arXiv subjects

F. C. Marques

Publications and source records attributed to F. C. Marques.

7 recordsLinked to original sources

arXiv2025

Reporting on pTP sublimation during evaporation deposition

Noble liquid detectors rely on wavelength shifter materials, such as p-terphenyl (pTP) and Tetraphenyl-butadiene (TPB), which are widely used in neutrino and dark matter experiments. Given their importance, a thorough understanding and characterization of these compounds are essential for optimizing experimental techniques and enhancing detector performance. In this study, we report a novel phenomenon in which commonly used wavelength shifters undergo spontaneous sublimation under high vacuum conditions. We quantify the sublimation rates of pTP and TPB as a function of pressure and temperature, assessing their impact on material growth and physical properties. Additionally, we investigate how variations in film thickness and growth rate influence the sublimation process. These findings provide critical insights into improving the handling and preparation of wavelength shifters during the fabrication of light detectors for these experiments, ensuring their stability and performance in low-background photodetection systems.

physics.ins-det↗

arXiv2018

Anderson localization of light: Strong dependence with incident angle

This paper studies the transport of light for different incidence angles in a strongly disordered optical medium composed by core-shell nanoparticles (TiO2@Silica) suspended in ethanol solution. A decrease of optical conductance and an increase of absorption near the input border are reported when the incidence angle is increased. We associated this phenomenon to an increase of the density of localized states (localization increase) near the input border, which could be explained by a large increase of internal reflection with the incidence angle, which in turn would be a direct consequence of the enhancement of the effective refractive index near the input border by localization itself. The specular reflection, measured for the photons that enter the sample, is considerably lower than the effective internal reflection undergone by the coherently backscattered photons in the exact opposite direction, indicating a non-reciprocal propagation of light (mirror-symmetry breaking). This study represents a novel approach in order to understand the complex physics involved in a strongly disordered optical medium at the critical regime of approaching localization.

cond-mat.mes-hall↗

arXiv2011

Rigidity of min-max minimal spheres in three-manifolds

In this paper we consider min-max minimal surfaces in three-manifolds and prove some rigidity results. For instance, we prove that any metric on a 3-sphere which has scalar curvature greater than or equal to 6 and is not round must have an embedded minimal sphere of area strictly smaller than $4π$ and index at most one. If the Ricci curvature is positive we also prove sharp estimates for the width.

math.DG↗

arXiv2010

Deformations of the hemisphere that increase scalar curvature

Consider a compact Riemannian manifold M of dimension n whose boundary \partial M is totally geodesic and is isometric to the standard sphere S^{n-1}. A natural conjecture of Min-Oo asserts that if the scalar curvature of M is at least n(n-1), then M is isometric to the hemisphere S_+^n equipped with its standard metric. This conjecture is inspired by the positive mass theorem in general relativity, and has been verified in many special cases. In this paper, we construct counterexamples to Min-Oo's conjecture in dimension n \geq 3.

math.DG↗

arXiv2010

Recent progress on the Yamabe problem

We give a survey of various compactness and non-compactness results for the Yamabe equation. We also discuss a conjecture of Hamilton concerning the asymptotic behavior of the parabolic Yamabe flow.

math.DG↗

arXiv2010

Scalar curvature rigidity of geodesic balls in S^n

In this paper, we prove a scalar curvature rigidity result for geodesic balls in S^n. This result contrasts sharply with the recent counterexamples to Min-Oo's conjecture for the hemisphere (cf. [5]).

math.DG↗

arXiv2009

Blow-up phenomena for the Yamabe equation II

Let n be an integer such that 25 \leq n \leq 51. We construct a smooth metric g on S^n with the property that the set of constant scalar curvature metrics in the conformal class of g is not compact.

math.DG↗