Showing papers on "Shields published in 2000"

Electric module structure formed with a polymer shrunk material

Abstract: A microelectric module including a circuit substrate having one or more covers or electromagnetic shields disposed thereon. To secure the covers or electromagnetic shields to the circuit substrate, and provide an electrical contact with an underlying ground pattern, a thin plastic film is extended over the covers or electromagnetic shields and the circuit substrate. This film is subjected to heat, causing it to shrink and effectively provide a controlled force that acts to hold and lock the covers or electromagnetic shields to the circuit substrate. Thus the heat-shrunk film mechanically secures the covers or electromagnetic shields to the circuit substrate and at the same time seals the microelectric module formed.

Dual spin valve CPP MR with flux guide between free layers thereof

Abstract: A current perpendicular-to-the-plane magnetoresistance (CPP-MR) device includes a first magnetic shield, a second magnetic shield, and a spin valve structure. The first and second magnetic shields are formed of an electrically conductive and magnetically shielding material. A read gap is defined between the first and second magnetic shields, and the spin valve structure is disposed between the first and second magnetic shields. The spin valve structure is electrically connected and magnetically separated from the first and second magnetic shields such that the first and second magnetic shields act as electrical contact leads.

Formulas Giving Buildup Factor for Double-Layered Shields

Abstract: Formulas that give absorbed dose buildup factors for two-layered shields have been developed based on gamma-ray absorption buildup factors computed with the Monte Carlo Neutral Particle Transport Code System (MCNP). The shielding materials considered were water, lead, steel, concrete, and some of their combinations for two-layered shields with thicknesses between 1 to 10 mfp. Gamma energy considered ranged from 0.5 to 6 MeV. The formulas reproduce MCNP results with a difference of <10%, in most cases <3%.

Apparatus for local reduction of electromagnetic field using an active shield and method thereof

Abstract: An apparatus and method for shielding an operator from electromagnetic fields emitted from an antenna in a portable communication device. A plurality of active shields are placed between the operator's earpiece and the antenna to dampen the effects of the electromagentic fields. The active shields are coupled to adjustment circuits which may include variable gain amplifiers and phase couplers to offset the antenna signal.

Development of a High Performance Transfer Line System

Abstract: High performance transfer lines are key components for design and construction of cryogenic systems for superconducting magnets and cavities. We have developed two types of high performance transfer lines; main transfer lines with liquid helium flow and cold gas return dual path and sub-transfer line with single path, all helium lines in these are guarded by 80K liquid nitrogen cooled thermal shields. We have adopted the aluminum molding made by extrusion for the 80K thermal shields. The structure of the transfer lines was designed to be easy to assemble. The performance of these transfer lines were tested. The heat loss of the main transfer lines at straight section are 0.04W/m and 0.06W/m for supply and return line, respectively.

General Formalism for Calculating Gamma-Ray Buildup Factors in Multilayer Shields into MERCURE-6 Code

Abstract: This study proposes a new method for calculating gamma-ray buildup factors in multilayer shields. The formula combines the buildup of single-layer shields with products and quotients. The tests have shown that the approximating formula reproduces the reference data of double layer shields very well for most cases. With the same parameters and with a new physical consideration that takes into account in a global way the degradation of the gamma-ray energy spectrum, the buildup factors of three and five layer shields were also very well reproduced. The new formula is incorporated in the new version of the MERCURE-6 point-kernel code.

Radiation Shielding and Protection of the European Spallation Neutron Source (ESS)

Abstract: The shielding and the radiation protection of high intensity spallation neutron sources as ESS has special features and importance compared to usual accelerator shielding and protection considerations. For the shielding we are interested in very thick shields, so small uncertainties e.g. in cross sections lead to large errors; we are interested in detailed predictions, such as accurate particle spectra over large energy ranges, and the geometries of interest are complex, e.g. shields with multiple beam holes. Containment of radioactivity for the high power target station is also a very important issue and has highest hazard. The different methods, which are used for designing the ESS shielding, are discussed. Comparison with performed measurements is also given.

Laboratory tests on neutron shields for gamma-ray detectors in space

Abstract: Shields capable of suppressing neutron-induced background in new classes of c-ray detectors such as CdZnTe are becoming important for a variety of reasons. These include a high cross section for neutron interactions in new classes of detector materials as well as the ine$cient vetoing of neutron-induced background in conventional active shields. We have previously demonstrated through Monte-Carlo simulations how our new approach, supershields, is superior to the monolithic, bi-atomic neutron shields which have been developed in the past. We report here on the "rst prototype models for supershields based on boron and hydrogen. We verify the performance of these supershields through laboratory experiments. These experimental results, as well as measurements of conventional monolithic neutron shields, are shown to be consistent with Monte-Carlo simulations. We discuss the implications of this experiment for designs of supershields in general and their application to future hard X-ray/c-ray experiments. ( 2000 Elsevier Science B.V. All rights reserved.

Kabelschirm aus Faserverbundwerkstoffen mit hohem Anteil an elektrisch leitfähigen Fasern zur elektromagnetischen Abschirmung

Abstract: The invention relates to a device for electromagnetically shielding any kind of electrical conductors (e.g. component conductors, conductor bundles and coaxial cables). The main advantage in comparison with the shields used so far is a significant reduction in weight and an improved damping in the high MHz range. This is achieved by using materials (e.g. carbon fibres) as shields, whereby said materials are provided with an essentially lower conductivity than metal shields. Even metal shields are not damped in the lower frequency range, the existing conductivity in the higher frequency range (> 1 MHz), however, is high enough to attain the transfer impedance values of metal shields due to the fact that inductive and capacitive losses are less important, whereby said effect is utilised. Another advantage of the invention is that the shield is not affected by corrosion and can be produced in a substantially easier manner in relation to metallic conductive shields. The invention can be especially be used as cabling in aircrafts and motor vehicles requiring weight-reducing solutions.

An Improved Approximation Formula of Gamma-Ray Buildup Factors for a Point Isotropic Source in Two-Layer Shields

Abstract: An approximation formula of buildup factor for two-layer shields proposed previously was improved to fitting to the newly calculated buildup factors for point isotropic source gamma-rays of 0.1, 0.3, 0.6, 1,3,6 and 10 MeV penetrating two-layer shields combinations of water, iron or lead materials with the Monte Carlo code EGS4 included the effects of Bremsstrahlung and fluorescent radiations. A f-function in the formula was modified to reproduce precisely the reference data up to the total thickness 40 mfp and the value of buildup factor at the interface of two-layer shields. The functions α and β used in improved f-function f(x1,x2) = α(x1)/{α(x1)+B2(x1)*β(x1,x2)x2} were represented by simple formula fitted to reference data in excellent agreement. Consequently, the two-layer shields buildup factor for any arbitrary thickness of the first-layer x1, and the second-layer x2, and for arbitrary source energy can easily be estimated by interpolation of functions α and β with respect to energy.

Current perpendicular-to-the-plane magnetoresistive spin-value type read heads having a flux guide and common shields and leads

Abstract: A current perpendicular-to-the-plane magnetoresistance (CPP-MR) device includes a first magnetic shield, a second magnetic shield, and a spin valve structure. The first and second magnetic shields are formed of an electrically conductive and magnetically shielding material. A read gap is defined between the first and second magnetic shields, and the spin valve structure is disposed between the first and second magnetic shields. The spin valve structure is electrically connected and magnetically separated from the first and second magnetic shields such that the first and second magnetic shields act as electrical contact leads.

Cable shield made of fibre reinforced material

Abstract: The invention relates to a device for electromagnetically shielding any kind of electrical conductors (e.g. component conductors, conductor bundles and coaxial cables). The main advantage in comparison with the shields used so far is a significant reduction in weight and an improved damping in the high MHz range. This is achieved by using materials (e.g. carbon fibres) as shields, whereby said materials are provided with an essentially lower conductivity than metal shields. Even metal shields are not damped in the lower frequency range, the existing conductivity in the higher frequency range (⊃ 1 MHz), however, is high enough to attain the transfer impedance values of metal shields due to the fact that inductive and capacitive losses are less important, whereby said effect is utilised. Another advantage of the invention is that the shield is not affected by corrosion and can be produced in a substantially easier manner in relation to metallic conductive shields. The invention can be especially be used as cabling in aircrafts and motor vehicles requiring weight-reducing solutions.

Magnet device and magnetic resonance imaging apparatus using the same

Abstract: PROBLEM TO BE SOLVED: To reduce asymmetry of eddy current caused by a connecting section in a superconductive magnet device in which upper and lower vacuum tubes are connected by a connecting tube. SOLUTION: The upper and lower vacuum tubes 9 and the connecting tube 24 connecting the vacuum tubes are made of materials with high electric resistance. A magnetic flux generated by a gradient magnet field coil is allowed to reach a pair of upper and lower secondary thermal shields 8 and a connective tube 23 that connects the upper and lower secondary thermal shields 8. A vertical slit 41 is located at the connective tube 23 connecting the upper and lower secondary thermal shields 8 so as to prevent the eddy current from flowing. As a result, the asymmetry of the eddy current occurring at the section of the connective tube 23 is reduced.

Shielding structure for circuit board, and shielded circuit-board assembly

Abstract: PROBLEM TO BE SOLVED: To achieve the high separability of signals from each other with the more reduced assembling time and manufacturing cost of a shielded circuit-board assembly, by making the first and second previously deformed surfaces of respective conductive shields consistent surfaces with the first and second surfaces of a circuit board. SOLUTION: Each of conductive shields 11a, 11b has such a profiled coupling surface as to become flat or the consistent surface with the surface of a circuit board 16 in the interface between it and the circuit board 16, when the conductive shields 11a, 11b are secured on both the surfaces of the circuit board 16. The special profiles of these coupling surfaces compensate the deformations of the respective shields 11a, 11b even when respective securing places 14 of the coupling surfaces are provided at intermittent pitches. When a plurality of compressive and conductive gaskets 15a, 15b are interposed between the conductive shields 11a, 11b and the circuit board 16, respective abutting portions 19 are provided to receive the thicknesses of the gaskets 15a, 15b. As a result, a high separability of signals from each other is achieved to achieve the more reduced assembling time and manufacturing cost of a shielded circuit- board assembly.

Hot air body drier

Abstract: A hot air body drier comprises an array of electric fans 1 with heater wires 2 and protective shields 5 mounted on a stand 3.

Multi-fuel kick back receiver

Abstract: A device for the retention of multi-fuels which may be built in or used in a portable mode. It will seal at the top of the fuel fillpipe and allow for the insertion of a utility hose nozzle into the top of the fuel fillpipe. When fluid comes out of the fillpipe, it will be contained by deflection shields while still allowing air to escape due to the arrangement of the shields and basin.

Shield to prevent electrostatic discharge and electromagnetic and radio frequency interference

Abstract: Shields providing protection from electrostatic discharge, electromagnetic interference and radio frequency interference provide effective shielding of susceptible portions of slot machines, video games, pinball machines and other electronic amusement devices. The shields are cost-effective and permit high visible light transmissivity for high-quality backlit graphical images. They are easily installed using semi-permanent adhesive that allows the shields to be removed if necessary for servicing, or to remain in place permanently. ITO-coated polyester provides a clear conductor and, with proper grounding, is used to create an effective ESD shield. Shields preferably include a silver conductive trace at the perimeter to create a Faraday cage that effectively traps RFI.

Nomograms for designing shields against direct X-rays

Abstract: Revised nomograms for calculating thicknesses of shields against direct X-rays emitted at voltages of 75 to 450 kV are given. The nomograms have been obtained for the most common shielding materials, such as lead, iron, and concrete, with due account of accurately measured spectra of primary radiation from the source, contribution of the secondary radiation, and recently introduced NRB-96 regulations of radiation safety.

Method and apparatus for directional well logging using an electromagnetic shield

Abstract: Directional measurements of earth formations surrounding a borehole may be achieved by using an antenna coil shield (16) to provide selective attenuation of at least one electromagnetic energy field component as the component interacts with the shield. The shields are implemented in several downhole tool configurations to shield transmission and/or receiving coils to provide azimuthally focussed formation measurements by filtering electromagnetic energy field components to pass those components corresponding to a magnetic dipole oriented at an angle from the tool axis. The shields alter a coil envelope of influence to electromagnetic energy and are formed of a conductive material with sloped slots therein or are formed from a sloped conductive element. The shields may be used in a system for making directional measurements while drilling.