Mapping the Sensitive Volume of an Ion-Counting Nanodosimeter

We present two methods of independently mapping the dimensions of the sensitive volume in an ion-counting nanodosimeter. The first method is based on a calculational approach simulating the extraction of ions from the sensitive volume, and the second method on probing the sensitive volume with 250 MeV protons. Sensitive-volume maps obtained with both methods are compared and systematic errors inherent in both methods are quantified.Comment: 27 pages, 8 figures. Submitted to JINST, Jan. 16 200

Experimental study of a transformer with superconducting elements for fault current limitation and energy redistribution

Numerous proposed and developed superconducting fault current limiters and self-limiting transformers limit successfully fault currents but do not provide uninterrupted supplying of consumers. A design investigated in the work combines the functions of a conventional transformer with the functions of fast energy redistribution and fault protection. The device constitutes a transformer containing an additional high-temperature superconducting (HTS) coil short-circuited by a thin film HTS switching element. Fault current limitation and redistribution of the power flow to a standby line are achieved as a result of a fast transition of the superconducting switching element from the superconducting into the normal state. Transient and steady-state characteristics were experimentally investigated. A mathematical model of the device operation was proposed, and the calculated results were found to be in good agreement with the experimental data. The application field and basic requirements to such devices were discussed and it was shown that the proposed device meets these requirements.Comment: 15 pages incl. 4 figures. Submitted to "Cryogenics

Crystal structure, magnetic and electrical properties and thermal expansion of ferrites of the system Sr1–xSmxFe12–xZnxO19 ( x= 0–0.5)

High-coercivity ferrite samples Sr1–xSmxFe12–xZnxO19 (x = 0–0.5) with magnetoplumbite structure were prepared from oxides Fe2O3, Sm2O3, ZnO and carbonate SrCO3by solid-state ceramic method, the dependence of the unit cell parameters aand con the value of x was determined. It was determined that samples of Sr1–xSmxFe12–xZnxO19were single-phased up to x= 0.2, and also contained ?-Fe2O3for x ?0.3 phase, quantity of which gradually increased with increasing xup to 0.5, and small quantities of phases ZnFe2O4and SmFeO3were present in the samples with x= 0.4 and 0.5. The magnetic, electrical properties and thermal expansion of these ferrite samples were studied, the values of specific saturation magnetization (?s ) were determined by magnetic hysteresis loops at 5 and 300 K. It was found that the solid solution Sr0.9Sm0.1Fe11.9Zn0.1O19at 300 K has specific saturation magnetization (?s ) and coercive force (?Hc) respectively by 0.4 and 9.7% higher than the base ferrite SrFe12O19

Crystal structure and magnetic properties of Gd1-xLaxMO3 (M= Sc, In, Ga) solid solutions

Gd1–xLaxScO3, Gd1–xLaxInO3and Gd1–xLaxGaO3solid solutions were synthesized by the ceramic method, their crystal structure and magnetic properties were investigated. It has been established that the range of solid solutions Gd1–xLaxScO3(0.0 < х ?1.0), Gd1–xLaxInO3(0.2 ? х ?1.0) and Gd1–xLaxGaO3(0.5 ? х ?1.0) with the structure of orthorhombically distorted perovskite was formed. The effective magnetic moment of the Gd 3+ ion (µef, Gd 3+) for Gd1–xLaxScO3solid solutions with x= 0.10, 0.50 is equal to 7.76 ?В, 7.61 µВ, respectively and it is slightly lower than the theoretical value ?ef. theor, Gd 3+= 7.94 µВ, and for x= 0.75, 0.90 it is practically equal to the theoretical value. For Gd1–xLaxGaO3solid solutions with x= 0.8, 0.9 the effective magnetic moment ?ef, Gd 3+ is 7.90 ?В, 7.99 ?В, respectively, and it is close to the theoretical value 7.94 ?В. For Gd1–xLaxInO3solid solutions the effective magnetic moment ?ef, Gd 3+ varies without certain dependence in the interval from 6.91 ?Вto 7.54 µВand is lower than theoretical value ?эф. теор, Gd 3+

Crystal structure and magnetic properties of highly-coercive Sr[1–x]Gd[x]Fe[12–x]Zn[x]O[19] ferrites

High-coercivity ferrite samples Sr[1–x]Gd[x]Fe[12–x]Zn[x]O]19] (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) with magnetoplumbite structure were prepared from oxides Fe[2]O[3], Gd[2]O[3], ZnO and carbonate SrCO[3] by solid-state ceramic method, the dependence of the unit cell parameters aand con the value of xwas determined. XRD showed that the samples with x >0.1 were not single-phase, and the samples with x > 0.2 contained not only bases phase with the structure of magnetplumbite, but also the a-Fe[2]O[3] and Gd[3]Fe[5]O[12] phases. It was found that increase of the xvalue leads to a slight decrease in the Curie temperature (from 727 K for the basic ferrite SrFe[12]O[19] to 714 K for Sr[1–x]Gd[x]Fe[12–x]Zn[x]O[19] solid solution with x = 0.5). It has been found that at 300 K values of spontaneous magnetization (no) and coercive force (?Hc) of solid solution Sr[0.9]Gd[0.1]Fe[11.9]Zn[0.1]O[19] are respectively 1.3 and 2.3% higher than for the base ferrite SrFe[12]O[19], and values of samples with x > 0.1 of these magnetic properties decreases gradually

New and old N=8 superconformal field theories in three dimensions

We show that an infinite family of N=6 d=3 superconformal Chern-Simons-matter theories has hidden N=8 superconformal symmetry and hidden parity on the quantum level. This family of theories is different from the one found by Aharony, Bergman, Jafferis and Maldacena, as well as from the theories constructed by Bagger and Lambert, and Gustavsson. We also test several conjectural dualities between BLG theories and ABJ theories by comparing superconformal indices of these theories.Comment: 16 pages, late

Index for Three Dimensional Superconformal Field Theories and Its Applications

We review aspects of superconformal indices in three dimension. Three dimensional superconformal indices can be exactly computed by using localization method including monopole contribution, and can be applied to provide evidences for mirror duality, AdS_4/CFT_3 correspondence and global symmetry enhancement of strongly coupled gauge theories. After reviewing, we discuss the possibility of global symmetry enhancement in a finite rank of gauge group.Comment: 14 pages, Proceedings of the Seventh International Conference Quantum Theory and Symmetries (QTS-7) in Prague, Czech Republic, August, 2011; v2: minor modifications, discussion of supersymmetry enhancement of abelian ABJM theory by using an index were adde

Magnetic properties of solid solutions of BiFeO3– SmCoO3 system

Solid solutions of BiFeO3– SmCoO3were synthesized by a solid-state method. Peculiarities of the influence of isovalent substitution of Bi 3+ and Fe 3+ ions in BiFeO3by Sm 3+ , Co 3+ ions on the crystal structure and magnetic properties of Bi1–xSmxFe1–xCoxO3solid solutions are found. It is shown that the substitution 3-25% of the Bi 3+ , Fe 3+ ions in BiFe0O3by Sm 3+ , Co 3+ ions results in the gradual destruction of the antiferromagnetic and conception of ferromagnetic ordering. In this case replacing up to 10% of Sm 3+ and Co 3+ ions in SmCoO3by Bi 3+ and Fe 3+ ions leads to the stabilization of Co 3+ ions in a diamagnetic state

Synthesis, magnetic and luminescent properties of Nd[1–x]La[x]GaO[3] (0.7 ≤ х ≤ 1.0) solid solutions

Nd[1–x]La[x]GaO[3] (0.7 < х < 1.0) solid solutions were synthesized by the ceramic method, their crystal structure, magnetic and luminescent properties were investigated. The solid solutions investigated behave as paramagnetics in temperature region of 5–300 K. Calculated values of Nd{3+} ion effective magnetic moment in solid solutions investigated are lower than theoretical. There probably exists „partial freezing” of orbital moment of Nd{3+} ions by the crystal field of the orthorhombically distorted perovskite structure of Nd[1–x]La[x]GaO[3] gallates. It is shown that Nd[0.1]La[0.9]GaO[3] is an efficient phosphor with IR-emission, so it is prospective for use in IR-LEDs

Supersymmetry enhancement by monopole operators

We describe a method which allows one to study hidden symmetries in a large class of strongly coupled supersymmetric gauge theories in three dimensions. We apply this method to the ABJM theory and to the infrared limit of N=4 SQCD with adjoint and fundamental matter. We show that the U(N) ABJM model with Chern-Simons level k=1 or k=2 has hidden N=8 supersymmetry. Hidden supersymmetry is also shown to occur in N=4 d=3 SQCD with one fundamental and one adjoint hypermultiplet. The latter theory, as well as the U(N) ABJM theory at k=1, are shown to have a decoupled free sector. This provides evidence that both models are dual to the infrared limit of N=8 U(N) super-Yang-Mills theory.Comment: 29 pages, late