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High critical temperature superconductors (HTS) based devices can have impact in the study of the phase dynamics of Josephson junctions (JJs) thanks to the wide range of junction parameters they offer and to their unconventional properties. Measurements of current-voltage characteristics and of switching current distributions constitute a direct way to classify different regimes of the phase dynamics and of the transport, also in nontrivial case of the moderately damped regime (MDR). MDR is going to be more and more common in JJs with advances in nanopatterning superconductors and synthesizing novel hybrid systems. Distinctive signatures of macroscopic quantum tunneling and of thermal activation in presence of different tunable levels of dissipation have been detected in YBCO grain boundary JJs. Experimental data are supported by Monte Carlo simulations of the phase dynamics, in a wide range of temperatures and dissipation levels. This allows us to quantify dissipation in the MDR and partially reconstruct a phase diagram as guideline for a wide range of moderately damped systems. (C) 2014 Elsevier B.V. All rights reserved.

Growth by the micro-pulling-down technique (μ-PD) of homogeneous and crack-free fiber single crystals with composition Ba 2 Na 1− x Yb x Nb 5 O 15 ( 0 ) is reported. The effect of Yb 3+ addition to barium sodium niobate (BNN, x=0 ), having the tungsten bronze-type structure, was examined by room temperature X-ray powder diffraction and differential thermal analysis coupled to thermogravimetry. In the region of the monophased field the structure is tetragonal from x=0.02 to 0.16. Volume change is mainly by variation of the a -axis length. Addition of Yb 3+ to BNN could be effective for the production of high optical quality, crack-free, bulk crystals by the Czochralski technique.

The properties of YBa 2 Cu 3 O 7− x grain boundary Josephson junctions have been reproducibly modified by a focused electron beam irradiation. The original junctions were fabricated by using the biepitaxial technique on (110) SrTiO 3 substrates. The technique utilizes the property of YBa 2 Cu 3 O 7− x film to grow (103)-oriented on the bare substrate and (001)-oriented on the part of the substrate with the MgO seed layer, providing Josephson junctions of good quality and excellent reproducibility. The junction parameters can be adjusted controllably by applying an appropriate irradiation dose. Electron irradiation reduced the critical current of the junctions I C and increased the normal state specific resistivity. The disappearance of the excess current and the shift of the voltage position of the Fiske steps were also observed. Isothermal annealing partly restores the original junction properties. We also speculate that some aspects of the nature of the grain boundary barriers can be better understood from the study of the transport properties of irradiated junctions. PACS: 74.50+r, 74.72Bk, 74.76Bz, 85.25Cp

Introduction Treatment of breast cancer with lymph nodes (internal mammary and clavicular nodes) is achieved in most of the centers using a conventional radiotherapy based on electron-photon beams with junctions and wedge filters. Wedge filters correct for surface obliquities but do not provide optimal dose homogeneity within the breast volume. This study aims at comparing treatment plans using the ‘‘field in field” technique, equivalent to a ‘‘simplified” intensity modulation with treatment plans using wedge filters. Material and methods This study focused on eight patients (for half of the patients, the internal mammary nodes were included in the breast fields) treated for breast cancer with lymph nodes using wedge filters. For these patients a ‘‘field in field” plan was prepared retrospectively. Patients were positioned supine with ipsilateral arm above the head and head turned to the opposite treatment side. The prescribed dose was 50 Gy to the PTV breast and 46–50 Gy for the lymph nodes. For both technics, after treatment plan optimization, doses delivered to targets, heart and ipsilateral lung are reported. Results For the 8 patients and for the same coverage of breast and lymph nodes PTV, the volume of 105% (52.5 Gy) of the dose remaining in the breast volume was 2.65–24.29 cc (mean 13.9 cc) with the ‘‘field in field” technic and 9.49–231.63 cc (mean 98.5 cc) with wedge filters technic. For ipsilateral lung, the mean dose, V20 and V30 were respectively 15.1–16.6 Gy (average 15.8 Gy), 25.4–27.1 Gy (average 26.1 Gy), and 17.3–19 Gy (mean 17.9 Gy) for both technics. Conclusion For 8 patients, ‘‘field in field” treatment plans showed that remaining volume of 105% of the dose was up to 10 times smaller than using wedge filters treatment plans. This technics allowed reducing significantly overdosage areas and therefore having a better dose homogeneity in the breast.