Photoneutron production and backscattering in high density concretes used for radiation therapy shielding

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In the current study, the effect of high density concretes on photoneutron productions in radiation therapy was studied using Monte Carlo simulations. The photon and neutron spectra of an 18 MeV photon beam of the Varian linac head were used for all simulations. Ordinary and five high density concretes made of high density elements were simulated. The studied concretes consisted of Magnetite, Datolite-Galena, Magnetite–Steel, Limonite–Steel, and Serpentine. Our results showed that photoneutron production in these concretes strongly depends on their composition. It appears that the application of high density elements with higher probability for photoneutron production, such as Fe and Pb, increases the photoneutron production in concrete walls of radiation therapy bunkers. Further studies on the effect of concrete composition on photoneutrons in radiation therapy room are recommended.

لغات فارسی کتاب high 2

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ترم high 2

The New Applications of High Resolution GIS Digital Terrain Analysis Tools (TOPMANGE) To Study the Management of Flow on Farms

اختصاصی از زد فایل The New Applications of High Resolution GIS Digital Terrain Analysis Tools (TOPMANGE) To Study the Management of Flow on Farms دانلود با لینک مستقیم و پر سرعت .

عنوان مقالهThe New Applications of High Resolution GIS Digital Terrain Analysis Tools (TOPMANGE) To Study the Management of Flow on Farms

نام نویسنده

Nasser Najibi, Mahmoud Reza Delavar

پست الکترونیکی

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حجم فایل

378 کیلو بایت  

کلمات کلیدی مقاله :

Runoff Management, TOPMANGE, Terrain analysis, GIS

چکیده مقاله :

We know Runoff Management is a concept that involves understanding how flow is lost from farmers fields and how this can be changed for the purpose of pollution remediation and flood storage. In order to support this concept a software tool called TOPMANGE has been developed to simulate hydrological flow paths which include the effects of manmade features [1]. TOPMANGE is a high resolution GIS terrain analysis toolkit that allows the user to manipulate flows for the net benefit to the environment. This study involves a number of case studies looking at fields prone to overland flow lost and examples for fields dominated by subsurface flow and land drains. Man made features such as tramlines, tire tracks; land drains and ditches all control runoff [2]. These features can be altered to change the nature of the runoff on the farm, such as altering the cultivation direction. New landscape features such as ponds and new hedgerows can be used to simulate the effect of disconnecting polluting flows and increasing the buffering capacity of the land. Diffuse temporary storage ponds also offer opportunities to remediate flows, whilst still on the farm itself.