A study of Channeling, Volume Reflection and Volume Capture of 3.35-14.0 GeV Electrons in a bent Silicon Crystal

We present the experimental data and analysis of experiments conducted at SLAC National Accelerator Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the (111) plane in a strongly bent quasi-mosaic silicon crystal. These phenomena were investigated at 5 energies: 3.35, 4.2, 6.3, 10.5 and 14.0 GeV with a crystal with bending radius of 0.15m, corresponding to curvatures of 0.070, 0.088, 0.13, 0.22 and 0.29 times the critical curvature respectively. Based on the parameters of fitting functions we have extracted important parameters describing the channeling process such as the dechanneling length, the angle of volume reflection, the surface transmission and the widths of the distribution of channeled particles parallel and orthogonal to the plane

Proper land use for heavy metal-polluted soil based on enzyme activity analysis around a Pb-Zn mine in Feng County, China

Enzymes in the soil are useful for assessing heavy metal soil pollution. We analyzed the activity of a number of enzymes, including urease, protease, catalase, and alkaline phosphatase, in three types of land (farmland, woodland, and grassland) to evaluate soil pollution by heavy metals (Pb, Zn, and Cd). Our results showed that the tested soil was polluted by a combination of Pb, Zn, and Cd, but the primary pollutant was Cd. An ecological dose analysis demonstrated that urease was the most sensitive enzyme to Pb and Cd in the farmland, and catalase and phosphatase were the most sensitive enzymes to Pb, Zn, and Cd in the woodland and grassland. The ecological risk of Cd (E (Cd) ) was the smallest in all three types of land, suggesting that Cd was the major metal inhibiting enzyme activity. Electrical conductivity (EC) was shown to be a negative regulator, while nitrogen, phosphorus, and clay contents were positive regulators of soil enzyme activity. The total enzyme index (TEI) inhibition rates in the woodland were 22.2 and 38.6% under moderate and heavy pollution, respectively, which were lower than those of the other two types of land. Therefore, woodlands might be the optimum land use choice in relieving heavy metal pollution. Taken together, this study identified the key metal pollutant inhibiting soil enzyme activity and suitable land use patterns around typical metal mine. These results provide possible improvement strategies to the phytomanagement of metal-contaminated land around world