Results 1 - 10 of 1252
Results 1 - 10 of 1252. Search took: 0.024 seconds
|Sort by: date | relevance|
[en] Natural SUSY with light, nearly mass-degenerate higgsinos is a theoretically well motivated scenario which would in general escape LHC searches. A high-energy electron-positron collider like the International Linear Collider with a centre-of-mass energy of 500 GeV would provide a clean environment where the higgsinos would be either discovered or excluded. Higgsino pair production has been studied with a detailed simulation of the International Large Detector. It is expected that higgsino masses and polarised cross sections can be measured to the percent-level accuracy. We show that these precise measurements, together with precise measurements of the Higgs, allow determining some of the underlying SUSY parameters with Fittino. In particular the weak scale gaugino mass parameters can be determined. We quantify the possibilities for running the gaugino mass parameters to the GUT scale and for distinguishing between different supersymmetry breaking scenarios. In addition, the properties of some heavy sparticles can be predicted, giving motivation for new high-energy colliders.
[en] Compatible blends of polyvinyl chloride/vulcanized nitrile butadiene rubber, PVC/ NBR, can be readily prepared based on the common polymer polar characters. However, the enhancement of PVC contributes to the aging resistance of NBR and the fact that NBR can act as a permanent plasticizer for PVC deserve progressive evaluation of their composites. Compounding of polyvinyl chloride (PVC)/nitrile butadiene rubber (NBR) at various ratios were produced by melt mixing. Neat PVC and PVC/NBR formulations were then gamma irradiated with the integral doses of 25, 50, 100 and 150kGy. It has been indicated, that radiation- induced microstructural changes were imparted to the pristine and blend formulations. Developed unirradiated and irradiated blends were characterized by various physical, mechanical and thermal investigations: In toluene swelling and, motor and brake oils resistance, tensile strength, elastic modulus and elongation at break and, the rmogravimetric and differential scanning calorimetry analyses. The examinations described distinctive improvement in the blend respective behaviors correlated with the rubbery feed ratio and radiation dose.
[en] El Missikat fluorite-bearing ore material, Eastern Desert, Egypt, has been identified as containing a quantity of heavy rare earth elements (REE) such as yttrium fluorite mineral. Rare earth concentrate prepared from sulfate solution of El Missikat fluorite-bearing ore material assays 0.615% of REE. The solution was prepared from ore material by two subsequent thermal steps namely; fluorine deactivation by MgO and roasting by (NH4)2SO4 .The deactivated roasted matrix was leached with hot distilled H2O to prepare the solution which assays 0.846 g/L of REE. This solution was treated with 20 g of oxalic acid to produce impure RE oxalate cake which was ignited at 950 degree C. It was then dissolved in concentrated HNO3 to prepare the RE nitrate solution for extracting yttrium using tributyl phosphate (TBP) in kerosene. The produced yttrium oxide was of 97.2% purity.
[en] Here, we provide a potential solution to the longstanding problem relating Fermi surface reconstruction to the number of holes contained within the Fermi surface volume in underdoped high Tc superconductors. On considering uniaxial and biaxial charge-density wave order, we show that there exists a relationship between the ordering wave vector, the hole doping, and the cross-sectional area of the reconstructed Fermi surface whose precise form depends on the volume of the starting Fermi surface. We consider a “large” starting Fermi surface comprising 1+p hole carriers, as predicted by band structure calculations, and a “small” starting Fermi surface comprising p hole carriers, as proposed in models in which the Coulomb repulsion remains the dominant energy. Using the reconstructed Fermi surface cross-sectional area obtained in quantum oscillation experiments in YBa2Cu3O6+x and HgBa2CuO4+x and the established methods for estimating the chemical hole doping, we find the ordering vectors obtained from x-ray scattering measurements to show a close correspondence with those expected for the small starting Fermi surface. We therefore show the quantum oscillation frequency and charge-density wave vectors provide accurate estimates for the number of holes contributing to the Fermi surface volume in the pseudogap regime.
[en] The fourth international user workshop focusing on high-power lasers at the Linac Coherent Light Source (LCLS) was held in Menlo Park, CA, USA, on October 3–4, 2016. The workshop was co-organized by Los Alamos National Laboratory and SLAC National Accelerator Laboratory (SLAC), and garnered the attendance of more than 110 scientists. Participants discussed the warm dense matter and high-pressure science that is being conducted using high-power lasers at the LCLS Matter in Extreme Conditions (MEC) endstation. During the past year, there have been seven journal articles published from research at the MEC instrument. Here, the specific topics discussed at this workshop were experimental highlights from the past year, current status and future commissioning of MEC capabilities, and future facility upgrades that will enable the expanded science reach of the facility.
[en] Solar neutrinos interact within double-beta decay (ββ) detectors and contribute to backgrounds for ββ experiments. Background contributions due to solar neutrino interactions with ββ nuclei of 82Se, 100Mo, and 150Nd are evaluated. They are shown to be significant for future high-sensitivity ββ experiments that may search for Majorana neutrino masses in the inverted-hierarchy mass region. In conclusion, the impact of solar neutrino backgrounds and their reduction are discussed for future ββ experiments.
[en] Here, we have measured vibronic emission spectra of an oxide of uranium formed after laser ablation of the metal in gaseous oxygen. Specifically, we have measured the time-dependent relative intensity of a band located at approximately 593.6 nm in 16O2. This band grew in intensity relative to neighboring atomic features as a function time in an oxygen environment but was relatively invariant with time in argon. In addition, we have measured the spectral shift of this band in an 18O2 atmosphere. Based on this shift, and by comparison with earlier results obtained from free-jet expansion and laser excitation, we can confirm that the oxide in question is UO, consistent with recent reports based on laser ablation in 16O2 only.
[en] Here, we investigate the critical Berezinskii-Kosterlitz-Thouless (BKT) behavior of disordered two-dimensional Josephson-junction arrays (JJA) on the insulating side of the superconductor-insulator transition (SIT) taking into account the effect of hitherto ignored residual random dipole moments of the superconducting grains. We show that for weak Josephson coupling the model is equivalent to a Coulomb gas subjected to a disorder potential with logarithmic correlations. We demonstrate that strong enough disorder transforms the BKT divergence of the correlation length, ξBKT ∝ exp (const / √T-TBKT), characterizing the average distance between the unbound topological excitations of the opposite signs, into a more singular Vogel-Fulcher-Tamman (VFT) behavior, ξVFT ∝ exp [const / (T-TVFT)] , which is viewed as a hallmark of glass transitions in glass-forming materials. We further show that the VFT criticality is a precursor of the transition into a nonergodic superinsulating state, while the BKT critical behavior implies freezing into an ergodic confined BKT state. Finally, our finding sheds light on the yet unresolved problem of the origin of the VFT criticality.