نتایج جستجو برای: Electron Field Diode

تعداد نتایج: 1079656  

Journal: :iranian journal of medical physics 0
mohammad amin mosleh-shirazi 1- center for research in medical physics and biomedical engineering, shiraz university of medical sciences, shiraz, iran 2- physics unit, department of radiotherapy and oncology, namazi hospital, shiraz university of medical sciences, shiraz, iran sareh karbasi physics unit, department of radiotherapy and oncology, namazi hospital, shiraz university of medical sciences, shiraz, iran reza faghihi department of medical radiation and radiation research center, school of mechanical engineering, shiraz university, shiraz, iran

introduction radiotherapy planning systems require many percentage depth dose (pdd) and profile measurements and there are various dosimeters that can be used to obtain these scans. as dose perturbation is particularly troublesome in smaller photon fields, using a low-perturbation, unshielded electron field diode (efd) in these fields is of interest. the aim of this work was to investigate the ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه یاسوج - دانشکده علوم 1391

in this investigation the effect of external field on the electron density of nanostructures of cds, cdse, cdte, gaas and polymeric structure of three, four, five and six units of cds as a kind of nanosolar cells has been studied theoretically. as modeling this system in nanodimension, molecular structures has used. specific properties of molecular structures permit us to consider different sym...

2000
R. A. Bosch T. A. Spencer

Deflection of carbon dioxide and helium-neon laser beams has been used to measure plasma and neutral density gradients during the operating mode and after the shorting time of a long-pulse field-emission electron beam diode. Plasma density gradients of (10’4-10’5) cme4 were observed throughout the diode during the fmal microsecond of the 2-3 ps electron beam pulse. The neutral density gradient ...

Introduction Radiotherapy planning systems require many percentage depth dose (PDD) and profile measurements and there are various dosimeters that can be used to obtain these scans. As dose perturbation is particularly troublesome in smaller photon fields, using a low-perturbation, unshielded electron field diode (EFD) in these fields is of interest. The aim of this work was to investigate the ...

Journal: :Physics in medicine and biology 2013
P H Charles S B Crowe T Kairn R T Knight B Hill J Kenny C M Langton J V Trapp

Due to their small collecting volume, diodes are commonly used in small field dosimetry. However, the relative sensitivity of a diode increases with decreasing small field size. Conversely, small air gaps have been shown to cause a significant decrease in the sensitivity of a detector as the field size is decreased. Therefore, this study uses Monte Carlo simulations to look at introducing air u...

2004
H. J. Peng C. F. Qiu Z. L. Xie H. Y. Chen M. Wong H. S. Kwok

An optical model based on classical electrodyanmics has beeb exploited to simulate the optical effects for the top-emitting organic light emitting diodes. The optical performance of the devices can be obtained through calculation of the power density in each planar thin film. The far field emission profile and spectrum are derived base on this model. Predicated optical performance is compared w...

Journal: :Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 2008
J L Davidson W P Kang K Subramanian Y M Wong

Nanocarbon-derived electron emission devices, specifically nanodiamond lateral field emission (FE) diodes and gated carbon nanotube (CNT) triodes, are new configurations for robust nanoelectronic devices. These novel micro/nanostructures provide an alternative and efficient means of accomplishing electronics that are impervious to temperature and radiation. For example, nitrogen-incorporated na...

2014
Wolfram U. Laub Richard Crilly

A commercial version of a synthetic single crystal diamond detector (SCDD) in a Schottky diode configuration was recently released as the new type 60019 microDiamond detector (PTW-Freiburg, Germany). In this study we investigate the dosimetric properties of this detector to independently confirm that findings from the developing group of the SCDDs still hold true for the commercial version of t...

2012
M. Makarova E. M. Vinogradova

This work is devoted to the question of the effect of space charge on the field electron emission. The electrostatic potential distributions for the diode emission systems are calculated. The diode systems, which can be readily constructed, are generally used for the characterization of field emission properties of novel materials. They have some effective applications in vacuum nanoand microel...

1998
P. I. Melnikov J. B. Greenly D. A. Hammer

Active Stark Atomic Spectroscopy (ASAS) method can be used to determine the electric field in the diode of an ion or electron accelerator as a function of position and time, including the positions of anode and cathode plasma emission surfaces (in order to obtain the effective accelerating gap). As possible probe beams, we suggest the use of lithium and sodium atoms. The diagnostic provides a m...

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