[en] An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep in a Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed

[en] A proportional drift chamber, which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and a length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over a drift space of 50 mm, depending on incident angle and distance from the sense wire. 1 ref

No abstract available

[en] A 40 mm thick vessel model made of SUS304 austenitic stainless steel was subjected to cyclic thermal transients, in which sodium of 600⁰C and 250⁰C flowed repeatedly. The period of each transient was 2 hours. 7 tests portions in the model were cracked after 1002 cycles of the thermal transients. (orig.)

[en] The bellows expansion joints for Fast Breeder Reactor piping usually consist of bellows and hardware structures that connect bellows and piping. The bellows are required to absorb thermal deformation of the piping system and to withstand internal and external pressures, seismic loadings, and so on. For thermal-transient loadings, the bellows are a thin-walled uniform structure, so the thermal stress is generally small. Hardware structures, however, incorporate various structural discontinuities, such as Y-shaped and E-shaped junctions. The thermal stress originating from the temperature difference between adjoining members is significant in usual cases. The important issue in the design of the bellows expansion joints for thermal-transient loadings is the creep-fatigue failure of hardware structures due to repeated thermal stresses. This paper describes the results of the thermal-transient test of piping-bellows models of an internally pressurized type of bellows and an externally pressurized type of bellows. The piping bellows were subjected to cyclic cold and hot thermal transients in sodium over the temperature range 250 to 600⁰C. Heat-transfer and thermal-elastic-stress analyses were carried out to evaluate the creep-fatigue strength. The method of evaluating creep-fatigue damage in the Design Guide of Japan was demonstrated to be capable of ensuring a high degree of integrity of the specific structure of the bellows type of expansion joint. (author)

[en] Measurements of the energy gap in Ce₃Bi₄Pt₃ have been carried out using break junctions. Observed gap magnitude of 2Δ_p-p (4.2 K) = 85 ± 18 meV is much larger than the transport gap. The ratio 2Δ_p-p/k_BT_χ ∼ 13 ± 2 with T_χ ∼ 80 K (the temperature of the susceptibility maximum) agrees with that of CeNiSn and CeRhSb, thereby indicating that the origin of the gap formation is common to these compounds. (orig.)

[en] To improve the damage evaluation methods in the design code for Fast Breeder Reactors (FBRs), a series of creep-fatigue tests of structural models under thermal transient loadings are going on at Oarai Engineering Center of the Power Reactor and Nuclear Fuel Development Corporation (PNC). Test models are designed to incorporate representative structures of components and pipings used in FBRs and are subjected to severer cyclic thermal transients than those experienced in FBRs. The test is planned to be continued until failure occurs. This paper describes the creep-fatigue test results and their damage evaluation for the first test model. A 40 mm thick vessel model made of SUS304 austenitic stainless stell was subjected to cyclic thermal transients, in which sodium at 600deg C and 250deg C flow repeatedly. The period of each transient was 2 h. Cracks were observed at seven test portions in the model after 1002 cycles of the thermal transients. Elastic and inelastic analyses were performed to evaluate creep-fatigue damage and crack propagation. The safety margins included in the creep-fatigue design methods based on elastic analysis as well as those based on inelastic analysis are discussed. Finally fracture mechanics analyses were performed to explain the observed crack growth. (orig.)

[en] We investigate neutrino events from presupernova stars at the distance of 200 pc detected by current and future neutrino observatories. The spectrum evolution of neutrinos emitted from presupernova stars of 12, 15, and 20 M _⨀ after the O burning until the core collapse is evaluated. The expected ${\stackrel{¯<!--\; ??\; -->}{\mathrm{\nu <!--\; ??\; -->}}}_e$ events are several to more than ten for KamLAND and are hundreds for JUNO and Hyper-K. The time evolution of the ${\stackrel{¯<!--\; ??\; -->}{\mathrm{\nu <!--\; ??\; -->}}}_e$ events could reveal the evidence for the change of burning processes during the nal evolution of massive stars. We propose the detection of presupernova neutrinos by Gd-loaded Super-K and Hyper-K using the delayed γ-ray signals of Gd(n, γ) reaction. Gd-loaded Super-K and Hyper-K have a possibility for the detection of hundreds and thousands neutrino events, respectively. We also estimate the time for supernova alarms using presupernova neutrinos. KamLAND, JUNO, and other neutrino detectors could send supernova alarms using presupernova neutrinos several hours to one day before a supernova explosion. Multiple observations of presupernova neutrinos will raise the reliability of the supernova alarm. (paper)

[en] Analyzing the Solar System abundance, we have found two universal scaling laws concerning the p- and s-nuclei with the same atomic number. They are evidence of the p-nucleus origin that has been discussed for long years. The first scaling is the correlation of the isotope abundances between a p-nucleus and an s-nucleus that is two neutron heavier than the p-nucleus. The abundance ratios of the s-nucleus to the p-nucleus are almost constant in a wide range of atomic numbers. This scaling indicates that the p-nucleus is dominantly produced from the s-nucleus by (γ, n) reactions in huge photon bath in supernova explosions. The second scaling indicates that the isotope abundance ratio between two p-nuclei with the same atomic number is almost unity. These two scalings are a new useful method to verify nucleosynthesis models for the p-process. We have calculated these ratios by a p-process nucleosynthesis based on a typical core-collapse supernova explosion model. The results are consistent with the scaling in the solar abundances. In addition, the scalings provide new concepts: a universality of the p-process, a rate meter for the s-process and a new nuclear cosmochronometer. (orig.)

[en] We present an evidence for the origin of the p-nuclei at the solar system abundances. We carry out nucleosynthesis calculations of the p-process in oxygen-neon layers in typical core-collapse SN explosion models. The calculated N(s)/N(p) and N(1st p)/N(2nd p) ratios are consistent with the observed scalings. The observed scalings and calculation results indicate a novel concept: the universality of the p-process that the two ratios are almost independent on astrophysical conditions such as the metallicity and progenitor mass of the massive stars. (author)