Search results for " dar"
showing 10 items of 1907 documents
Extending the DAMA annual-modulation region by inclusion of the uncertainties in astrophysical velocities
1999
The original annual-modulation region, singled out by the DAMA/NaI experiment for direct detection of WIMPs, is extended by taking into account the uncertainties in the galactic astrophysical velocities. Also the effect due to a possible bulk rotation for the dark matter halo is considered. We find that the range for the WIMP mass becomes 30 GeV < m_chi < 130 GeV at 1-sigma C.L. with a further extension in the upper bound, when a possible bulk rotation of the dark matter halo is taken into account. We show that the DAMA results, when interpreted in the framework of the Minimal Supersymmetric extension of the Standard Model, are consistent with a relic neutralino as a dominant componen…
The neutron background of the XENON100 dark matter search experiment
2013
TheXENON100 experiment, installed underground at the LaboratoriNazionali del Gran Sasso, aims to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering off xenon nuclei. This paper presents a study on the nuclear recoil background of the experiment, taking into account neutron backgrounds from (alpha, n) reactions and spontaneous fission due to natural radioactivity in the detector and shield materials, as well as muon-induced neutrons. Based on MonteCarlo simulations and using measured radioactive contaminations of all detector components, we predict the nuclear recoil backgrounds for the WIMP search results published by theXENO…
Supernova bounds on resonant active-sterile neutrino conversions
1997
We discuss the effects of resonant $\nu_e \to \nu_s$ and $\bar{\nu}_e \to \bar{\nu}_s$ ($\nu_s$ is a sterile neutrino) conversions in the dense medium of a supernova. In particular, we assume the sterile neutrino $\nu_s$ to be in the hot dark matter few eV mass range. The implications of such a scenario for the supernova shock re-heating, the detected $\bar\nu_e$ signal from SN1987A and for the r-process nucleosynthesis hypothesis are analysed in some detail. The resulting constraints on mixing and mass difference for the $\nu_e-\nu_s$ system are derived. There is also an allowed region in the neutrino parameter space for which the r-process nucleosynthesis can be enhanced.
In-flight performance of the DAMPE silicon tracker
2018
Abstract DAMPE (DArk Matter Particle Explorer) is a spaceborne high-energy cosmic ray and gamma-ray detector , successfully launched in December 2015. It is designed to probe astroparticle physics in the broad energy range from few GeV to 100 TeV. The scientific goals of DAMPE include the identification of possible signatures of Dark Matter annihilation or decay, the study of the origin and propagation mechanisms of cosmic-ray particles, and gamma-ray astronomy . DAMPE consists of four sub-detectors: a plastic scintillator strip detector, a Silicon–Tungsten tracKer–converter (STK), a BGO calorimeter and a neutron detector . The STK is composed of six double layers of single-sided silicon mi…
Tachyonic production of dark relics : a non-perturbative quantum study
2023
We study production of dark relics during reheating after the end of inflation in a system consisting of a non-minimally coupled spectator scalar field and the inflaton. We derive a set of renormalized quantum transport equations for the one-point function and the two-point function of the spectator field and solve them numerically. We find that our system can embody both tachyonic and parametric instabilities. The former is an expected result due to the non-minimal coupling, but the latter displays new features driven by a novel interplay of the two-point function with the Ricci scalar. We find that when the parametric instability driven by the two-point function takes place, it dominates …
A mechanical picture of fractional-order Darcy equation
2015
Abstract In this paper the authors show that fractional-order force-flux relations are obtained considering the flux of a viscous fluid across an elastic porous media. Indeed the one-dimensional fluid mass transport in an unbounded porous media with power-law variation of geometrical and physical properties yields a fractional-order relation among the ingoing flux and the applied pressure to the control section. As a power-law decay of the physical properties from the control section is considered, then the flux is related to a Caputo fractional derivative of the pressure of order 0 ⩽ β ≤ 1 . If, instead, the physical properties of the media show a power-law increase from the control sectio…
Organizācijas kultūra attālinātā darba formātā uzņēmumā SIA „Euroaptieka”
2022
Bakalaura darba tēma ir organizācijas kultūra attālinātā darba formātā uzņēmumā SIA „Euroaptieka”. Darba mērķis ir izstrādāt uzņēmuma SIA „Euroaptieka” organizācijas kultūras pilnveides pasākumus darbam attālinātā formātā, lai sasniegtu šo mērķi tika izvirzīti šādi uzdevumi - pamatojoties uz zinātnisko literatūru, novērtēt organizācijas kultūru; noskaidrot attālinātā darba formāta; raksturot uzņēmumu SIA „Euroaptieka” esošos procesus; izmantojot OCAI - Organizācijas kultūras vērtēšanas instrumentu, izvērtēt darbinieku viedokļus par esošo un vēlamo organizācijas kultūru; analizēt iegūtos aptauju rezultātus un izdarīt secinājumus; veikt secinājumus un izstrādāt priekšlikumus, lai uzlabotu org…
Seawater carbonate chemistry and kelp densities and coral coverages at three study locations and photosynthesis and calcification of corals measured …
2021
Ocean warming is altering the biogeographical distribution of marine organisms. In the tropics, rising sea surface temperatures are restructuring coral reef communities with sensitive species being lost. At the biogeographical divide between temperate and tropical communities, warming is causing macroalgal forest loss and the spread of tropical corals, fishes and other species, termed “tropicalization”. A lack of field research into the combined effects of warming and ocean acidification means there is a gap in our ability to understand and plan for changes in coastal ecosystems. Here, we focus on the tropicalization trajectory of temperate marine ecosystems becoming coral-dominated systems…
Direktīvas 2004/35/EK ieviešanas problēmas Latvijā: fizisko personu un operatora atbildības praktiskie aspekti un būtiskuma slieksnis
2019
Ņemot vērā vides atbildības korektas piemērošanas nozīmi mūsdienu situācijā, darba mērķis ir izvērtēt Direktīvas 2004/35/EK ieviešanas problemātiku Latvijā saistībā ar atbildības subjektu un būtiskuma slieksni. Tādējādi darba uzdevums ir sākotnēji izpētīt Direktīvas 2004/35/EK izpratni Latvijas tiesību sistēmā, analizējot tās materiāltiesisko, personu un laika tvēruma robežas. Tālākajā darba gaitā tiek aplūkoti ar direktīvu ieviestie jauninājumi Latvijas vides tiesību jomā salīdzinājumā ar iepriekš pastāvošo regulējumu. Darba praktiskajā daļā tiek turpmāk izvērsta operatora tiesiskā regulējuma attiecināšana uz fizisku personu, kā arī būtiskuma sliekšņa problemātika. Secināms, ka Latvija dir…
Pseudo-Abelian integrals along Darboux cycles
2008
We study polynomial perturbations of integrable, non-Hamiltonian system with first integral of Darboux-type with positive exponents. We assume that the unperturbed system admits a period annulus. The linear part of the Poincare return map is given by pseudo-Abelian integrals. In this paper we investigate analytic properties of these integrals. We prove that iterated variations of these integrals vanish identically. Using this relation we prove that the number of zeros of these integrals is locally uniformly bounded under generic hypothesis. This is a generic analog of the Varchenko-Khovanskii theorem for pseudo-Abelian integrals. Finally, under some arithmetic properties of exponents, the p…