Search results for "vacuum"
showing 10 items of 352 documents
Study of scintillation light collection, production and propagation in a 4 tonne dual-phase LArTPC
2020
The $3 \times 1 \times 1$ m$^3$ demonstrator is a dual phase liquid argon time projection chamber that has recorded cosmic rays events in 2017 at CERN. The light signal in these detectors is crucial to provide precise timing capabilities. The performances of the photon detection system, composed of five PMTs, are discussed. The collected scintillation and electroluminescence light created by passing particles has been studied in various detector conditions. In particular, the scintillation light production and propagation processes have been analyzed and compared to simulations, improving the understanding of some liquid argon properties.
Muon Anomaly from Lepton Vacuum Polarization and The Mellin--Barnes Representation
2008
We evaluate, analytically, a specific class of eighth--order and tenth--order QED contributions to the anomalous magnetic moment of the muon. They are generated by Feynman diagrams involving lowest order vacuum polarization insertions of leptons $l=e,\mu$, and $\tau$. The results are given in the form of analytic expansions in terms of the mass ratios $m_e/m_\mu$ and $m_\mu/m_\tau$. We compute as many terms as required by the error induced by the present experimental uncertainty on the lepton masses. We show how the Mellin--Barnes integral representation of Feynman parametric integrals allows for an easy analytic evaluation of as many terms as wanted in these expansions and how its underlyi…
Chemical-based methodologies approaches to extend the shelf life of fresh fish — a review
2021
Due to its characteristics, fresh fish is a highly perishable food with a very short shelf-life under refrigeration. Several methods have been introduced to slow down its deterioration, such as by means of oxygen depletion of the food package (vacuum packaging), or by changing the natural atmosphere that is in contact with the fresh fish (modified atmosphere packaging), or by the use of chemicals generally recognized as safe: such compounds can be directly applied (by dipping or spraying) or incorporated into packaging materials and slowly migrate to the product, exerting a hurdle effect against microbial development and lipid oxidation (active packaging). This review aims to cover the most…
Laser-induced plasma spectroscopy in near vacuum ultraviolet using ordinary spectrograph and ICCD
2002
An experimental setup to measure laser-induced plasma emission spectra with an ordinary Czerny-Turner spectrograph and intensified charge-coupled device in the near vacuum ultraviolet down to 130 nm is described. Spectra of bromine, chlorine and iodine were recorded to demonstrate the performance of the setup.
Tau lepton mixing with charginos and its effects on chargino searches at e+e− colliders
1998
In bilinear R-Parity violating models where a term \epsilon_3L_3H_2 is introduced in the superpotential, the tau lepton can mix with charginos. We show that this mixing is fully compatible with LEP1 precision measurements of the Z\tau\tau and W\tau\nu_\tau couplings even for large values of \epsilon_3 and of the induced vacuum expectation value v_3 of the tau-sneutrino. The single production of charginos at e+e- colliders is possible in this case and we present numerical values of the cross-section at LEP1, LEP2 and an NLC. We find maximum values of 10 pb at LEP1 and 1 fb at NLC, while the corresponding values at LEP2 are too small to observe.
Collective spontaneous emission of two entangled atoms near an oscillating mirror
2020
We consider the cooperative spontaneous emission of a system of two identical atoms, interacting with the electromagnetic field in the vacuum state and in the presence of an oscillating mirror. We assume that the two atoms, one in the ground state and the other in the excited state, are prepared in a correlated (symmetric or antisymmetric) {\em Bell}-type state. We also suppose that the perfectly reflecting plate oscillates adiabatically, with the field modes satisfying the boundary conditions at the mirror surface at any given instant, so that the time-dependence of the interaction Hamiltonian is entirely enclosed in the instantaneous atoms-wall distance. Using time-dependent perturbation …
Automatic mass spectra recognition for Ultra High Vacuum systems using multilabel classification
2021
Abstract In Ultra High-Vacuum (UHV) systems it is common to find a mixture of many gases originating from surface outgassing, leaks and permeation that contaminate vacuum chambers and cause issues to reach ultimate pressures. The identification of these contaminants is, in general, done manually by trained technicians from the analysis of mass spectra. This task is time consuming and can lead to misinterpretation or partial understanding of issues. The challenge resides in the rapid identification of these contaminants by using some automatic gas identification technique. This paper explores the automatic and simultaneous identification of 80 molecules, including some of the most commonly p…
Improving the kinetic couplings in lattice nonrelativistic QCD
2019
We improve the non-relativistic QCD (NRQCD) action by comparing the dispersion relation to that of the continuum through $\mathcal{O}(p^6)$ in perturbation theory. The one-loop matching coefficients of the $\mathcal{O}(p^4)$ kinetic operators are determined, as well as the scale at which to evaluate $\alpha_s$ in the $V$-scheme for each quantity. We utilise automated lattice perturbation theory using twisted boundary conditions as an infrared regulator. The one-loop radiative corrections to the mass renormalisation, zero-point energy and overall energy-shift of an NRQCD $b$-quark are also found. We also explore how a Fat$3$-smeared NRQCD action and changes of the stability parameter $n$ aff…
Acceleration radiation and the Planck scale
2008
A uniformly accelerating observer perceives the Minkowski vacuum state as a thermal bath of radiation. We point out that this field-theory effect can be derived, for any dimension higher than two, without actually invoking very high energy physics. This supports the view that this phenomenon is robust against Planck-scale physics and, therefore, should be compatible with any underlying microscopic theory.
Interfacial Modification for High-Efficiency Vapor-Phase-Deposited Perovskite Solar Cells Based on a Metal Oxide Buffer Layer.
2018
Vacuum deposition is one of the most technologically relevant techniques for the fabrication of perovskite solar cells. The most efficient vacuum-based devices rely on doped organic contacts, compromising the long-term stability of the system. Here, we introduce an inorganic electron-transporting material to obtain power conversion efficiencies matching the best performing vacuum-deposited devices, with open-circuit potential close to the thermodynamic limit. We analyze the leakage current reduction and the interfacial recombination improvement upon use of a thin (<10 nm) interlayer of C60, as well as a more favorable band alignment after a bias/ultraviolet light activation process. This wo…