نتایج جستجو برای: neutron activation
تعداد نتایج: 471710 فیلتر نتایج به سال:
introduction there is a growing interest in determining the concentration of various elements in food spices. in the present study, the instrumental neutron activation analysis (inaa) was employed to measure the trace elements in 11 commonly food spices consumed in tehran, iran. materials and methods the levels of k, mn, na, cl, v, br, al, and as were determined and their effects on human healt...
gamma-scintigraphy is applied extensively in the development and evaluation of pharmaceutical delivery systems, particularly for monitoring formulations in the gastrointestinal and respiratory tracts. the radiolabelling is generally achieved by the incorporation of an appropriate radionuclide such as technetium-99m or indium-111 into the formulation or by addition of a non-radioactive isotope s...
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The silver activation counters are commonly used for pulsed-neutron yield measurements especially in plasma focus devices. The counter normally consists of a Geiger-Muller tube along with silver foils and polyethylene (as a moderator), which is calibrated against an Am-Be radioisotope neutron source. The neutrons, after being slowed-down in the polyethylene, activate the silver foils. By measur...
In this study, a mixture of waste lead mine Nakhlak and cement with different percentages of boric acid are used to construct a proper shield for gamma and neutron radiations emitted from the Am-Be source. Neutron dose rate reduction by the prepared samples was investigated by thermal neutron irradiation system of Isfahan University, TLD 600 and TLD 700. Neutron dose rate changes, compressive...
In order to achieve a thermal neutron beam for neutron radiography applications, a new neutron collimator has been designed, installed and characterized at Tehran Research Reactor (TRR). TRR is a 5 MW, open pool and light water coolant reactor with seven beam tubes. Neutron collimator that is an important part of neutron radiography system was installed in the six inch E beam tube. Collimator d...
A current challenge in the field of magnetoelectric multiferroics is to identify systems that allow a controlled tuning of states displaying distinct magnetoelectric responses. Here we show that the multiferroic ground state of the archetypal multiferroic TbMnO3 is dramatically modified by epitaxial strain. Neutron diffraction reveals that in highly strained films the magnetic order changes fro...
Based on a study of high-energy epithermal (HEE) neutrons in data from the Lunar Exploration Neutron Detector (LEND) on NASA's Lunar Reconnaissance Orbiter (LRO), the background from HEE neutrons is larger than initially estimated. Claims by Mitrofanov et al. (Reports, 22 October 2010, p. 483) of enhanced hydrogen abundance in sunlit portions of the lunar south pole and quantitative hydrogen co...
Neutron diffraction analysis was employed to measure residual stresses near welds in used anhydrous ammonia nurse tanks. Tensile residual stresses contribute to stress corrosion cracking of nurse tanks, which can cause tanks to release toxic ammonia vapor. The analysis showed that tensile residual stresses were present in the tanks measured, and the magnitudes of these stresses approached the y...
background: prompt gamma neutron activation analysis (pgnaa) is known as a non-invasive technique capable of measuring elemental concentration in voluminous samples in a short period of time. also it is a valuable diagnostic tool for total body elemental measurements. 252cf and 241am-be sources which are usually used in this method, generate not only neutrons, but also emit high-energy and unwa...
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