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We will measure the X-rays from kaonic 3He 3d → 2p transition with a precision below 2 eV. It can provide crucial information on the kaon-nucleus strong interaction. The experiment (J-PARC E17) will be performed as Day-1, which is one of the first experiments in the J-PARC hadron facility in the year 2011. An overview and the present status of the J-PARC E17 experiment are described. [ABSTRACT FROM AUTHOR]

We have succeeded in making a superconducting V—Ti alloy multifilament wire using the diffusion reaction between constituent pure-metal subelements, which can omit the melt-and-casting step and may reduce the fabrication cost. A monofilament billet prepared by restacking hexagonal Ti/V composites in a Cu/V tube and a multifilament billet by re-stacking such Cu/V/(Ti/V) composites in a Cu tube were hydrostatically extruded and drawn down to wires. Four kinds of heat treatment were investigated, with respect to mi-crostructure and superconducting properties; (1) an alloying heat treatment (HTalloy) which is carried out at the final size (‘fs-HTalloy’), (2) HTalloy is followed by cold-working (W) down to the final size (‘HTalloy+W1’), (3) an precipitation heat treatment (HTprec) is carried out after the W stage (‘HTalloy+W1+HTprec’) and (4) an intermediate HTprec is carried out during the W stage coming after the HTalloy stage (‘HTalloy+W1+HTprec+W2’). The ‘HTalloy+W1+HTprec+W2’ treatment was found to be most effective in enhancing the critical current densities (Jc), despite the HTprec treatment having slightly degraded the critical temperature (Tc) and critical magnetic field (Bc2). The highest Bc2 was obtained using the ‘HTalloy+W1’ treatment, irrespective of the HTalloy temperatures. [ABSTRACT FROM AUTHOR]

This paper describes performances of a Stirling type pulse tube cryocooler as a nitrogen sub-cooler. The main objective of this work is a demonstration of a cooling system for High Tc Superconducting (HTS) power applications such as fault current limiters, cables and transformers. Cooling capacity necessary for these applications is more than several hundred watts at 77 K level. High efficiency and high reliability are also required. Developments of several hundred watts class compact cryocooler such as Stirling-type pulse tube cryocooler are expected for the HTS power applications. A liner-motor-driven compressor (model:2S241K) and coldhead, which were developed by CFIC Inc., were used in our system to evaluate efficiency and reliability for our application. A cooling stage of the cold head was designed as a heat exchanger to cool a sub-cooled nitrogen flow to reduce a temperature difference between working gas of cryocooler (helium) and the sub-cooled nitrogen. A cooling capacity of 207 W at 77 K was obtained with an input power of 4.33 kW. The Carnot efficiency was 13.8 %, which is about 1.7 times higher than that of commercial GM cryocooler (for reference). The long-term operation over 0.5 year (4414 hours) without performance degradation was obtained. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

This paper describes the development of a 4 K cryogenic probe for 500 MHz Nuclear Magnetic Resonance (NMR) analyses. As thermal noise is proportional to the square root of the RF coil temperature, sensitivity of a 4 K probe is expected to be double that of conventional 25 K probes. The 4 K probe apparatus consists of a closed-cycle cooling system, a 5 m long helium transfer line and the NMR probe itself. The cooling system produces cold helium mist with a Gifford-McMahon/Joule-Thomson (GM/JT) cryocooler. The helium mist traverses the transfer line and then cools the RF coil. An acceptable power input of 3.6 W for the NMR pulse sequence was demonstrated, which was more than the time-averaged heat input, 2 W, generated by a multi-dimensional NMR pulse sequence. The basic NMR sensitivity of the cryogenic probe remains insufficient at present, but increasing B1xy (the field component in the xy plane generated by unit current of the RF coil) and decreasing the noise temperature of the preamplifier are promising approaches for achieving higher sensitivity in the future. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We have tried to study low activation superconducting materials of the many V-based compound superconductors, and selected the V based Laves phase (V2(Hf,Zr)) compound because of its high upper critical field (Hc2) exceeding 20 T, its neutron irradiation resistance, and its low activation in the fusion reactor compared with those of Nb-based A15 wires. The fabrication, microstructure and superconductivity of V2(Hf,Zr) multifilamentary wire synthesized by applying a rapidly-heating/quenching (RHQ) and annealing process to the simple precursor using pure Hf and Zr mixture powder and pure V tube matrix were investigated. We found that a thick reaction layer was formed between the powder mixture filament and V matrix after the RHQ treatment and then it was increased with an increment of heating energy. Offset Tc values of samples were raised by increasing heating energy, and maximum Tc values occurred at 8.3 K. The maximum Jc value was obtained for a sample of post-annealing at 600°C for 10 h. Jc dependence on the magnetic field of the post-annealed samples was higher than that of the as-quenched sample, and the Hc2 value of the annealed sample was also improved compared to the as-quenched sample. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

As a part of the Super-conductive AC Equipment (Super-ACE) project presently being performed, an AC magnet for a fault current limiter (FCL) is being developed. The goal of the project is the development of 66 kV/750A High Tc Superconducting (HTS) FCL magnet, which is composed of six HTS coils operating at around 65 K. This paper describes a design of a sub-cooled nitrogen cryostat for the FCL magnet. Three sets of Gifford-McMahon (GM) cryocooler were used for cooling liquid nitrogen in the cryostat. Experimental results of cooling down and temperature stability during current flowing tests of the magnet were reported in this paper. The sub-cooled nitrogen of 65 K was successfully obtained in the vessel with 2.6 m3 in volume. And the temperature uniformity was observed in both of the cooling down process and the coil energizing process. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Aiming at further improvement of high-field critical current density, Jc, in the Nb3Al conductors, Si addition was attempted. To fabricate the Nb3(Al,Si) conductors, we used two times the rapid-heating and quenching (RHQ) technique. First, drawability of the Nb/Al-Si composite wire has been improved by specially using the RHQ technique at an early stage of the precursor fabrication, where only the Al-alloy core is rapidly solidified from the molten state to form a fine microstructure of the core without any reaction with the Nb. This process makes the subsequent restacking and drawing process easier. Using this technique, multifilamentary Nb/Al-Si precursors with piece length of 30 m have been successfully fabricated at our laboratory workshop. For the prepared precursors, another RHQ was attempted for the formation of the high stoichiometric A15 phase. With increasing Si content, the upper critical field was enhanced, while providing the high Jc property in high magnetic fields such as 150 A/mm2 at 25 T, 4.2 K. Meanwhile, with Si additions of 2 at% to the core, metastable BCC Nb(Al,Si)ss phase was formed by the second RHQ process. This phase can be transformed to the A15 phase by a subsequent annealing around 800°C. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Nb3(Al,Ge) conductors prepared from multifilamentary Nb/Al-25at%Ge precursors with a diffusion reaction process at temperatures around 1400°C, have shown critical current density (Jc) in excess of 300 A/mm2 at 21 T and 220 A/mm2 at 23 T at 4.2 K. The diffusion spacing between the Nb and Al-Ge was not required to be reduced down to sub-micron order, which is better to reduce the fabrication difficulties. With large diffusion spacing, the A15 phase formed in equilibrium together with large region of o-phase. The A15 phase was quite Nb-rich. The attainable upper critical field (Hc2) exceeds 28.5 T, which is about 2 T larger than that of the so-called RHQT Nb3Al. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Recent progress of the externally and internally stabilized RHQT (rapid-heating, quenching and transformation) processed Nb3Al superconductors are described and compared. The internal stabilization method has been improved by demonstrating that the Ag can be included in the strand in various places, increasing the Ag volume ratio, decreasing an overall residual resistivity of conductor, and enhancing the RRR. An attempt was made to fabricate a coil using such an internally stabilized conductor, and its result has been compared to that of Cu clad conductors. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We will measure the x-rays from kaonic 3He and 4He 3d→2p transition by using silicon drift detectors. Our precision goal is set to 1 eV to provide crucial information on the kaon-nucleus strong interaction in the low energy limit. The experiment is to be performed as one of the first experiment in the J-PARC hadron facility (J-PARC E17). An overview and the present status of the experiment are presented. [ABSTRACT FROM AUTHOR]

We present an experimental study of Λ(1405) via the in-flight (K-,n) reaction on the deuteron target (J-PARC E31). We will measure all Σ+π-, Σ-π+ and Σ0π0 final states so that the isospin structure of the produced hyperon resonance state can be decomposed. In this report, we present an overview of the experiment and preparation status. [ABSTRACT FROM AUTHOR]