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In this paper, performances of spatial homogenization methods for fuel or non-fuel cells are compared in slab geometry in order to facilitate pin-by-pin core calculations. Since the spatial homogenization methods were mainly developed for fuel assemblies, systematic study of their performance for the cell-level homogenization has not been carried out. Importance of cell-level homogenization is recently increasing since the pin-by-pin mesh core calculation in actual three-dimensional geometry, which is less approximate approach than current advanced nodal method, is getting feasible. Four homogenization methods were investigated in this paper; the flux-volume weighting, the generalized equivalence theory, the superhomogenization (SPH) method and the nonlinear iteration method. The last one, the nonlinear iteration method, was tested as the homogenization method for the first time. The calculations were carried out in simplified colorset assembly configurations of PWR, which are simulated by slab geometries, and homogenization performances were evaluated through comparison with the reference cell-heterogeneous calculations. The calculation results revealed that the generalized equivalence theory showed best performance. Though the nonlinear iteration method can significantly reduce homogenization error, its performance was not as good as that of the generalized equivalence theory. Through comparison of the results obtained by the generalized equivalence theory and the superhomogenization method, important byproduct was obtained; deficiency of the current superhomogenization method, which could be improved by incorporating the “cell-level discontinuity factor between assemblies”, was clarified.

A series of experiments was carried out by using the Kyoto University Critical Assembly and a pulsed neutron generator attached. The experiments were intended to investigate a variance-to-mean technique for measuring the prompt neutron decay constant α of the subcritical reactor system that was driven by the periodic and pulsed neutron source. As the results, it was confirmed that the α value measured by the present technique agreed with a reference value evaluated by the pulsed neutron technique. Furthermore, it was demonstrated that the present technique was available to measure the α value even when the product of α and the repetition period of pulsed neutrons was smaller than unity. Since measurement of α by the pulsed neutron technique is generally difficult under such conditions, it was concluded that the present technique was convenient for measuring the α value.

Derivation of a variance-to-mean formula was performed to obtain the prompt neutron decay constant α of the subcritical reactor system that is driven by the periodic and pulsed neutron source. The formula was derived for an experimental technique where the Y value is measured by choosing an injection of pulsed neutrons as the origin of the counting gate. By using the derived formula, it was indicated that the α value can be easily determined. From this fact, it was concluded that the present formula was useful to measure the α value for future experiments with the accelerator driven system.

Previous measurements of the composition of Ultra-High Energy Cosmic Rays(UHECRs) made by the High Resolution Fly's Eye(HiRes) and Pierre Auger Observatory(PAO) are seemingly contradictory, but utilize different detection methods, as HiRes was a stereo detector and PAO is a hybrid detector. The five year Telescope Array(TA) Middle Drum hybrid composition measurement is similar in some, but not all, respects in methodology to PAO, and good agreement is evident between data and a light, largely protonic, composition when comparing the measurements to predictions obtained with the QGSJetII-03 and QGSJet-01c models. These models are also in agreement with previous HiRes stereo measurements, confirming the equivalence of the stereo and hybrid methods. The data is incompatible with a pure iron composition, for all models examined, over the available range of energies. The elongation rate and mean values of Xmax are in good agreement with Pierre Auger Observatory data. This analysis is presented using two methods: data cuts using simple geometrical variables and a new pattern recognition technique., Comment: 23 pages, 30 figures

We search for ultra-high energy photons by analyzing geometrical properties of shower fronts of events registered by the Telescope Array surface detector. By making use of an event-by-event statistical method, we derive upper limits on the absolute flux of primary photons with energies above ${10}^{19}$, ${10}^{19.5}$, and ${10}^{20}\text{ }\text{ }\mathrm{eV}$ based on the first three years of data taken.

Recently, the bunching technique has been widely utilized in the Feynman-α experiment using a multi-channel scaler (MCS) to measure the prompt neutron decay constant α p . Although the bunching technique enables us to perform efficient experiments, it was pointed out that an inherent count-loss process arises due to the channel advance time Δ between adjacent MCS channels. Through derivation of a Feynman-α variance-to-mean formula containing Δ by means of the multi-gate Pal-Bell equation, Yamane and Hayashi ([Yamane, Y. & Hayashi, Y. 1995]. Annals of Nuclear Energy, 22(8), 533) indicated that this count-loss process does not play any important roles when the channel advance time is much smaller than the dwell time T. However, the Δ / T ratio often becomes large in thermal systems at deep-subcritical states or fast ones, because the dwell time should be chosen to be much smaller than reciprocals of α p values for such systems. On the other hand, since the ratio of the dead time d of neutron detectors to the dwell time becomes also large when the Δ / T ratio is not small, the count-loss process due to the dead time cannot be neglected. Therefore, Feynman-α variance-to-mean and covariance-to-mean formulae containing both Δ and d were derived by means of the compound detection probabilities. Based on the covariance-to-mean formula, a new experimental technique was developed and examined at the Kyoto University Critical Assembly. The result of the examination indicated that one can measure exact α p values when Δ / T ratios are known, even though Δ / T and d / T ratios are not small.

An acquisition system for the time series data of a pulse train was developed to perform the reactor noise experiments. Using this acquisition system, some important reactor kinetic parameters can be obtained by using various data analysis methods for the reactor noise experiments, which facilitates to achieve new experimental knowledge about characteristics of them proposed so far through direct comparison among the results of various methods. In the present study, the prompt neutron decay constant αpat two near delayed critical states of a core constructed in the Kyoto University Critical Assembly were measured by four well-known data analysis methods; the Feynman-α, the Rossi-α (Type-I and Type-II) and the frequency analysis methods. The results showed that ap values measured by the Type-I Rossi-α and the frequency analysis methods agreed with those by the Feynman-α method considering both effects of the delayed neutrons and the counting loss of neutron counter, whereas it was impossible to obtain the ...

Time-spatial neutron measurement was carried out by using a position-sensitive 3He proportional counter (PSPC) in the Kyoto University Critical Assembly. The data of the output pulses from the PSPC were acquired by a data acquisition system which was based on the LN-9000 system of Laboratory Equipment Corporation. In this system, the time and the position data of the neutron detection pulses were simultaneously accumulated by a personal computer. In the present study, the Rossi-α method, which was derived for time-domain neutron correlation analysis, was extended in order to process the measured two-dimensional data of time and space. The processed experimental results and a theoretical formula based on the one-group diffusion approximation neglecting the higher modes agreed well with each other, which indicates the present system is applicable for reactor physics experiments including reactor kinetics.

The Telescope Array's Middle Drum fluorescence detector was instrumented with telescopes refurbished from the High Resolution Fly's Eye's HiRes-1 site. The data observed by Middle Drum in monocular mode was analyzed via the HiRes-1 profile-constrained geometry reconstruction technique and utilized the same calibration techniques enabling a direct comparison of the energy spectra and energy scales between the two experiments. The spectrum measured using the Middle Drum telescopes is based on a three-year exposure collected between December 16, 2007 and December 16, 2010. The calculated difference between the spectrum of the Middle Drum observations and the published spectrum obtained by the data collected by the HiRes-1 site allows the HiRes-1 energy scale to be transferred to Middle Drum. The HiRes energy scale is applied to the entire Telescope Array by making a comparison between Middle Drum monocular events and hybrid events that triggered both Middle Drum and the Telescope Array's scintillator Ground Array., Comment: 27 pages, 21 figures

Eight fragments which cover the whole range of the mitochondrial genome of Penicillium urticae were subcloned into the yeast integration vector YIp5. Transformation of Saccharomyces cerevisiae with the constructed plasmids by the alkali cation method indicated that six plasmids are able to replicate in yeast. Both closed and open circular forms of the plasmids were detected in the DNA extracts from transformants. Distribution of the autonomously replicating sequence in the mitochondrial genome was similar to that in P. chrysogenum except for one small region.

The Telescope Array (TA) collaboration has measured the energy spectrum of ultra-high energy cosmic rays with primary energies above 1.6 x 10^(18) eV. This measurement is based upon four years of observation by the surface detector component of TA. The spectrum shows a dip at an energy of 4.6 x 10^(18) eV and a steepening at 5.4 x 10^(19) eV which is consistent with the expectation from the GZK cutoff. We present the results of a technique, new to the analysis of ultra-high energy cosmic ray surface detector data, that involves generating a complete simulation of ultra-high energy cosmic rays striking the TA surface detector. The procedure starts with shower simulations using the CORSIKA Monte Carlo program where we have solved the problems caused by use of the "thinning" approximation. This simulation method allows us to make an accurate calculation of the acceptance of the detector for the energies concerned., Comment: Accepted for publication by Astrophysical Journal Letters

To investigate the applicability of the Feynman- (or variance-to-mean) and Rossi-α techniques to subcriticality monitoring of the future accelerator-driven subcritical reactor (ADSR), a series of experiments was performed at the Kyoto University Critical Assembly (KUCA). To simulate the pulse mode operation of the ADSR, a D-T pulsed neutron generator was employed. As a result, it was observed that the α-values measured by these techniques clearly depended on the subcriticality, ranging from $0.65 to $2.72. Furthermore, through measurements in transient states that were realised by operating control rods, it was found that one can detect subcriticality changes in quasi-real-time.

The reaction of β-azidostyrene with trifluoro-, trichloro-, dichloro-, or monochloro-acetic acid gave 2-halogenomethyl-5-phenyloxazole via attack of halogenoacetate anion on a benzylic carbocation or a conjugate acid of the azide.