Minimum Absorption Coefficient Available for Measurements Using Time-resolved Photothermal Common-path Interferometry on the Example of Synthetic Crystalline Quartz

Using the example of an absorption measurement in synthetic crystalline quartz, which has specific ratios of the physical parameters, it was possible to observe the competition among various effects using a time-resolved photothermal common-path interferometry scheme, namely, the thermo-optical effect, nonlinearity of the refractive index in the heating beam field, and heat diffusion. This competition masks the contribution of the thermo-optical effect weakened by stresses in the heating region, and determines the minimum absorption coefficient that can still be correctly calculated from the measurement results. The time-resolved photo-thermal common-path interferometry scheme facilitates separating the contributions to the measured signal of these effects and increases the measurement range in the direction of smaller absorption values. The amount of absorption in various materials at which such competition occurs depends on the ratio of its physical constants, which is ≤ 10-7 cm-1 for crystalline quartz, ≤ 10-8 cm-1 for quartz glass and ≤ 10-5 cm-1 for crystalline silicon. The problems of using experiment measurements of small absorption values in samples of synthetic crystalline quartz are discussed using an example crystal grown through the hydrothermal method at the Russian company Quartz Technologies

Subthreshold oscillations in a map-based neuron model

Self-sustained subthreshold oscillations in a discrete-time model of neuronal behavior are considered. We discuss bifurcation scenarios explaining the birth of these oscillations and their transformation into tonic spikes. Specific features of these transitions caused by the discrete-time dynamics of the model and the influence of external noise are discussed.Comment: To be published in Physics Letters

Chronic Triple Infection with Hepatitis B, C, and D Viruses in the Republic of Sakha (Yakutia)

The purpose of this work was to study the features of the clinical course of mixed infections with hepatitis B+C+D viruses in the Republic of Sakha (Yakutia) (RS(Y)). Materials and Methods: The incidences of these infections were studied in the infectious disease department of the Yakutsk City Clinical Hospital. A total of 74 patients with chronic infection with hepatitis B, C, and D viruses were analyzed. The following markers of HBV (HBsAg, HBeAg, anti-HBcIgG, HBV DNA), HCV (anti-HCV) and HDV (anti-HDV, HDV RNA) were detected. According to PCR (n=35), HCV-RNA was detected in 29(82.8%) patients. In 65.8% of cases, HCV-RNA replication was observed in the absence of HDV-DNA. Mono-replication of HBV (HBV-DNA+, HCV-RNA-) was detected in 17.1% patients, mono-replication of HCV (HBV-DNA-, HCV-RNA+) in 65.7% patients and mixed replication of viruses C, D and/or G (HBV-DNA-, HCV-RNA+, HDV-RNA+/HGV-RNA+) in 17.1% patients. Results: The comparison of biochemical parameters of patients with chronic mixed hepatitis showed that more expressed changes are observed with the mixed replication than with the mono-replicative form of hepatitis

Andreev conductance of a domain wall

At low temperatures, the transport through a superconductor-ferromagnet tunnel interface is due to tunneling of electrons in pairs. Exchange field of a monodomain ferromagnet aligns electron spins and suppresses the two electron tunneling. The presence of the domain walls at the SF interface strongly enhances the subgap current. The Andreev conductance is proven to be proportional to the total length of domain walls at the SF interface.Comment: 4 pages and 1 figur

Superconducting helical solenoid systems for muon cooling experiment at Fermilab

Novel configurations of superconducting magnet system for Muon Beam Cooling Experiment is under design at Fermilab. The magnet system has to generate longitudinal and transverse dipole and quadrupole helical magnetic fields providing a muon beam motion along helical orbit. It was found that such complicated field configuration can be formed by a set of circular coils shifted in transverse directions in such a way that their centers lay on the center of the helical beam orbit. Closed beam orbit configurations were also proposed and investigated. This paper describes the magnetic and mechanical designs and parameters of such magnetic system based on a NbTi Rutherford type cable. The helical solenoid fabrication, assembly and quench protection issues are presented

Supercurrents through gated superconductor-normal-metal-superconductor contacts: the Josephson-transistor

We analyze the transport through a narrow ballistic superconductor-normal- metal-superconductor Josephson contact with non-ideal transmission at the superconductor-normal-metal interfaces, e.g., due to insulating layers, effective mass steps, or band misfits (SIN interfaces). The electronic spectrum in the normal wire is determined through the combination of Andreev- and normal reflection at the SIN interfaces. Strong normal scattering at the SIN interfaces introduces electron- and hole-like resonances in the normal region which show up in the quasi-particle spectrum. These resonances have strong implications for the critical supercurrent $I_c$ which we find to be determined by the lowest quasi-particle level: tuning the potential $\mu_{x0}$ to the points where electron- and hole-like resonances cross, we find sharp peaks in $I_{\rm c}$, resulting in a transitor effect. We compare the performance of this Resonant Josephson-Transistor (RJT) with that of a Superconducting Single Electron Transistor (SSET).Comment: to appear in PRB, 11 pages, 9 figure

Design Studies of Nb3Sn High-Gradient Quadrupole Models for LARP

Insertion quadrupoles with large aperture and high gradient are required to achieve the luminosity upgrade goal of 10{sup 35} cm{sup -2} s{sup -1} at the Large Hadron Collider (LHC). In 2004, the US Department of Energy established the LHC Accelerator Research Program (LARP) to develop a technology base for the upgrade. Nb{sub 3}Sn conductor is required in order to operate at high field and with sufficient temperature margin. We report here on the conceptual design studies of a series of 1 m long 'High-gradient Quadrupoles' (HQ) that will explore the magnet performance limits in terms of peak fields, forces and stresses. The HQ design is expected to provide coil peak fields of more than 15 T, corresponding to gradients above 300 T/m in a 90 mm bore. Conductor requirements, magnetic, mechanical and quench protection issues for candidate HQ designs will be presented and discussed