No abstract available

[en] The authors present a progress report on a program to develop a high-power X-band magnicon amplifier for linear accelerator applications. The goal of the program is to generate 50 MW at 11.4 GHz, using a 200 A, 500 keV electron beam produced by a cold-cathode diode on the NRL Long-Pulse Accelerator Facility. The initial experiment, designed to study the gain from the first (driven) deflection cavity to a second (passive) deflection cavity, has been completed. A gain of ∼15 dB has been observed in the preferred circular polarization, at a frequency shift of approximately -0.18%, in good agreement with theory and simulation. In addition, a design study for a complete magnicon circuit is under way

[en] The input-output phase relationships for the doubly degenerate superconducting unbiased parametric amplifier (SUPARAMP) are given. The general analysis is performed for the case when the information is injected into both the signal and idler input channels of the amplifier and the phases of the signal, idler, and pump waves are correlated. The expressions for the phase-dependent power gains are evaluated. The operation for a double-sideband input with symmetry and the usual single-sideband input is treated as a special case. Double-sideband input operation may result in an effective increase of the output signal-to-noise ratio. Another improvement in the signal processing can be achieved by synchronous detection of the SUPARAMP's output

[en] A permanent automatic recalibration system for a scintillation camera, of the type consisting chiefly of a collimator if necessary, a scintillator, a light guide and a network of n photomultipliers coupled to a display system, is described. It uses a device to form a single reference light signal common to all the photomultiplication lines, integrated to these latter and associated with a periodic calibration control generator. By means of associated circuits governed by the control generator the gain in each line is brought to and/or maintained at a value between fixed upper and lower limits. Steps are taken so that any gain variation in a given line is adjusted with respect to the reference light signal common to all the lines. The light signal falls preferably in the same part of the spectrum as the scintillations formed in the scintillator

[en] It is shown that the use of a toothed nozzle array in the active medium generator (AMG) of continuous-wave chemical lasers (CWCLs) allows more efficient mixing of reagents to be achieved in the laser chamber than in an AMG with a slit nozzle array. The results of calculations of parameters of the active medium of a DF CWCL operating in the gain regime for the AMG with traditional and promising nozzle array designs are presented. A kinetic model of processes in the DF CWCL active medium is proposed, which allows obtaining a good agreement with the results of measurements of the small-signal gain. (paper)

[en] Highlights: • A four-atom chain encapsulated into a giant fullerene. • The observed clusterfullerene Y₂C₂@C₁(1660)-C₁₀₈ is computed. • The observed/computed features: near-linear Y₂C₂ with a near-triple CC bond. • The endohedral stability is related to energy gain upon encapsulation. • The encapsulation energy can presently be calculated but not measured. The very recently prepared clusterfullerene Y₂C₂@$C_1$(1660)-C₁₀₈ is computed and the observed structural features are confirmed, including the quasi-linear arrangement of the encapsulate and its near-triple CC bond. Its stability is explained by sizeable encapsulation energy. The endohedral stability is evaluated at both DFT and MP2 levels.

[en] We introduce a small correction term, δM_ν, in the neutrino sector and examine whether a large θ₁₃ and an almost maximal θ₂₃ can simultaneously be obtained starting from the tri-bimaximal neutrino mixing. It is found that one can easily gain θ₁₃≅10 deg., which is favored by the recent T2K experiment, by taking account of the enhancement due to the degeneracy among three neutrino masses. We also find that (δM_ν)₂₂=(δM_ν)₃₃ is a key condition for θ₂₃≅45 deg.

No abstract available

[en] Morse theoretic concepts are today widely employed for the formal characterisation of surfaces and surface features. Although nowhere explicitly mentioned, several core concepts of surface metrology, such as the geometrical feature terms being specified in ISO 25178-2 and ISO 16610-85, are also closely related to Morse theory. The current lack of adequate formal definitions, however, implies that several inconsistencies and ambiguities can actually be found within the two standards. As a consequence, in the present paper the focus is laid on (a) the investigation of the interrelationships between Morse theory and the geometrical feature terms and (b) the presentation of some modifications of the existing definitions in order to eliminate the addressed ambiguities. Apart from the benefit of a consistent topological framework with respect to the definitions of the geometrical feature terms, the application of Morse theory would have the additional advantage that a powerful mathematical tool could be exploited in order to gain new insights into surface structures. (paper)

No abstract available