Features of the optical medium of the surface of plant seeds

It was found that the integumentary tissue of plant seeds has the property of enhancing luminescence light. This phenomenon manifests itself in both the time and frequency domain. The gain factor (in power), depending on the type of seed, varies from 1.7 (beans) to 2.6 (rye). To determine it, the optical medium of the plant seed surface was represented as a dynamic link having an input and output. The impulse (time) characteristic of the link was found by the relaxation curve of luminescence. The dependence of the gain on temperature is expressed in the fact that when it decreases from 50 oC to –30 oC, the gain increases from 1.73 to 2.48. This phenomenon can be explained by the fact that at the stage of relaxation of luminescence, the absorption coefficient of the optical medium of the seed surface takes a negative value

Mixed ZnSxSe1–x Crystals as a Possible Material for Alpha-Particle and X-ray Detectors

A possibility to use ZnSxSe1−x as a material for the detection of X-rays and alpha particles has been studied. The influence of the sulfur content on the properties of bulk ZnSxSe1−x crystals is analyzed. Six specimens with different component contents were grown, by using the Bridgman–Stockbarger method: ZnS0.07Se0.93, ZnS0.15Se0.85, ZnS0.22Se0.78, ZnS0.28Se0.72, ZnS0.32Se0.68, and ZnS0.39Se0.61. The intensity of X-ray luminescence spectra of ZnSxSe1−x crystals is found to increase with the sulfur content and reaches a maximum for the composition ZnS0.22Se0.78. The luminescence light yield of mixed ZnSxSe1−x crystals is higher than that of commercial ZnSe(Te) and ZnSe(Al) crystals. The advantages of mixed crystals based onZnSxSe1−x over the ZnS(Te) and ZnSe(Al) crystals have been discussed.

Ongoing magnetic monopole searches with IceCube

The IceCube collaboration has instrumented a cubic kilometer of ice with 5160 photo-multipliers. While mainly developed to detect Cherenkov light, any visible light can be used to detect particles within the ice. Magnetic monopoles are hypothetical particles predicted by many theories that extend the Standard model of Particle Physics. They are carriers of a single elementary magnetic charge. For this particle, different light production mechanisms dominate from direct Cherenkov light at highly relativistic velocities (> 0:76 c), indirect Cherenkov light at mildly relativistic velocities (> 0:5 c to 0:76 c), luminescence light at low relativistic velocities (≳ 0:1 c to 0:5 c), as well as catalysis of proton decay at non relativistic velocities (≲ 0:1 c). For each of this speed ranges, searches for magnetic monopoles at the IceCube experiment are either in progress or they have already set the worlds best limits on the flux of magnetic monopoles. A summary of these searches will be presented, outlining already existing results as well as methods used by the currently conducted searches.

Influence of Fine-Dispersed Dielectric Particles on Dye Luminescence in a Polymer Matrix

The behaviour of the luminescence spectra of the organic dye R6G in a multiple scattering polymer matrix was studied with reference to the parameters of the scattering media. It was found that some of the luminescent parameters depend on the concentration of scattering particles, the refractive index of the scattering particles and the sample thickness. As it was shown, that the reason for these dependences is the reabsorption of luminescence light enhanced by multiple light scattering. In addition, an increase in the absorption caused by multiple scattering was observed.