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We developed a new positron detector system called Kalliope, which is based on multi-pixel avalanch photo-diode (m-APD), application specific integrated circuit (ASIC), field programmable gated array (FPGA) and ethernet-based SiTCP data transfer technology. We have manufactured a general-purpose spectrometer for muon spin relaxation (μSR) measurements, employing 40 Kalliope units (1280 channels of scintillators) installed in a 0.4 T longitudinal-field magnet. The spectrometer has been placed at D1 experimental area of J- PARC Muon Science Establishment (MUSE). Since February of 2014, the spectrometer has been used for the user programs of MUSE after a short commissioning period of one week. The data accumulation rate of the new spectrometer is 180 million positron events per hour (after taking the coincidence of two scintillators of telescopes) from a 20×20 mm sample for double-pulsed incoming muons.

The muon science facility (MUSE), along with the neutron, hadron, and neutrino facilities, is one of the experimental areas of the J-PARC project. The MUSE facility is located in the Materials and Life Science Facility (MLF), which is a building integrated to include both neutron and muon science programs. Since the autumn of 2008, users operation is effective and making use of the pulsed muon beam particularly at the D-Line. Unfortunately, MUSE suffered severe damages from the earthquake on March 11, 2011, the so-called "Higashi-Nippon Dai-Shinsai". We managed to have a stable operation of the superconducting solenoid magnet with use of the on-line refrigerator on December, 2012, although we had to overcome a lot of difficulties against components not working properly. But we had to stop again the whole operations on May 2013, because of the radioactive materials leakage accident at the Hadron Hall Experimental Facility. Finally we restarted the users' runs on February 2014.

We have performed muon spin rotation ( μ SR ) measurements in the radioactive Pu-based superconductor PuCoGa 5 to study the effects of radiation damage on the superconducting properties. The same single crystals were studied 25 days (fresh) and 400 days (aged) after initial preparation. We find that the μ SR rate σ v , which is proportional to superfluid density ρ s , is steeply reduced in the aged sample compared with its reduction of T c . This result is inconsistent with conventional Abrikosov–Gor’kov pair-breaking theory, but can be explained by the local suppression of the order parameter in a strong-scattering, short-coherence-length superconductor.

Strongly over-doped HgBa2Ca2Cu3O8+δ samples with a T c as low as 97 K were successfully obtained using highly oxidized BaCuO2+e (e ≈ 0.13) and BaO2 powders as starting materials for the high-pressure synthesis at 5 GPa and 950 °C. The over-doped state was confirmed by observing a negative value for the Seebeck coefficient at temperatures above T c in a thermoelectric power measurement. Synthesis from less oxidized BaCuO2+e (e ≈ 0.06) yielded material with a lower doping level. By subsequent annealings in O2 at 300 °C and in Ar at 400 °C optimized (T c = 134 K) and under-doped(T c = 118 K) samples, respectively, were obtained. According to the magnetization experiments, the heavier the doped hole concentration was, the better was the H irr -versus-(T/T c ) characteristics.

The influence of hydrogen impurities on the electronic properties of undoped BaTiO3 was studied from a microscopic point of view using the muon spin rotation and relaxation technique. Electron localization around an implanted positive muon, by analogy a hydrogen impurity, was observed below ∼80 K. The effective electron binding energy was estimated to be ∼10−2 eV, indicating that the hydrogen-induced defect forms a shallow donor level. At room temperature, the weakly bound electron is excited into the conduction band and behaves as a free carrier, which causes insulation degradation undesirable for capacitor applications.

In A15 superconducting wires, it is known that the critical current has a dependence on the strain in a magnetic field. Therefore, RHQ-Nb3Al wires are being studied to develop a high field magnet. Since the wire is usually composed of three or more materials, residual strain is induced by the different coefficients of thermal expansion in the materials in the cooling process after A15 phase transformation. In neutron diffraction measurements at room temperature, we previously reported that the residual strain of Nb3Al filaments in the wire is tensile. We also reported that the difference of the residual strain in Nb3Al filaments, as obtained at room temperature, has an effect on the tensile strain dependence of the critical current. In this study, we effectively reduced the residual strain by using a thermal cycle method after A15 phase transformation. By applying one thermal cycle process, the tensile residual strain was decreased by approximately 0.08%. This is the first investigation of the thermal cycle effect on the residual strain in the RHQ-Nb3Al wire. Studies on the thermal cycle are necessary to understand the mechanical properties of the wire. In this paper, we report the details of the thermal cycle method, its effect on the lattice structures of Nb3Al and Cu at room temperature, and the analysis results from the perspective of material strength in strain recovery and its hysteresis.

Diluted magnetic semiconductor (DMS) exhibits unique magnetic and transport properties. The well known DMS is (Ga,Mn)As that is in thin film form so far only. However Mn dopant brings both localized spins and carriers in Ga1−xMnxAs, result in the lack of independent control of local moment and carrier densities. It is therefore difficult to study or control charge and spin variable quantitatively. Here we report that an individual control of carrier and spin can be realized in a new type of DMS for Mn-doped I-II-V type semiconductor Li1+yZn1-xMnxAs in bulk. The Li(Zn,Mn)As polycrystalline samples showed ferromagnetic transition temperature (TC) up to 50K and spontaneous magnetization up to 2.9 μB per Mn. The other advantage of new DMS over III-V DMSs is the availability of bulk specimens so far for these type of DMS Moreover the new DMS shows a soft magnetic behavior with the coercive force < 100Oe which would be promising for prospective application. Muon spin relaxtion (μSR) probed static magnetic order of full volume in the ferromagnetic region. Electrical transport properties showed Li1+y(Zn,Mn)As (y = 0.05–0.1) compounds have p-type carriers since excess Li substitutes Zn sites presumably[1].

Neutron powder diffraction techniques of small-volume samples at high pressure using compact opposed-anvil cells were developed at J-PARC pulsed neutron source. For this purpose we apply a few types of super-hard materials as opposed anvils with culet diameters between 3 to 5 mm. Generated pressures with these anvils were up to 9 GPa for 2 to 4 mm3 and up to 14 GPa for 0.7 mm3 sample volumes, which not only depends on the anvil geometry and material but even more depends on the metallic gasket geometry and material. A representative anvil geometry with 4 mm in culet diameter, along with TiZr "null alloy" metallic gasket containing varying sample volumes, were then applied to time-of-flight neutron powder diffraction experiments, where methane hydrate of 4 mm3 volume and lead of 0.7 mm3 volume were separately measured and their signal-to-background ratios were evaluated. A neutron-focusing optics was used to concentrate the neutron beam into these small-volume samples to increase the intensity of diffraction. Although spurious diffraction peaks from the anvils were prominent, more than seven diffraction peaks are clearly observed from both of the samples. In spite of the smaller sample capacity than previous standard high-pressure apparatus for neutron, it is concluded that the opposed-anvil cells will become alternative apparatuses for neutron scattering at strong pulsed neutron sources where sufficient neutron intensity was granted.

We report on muon spin relaxation (µSR) studies of Sm Tr 2 Al 20 ( Tr : Ti, V, Cr) with a cubic Γ 8 crystalline-electric-field ground state. A coherent muon spin precession was observed below the phase transition temperature in a zero applied field for each compound, manifesting long-range magnetic ordering from a microscopic point of view. The muon spin precession frequency distribution is qualitatively different among the three compounds, indicating differences in the magnetic structure and/or the muon stopping site.

A muon spin relaxation (µSR) study of the cubic Γ 3 ground doublet system PrTi 2 Al 20 is presented. The zero-field µSR rate shows no significant change while passing through the phase transition temperature T O =2.0 K, indicating that a nonmagnetic order parameter lies behind the ordered state. This is consistent with a ferroquadrupole ordering scenario standing on quadrupole degrees of freedom active in the Γ 3 subspace. We also found that slow spin fluctuations remain even at 0.1 K well below T O , ascribed to 141 Pr hyperfine-enhanced nuclear magnetism in the nonmagnetic ground state. The 4 f electronic exchange constant and 141 Pr nuclear order temperature were estimated to be 0.64 K in the temperature unit and 0.13 mK, respectively, from the 141 Pr nuclear spin fluctuation frequency 5.8(2) MHz at 0.1 K.

Magnetic susceptibility and muon spin relaxation (µSR) measurements in the intermetallic cubic compound SmIn 3 with a Γ 8 crystalline-electric-field ground state are reported. Anomalies corresponding to successive phase transitions were observed in the magnetic susceptibility at T I ∼16.5 K, T II ∼15.1 K, and T III ∼14.7 K. A spontaneous local magnetic field was detected below T I using the µSR technique in zero applied field in contrast to the pure quadrupolar ordering scenario proposed in the phase between T I and T II . This result clearly indicates that the primary order parameters in all the ordered phases are magnetic. The local field distribution changes at around T II from a continuous broad one to a sharp one with decreasing temperature, suggesting that an incommensurate-to-commensurate magnetic phase transition takes place at this temperature. A possible magnetic structure in the ground state and the importance of multipolar interactions in the Γ 8 subspace are discussed.

Magnetic susceptibility and muon spin relaxation (µSR) measurements were performed on single-crystalline samples of SmPb 3 in order to investigate magnetic properties in an antiferromagnetic state below T N ∼5 K, where a simultaneous order of dipole and quadrupole moments had been proposed. A clear hysteretic behavior was observed in the temperature dependence of magnetic susceptibility, indicating the first-order nature of the phase transition. µSR data in a zero applied field indicate that an interstitial muon site splits into more than five magnetically inequivalent sites in the ordered state. In consideration of the most plausible muon site (3 d in Wycoff notation) in isomorphous compounds, this result suggests that a commensurate and possibly long-periodic magnetic structure is realized in SmPb 3 .

We report zero-field µ + SR measurements made at J-PARC on CeRu 2 Al 10 . Below the phase transition temperature T 0 ∼27 K, a clear modulation of µ + polarization due to an internal field is observed, indicating that magnetic ordering takes place. Compared with the internal field expected from the effective magnetic moment in the disordered state, the observed internal field at the µ + site is quite small. This indicates that the ordered Ce magnetic moment is small (∼10 -2 µ B ) and/or the nearest pair of Ce magnetic moments are mutually anti-parallel. The T -dependence of the internal field is somewhat peculiar, suggesting that another ordering is taking place as well.

The remote control system for muon beam line devices of J-PARC MUSE has been developed with the Experimental Physics and Industrial Control System (EPICS). The EPICS input/output controller was installed in standard Linux PCs for slow control of the devices. Power supplies for 21 magnetic elements and four slit controllers for the decay-surface muon beam line in the Materials and Life Science Experimental Facility are now accessible via Ethernet from a graphical user interface which has been composed using the Motif Editor and Display Manger.

Positive muon (μ+) diffusion was observed in cubic f-electron compounds PrPb3 and SmAg2In by means of the μ+ spin rotation (μ+SR) method in high transverse field applied along the [001] direction. The applied field splits one crystallographic site into two magnetically inequivalent sites. The μ+ diffusion between these magnetically different sites drastically influences the μ+SR frequencies, so that two lines are gradually merged into one line at increasing temperature due to the motional narrowing effect. The μ+ hopping rate Ω derived from the μ+SR line shape follows the Arrhenius law, namely, Ω = Ω0 exp(−U/kBT) in both cases. The preexponential factor Ω0 suggests that the dominant mechanism of μ+ diffusion is classical over-the-barrier hopping in PrPb3 for 140

At ambient pressure CeRhIn5 is an incommensurate antiferromagnet with N?el temperature TN = 3.8 K. The application of pressure reduces TN and yields (1) a state in which AFM coexists with superconductivity, and then (2) a superconducting state in the absence of AFM. We report transverse-field muon spin relaxation (?SR) measurements at pressures 2.07 and 2.26 GPa in the pure superconducting state of single-crystalline CeRhIn5, which has a tetragonal structure. ?SR is sensitive to the local field distribution produced by the vortex lattice in a mixed superconducting state, allowing a measurement of the magnetic field penetration depth ?(T). We measured ?ab(T) for applied field along the c-axis as a function of temperature T, and find ?ab(0) = 372(5) nm and 338(6) nm for P = 2.07 GPa and 2.26 GPa, respectively. The temperature dependence of the superfluid density ?s(T) ??2(T) was found to be ?s(T) Tn with n = 1.9(2).

The new Muon Science Facility (MUSE) that is now under construction at J-PARC in the Materials and Life Science Facility (MLF) building will comprise four types of muon channels. In the first stage, a conventional superconducting decay muon channel (D-Line) was constructed, which can extract surface (positive) muons with an expected muon yield of 107/s and decay positive/negative muons up to 120 MeV/c, with an expected muon yield of a few 106/s at 60 MeV/c for both positive and negative muons. This channel will be used for various kinds of muon experiments like ?SR, muon catalyzed fusion and nondestructive elements analysis.

A compact cubic-anvil high-pressure device was developed for in situ neutron powder diffraction studies. In this device, a cubic shaped pressure medium is compressed by six anvils, and neutron beams pass through gaps between the anvils. The first high-pressure experiment using this device was conducted at J-PARC and clearly showed the neutron diffraction patterns of Pb. Combining the cubic-anvil high-pressure device with a pulsed neutron source will prove to be a useful tool for neutron diffraction experiments.

Measurements of muon spin relaxation have been performed on Ce2RhIn8?xSnx (x = 0.0,0.1,0.5 and 0.7) single crystals down to 0.3 K. A clear muon spin precession signal was observed in x = 0.0 and 0.1 samples due to antiferromagnetic ordering with magnetic volume fraction of ~75% below TN. While an increase of relaxation rate was observed in x = 0.5 below 0.5 K, no precession signal was observed, suggesting the suppression of antiferromagnetism with increasing Sn concentration.

The muon science facility (MUSE, abbreviation of MUon Science Establishment), along with the neutron, hadron, and neutrino facilities, is one of the experimental areas of the J-PARC project, which was approved for construction in a period from 2001 to 2008. The MUSE facility is located in the Materials and Life Science Facility (MLF), which is a building integrated to include both neutron and muon science programs. Construction of the MLF building was started in the beginning of 2004, and was completed at the end of the 2006 fiscal year. For Phase 1, we managed to install one super-conducting decay/surface muon channel with a modest-acceptance (about 45 mSr) pion injector in the summer of 2008. Finally, on September 19th, 2008, the 20 mm thick edge-cooled, non-rotating graphite target, which is surrounded by a copper frame, was, for the first time, placed into the 3GeV proton beam obtained from the rapid cycling synchrotron (RCS). The nuclear reactions between the 3 GeV proton beam and the nucleus of carbon produce both positively (π+) and negatively (π−) charged pions. On September 26th, 2008, we finally succeeded to extract? surface muons (μ+), which are obtained from the decay of π+ near the surface of the pion production target in the proton beam line. First, we commissioned the secondary muon beam line optics by tuning the superconducting magnet, the quadrupole and bending magnets, and the DC separator in order to optimize the transport of the surface muon beam and to eliminate the e+ contamination. Then, on December 25th, 2008, we also succeeded in the extraction of the "decay muons (μ+/μ-)", which are obtained through the in-flight decay of π+/π−

J-PARC, a high-intensity proton accelerator facility in Japan, has been open to public use since December 2008, and various high-pressure experiments are expected to be conducted using its high-intensity pulsed neutron beam. The first test experiment using a Paris-Edinburgh (PE) press was performed with the Engineering Materials Diffractometer "TAKUMI". The powder diffractions of standard samples in the press were successfully obtained using two different geometries (vertical scattering geometry and horizontal scattering geometry). Although the signal was weak and there are still many issues to be solved, it has been confirmed that in situ high-pressure neutron powder diffraction is feasible at J-PARC.

The behavior of impurity atoms in graphite is one of the most intriguing subjects in current materials science. It is well known, for graphite intercalation compounds, that the type and concentration of intercalated impurities control their physical and chemical properties. It is thus of great importance to investigate the behavior of intercalants in the two dimensional layers for further understanding of their interacting nature with the graphite matrix. In order to investigate such interactions, it is essential to introduce impurities of interest into graphite; and, for that purpose, the ion-implantation method would be the simplest method. Nuclear techniques with radioactive probes are highly suited to such studies on the behavior of dilute impurities because of their high sensitivity. In our recent study, we developed a new detection apparatus for radioactive impurities: an online time-differential perturbed angular correlation (TDPAC) measurement system. The TDPAC method is a spectroscopy using unstable nuclei as the probe; by observing the time-variant angular correlation of rays successively emitted in the disintegration process of the excited nucleus of the probe, we can obtain direct information on the local field in the vicinity of the probe nucleus through electromagnetic interactions between the probe nucleus and extranuclear field. The newly developed system enables the application of shortlived unstable nuclei to the spectroscopy as the parents of probes; they are implanted in samples of interest at high energy immediately after their production by acceleratorbased nuclear reactions. In our previous paper, we demonstrated the applicability of the present online system and reported on the residence site of F( O) implanted in highly oriented pyrolytic graphite (HOPG). In comparison with the previous data obtained at 18K, we here discuss the displacement of the F( O) nuclei at room temperature on the basis of the damping trend of the TDPAC spectra. The online TDPAC experiment was carried out at the RIKEN Nishina Center. Ionized Ne was accelerated by a two-stage acceleration with the AVF cyclotron and the ring cyclotron up to 110MeV/u at a beam intensity of 150 pnA. A variety of radioactive nuclides were produced at a Be production target by projectile-fragmentation reactions; the secondary beam of interest, O (t1=2 1⁄4 26:9 s), was separated out of these heavy ions at a purity of 98% or higher by the RIKEN projectile-fragment separator (RIPS). A wellfocused pulsed beam of O was implanted deep in an HOPG sheet at a beam intensity of 10 s . The online TDPAC measurements were performed at room temperature on the 1357–197 keV cascade rays from F nuclei, whose 197 keV intermediate state with nuclear spin of I 1⁄4 5=2 has a half-life of 89.3 ns. In the present work, the time evolution of the angular correlations of the cascade rays was observed at =2 and directions. In order to obtain better counting statistics, we used sixteen BaF2 detectors. They were arranged in four independent detector planes for the investigation of the sample-to-detector configuration dependence of perturbation patterns for a single-crystalline sample. All the events were taken in a list mode using a CAMAC system so that we could work on off-line data processing searching for the optimum conditions on energy gates for the detected rays of interest. The experimental details are described elsewhere. The TDPAC spectra of F( O) implanted in the HOPG sheet at room temperature are shown in Fig. 1 together with the previous data obtained at 18K. In the present experiment, we derive the time evolution of the angular correlation as a function of the time interval between the cascade -ray emissions, RðtÞ, from the following simple arithmetic operation: -0.2

We performed muon spin relaxation measurements on randomly aligned single-crystalline samples of SmRu 4 P 12 down to 0.02 K to investigate static and dynamical magnetic properties in low fields. Th...

Superconducting and magnetic properties of the heavy fermion superconductor CePt 3 Si were studied in a polycrystalline sample by means of the muon spin rotation and relaxation method. The muon Knight shift is invariant on passing the temperature through T c down to 20 mK at 17 kOe, indicating that the local spin susceptibility does not change in the superconducting state. The possible symmetry of superconductivity and the magnetic state in CePt 3 Si are discussed.

We have developed experimental equipment at the J-PARC MLF muon science facility (MUSE) for muon spin rotation/relaxation experiments. To overcome the limited time resolution which comes from the time structure of the proton beam, the “muon beam slicer” is installed at the extraction part of the decay muon line. Here we report the detail of the muon beam slicer.

At J-PARC Muon Science Facility a conventional superconducting decay muon beamline (D-Line) was constructed that can extract surface (positive) muons and decay positive/negative muons up to 120 MeV/c. This beamline will be used for various kinds of muon experiments like μSR, muon catalyzed fusion and nondestructive elements analysis. Similarly to the ISIS facility at RAL, the muon beam produced at J-PARC has a double-pulsed structure. To utilize the muon beam more efficiently, a muon kicker system will be installed to separate the double-pulsed beam and send the two pulses to two experimental areas simultaneously, allowing μSR experiments with single-pulsed muons. A muon kicker system, comprising two magnetic kicker magnets, two switchyard magnets and a septum magnet, is now been constructed. Single-pulsed muon beam up to 60 MeV/c can be transported. New state-of-the-art power supplies are also been fabricated. The installation in the beamline is planned in summer 2011.

Single administration of collagen wound dressing (CAS) made from bovine derm in the form of finely ground powders was given to mice and rats via i.p., s.c. and p.o. routes and via i.v. route in the form of physiological saline extracts and it was continuously injected into mice for 28 days via s.c. route to study its acute and subacute toxicity. Examinations were made of on general conditions, body weight, food and water consumption, hematology, serum biochemistry, organ weight, and gross and microscopic findings. Results showed no marked toxicity except for local irritation which was seen only after parenteral administration. We concluded on the basis of these animal experiments that there should be no problem in regard to safety after somewhat more extensive therapeutic application of CAS as a wound dressing in clinical practice.