Search results for "Particle"

Thermoelectric radiation detector based on a superconductor-ferromagnet junction : Calorimetric regime

2018

We study the use of a thermoelectric junction as a thermal radiation detector in the calorimetric regime, where single radiation bursts can be separated in time domain. We focus especially on the case of a large thermoelectric figure of merit ZT affecting significantly, for example, the relevant thermal time scales. This work is motivated by the use of hybrid superconductor/ferromagnet systems in creating an unprecedentedly high low-temperature ZT even exceeding unity. Besides constructing a very general noise model which takes into account cross correlations between charge and heat noise, we show how the detector signal can be efficiently multiplexed by the use of resonant LC circuits givi…

Observational constraints on the modelling of SN 1006

2011

Supersymmetric technicolor

2011

In this thesis, we consider a supersymmetrized version of the Standard Model extended with a technicolor sector. We specialize in the regime of the model in which the technicolor sector is fully responsible of the electroweak symmetry breaking and the natural elementary Higgses of the supersymmetric model only transmit the breaking to the Standard Model fermions, thereby giving them masses. In particular, we consider the vacuum structure of the effective theory, find it to be different to that of a mere technicolor model and study the contributions of the new sector to the oblique electroweak parameters. Relative to the current experimental limits, we find the model viable.

Shell-model study on event rates of lightest supersymmetric particles scattering off 83Kr and 125Te

2016

We investigate the elastic and inelastic scattering of lightest supersymmetric particle (LSP) dark matter off two possible target nuclei, 83Kr and 125Te. For the nuclear-structure calculations, we employ the nuclear shell model using recently generated realistic interactions. We have condensed the nuclear-physics contribution to a set of nuclear-structure factors that are independent of the adopted supersymmetric (SUSY) model. Total event rates are then easily calculated by combining the nuclear-structure factors with SUSY parameters of choice. In particular, 125Te shows promise as a detector material with both the elastic and inelastic channels yielding an appreciable nuclear response. pee…

Global analysis of the pMSSM in light of the Fermi GeV excess: prospects for the LHC Run-II and astroparticle experiments

2016

We present a new global fit of the 19-dimensional phenomenological Minimal Supersymmetric Standard Model (pMSSM-19) that comply with all the latest experimental results from dark matter indirect, direct and accelerator dark matter searches. We show that the model provides a satisfactory explanation of the excess of gamma-rays from the Galactic centre observed by the Fermi~Large Area Telescope, assuming that it is produced by the annihilation of neutralinos in the Milky Way halo. We identify two regions that pass all the constraints: the first corresponds to neutralinos with a mass ~80-100 GeV annihilating into WW with a branching ratio of 95% ; the second to heavier neutralinos, with mass ~…

Field dependence of the vortex-core sizes in dirty two-band superconductors

2019

We study the structure of Abrikosov vortices in two-band superconductors for different external magnetic fields and different parameters of the bands. The vortex core size determined by the coherence lengths are found to have qualitatively different behaviour from that determined by the quasiparticle density of states spatial variation. These different vortex core length scales coincide near the upper critical field, while the discrepancy between them becomes quite significant at lower fields. Within the diffusive approximation we demonstrate several generic regimes in the field dependence of the vortex core sizes determined by the disparity of diffusion constants in the two bands.

Antibacterial Activity of Positively and Negatively Charged Hematite (α-Fe2O3) Nanoparticles to Escherichia coli, Staphylococcus aureus and Vibrio fi…

2021

This research and work has been supported by the European Regional Development Fund within the Activity 1.1.1.2 “Post-doctoral Research Aid” of the Specific Aid Objective 1.1.1 (i.e., “to increase the research and innovative capacity of scientific institutions of Latvia and the ability to attract external financing, investing in human resources and infrastructure”) of the Operational Programme “Growth and Employment” (No. 1.1.1.2/VIAA/2/18/331).

[Ag67(SPhMe2)32(PPh3)8]3+: Synthesis, Total Structure, and Optical Properties of a Large Box-Shaped Silver Nanocluster

2016

Engineering the surface ligands of metal nanoparticles is critical in designing unique arrangements of metal atoms. Here, we report the synthesis and total structure determination of a large box-shaped Ag67 nanocluster (NC) protected by a mixed shell of thiolate (2,4-dimethylbenzenethiolate, SPhMe2) and phosphine (triphenylphosphine, PPh3) ligands. Single crystal X-ray diffraction (SCXRD) and electrospray ionization mass spectrometry (ESI-MS) revealed the cluster formula to be [Ag67(SPhMe2)32(PPh3)8]3+. The crystal structure shows an Ag23 metal core covered by a layer of Ag44S32P8 arranged in the shape of a box. The Ag23 core was formed through an unprecedented centered cuboctahedron, i.e.,…

UV-VISIBLE LUMINESCENCE OF SILICA NANOPARTICLES

Particle tracking in a gap of aquatic vegetation meadow

2009

Aquatic vegetation considerably affects the flow field in water bodies, with influence increasing as the depth decreases. As a consequence, vegetation also affects suspended particle transport. In inshore sandy beds less than 40 m deep of the Mediterranean Sea, meadows of Posidonia oceanica are widespread. This plant is constituted by a tuft of very thin and flexible ribbon-like leaves about 1 cm wide and up to 1.5 m long; the meadow areal density can reach 1000-1200 plant/m2. Frequently, such meadows are not continuous but vegetated areas alternate with sand strips (“gaps”). The presence of such discontinuities noticeably affects the flow field and gaps can actually act as particle traps. …