فهرست مطالب سارا زارعی

The development of electron beam applications motivates electron gun research. In addition to the beam energy and current, its quality also plays a significant role in the spread of electron guns. Herein, we present the design of an electron gun for use as an electron source in a linear accelerator with high beam current and quality. In this design, starting with the Pierce geometry, a stay-by-stay optimization based on the physics governed by the beam behavior has been carried out to control the emittance growth and get a beam of outstanding quality. In particular, non-linear transverse force, space charge effect, and spherical aberration are considered. This resulted in a threefold improvement in the beam quality as measured by the beam emittance.

The frequency of cavities in electron linear accelerators changes because of volume variation and manufacturing error. Adjusting the frequency of cavities is one of the most important steps in a cold test, which must be considered in the design. In constructing a standing-wave tube for dual-energy linac, an aluminum tube (including two half-acceleration cavities and one coupling cavity) was constructed. In this project, to modify the changes caused by a manufacturing error, adjustment screws were used. These screws change the frequency by somewhat changing the volume of the cavities. In this paper, the calculation and simulation of frequency changes due to dimensional variation were carried out. Based on the calculation and simulation, the design of screws for a frequency adjustment in experimental conditions is done. According to the results of this paper, using the screws on the cavities wall, the resonant frequency can be changed up to 10 MHz. Therefore, using the selected method, the frequency changes caused by the manufacturing error can be compensated to the extent mentioned. In this study, the tube's resonant frequency for the π/2 mode was set equal to 2998.5 MHz, and the mechanical accuracy of the construction was obtained at 200 μm.

The purpose of this research is to analyze the structural analysis of the mediating role of creativity in the relationship between organizational intelligence and organizational performance among engineers working in Qazvin city. The current research method is descriptive and correlational, and the statistical population of the research includes all working civil engineers with more than 10 years of work experience and members of Qazvin Engineering System Organization, which were 1000 people in total. The sample size was 278 people who were selected using Cochran's table and random sampling method. Data collection tools are the standard questionnaires of Karl Albrecht's organizational intelligence, Hersey and Goldsmith's organizational performance, and the organizational creativity questionnaire that was distributed among the sample. Validity and reliability tests were performed using SPSS software, and research hypotheses were tested using SEM method with the help of PLS software. The results indicate that the coefficient of significance of the three paths between the variables of organizational intelligence, creativity and organizational performance (2.505, 7.544, 5.147) are greater than 1.96, which indicates that the direct effect of organizational intelligence on organizational performance and also the indirect effect Organizational intelligence on organizational performance through the mediating variable of creativity is significant with a confidence level of 0.95 and confirms the hypotheses of the research. Also, based on the results of the research, all the components separately had a positive and significant relationship with creativity based on the Pearson correlation coefficient. As a result, the members of the engineering system of Qazvin city in today's competitive environment, in order to improve organizational performance, should pay attention to the establishment and implementation of organizational intelligence and pay attention to the components of creativity.

One of the usual ways to find sensitive data or secret parameters of cryptographic devices is to use their physical leakages. Power analysis is one of the attacks which lay in such a model. In comparison with other types of side-channels, power analysis is so efficient and has a high success rate. So it is important to provide a countermeasure against it. Different types of countermeasures use different methods and can be applied at different levels. Masking is an effective one which provides provable security in algorithm level. however even masked algorithms are sometimes suspected to leak kind of information in a condition that implemented in hardware leads to power analysis attacks. Threshold implementation is a way to secure hardware implementations against such probable challenges. In this paper, first we will introduce the different attack models in block ciphers, then we will concentrate on the gray-box model and explain the concepts of power analysis attacks and fundamentals of masking countermeasure. Later we will discuss the challenges of masking method in hardware implementations and introduce threshold implementation and its different aspects.

Side coupled standing wave accelerating cavities are widely used in a low energy linear accelerator because of relatively high accelerating gradient and low sensitivity to construction tolerances. The effective interaction of particles and electromagnetic fields is important to accelerate electrons to the intended energy with the greatest efficiency and beam quality output. Beam dynamics study is essential for determining the coordinates of the output beam from the cavity. In this paper, we present the beam dynamics of a 6 MeV accelerating cavity using a space charge tracking algorithm (ASTRA). The designed accelerating cavity that feeds by magnetron with a maximum power of 3.2 MW is operating in π/2 mode at a frequency of 2856 MHz. The results show that after the construction of the designed cavity, the vertical and horizontal emittances of the output beam, the transverse profile and the beam energy spread respectively 3.55 pi-mm-mrad, 1 mm and 0.88 MeV as expected.

Side-coupled standing wave tubes in AWT IMAGE mode are widely used in the low-energy electron linear accelerator, due to high accelerating gradient and low sensitivity to construction tolerances. The use of various simulation software for designing these kinds of tubes is very common nowadays. In this paper, SUPERFISH code and COMSOL are used for designing the accelerating and coupling cavities for a 6 MeV electron linear accelerator. Finite difference method in SUPERFISH code and Finite element method in COMSOL are used to solve the equations. Besides, dimension of accelerating and coupling cavities and also coupling iris dimension are optimized to achieve resonance frequency of 2.9985 MHz and coupling constant of 0.0112. Considering the results of this study and designing of the RF energy injection port subsequently, the construction of 6 MeV electron tube will be provided

Calculations and simulation of the designed shield for Bonab Industrial Irradiation Unit has been investigated in this work. This irradiator is panoramic wet source storage which is used to irradiation of medical equipment, some kinds of food & healthcare products, spices, … in order to sterilization and increasing of durability. Irradiation is performed in irradiation room using emitted photons of 60Co source. The internal dimensions of the room is 10.5 (m) *7.1 (m) *3.2 (m) (L*W*H) which is made of ordinary concrete walls and roof with thicknesses of 2.1 m to reduce dose rate less than 0.1 µSv/hr out of the shield. Two separated mazes have been considered as entrance of the room for passage of personals and goods and prevent leakage & streaming of radiation through ducts into outside. The calculations were performed with Monte Carlo MCNP4C Code and variance reduction methods to obtain the dose rate in various layers and beyond the shield. The obtained results showed the safety of existent scheme for getting started the operations of the irradiation unit.

In this paper، the importance and applications of accelerators in today’s world have been investigated. A survey on diverse applications of accelerators in modern world’s issues and their growth in various fields of technology has been conducted. In addition، some statistics of miscellaneous accelerator numbers in different countries and a comparison of them with present situation in Iran’s statistics are presented