نتایج جستجو برای: epithermal neutron
تعداد نتایج: 46585 فیلتر نتایج به سال:
A novel means of combined spectroscopic and radiographic zero-knowledge warhead verification has been developed and investigated using Monte Carlo simulations. This verification approach, henceforth called "epi-ZK," uses timestructured beams of epithermal neutrons to verify weapon isotopics and geometry without creating or transmitting meaningful information about the device design. This method...
The use of epithermal neutron beam in clinical trials of Boron Neutron Capture Therapy for patients with malignant brain tumors had been carried out for half a decade at the Brookhaven's Medical Reactor. The decision to permanently close this reactor in 2000 cut short the efforts to implement a new conceptual design to optimize this beam in preparation for use with possible new BNCT protocols. ...
Preclinical studies for boron neutron capture therapy (BNCT) using epithermal neutrons are ongoing at several laboratories. The absorbed dose in tumor cells is a function of the thermal neutron flux at depth, the microscopic boron concentration, and the size of the cell. Dosimetry is therefore complicated by the admixture of thermal, epithermal, and fast neutrons, plus gamma rays, and the array...
Boron neutron capture therapy (BNCT) is an effective method for treatment of deep seated brain tumors. This method consists of two stages: injection of boron compound in the patient body, and then irradiation of the region tumors with the neutron beam. It allows for delivery of high linear energy transfer (LET) radiation (particles 4He and 7Li nuclei) to tumors at the cellular level whilst avoi...
The most important part of neutron therapy treatment (NCT1) is to achieve a beam of neutrons with suitable energy and intensity, as well as the least pollution and damage. In this study, in order to correct the neutron spectrum from D-D fusion and its use in neutron therapy, a set of different materials which are called the Beam Shaping Assembly (BSA) was placed in the direction of energy 2.45 ...
LCROSS hints of increasing volatile concentration at increasing depths, to 3 meters or more into the Moon, as indicated by amount of water seen as the event developed. [1] In comparison new epithermal neutron results indicate that within the first two meters depth of regolith resides a desiccated layer in the top 0.4 meters. LRO’s LEND (Lunar Exploration Neutron Detector) found 4% water-equival...
Magnesium-walled argon gas flow ionization chamber (Mg(Ar)) is used for photon dose measurements in the epithermal neutron beam of FiR 1 reactor in Finland. In this study, the photon dose measurements were re-evaluated against calculations applying a new chamber calibration factor defined in water instead of in air. Also, effect of the build-up cap on the measurements was investigated. The new ...
An epithermal neutron beam has been designed for Boron neutron Capture Therapy (BNCT) at the thermal column of Tehran Research Reactor (TRR) recently. In this paper the whole body effective dose, as well as the equivalent doses of several organs have been calculated in this facility using MCNPX Monte Carlo code. The effective dose has been calculated by using the absorbed doses determined for e...
A modeling investigation was performed to choose moderator material and size for creating optimal epithermal neutron beams for BNCT based on a proton accelerator and the (7)Li(p,n)(7)Be reaction as a neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine to be placed on high current IPPE proton accelerator KG...
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