We present a novel approach for the search of dark matter in the DarkSide-50 experiment, relying on Bayesian Networks. This method incorporates the detector response model into the likelihood ...function, explicitly maintaining the connection with the quantity of interest. No assumptions about the linearity of the problem or the shape of the probability distribution functions are required, and there is no need to morph signal and background spectra as a function of nuisance parameters. By expressing the problem in terms of Bayesian Networks, we have developed an inference algorithm based on a Markov Chain Monte Carlo to calculate the posterior probability. A clever description of the detector response model in terms of parametric matrices allows us to study the impact of systematic variations of any parameter on the final results. Our approach not only provides the desired information on the parameter of interest, but also potential constraints on the response model. Our results are consistent with recent published analyses and further refine the parameters of the detector response model.
We demonstrate the fabrication of self-aligned laser-reduced graphene oxide patterns with a spatial resolution/laser spot size ratio of 1/10, lower than anything reported before using ...laser-reduction. Laser light modifies graphene oxide (GO) by removing the oxygen-containing groups turning GO into a more graphene-like nanomaterial. Our method is based on high laser power density used for the reduction of GO that results in ablation of the GO film. This enabled us to remove the laser spot illuminated area while inducing the selective graphene oxide reduction at the periphery of the laser spot achieving resistivity of 1.6·10−5 Ω m, as low as values previously reported for other rGO. Therefore, we can exploit laser-induced reduction at high laser power density to pattern GO films with conductive dimensions that are a fraction of the laser spot size. This innovative method is scalable, inexpensive, and straightforward, allowing conductive circuits on arbitrary, flexible, and transparent substrates for applications in lightweight electronics and wearables.
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•Graphene oxide (GO) and reduced GO (rGO) are two promising materials for carbon-based electronics.•Conductive rGO wires are obtained at the edges of the ablated area in a single-pass by laser patterning.•The parallel conducting rGO lines have dimensions as small as 1:10 the laser spot size.•The low resistivity of rGO patterns 1.6·10−5 Ω m is comparable to values previously reported using other methods.
In this paper the behaviour of steel under the influence of the first harmonic YAG: Nd laser is investigated. The energy density in the spot varied from 0.1 to 50 J/cm2. The amplitude of the glow of ...the plasma flare; a pressure pulse propagation into the sample; initial velocity of expansion of the plasma were measured. Experimental dependences of the plasma emission amplitude, the rate of its expansion into vacuum, and the pressure under plasma limitation and expansion conditions on the energy density of the laser pulse are obtained. The values of all these parameters increase with the level of laser action. Characteristic growths slow at high levels (>10 J/cm2) of laser exposure. Attenuation of the energy supplied to the sample surface with ns laser pulses is negligible. The pressure of expanding plasma reaches values sufficient to provide shear deformations.
Scientific-methodical approaches to a study of nonlinear physicochemical processes are considered and an experimental setup intended for investigation of nonlinear physical and chemical processes ...accompanying irradiation of solids of various classes (including energetic materials) by UV, visible, and IR laser radiation is described. The possibility of synchronous multi-parameter measurements of the amplitude, spectral, kinetic, and spatial characteristics of the near-surface and bulk luminous laser plasma, solid-phase luminescence, acoustic pulses formed in the bulk of the samples, and morphology of residual damages has been demonstrated with a nanosecond time resolution. The energy density on the irradiated target surfaces varied from fractions of mJ/cm
2
to 10
4
J/cm
2
depending on the problem to be solved. The spectral range recorded for one irradiation pulse was 200–1100 nm, the spectral resolution was ~1.5 nm, and the spatial resolution was ~10 μm. A pressure pulse formed in the sample volume was recorded by an acoustic sensor with sensitivity of 0.15 V/bar and temporal resolution of ~5 ns.
This paper describes the results of an investigation of the effect of small hardening spots (about 1 mm) created on the surface of a sample by laser complex with solid-state laser. The melted area of ...the steel sample is not exceed 5%. Steel microhardness change in the region subjected to laser treatment is studied. Also there is a graph of the deformation of samples dependence on the tension. As a result, the yield plateau and plastic properties changes were detected. The flow line was tracked in the series of speckle photographs. As a result we can see how mm surface inhomogeneity can influence on the deformation and strength properties of steel.
Over the last 25 years, radiowave detection of neutrino-generated signals, using cold polar ice as the neutrino target, has emerged as perhaps the most promising technique for detection of ...extragalactic ultra-high energy neutrinos (corresponding to neutrino energies in excess of 0.01 Joules, or 1017 electron volts). During the summer of 2021 and in tandem with the initial deployment of the Radio Neutrino Observatory in Greenland (RNO-G), we conducted radioglaciological measurements at Summit Station, Greenland to refine our understanding of the ice target. We report the result of one such measurement, the radio-frequency electric field attenuation length $L_\alpha$. We find an approximately linear dependence of $L_\alpha$ on frequency with the best fit of the average field attenuation for the upper 1500 m of ice: $\langle L_\alpha \rangle = ( ( 1154 \pm 121) - ( 0.81 \pm 0.14) \, ( \nu /{\rm MHz}) ) \,{\rm m}$ for frequencies ν ∈ 145 − 350 MHz.
The stability of a dark matter detector on the timescale of a few years is a key requirement due to the large exposure needed to achieve a competitive sensitivity. It is especially crucial to enable ...the detector to potentially detect any annual event rate modulation, an expected dark matter signature. In this work, we present the performance history of the DarkSide-50 dual-phase argon time projection chamber over its almost three-year low-radioactivity argon run. In particular, we focus on the electroluminescence signal that enables sensitivity to sub-keV energy depositions. The stability of the electroluminescence yield is found to be better than 0.5%. Finally, we show the temporal evolution of the observed event rate around the sub-keV region being consistent to the background prediction.
Dark matter induced event rate in an Earth-based detector is predicted to show an annual modulation as a result of the Earth's orbital motion around the Sun. We searched for this modulation signature ...using the ionization signal of the DarkSide-50 liquid argon time projection chamber. No significant signature compatible with dark matter is observed in the electron recoil equivalent energy range above \(40~{\rm eV_{ee}}\), the lowest threshold ever achieved in such a search.
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