Search

We developed a CANDLES-III system to study the neutrino-less double beta (0$\nu\beta\beta$) decay of $^{48}$Ca. The proposed system employs 96 CaF$_{2}$ scintillation crystals (305 kg) with natural Ca ($^{\rm nat.}$Ca) isotope which corresponds 350\,g of $^{48}$Ca. External backgrounds were rejected using a 4$\pi$ active shield of a liquid scintillator surrounding the CaF$_2$ crystals. The internal backgrounds caused by the radioactive impurities within the CaF$_2$ crystals can be reduced effectively through analysis of the signal pulse shape. We analyzed the data obtained in the Kamioka underground for a live-time of 130.4\,days to evaluate the feasibility of the low background measurement with the CANDLES-III detector. Using Monte Carlo simulations, we estimated the background rate from the radioactive impurities in the CaF$_{2}$ crystals and the rate of high energy $\gamma$-rays caused by the (n, $\gamma$) reactions induced by environmental neutrons. The expected background rate was in a good agreement with the measured rate, i.e., approximately 10$^{-3}$ events/keV/yr/(kg of $^{\rm nat.}$Ca), in the 0$\nu\beta\beta$ window. In conclusion, the background candidates were estimated properly by comparing the measured energy spectrum with the background simulations. With this measurement method, we performed the first search for 0$\nu\beta\beta$ decay in a low background condition using a detector with a Ca isotope, in which the Ca present was not enriched, in a scale of hundreds of kg. The $^{48}$Ca isotope has a high potential for use in 0$\nu\beta\beta$ decay search, and is expected to be useful for the development of a next-generation detector for highly sensitive measurements.

We investigated local magnetism at the interface between Co2FeGe Heusler alloy and Ag by 57Fe Mossbauer spectroscopy. Interface-sensitive samples, where the 57Fe isotope was used only for several interfacial atomic layers of the Co2FeGe layer on the Ag layer, were prepared using atomically controlled alternate deposition at various deposition temperatures. The 57Fe Mossbauer spectra measured at room temperature indicated that the interface region of the Co2FeGe layers for the samples deposited below 500 ° C retains the ferromagnetic B2 structure. On the other hand, interdiffusion between the Co2FeGe and Ag layers occurs and a nonmagnetic phase grows for the samples deposited at the substrate temperature higher than 550 ° C. We observed magnetoresistance (MR) ratio of 3.6% at room temperature for Co2FeGe/Ag/Fe current-perpendicular-to-plane giant-magnetoresistive (CPP-GMR) structures grown at 300 ° C, whereas we could not observe distinct MR effect for samples grown at 600 ° C. These results support that the existence of interfacial nonmagnetic phase due to the interdiffusion between Heusler alloy and nonmagnetic-metal layers severely reduces the performance of CPP-GMR devices.

Background Complex ATs with a complicated circuit have been increasing because of the native or iatrogenic scars in atrium. However, development of resolution in the EAM allows us to reach the correct diagnosis. The purpose of this study was to reassess the relationship between characteristics of ATs and cycle length based on the correct diagnosis with high-resolution mapping system. Method Among 85 consecutive AT patients treated with with high-resolution mapping system “Rhythmia”, patients with at least one mappable AT during procedure were prospectively included in this study. Maximal, minimal, and variation of ATCL was calculated from the decapolar in the coronary sinus (CS) during 2minutes, and the relation between CL and respiration was measured on the Rhythmia (Figure 1). These values were compared to AT types. Results 90 ATs in 65 patients (mean 59±13 yrs, 16 females, 55 post-AF ATs) including 4 focal-ATs, 23 localized-AT, and 63 macroreentrant ATs were analyzed. As shown in the table 1, the maximum and minimum CL was similar between focal-AT, localized-AT, and, macroreentrant-AT. However, both absolute CL-variation and ratio of CL-variation were significantly smaller in macroreentrant ATs (P=0.009 and P=0.0012, respectively). Table 2 described the comparison between 66 left-ATs and 24 right-ATs. Although the maximum and minimum CL were similar, both absolute CL-variation and ratio of CL-variation were significantly larger in right ATs (P=0.001 and P=0.007, respectively). Additionally, the correlation of CL to the respiration was significantly more frequently seen in the right-ATs (3.0% in left-ATs and 62.5% in right-ATs, P Table 1, 2 and Figure 1 Conclusions CL-variation of ATs may be significantly smaller in macroreentrant ATs and significantly larger in right ATs. CL-variation correlated to the respiration may suggest right-ATs. These information may be helpful to diagnose ATs before mapping.

We have studied the neutrino-less double beta decay(0νββ) of 48Ca by using CaF2(pure) scintillators. Analysis for rejection of backgrounds(212Bi→ 212Po events and 208Tl events) was effective to reduce backgrounds in Qββ-value region. No events are observed in the Qββ-value region for the data of 131 days × 86 kg. It gives a lower limit (90% confidence level) of (math) > 6.2 × 1022 year (preliminary) for the half-life of 0νββ of 48Ca.

A new data acquisition (DAQ) system for the CANDLES experiment was developed using the SpaceWire protocol and the DAQ-Middleware framework. The CANDLES experiment uses a trigger board and Flash Analog-to-Digital Converters (FADCs). The SpaceWire helps us construct the DAQ system with a flexible and multi-path access to FADCs and the trigger board. FADCs have a ring buffer with three buffers to detect sequential decays from backgrounds. We developed the DAQ system with parallel read-out to reduce the dead time at high trigger rates using three read-out personal computers (PCs) that are connected to the three buffers in FADCs one by one. Each PC connects all FADCs and the trigger board and gathers a complete data set of one event without any event builder. The maximum DAQ speed of parallel read-out by three PCs was 2.4 times higher than that of single read-out. In order to collect event data sets from PCs, we built the network distributed DAQ system through Ethernet, which is naturally introduced with the DAQ-Middleware. To realize remote monitoring and histogram modification while the DAQ running, we also developed a dynamic online monitor system independent with the DAQ-Middleware.

CANDLES is the project to search for neutrino-less double beta decay ( 0νββ ) of 48 Ca. The observation of 0νββ will prove existence of a massive Majorana neutrino. For the 0νββ measurement, we need a low background condition because of a low decay rate of 0νββ . Now we installed the CANDLES III system at the Kamioka underground laboratory. The CANDLES III system realizes the low background condition by a characteristic structure and data analyses for background rejection. Here we report performances of the CANDLES III system.

CANDLES studies the double beta decay of 48Ca through CaF2 scintillation crystals. The CANDLES III detector, located in Kamioka underground laboratory, is currently running. Here we describe recent status of data analysis which includes detector performance, detector stability, and background estimation. Current sensitivity for 0 ν β β half-life is also discussed in this paper.

The neutrino-less double beta decay is acquiring great interest after the confirmation of neutrino oscillation which demonstrated nonzero neutrino mass. In order to search for neutrino-less double beta decay of $^{48}$Ca, we proposed the CANDLES project by using CaF$_{2}$(pure) scintillators. Now we installed the CANDLES III system at the Kamioka underground laboratory. The CANDLES III system realizes the low background condition by a characteristic structure and data analyses for background rejection. Furthermore we installed new shielding system in order to reduce $\gamma$-ray backgrounds from neutron capture reaction. Here we report performances of the CANDLES III system.

A low background HPGe detector system was developed at CANDLES Experimental Hall for multipurpose use. Various low background techniques were employed, including hermatic shield design, radon gas suppression, and background reduction analysis. A new pulse shape discrimination (PSD) method was specially created for coaxial Ge detector. Using this PSD method, microphonics noise and background event at low energy region less than 200 keV can be rejected effectively. Monte Carlo simulation by GEANT4 was performed to acquire the detection efficiency and study the interaction of gamma-rays with detector system. For rare decay measurement, the detector was utilized to detect the nature’s most stable isomer tantalum-180m (180Tam) decay. Two phases of tantalum physics run were completed with total livetime of 358.2 days, which Phase II has upgraded shield configuration. The world most stringent half-life limit of 180Tam has been successfully achieved.

Environmental processes have been modelled for decades. However. the need for integrated assessment and modeling (IAM) has,town as the extent and severity of environmental problems in the 21st Century worsens. The scale of IAM is not restricted to the global level as in climate change models, but includes local and regional models of environmental problems. This paper discusses various definitions of IAM and identifies five different types of integration that Lire needed for the effective solution of environmental problems. The future is then depicted in the form of two brief scenarios: one optimistic and one pessimistic. The current state of IAM is then briefly reviewed. The issues of complexity and validation in IAM are recognised as more complex than in traditional disciplinary approaches. Communication is identified as a central issue both internally among team members and externally with decision-makers. stakeholders and other scientists. Finally it is concluded that the process of integrated assessment and modelling is considered as important as the product for any particular project. By learning to work together and recognise the contribution of all team members and participants, it is believed that we will have a strong scientific and social basis to address the environmental problems of the 21st Century.

The CANDLES experiment is a study of the double beta decay of $^{48}{\rm Ca}$ nuclei. The detector consists of two scintillators. One is the ${\rm CaF}_{2}$ crystal that acts as a source of double beta decay and a scintillator. The other is a liquid scintillator, which is used for gamma-veto. The total light collected from the liquid scintillator is on the same order of magnitude as that of the ${\rm CaF}_{2}$ scintillator, but the decay constant of the liquid scintillator is one or more orders of magnitude shorter than that of the ${\rm CaF}_{2}$ scintillator. Therefore, if we trigger the signal by pulse height, the energy threshold of the liquid scintillator light will be one or more orders of magnitude lower than that of the ${\rm CaF}_{2}$ scintillator. A high counting rate in the liquid scintillator causes deadtime; in order to avoid this problem, we have developed a new trigger system. In this paper, we describe the use of this trigger system in the CANDLES experiment and its performance after installation in 2013.

A method for magnetization reversal measurements in submicron magnetic wires was developed by utilizing the giant magnetoresistance effect, which enables us to determine a domain wall position as a function of time, and allows to evaluate the propagation velocity of the domain wall easily. It was found that the magnetization reversal in a wire occurs in association with the propagation of a single domain wall and that an artificial neck introduced into the wire acts as a pinning site of the magnetic domain wall. Injection of the magnetic domain wall from one end of the wire is demonstrated. Results on electric resistance measurements down to 20 mK for ultranarrow Ni wires are also presented. An increase of resistance proportional to T−1/2 was observed in a temperature range from 10 K to 80 mK. The result is discussed in terms of the electron–electron interaction and the weak localization effects.

Because of the higher Au, Ag, and Cu contents, seafloor massive sulfides (SMS) have received much attention as immediate commercial mining targets by private companies and nations. One of them is scheduled to start the commercial mining program in the end of 2013 and the expected profitability is presented. However, the geophysical and social conditions are quite different from Japan's ones. The material flow selected for the mining program, for example, has no economy under Japan's social condition. One of the key technologies necessary for improving the economy in Japan, a primary ore dressing of excavated SMS ores on the seafloor, is introduced in this issue.

The observation of neutrino-less double beta decay (0νββ) would be the most practical way to prove the Majorana nature of the neutrino and lepton number violation. CANDLES studies 48Ca double beta decay using CaF2 scintillator. The main advantage of 48Ca is that it has the highest Q-value (4.27 MeV) among all the isotope candidates for 0νββ. The CANDLES III detector is currently operating with 300kg CaF2 crystals in the Kamioka underground observatory, Japan. In 2014, a detector cooling system and a magnetic cancellation coil was installed with the aim to increase light emission of CaF2 scintillator and photo-electron collection efficiency of the photo-multipliers. After this upgrade, light yield was increased to 1000 p.e./MeV which is 1.6 times larger than before. According to data analysis and simulation, main background source in CANDLES is turned out to be high energy external gamma-ray originating neutron capture on the surrounding materials, so called (n,γ). Upgrading the detector by installing neutron and gamma-ray shield can reduce the remaining main backgrounds by two order magnitude. In this report, we discuss the detail of (n,γ) and background reduction by additional shielding.

Phytochemical studies on rhizome of Etlingera elatior have resulted in the isolation of 1,7-bis(4-hydroxyphenyl)-2,4,6-heptatrienone (1), demethoxycurcumin (2), 1,7-bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one (3), 16-hydroxylabda-8(17),11,13-trien-16,15-olide (4), stigmast-4-en-3-one (5), stigmast-4-ene-3,6-dione (6), stigmast-4-en-6b-ol-3-one (7), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (8). 1 and 4 were new compounds. Compounds 5 and 7 displayed high antitumour-promoting activity. Ethyl acetate extract showed a very significant cytotoxic activity against CEM-SS and MCF-7 cell lines (4 μg/ml and 6.25 μg/ml respectively). The antitumour-promoting activity was determined by EBV-EA assay and cytotoxic activity was determined by MTT assay.

CANDLES is the project to search for neutrino-less double beta decay (0νββ) of βCa. The observation of 0νββ will prove existence of a massive Majorana neutrino. Now we installed new detector system CANDLES III. Here expected performances of the system for background rejection are presented. It is also described current status of development for the detector system.

Neutrino‐less double beta decay (0νββ) is currently known to be an only experiment to verify whether lepton number is conserved or not. The lepton number non‐conservation is the key to create matter dominated universe with CP violation. The so‐called leptogenesys scenario presents a way to create the matter dominated universe by these violations. If neutrinos have Majorana mass, transition from a particle to an anti‐particle is possible and the left‐handed and right‐handed neutrinos could have different masses. It is highly likely that the neutrinos are Majorana particles. We have been studying double beta decay of 48Ca. Our first stage experiment using the ELEGANT VI detector system gave the best lower limit of the half life of 0νββ of 48Ca. We have been working on CANDLES detector system to sense much longer lifetime region. We have developed techniques to reduce backgrounds. The CADLES detector system was installed at Kamioka underground laboratory. Here I describe a schematic view of the system.

In order to measure the flow velocity field in coast, VHF(Very High Frequency) radar is often used recently, because it enables to obtained the velocity distribution in extended wide region simultaneously. The array antenna is needed fairly large area to operate the radar and it should be located at particular place such as a spot with sweeping view. Another type of the radar, loop antenna with monopole produced by CODAR, is small and useful for the measurement. If it can be used on board a moving vessel, the possibility of ocean field measurements will be extended extremely. However, it is obviously difficult to operate the radar on a steel vessel, because it affects extraordinarily. It should be considered that the vessel is a part of the radar. This paper describes the result of examination on inference of the radar on the steel vessel, using VLCC (Very Large Crude-oil Carrier). Although the characteristics of the receiving wave, called "antenna pattern" here, is deformed very much, it is possible to estimate the arrival directions of the radio waves in particular region. The result shows the possibility of measuring the flow velocity distribution by means of the VHF radar on the vessels.

An LC (liquid crystal) front-projector that uses three 3.1-inch a-Si TFT LC panels with 110920 pixels (236*470), to realize high-resolution, a high-density LC light valve with 345600 pixels has been developed. This projector accommodates EDTV and personal computer displays, and provides excellent color reproduction. It is capable of projecting high-quality video and data images onto 30 to 100 inch screens. The authors report on the developments which make this system possible, namely the lamp and optical system for the light source, the high-density LC panel, the optical system of dichroic mirrors used for color separation, and the combination and projection lens. >