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We present a new methodology which can determine magnetic helicity transport by the passage of helical magnetic field lines from sub-photosphere and the shuffling motions of foot-points of preexisting coronal field lines separately. It is well known that only the velocity component which is perpendicular to the magnetic field ($\upsilon_{\perp B}$) has contribution to the helicity accumulation. Here, we demonstrate that $\upsilon_{\perp B}$ can be deduced from horizontal motion and vector magnetograms, under a simple relation of $\upsilon_t = \mu_t + \frac{\upsilon_n}{B_n} B_t$ as suggested by D$\acute{e}$moulin & Berger (2003). Then after dividing $\upsilon_{\perp B}$ into two components, as one is tangential and the other is normal to the solar surface, we can determine both terms of helicity transport. Active region (AR) NOAA 10930 is analyzed as an example during its solar disk center passage by using data obtained by the Spectro-Polarimeter and the Narrowband Filter Imager of Solar Optical Telescope on board Hinode. We find that in our calculation, the helicity injection by flux emergence and shuffling motions have the same sign. During the period we studied, the main contribution of helicity accumulation comes from the flux emergence effect, while the dynamic transient evolution comes from the shuffling motions effect. Our observational results further indicate that for this AR, the apparent rotational motion in the following sunspot is the real shuffling motions on solar surface. more...

We have investigated the tunnelling properties of the interface between superconducting Sr2RuO4 and a single Ru inclusion in eutectic. By using a micro-fabrication technique, we have made Sr2RuO4/Ru junctions on the eutectic system that consists of Sr2RuO4 and Ru micro-inclusions. Such a eutectic system exhibits surface superconductivity, called the 3-K phase. A zero bias conductance peak (ZBCP) was observed in the 3-K phase. We propose to use the onset of the ZBCP to delineate the phase boundary of a time-reversal symmetry breaking state., Comment: To be published in Proc of 24th Int. Conf. on Low Temperature Physics (LT24); 2 pages more...

LXeGRIT is a balloon-borne Compton telescope employing a large volume liquid xenon time projection chamber (LXeTPC) as the central gamma-ray detector. It is designed to image gamma rays in the energy range of 200 keV to 20 MeV, with an angular resolution of about 3 degrees (1 sigma) at 2 MeV, within a field-of-view (FOV) of about 1 sr. The detector's energy and three-dimensional spatial resolution as measured during pre-flight calibration experiments, are $\Delta E_\mathrm{lxe}/E=8.8% : \sqrt{1\MeV /E}$ and < 1mm RMS, respectively. The detection efficiency for Compton events varies between 1.5% and 4% depending on energy and event selection. We describe the instrument as flown on May 7, 1999 and review its overall performance at balloon altitude. The launch occurred at 13:26:54 UT from Ft. Sumner, New Mexico and the flight was terminated about 9 hours later. The Crab was in the instrument FOV for a few hours. Analysis of these data is in progress., Comment: 16 pages, 15 figures; To appear in: X-Ray and Gamma-Ray Instrumentation for Astronomy XI, 2000; Proc. SPIE, vol. 4140; K.A. Flanagan & O.H. Siegmund, eds more...

LXeGRIT is a balloon-borne Compton telescope based on a liquid xenon time projection chamber (LXeTPC) for imaging cosmic \g-rays in the energy band of 0.2-20 MeV. The detector, with 400 cm$^2$ area and 7 cm drift gap, is filled with high purity LXe. Both ionization and scintillation light signals are detected to measure the energy deposits and the three spatial coordinates of individual \g -ray interactions within the sensitive volume. The TPC has been characterized with repeated measurements of its spectral and Compton imaging response to \g -rays from radioactive sources such as \na, \cs, \yt and Am-Be. The detector shows a linear response to \g -rays in the energy range 511 keV -4.4 MeV, with an energy resolution (FWHM) of $ \Delta E/E=8.8% \: \sqrt{1\MeV /E}$. Compton imaging of \yt \g -ray events with two detected interactions is consistent with an angular resolution of $\sim$ 3 degrees (RMS) at 1.8 MeV., Comment: To appear in: Hard X-Ray, Gamma-Ray and Neutron Detector Physics XI, 2000; Proc. SPIE, vol. 4140; K.A. Flanagan & O.H. Siegmund, eds more...