution. The application of this methodology to three-dimensional EBR-2 flux predictions is demonstrated; this improved methodology allows accurate core depletion calculations at reasonable cost. 13 refs., 4 figs., 3 tabs

[en] Attenuation characteristics for the fission neutron by various shielding materials have been studied for testing data and methods. Attenuation curves were determined for six kinds of hydrogenous material, seven sorts of concrete, and three kinds of metal under the condition of a narrow beam geometry. Transmission curves were obtained over the two decades of exponential decrease. They indicated in logarithmic expression to be more downward concave, compared with the single exponential attenuation for the all materials used in this study. A dose equivalent of neutrons through the shielding material may be represented by the following: Dsub(t) = Dsub(o) exp [-T/lambdasub(eff)] where Dsub(o) and Dsub(t) are dose equivalents at O cm and T cm thickness of the shielding materials, respectively, lambdasub(eff) is a relaxation length which depends on absorber materials and their thickness. A convenient approximation to the relaxation length is given by lambdasub(eff) = lambdasub(o) + α.T where lambdasub(o) and α were determined from the experimental results. (author)

[en] A large volume scintillation cell (LVSC) for radon activity concentration measurements has been reported at MARC-IV. Improvements in the detection efficiency of the LVSC and results of the radon activity concentration measurements for indoor air that were performed using the improved LVSC is described. The cell is a cylindrical shape and has two photomultiplier tubes that are attached to a condensing lens on the photocathode so as to provide good light collection. Individual counting efficiencies were determined to be 0.48 for ²²²Rn, 0.55 for ²¹⁸Po, and 0.61 for ²¹⁴Po. The average counting efficiency per alpha-particle from the radon and its short half-life progenies was 0.55. This value is smaller than the original value reported by LUCAS of 0.86. However, the sensitivity is approximately eight times higher than that of the Lucas cell, which has a smaller volume. A background counting rate of 0.015 cps was obtained. The lower limit of detection (LLD) for the measurements was estimated using the average background counts, the detection efficiency and measurement time. The LLD at 80% statistics confidence limits was less than 10 Bq/m³ when counted within two hours. (author)

[en] A large volume scintillation cell has been designed to detect low levels of radon and its progeny. The cell has a cylindrical shape (nominal volume 1.2 liters) with two photomultiplier tubes. In this study, the detection efficiency was estimated with Monte-Carlo calculations for 3-dimensional before fabrication. Counting efficiencies for ²⁴¹Am were measured along the axial of the cell with different distances between the source and the scintillation screen to confirm the calculation method. The counting efficiencies for the alpha particles from the ²²⁶Rn and its short-live progenies were measured using a radon generator. The efficiency was estimated to be 0.36 count per alpha-particle as the average of three alpha-particles. (author)

[en] anti pp annihilation cross sections into 2-, 4- and 6-prong topologies, and the exclusive annihilation cross sections for the π⁺ π^-, K⁺ K^-, π⁺ π^- π₀, π⁺ π⁺ π^- π^-, π⁺ π⁺ π^- π^- π₀, π⁺ π⁺ π⁺ π^- π^- π^-, and π⁺ π⁺ π⁺ π^- π^- π^- π₀ channels in the momentum range 374-680 MeV/c were measured. No prominent structure was observed in the momentum dependence of any of the above cross sections, but a small enhancement in the cross section was observed at 490 MeV/c corresponding to the S meson mass in the topological, and π⁺ π^- π₀ and π⁺ π⁺ π^- π^- π₀ cross sections. If the existence of the S meson with a mass and width of 1935.5 and 2.8 MeV/c₂ is assumed, our measurement gives a total resonant annihilation cross section into charged particles of 10.0 +- 3.0 mb. (orig.)

[en] X-ray computed tomography technique was used to observe microstructure formation during freeze-drying. A specially designed vacuum freeze-drying stage was equipped at the X-ray CT stage, and the frozen and dried microstructures of dextrin solutions were successfully observed. It was confirmed that the many parts of the pore microstructures formed as a replica of the original ice microstructures, whereas some parts formed as a consequence of the dehydration dependent on the relaxation level of the glassy phases, suggesting that the post-freezing annealing is advantageous for avoiding quality loss that relates to the structural deformation of glassy matters. (Author)

No abstract available

[en] The authors have measured the anti pp total cross sections at 24 incident momenta from 373 to 734 MeV/c and observed an enhancement in the cross section at around 490 MeV/c. A fit to a Breit-Wigner form superposed on a smoothly decreasing background gives the mass of this enhancement to be 1935.5+-1.0 MeV/c² with a width of 2.8+-1.4 MeV/c². The resonant total cross section is 14.5+-3.9 mb. (Auth.)

[en] anti pp elastic total and differential cross sections were measured at 17 incident momenta in the range 374-680 MeV/c. No prominent feature was seen in them to clearly indicate the existence of the S-meson. There is, however, a small enhancement at the S-meson mass, which is equivalent to the elastic total cross section of 4.6 +- 2.1 mb. The behavior of the Legendre expansion coefficients of the angular distributions with incident momentum agrees well with the prediction of the OBE model of Bryan and Phillips. (orig.)

[en] Exclusive anti pp pionic annihilation reactions in the momentum range of 403 to 670 MeV/c were analysed in terms of intermediate states involving resonances. The fractions of the various intermediate states showed no significant dependence on the incident momentum. They were compared with a statistical model incorporating SU(3) symmetry. The agreement between the model and data was moderate and qualitative. The exclusive as well as topological cross sections were compared with the same statistical model and a potential model incorporating quark rearrangement. The agreement with the latter model was better than with the first in general, but it was still mostly qualitative. (orig.)