Multiple junction biasing of superconducting tunnel junction detectors

We describe a new biasing scheme for single photon detectors based on superconducting tunnel junctions. It replaces a single detector junction with a circuit of three junctions and achieves biasing of a detector junction at subgap currents without the use of an external magnetic field. The biasing occurs through the nonlinear interaction of the three junctions, which we demonstrate through numerical simulation. This nonlinear state is numerically stable against external fluctuations and is compatible with high fidelity electrical readout of the photon-induced current. The elimination of the external magnetic field potentially increases the capability of these types of photon detectors and eases constraints involved in the fabrication of large detector arrays.Comment: 15 pages, including 3 figure

Multi-wavelength Signatures of Cosmic Rays in the Milky Way

Cosmic rays (CRs) propagate in the Milky Way and interact with the interstellar medium and magnetic fields. These interactions produce emissions that span the electromagnetic spectrum, and are an invaluable tool for understanding the intensities and spectra of CRs in distant regions, far beyond those probed by direct CR measurements. We present updates on the study of CR properties by combining multi-frequency observations of the interstellar emission and latest CR direct measurements with propagation models.Comment: 8 pages, 4 figures. Proceedings of the 35th International Cosmic Ray Conference, ICRC201

Bright hot impacts by erupted fragments falling back on the Sun: magnetic channelling

Dense plasma fragments were observed to fall back on the solar surface by the Solar Dynamics Observatory after an eruption on 7 June 2011, producing strong EUV brightenings. Previous studies investigated impacts in regions of weak magnetic field. Here we model the $\sim~300$ km/s impact of fragments channelled by the magnetic field close to active regions. In the observations, the magnetic channel brightens before the fragment impact. We use a 3D-MHD model of spherical blobs downfalling in a magnetized atmosphere. The blob parameters are constrained from the observation. We run numerical simulations with different ambient density and magnetic field intensity. We compare the model emission in the 171\AA~ channel of the Atmospheric Imaging Assembly with the observed one. We find that a model of downfall channelled in a $\sim~1$MK coronal loop confined by a magnetic field of $\sim~10-20$G, best explains qualitatively and quantitatively the observed evolution. The blobs are highly deformed, further fragmented, when the ram pressure becomes comparable to the local magnetic pressure and they are deviated to be channelled by the field, because of the differential stress applied by the perturbed magnetic field. Ahead of them, in the relatively dense coronal medium, shock fronts propagate, heat and brighten the channel between the cold falling plasma and the solar surface. This study shows a new mechanism which brightens downflows channelled by the magnetic field, such as in accreting young stars, and also works as a probe of the ambient atmosphere, providing information about the local plasma density and magnetic field.Comment: 17 pages, 14 figure

Fast partial decoherence of a superconducting flux qubit in a spin bath

The superconducting flux qubit has two quantum states with opposite magnetic flux. Environment of nuclear spins can find out the direction of the magnetic flux after a decoherence time $\tau_0$ inversely proportional to the magnitude of the flux and the square root of the number of spins. When the Hamiltonian of the qubit drives fast coherent Rabi oscillations between the states with opposite flux, then flux direction is flipped at a constant rate $\omega$ and the decoherence time $\tau=\omega\tau_0^2$ is much longer than $\tau_0$. However, on closer inspection decoherence actually takes place on two timescales. The long time $\tau$ is a time of full decoherence but a part of quantum coherence is lost already after the short time $\tau_0$. This fast partial decoherence biases coherent flux oscillations towards the initial flux direction and it can affect performance of the superconducting devices as qubits.Comment: 7 page

Pneumatic press equipped with the Vortex system for white grapes processing: First results

The interaction between mechanical, computer and electronic technologies offers nowadays highly innovative solutions to be applied to the oenological machinery industry. Grapes pressing for the extraction of must from the grapes has a fundamental role for obtaining wines with high quality. The pneumatic presses commonly used work with a discontinuous cycle, taking on average about 3 hours for the extraction of the juice from the grapes. During this period, the presence of oxygen in contact with grapes can modify the qualitative characteristics of the future wine. The aim of the research was to study the \u201cVortex System\u201d applied to a pneumatic press and to evaluate the quality of wines obtained in reduction. The study was carried out in a modern winery in the province of Palermo (Italy) using cv. Catarratto lucido grapes. The machine used in the tests was a pneumatic press with a capacity of 1,900 / 2,500 kg by Puleo Srl company (Italy), equipped with the patent "Vortex System". It consists in the recovery of the inert gas by means of a passage and recirculation apparatus during grapes pressing allowing the must extraction in inert and controlled atmosphere, the non-oxidation of the product and a re-use of the gaseous component. Two operating modes were applied: AP (Air Pressing) mode, the traditional pressing mode in presence of oxygen, and NP (Nitrogen Pressing) mode with the Vortex System, performed under inert gas with nitrogen recovery. The following analytical determinations were performed on wines in triplicates: alcohol [%/vol], density [g/l], sugar [g/l], pH, total acidity [g/l], volatile acidity [g/l], malic acid [g/l], citric acid [g/l], tartaric acid [g/l], potassium [g/l], glycerin [g/l], ashes [g/l], absorbance at 420, 520 and 620 nm, polyphenols [mg/l], catechins [mg/l], free sulfur dioxide [mg/l], total sulfur dioxide [mg/l]. The use of the pneumatic press equipped with the Vortex System allowed to obtain excellent values of volatile acidity, absorbance at 420 nm, catechins in white wines and a rich aromatic component both in primary and secondary aromas