Search Results (8)

We report the results achieved by the Experiment to Study Thunderstorm High-Energy Radiation (ESTHER), a small ground-based project devoted to the investigation of high-energy radiation in thunderstorms, installed on Mt. Etna (Italy), during the first observational campaign of summer 2024. The experimental setup was installed at high altitude, at the Citelli Refuge (1741 m a.s.l.) and at the Etnean Observatory (2818 m a.s.l.), and acquired data for more than 4 months, experiencing 22 days of thunderstorms and recording correlated variations in the gamma-ray background. The most interesting result encountered during these first data takes is the detection of a 6.3 min high-energy event that occurred during an intense thunderstorm, which was recorded at the first installation site, on 22 July 2024. The gamma-ray detection system revealed a high-energy emission consisting of several episodes: an initial weak gamma-ray glowing, a following shallow prolonged emission, and a final intense burst. The last two episodes exhibited a remarkable 511 keV emission, with the last burst releasing more than 12% of its total counts within $511\pm 25$ keV and exhibiting a count rate in that energy range five times higher than that typically encountered in the environmental background. We interpret this emission as the possible result of positron annihilation occurring inside the parent thundercloud. Several lightning discharges took place nearby the installation site, with the closest one occurring at less than 500 m from the detectors, just before the onset of the final burst dominated by positron annihilation. Full article

By using both the weak-value formulation as well as the standard probabilistic approach, we analyze Hardy’s experiment introducing a complex and dimensionless parameter ($ϵ$), which eliminates the assumption of complete annihilation when both the electron and the positron departing from a common origin cross the intersection point P. We then find that the paradox does not exist for all the possible values taken by the parameter. The apparent paradox only appears when $ϵ=1$, which is just a singular value. In this paper we demonstrate that this particular value is forbidden inside the scenario proposed by the experiment. Full article

The skew generalized power series ring $R\left[\right[S,\omega \left]\right]$ is a ring construction involving a ring R, a strictly ordered monoid $(S,\le )$, and a monoid homomorphism $\omega :S\to End\left(R\right)$. The ring $R\left[\right[S,\omega \left]\right]$ is a common generalization of ring extensions such as (skew) polynomial rings, (skew) Laurent polynomial rings, (skew) power series rings, (skew) Laurent series rings, (skew) Mal’cev–Neumann series rings, and (skew) monoid rings. In this paper, we study the nilpotent elements of skew generalized power series rings and the relationships between the properties of the rings R and $R\left[\right[S,\omega \left]\right]$ expressed in terms of annihilators, such as weak symmetry, weak zip, and the nil-Armendariz and McCoy properties. We obtain results on transferring the weak symmetry and weak zip properties between the rings R and $R\left[\right[S,\omega \left]\right]$, as well as sufficient and necessary conditions for a ring R to be $(S,\omega )$-nil-Armendariz or linearly $(S,\omega )$-McCoy. Full article

Defect annihilation of the IGZO/SiO₂ layer is of great importance to enhancing the bias stress stabilities of bottom-gate coplanar thin-film transistors (TFTs). The effects of annealing temperatures (T_a) on the structure of the IGZO/SiO₂ layer and the stabilities of coplanar IGZO TFTs were investigated in this work. An atomic depth profile showed that the IGZO/SiO₂ layer included an IGZO layer, an IGZO/SiO₂ interfacial mixing layer, and a SiO₂ layer. Higher T_a had only one effect on the IGZO layer and SiO₂ layer (i.e., strengthening chemical bonds), while it had complex effects on the interfacial mixing layer—including weakening M-O bonds (M: metallic elements in IGZO), strengthening damaged Si-O bonds, and increasing O-related defects (e.g., H₂O). At higher T_a, IGZO TFTs exhibited enhanced positive bias temperature stress (PBTS) stabilities but decreased negative bias temperature stress (NBTS) stabilities. The enhanced PBTS stabilities were correlated with decreased electron traps due to the stronger Si-O bonds near the interfacial layer. The decreased NBTS stabilities were related to increased electron de-trapping from donor-like defects (e.g., weak M-O bonds and H₂O) in the interfacial layer. Our results suggest that although higher T_a annihilated the structural damage at the interface from ion bombardment, it introduced undesirable defects. Therefore, to comprehensively improve electrical stabilities, controlling defect generation (e.g., by using a mild sputtering condition of source/drain electrodes and oxides) was more important than enhancing defect annihilation (e.g., through increasing T_a). Full article

The temperature-dependent intensities of the exciton (X) and biexciton (XX) peaks from single GaAs cone–shell quantum dots (QDs) are studied with micro photoluminescence (PL) at varied excitation power and QD size. The QDs are fabricated by filling self-assembled nanoholes, which are drilled in an AlGaAs barrier by local droplet etching (LDE) during molecular beam epitaxy (MBE). This method allows the fabrication of strain-free QDs with sizes precisely controlled by the amount of material deposited for hole filling. Starting from the base temperature T = 3.2 K of the cryostat, single-dot PL measurements demonstrate a strong enhancement of the exciton emission up to a factor of five with increasing T. Both the maximum exciton intensity and the temperature $T_{x,max}$ of the maximum intensity depend on excitation power and dot size. At an elevated excitation power, $T_{x,max}$ becomes larger than 30 K. This allows an operation using an inexpensive and compact Stirling cryocooler. Above $T_{x,max}$, the exciton intensity decreases strongly until it disappears. The experimental data are quantitatively reproduced by a model which considers the competing processes of exciton generation, annihilation, and recombination. Exciton generation in the QDs is achieved by the sum of direct excitation in the dot, plus additional bulk excitons diffusing from the barrier layers into the dot. The thermally driven bulk-exciton diffusion from the barriers causes the temperature enhancement of the exciton emission. Above $T_{x,max}$, the intensity decreases due to exciton annihilation processes. In comparison to the exciton, the biexciton intensity shows only very weak enhancement, which is attributed to more efficient annihilation processes. Full article

Processes of electron–positron annihilation into a pair of fermions were considered. Forward–backward and left–right asymmetries were studied, taking into account polarization of initial and final particles. Complete 1-loop electroweak radiative corrections were included. A wide energy range including the Z boson peak and higher energies relevant for future $e^{+}{e}^{-}$ colliders was covered. Sensitivity of observable asymmetries to the electroweak mixing angle and fermion weak coupling was discussed. Full article

We introduce the notions of meet, semi-prime, and prime weak closure operations. Using homomorphism of BCK-algebras $\phi :X\to Y$ , we show that every epimorphic image of a non-zeromeet element is also non-zeromeet and, for mapping $c{l}_Y:\mathcal{I}\left(Y\right)\to \mathcal{I}\left(Y\right)$ , we define a map $c{l}_Y^{\leftarrow }$ on $\mathcal{I}\left(X\right)$ by $A\mapsto {\phi }^{-1}\left(\phi {\left(A\right)}^{c{l}_Y}\right).$ We prove that, if “ $c{l}_Y$ ” is a weak closure operation (respectively, semi-prime and meet) on $\mathcal{I}\left(Y\right)$ , then so is “ $c{l}_Y^{\leftarrow }$ ” on $\mathcal{I}\left(X\right)$ . In addition, for mapping $c{l}_X:\mathcal{I}\left(X\right)\to \mathcal{I}\left(X\right)$ , we define a map $c{l}_X^{\to }$ on $\mathcal{I}\left(Y\right)$ as follows: $B\mapsto \phi \left({\phi }^{-1}{\left(B\right)}^{c{l}_X}\right).$ We show that, if “ $c{l}_X$ ” is a weak closure operation (respectively, semi-prime and meet) on $\mathcal{I}\left(X\right)$ , then so is “ $c{l}_X^{\to }$ ” on $\mathcal{I}\left(Y\right)$ . Full article

This paper introduces two new contractive conditions in the setting of non-Archimedean modular spaces, via a C-class function, an altering distance function, and a control function. A non-Archimedean metric modular is shaped as a parameterized family of classical metrics; therefore, for each value of the parameter, the positivity, the symmetry, the triangle inequality, or the continuity is ensured. The main outcomes provide sufficient conditions for the existence of common fixed points for four mappings. Examples are provided in order to prove the usability of the theoretical approach. Moreover, these examples use a non-Archimedean metric modular, which is not convex, making the study of nonconvex modulars more appealing. Full article