Measurement of the high energyγ-rays from heavy ion reactions usingČerenkov detector

The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collecting the Čerenkov light in the medium induced by the fast electrons generated in the Compton scattering or electromagnetic shower of the incident γray. Two types of detectors based on pure water and lead glass as sensitive materials were designed for this purpose. The γresponse and optical photon propagation in the detectors were simulated based on electromagnetic and optical processes in Geant4. The inherent energy resolutions of 0.022(4) + 0.51(2)∕E^(1/2)_(γ) for water and 0.0026(3) + 0.446(3)∕E^(1/2)_(γ) for lead glass were obtained. The geometry sizes of the lead glass and water were optimized to 30 cm × 30 cm × 30 cm and 60 cm × 60 cm ×120 cm, respectively, to detect high-energy γ-rays at 160 MeV. The Hough transform method was applied to reconstruct the direction of the incident γ-rays, providing the ability to experimentally distinguish the high-energy γ-rays produced in the reactions on the target from random background cosmic-ray muons.

Effects of Electrically Inert Fillers on the Properties of Poly(m-xylene adipamide)/Multiwalled Carbon Nanotube Composites

The effects of three types of electrically-inert fillers, calcium carbonate(CaCO_3), talc and glass fiber(GF), on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly(m-xylene adipamide)(MXD6)/multiwalled carbon nanotube(MWCNT) composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO_3, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.

Flotation separation of spodumene and albite with activation of calcium ion hydrolysate components

It is difficult to separate spodumene and albite by flotation with calcium ion as activator.In this study,microflotation experiment,solution chemistry calculation,density functional theory(DFT)calculation and X-ray photoelectron spectroscopy(XPS)analysis were conducted to investigate the effect mechanism of c alcium hydrolysate on the flotation separation of spodumene and albite.Results show that the weak interaction intensity of Ca^(2+)with O atoms on the mineral surface makes it difficult to activate minerals effectively.The O atom in the hydroxyl group of Ca(OH)^(+)and Ca(OH)_(2)can be strongly bonded with Al atom on the mineral surface,which greatly improves the adsorption strength.After the activation of Ca(OH)^(+),the adsorption forms of collectors on the surface of spodumene and albite are quite different,and the adsorption intensity on the surface of spodumene is higher,which is conducive to the flotation separation of spodumene and albite.After the action of Ca(OH)_(2),the adsorption of the collector on the albite surface is stronger than that of spodumene,which is not conducive to the flotation separation of the two minerals.By adjusting the initial concentration of calcium ions and pulp pH,Ca(OH)^(+)is the main active component,which is the key to improve the separation effect of spodumene and albite.