نتایج جستجو برای: gamma and fast neutron doses
تعداد نتایج: 16894404 فیلتر نتایج به سال:
Fast-neutron/gamma-ray pulse-shape discrimination has been performed for the organic liquid scintillators NE 213A and EJ 305 using a time-of-flight based neutron-tagging technique waveform digitization on an event-by-event basis. Gamma-ray sources Geant4-based simulation were used to calibrate scintillation-light yield. The difference in pulse shape neutron gamma-ray events was analyzed by inte...
Atomic bomb doses in Hiroshima and Nagasaki have been evaluated by many groups. In the 'Hiroshima Atomic Bomb Dosimetry Group' used in this study, radioactivities of l52Eu and 6"Co in exposed rock samples have been measured to evaluate neutron doses both in Hiroshima and Nagasaki. These radioactivities were induced by neutron capture reactions. Thermoluminescence dosimetry has also been applied...
Three algorithms for discriminating between fast neutrons, thermal neutrons and gamma rays in a Li loaded plastic scintillator have been compared. Following a literature review of existing pulse shape discrimination techniques, the performance of the charge comparison method, triangular filtering and frequency gradient analysis were investigated in this work. The scintillator was exposed to thr...
Background: Boron neutron capture therapy (BNCT) is a binary radiotherapy combining biochemical targeting with neutron irradiation. However, monitoring the boron distribution is a fundamental problem in BNCT. Prompt gamma rays emitted by boron capture reaction can be used to address the issue. Materials and Methods: The general-purpose Monte Carlo toolkits Geant4 and MCNP were used for the simu...
In this project the neutron spectra from the reaction of deutron on beryllium muclei is measured. The energies of deuterons were 7, 10, 13 and 15 MeV, and these measurements are performed at 10, 30 and 50 degrees relative to the beam of deutrons. The detector used is 76 by 76 mm right circular cylender of NE-213 liquid scintillator. The zero crossing technique is used for gamma discriminatin....
heteropoly acids (hpa) and their salts have advantages as catalysts which make them both economically and environmentally attractive, strong br?nsted acidity, exhibiting fast reversible multi-electron redox transformations under rather mild conditions, very high solubility in polar solvents, fairly high thermal stability in the solid states, and efficient oxidizing ability, so that they are imp...
Neutron beams for therapy always contain some gamma ray contamination that varies with depth and with distance from the beam axis. The problem therefore arises how the varying gamma ray contribution should be accounted for in dose specification. Not infrequently a "total effective dose" DE is quoted that is equal to the neutron dose plus the gamma ray dose divided by a constant weight factor ta...
Accurate neutron flux values in irradiation channels of research reactors are very essential to their usage. The total neutron flux of the Ghana Research Reactor-1 (GHARR-1) was measured after a beryllium reflector was added to its shim to compensate for excess reactivity loss. The thermal, epithermal and fast neutron fluxes were determined by the method of foil activation. The experimental sam...
This research aimed to measure the received photon and thermal neutron doses to contralateral breast (CB) surface in breast cancer radiation therapy for different field sizes in presence of dynamic and physical wedges. The photon and thermal neutron doses were measured by thermo uminescent dosimeter (TLDs) chips for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes in presence of physical and dynamic ...
background: the characteristics of secondary neutrons in a high energy radiation therapy room were studied using the mcnpx monte carlo (mc) code. materials and methods: two mc models including a model with full description of head components and a simplified model used in previous studies were implemented for mc simulations. results: results showed 4-53% difference between full and with the sim...
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