نتایج جستجو برای: paramagnetic shielding

تعداد نتایج: 19572  

1999
Gregory H. Canavan

This report estimates the impact of Raman restrictions and shielding penalties separately and together. Its goal is an overall assessment of likely impact rather than a review of the details of missile trajectories, Raman physics, and shielding techniques, whose individual treatments matter less than their overall integration. Raman scattering could produce a factor of 23 reduction on the perfo...

2011
C Dharma Raj D Vijaya Saradhi Chandra Sekhar

Electromagnetic shield made up of single conductor layer of chosen thickness and conducting material can be designed to achieve required shielding performance . This single conductor layer electromagnetic shield would be bulky and occupy more volume when the size of the electronic circuit is shrinking with the advent of microelectronic technologies. In order to optimize the thickness of the ele...

1979
David J. Frankel

Experiments have been carried out on the flux trapping and shielding capabilities of tubular superconductors in transverse dipole and quadrupole fields. Field profile measurements are reported for tubes of vapor-deposited Nb,Sn and samples assembled from spirally wound strips of Nb-Ti/Cu sheet composite. The flux trapping and shielding process is modeled by assuming that critical state currents...

Journal: :Journal of computational chemistry 2009
Inmaculada García Cuesta Alfredo M. J. Sánchez De Merás Stefano Pelloni Paolo Lazzeretti

The local response to an external magnetic field normal to the molecular plane of naphthalene and anthracene was investigated via current density and magnetic shielding density maps. The Biot-Savart law shows that the deshielding caused by pi-ring currents in naphthalene is stronger for alpha- than for beta-protons due to geometrical factors. The shielding tensor of the carbon nuclei in both mo...

Journal: :Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine 2001
I F Gonçalves E Martinho J Salgado

Epithermal neutron resonance self-shielding factors in foils of materials used as activation detectors or as targets for radionuclide production have been calculated using the MCNP code. Two irradiation conditions have been considered: (a) foils immersed into an isotropic neutron flux and (b) foils submitted to a collimated neutron beam. The self-shielding factors, Gres(t), for gold, indium, ma...

Journal: :iranian journal of radiation research 0
a. aghaz nuclear engineering department, shiraz university, shiraz, iran r. faghihi nuclear engineering department, shiraz university, shiraz, iran s.m.j. mortazavi medical physics department and the center for research on radiological sciences, shiraz university of medical sciences, shiraz, iran a. haghparast medical physics department, kermanshah university of medical sciences, kermanshah, iran s. mehdizadeh radiation research center, shiraz university, shiraz, iran s. sina radiation research center, shiraz university, shiraz, iran

background: it has recently been shown that the particle size of materials used for radiation shielding can affect the magnitude of radiation attenuation. over the past years, application of nano-structured materials in radiation shielding has attracted attention world-wide. the purpose of this study was to investigate the shielding properties of the lead-free shields containing micro and nano-...

Journal: :iranian journal of radiation research 0
s.m.j. mortazavi department of radiology, school of paramedical sciences, shiraz university of medical sciences, shiraz, iran m.a. mosleh-shirazi radiotherapy physics unit, radiotherapy department, namazee hospital, shiraz university of medical sciences, shiraz, iran m.r. maheri civil engineering department, school of engineering, shiraz university, shiraz, iran h. yousefnia department of nuclear engineering, school of engineering, shiraz university of medical sciences, shiraz, iran s. zolghadri department of nuclear engineering, school of engineering, shiraz university of medical sciences, shiraz, iran a. haji-pour civil engineering department, school of engineering, shiraz university, shiraz, iran

background: in megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. the use of high-density concrete decreases the required thickness of the concrete barrier hence, its disadvantage is its high cost. in a nuclear reactor, neutron radiation is the most difficult to shield. a method for p...

Journal: :journal of physical & theoretical chemistry 2008
m. monajjemi r. zhiani h. h. haeri f. mollaamin

polycyclic aromatic hydrocarbons (pahs) are a class of compounds consisting of more than twobenzene rings fused in a linear, angular, or clustered arrangement and do not contain hetero atomsor carry subsistent. pahs originate from various sources. they are primarily formed byincomplete combustion of carbon-containing fuels such as wood, coal, diesel, fat, or tobacco. thepresent study reports an...

Journal: :journal of physical and theoretical chemistry 0
neda ahmadinejad young research arezoo tahan 2semnan branch, islamic azad university, semnan, iran mostafa talebi tari1 young researchers and elite club, yadegar-e-imam khomeini(rah) , shahr-e-rey- branch, islamic azad university, tehran, iran

abstractl density functional theory (dft) was used to investigate the effects of intra-moecular interactions and implicit water molecules on the relative stability and the nmr shielding tensors of hallucinogenic harmine in the monomeric and dimeric states. results represented that the relative stability and the nmr shielding tensors are dependent on the resonance interactions and chemical envir...

Journal: :iranian journal of radiation research 0
s.m.r. aghamiri radiation medicine department, shahid beheshti university, tehran, iran s.m.j. mortazavi medical physics department, school of medicine, shiraz university of medical sciences, shiraz, iran m.a. mosleh shirazi physics unit, radiotherapy department, shiraz university of medical sciences, shiraz, iran m. baradaran-ghahfarokhi medical physics and medical engineering department, school of medicine, isfahan university of medical sciences, isfahan, iran f. rahmani department of physics, knt university of technology, tehran, iran a. amiri chemical engineering department, new mexico state university, las cruces, new mexico, usa

background: high density concrete is extensively used for efficient radiation attenuation in radiotherapy rooms and nuclear reactors. over the past eight years, some efficient galena-based concrete samples for shielding x or gamma rays was produced. the goal of this study was to produce a novel high density concrete against neutron and photon radiations using tourmaline and galena. materials an...

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