نتایج جستجو برای: neutron method
تعداد نتایج: 1672345 فیلتر نتایج به سال:
introduction bnct is an effective method to destroy brain tumoral cells while sparing the healthy tissues. the recommended flux for epithermal neutrons is 109 n/cm2s, which has the most effectiveness on deep-seated tumors. in this paper, it is indicated that using d-t neutron source and optimizing of beam shaping assembly (bsa) leads to treating brain tumors in a reasonable time where all iaea ...
The neutron density is one of the most important dynamical parameters in a reactor. It is directly related to the control and stability of the reactor power. Any change in applied reactivity and some of dynamical parameters in the reactor causes a change in the neutron density. Lyapunov exponent method is a powerful tool for investigating the range of stability and the transient behavior of the...
A new model is presented herein to calculate optimal value for ultra-cold neutron (UCN) production rate of a UCN source. The cold neutron (CN) converter is the main component of UCN source. In this paper, we study the UCN source which contains the D2O neutron moderator, the sD2 converter, 590 Mev proton beam, and the spallation target (a mixture of Pb, D2O and Zr). In order to determine the qua...
Bi-based and Ag-doped superconductors were irradiated by neutrons. Experimental result showed that XRD patern-intensity of irradiated Bi-based sample was decreased and The Tc of these samples were decreased by 7-10 K. The neutron irradiated sample was also found to decrease by 50% the normal state resistivity of samples. Therefore, neutron irradiation is a useful method to improve the supercon...
چکیده ندارد.
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...
background : in spite of clinically useful photon and electron beams, high energy linacs produce secondary particles such as neutrons (photo-neutron production). neutrons have important roles during treatment with high energy photons in terms of protection and dose escalation. in this project, neutron dose equivalent of 18 mv varian accelerators is calculated by tld600 and tld700. materials and...
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...
background: in high-intensity, mixed and pulsed neutron fields the use of spectrometers or area monitors with active detectors is useless in these conditions neutron measuring devices must have a passive detector. here a passive neutron area monitor with cr39 track detector was designed and the response was calculated. materials and methods: the response of a passive neutron area monitor with c...
abstract background: with respect to the difference in the interaction of thermal neutron and x rays with matter, using two radiography systems of thermal neutron and x rays will yield highly valuable information for studying the inner structure of biologic samples. methods: the high sensitivity of thermal neutron to hydrogen, in particular, has led to recognizing this system as a useful tool i...
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