Shields

About: Shields is a research topic. Over the lifetime, 1456 publications have been published within this topic receiving 10896 citations.

Radiation shielded electron discharge device

Abstract: An electron discharge device is provided with shields to protect against inadvertent emission of penetrating electromagnetic radiation. The positions and mounting of the shields is designed to provide shielding in all directions which is relatively undefeatable by inadvertent tampering by the user.

Performances investigation and material selection of PMT magnetic shields for the space experiments with GRIS and PING-M instruments

Abstract: PMT performances significantly change under the influence of magnetic field. Even the relatively weak geomagnetic field, which typically value is about 0.5 gauss, has an appreciable effect. Gain variations of PMT with 76 mm photocathode diameter may reach 10-20% depending on spatial orientation. Therefore, it is necessary to apply magnetic shields for PMT response stability enhancement. The performances investigation of magnetic shields made of steel, permalloy and amorphous metallic alloy ribbon for PMT with 51 and 76 mm photocathode diameters was carried out. Based on obtained data the choice of magnetic shield was made.

Magnetic shielding in a low-temperature torsion pendulum experiment.

Abstract: A new type of ether drift experiment searches for anomalous torques on a permanent magnet. A torsion pendulum is used at liquid helium temperature, so that superconducting cylinders can be used to shield magnetic fields. Lead shields attenuate the earth's field, while Nb-Sn shields fastened to the pendulum contain the fields of the magnet. The paper describes the technique by which the earth's field can be reduced below 0.0001 G while simultaneously the moment of the magnet can be reduced by a factor 7 x 10 to the 4th.

Fast Burst Reactor Neutron Damage in Silicon Transistors

Abstract: An experiment was performed to assess the magnitude of the differences in neutron damage to silicon transistors under various conditions encountered in fast burst reactor testing. Transistors were subjected to free-field pulse and free-field power run exposures, and to exposures shielded by lead and by paraffin. These tests provided data to compare to damage results obtained under routine test conditions, i.e., relatively unperturbed field but with the experiment table in place. Fission foils and an activation foil were exposed with each group of transistors. The objectives of the experiment were: 1) to determine if perturbations in the reactor testing environment would produce measurable differences in the relative damage in silicon transistors--greater than the statistical variations characteristics of the test groups, and 2) to determine if the observed differences in damage could be correlated with the results of fission and activation foil neutron fluence measurements. Neutron exposures were performed at the White Sands Missile Range (WSMR) Fast Burst Reactor (FBR). Thin fission foils were exposed adjacent to lexan plastic discs to record the resulting fission tracks. The fission foils were exposed inside cadmium shields which were placed inside 10B shields. Sulfur pellets were exposed both inside and outside the boron shields. The fission track and sulfur counter data were evaluated using techniques similar to those specified in ASTM standard procedures. Relative silicon damage measurements were obtained by exposing groups of carefully characterized transistors.

Analysis of Attenuation Effect of Grid-Like Spatial Shields Used in Lightning Protection of Buildings

Abstract: A frequency-domain-based electromagnetic model of the lightning protection system of buildings is presented in this paper. Numerical model can accurately take into account all conductors of the lightning protection system, i.e., air-termination system, down-conductor system and earthtermination system. Using the presented electromagnetic model, attenuation effects of a grid-like spatial shield — sometimes used in lightning protection of buildings — will be analyzed for both the electric field and the magnetic field caused by a lightning strike. Three-dimensional distributions of the fields inside the shield are provided in the paper.