X-rays have wide applications in medicine, industry, scientific research, security issues, etc. The use of X and gamma rays to inspect cargo, cars, as well as persons has about 50 years old and today they are widely used around the world to prevent the carrying of weapons and drugs. In general, nowadays transmission systems have been more developed than back-scattering imaging. On the other hand, x-ray backscatter imaging system have special and unique applications due to their inherent advantages. Also, because the entire imaging system is on one side of the object, mobile imaging is more possible for this type of modality. In this research, an x-ray backscatter imaging system was modeled using the Monte Carlo method by means of MCNPX CODE. First, a 160 kV X-ray tube was modeled then the tube output was examined with the spectrum of the commercial tube. In the next step, the geometry of the device, the detection system and the scanned object were designed and modeled. The results showed that it is possible to detect bubbles with a diameter of 5, 10 and 20 mm for an object at a distance of 5 cm.

Introduction: Investigation of radiation interaction with living organs has always been a thrust area in medical and radiation physics. The investigated results are being used in medical physics for developing improved and sensitive techniques and minimizing radiation exposure. In this study, mass attenuation coefficients of different human organs and biological materials such as adipose, blood, bone, brain, eye lens, lung, muscle, skin, and tissue have been calculated. Materials and Methods: In the present study, Monte Carlo N-Particle eXtended (MCNP-X) version 2. 4. 0 was used for determining mass attenuation coefficients, and the obtained results were compared with earlier investigations (using GEometry ANd Tracking [GEANT4] and FLUKA computer simulation packages) for blood, bone, lung, eye lens, adipose, tissue, muscle, brain, and skin materials at different energies. Results: The results of this study showed that the obtained results from MCNP-X were in high accordance with the National Institute of Standards and Technology data. Conclusion: Our findings would be beneficial for use of present simulation technique and mass attenuation coefficients for medical and radiation physics applications.

The accuracy of each simulating beta-voltaic battery parameter is very important, especially in microbatteries. The aim of this study is to improve the calculation of beta-battery parameters’ accuracy. For this purpose, at first, using the Monte Carlo N-Particle CODE (MCNPX), the energy accumulation distribution of the 63Ni beta particle spectrum inside a silicon semiconductor has been simulated. Then, the ATLAS C-Interpreter function in C ++ was defined, using one of the SILVACO CODE abilities (the parameter F. RADIATE BEAM statement). Finally, the device electric parameters have been obtained using ATLAS-SILVACO based on the location-dependent of MCNPX results. For validation, the calculations were performed for a battery sample made of 16 mm2 cross-section and 1 mCi activity of radioisotope 63Ni as a source, and finally, the results were compared with one experimental result and two analytical methods. The calculations repeated for the other sample with 100 mCi activity and 1 cm2 of geometry, and compared its results with an analytical method results. The results showed that the simulation of micro-battery characteristics by the MCNPX-SILVACO hybrid CODE using threedimensional electron-hole pairs’ distribution in semiconductor and the full spectrum of beta particles creates a significant increase in the accuracy of the computation, and provides a good capability to optimize the design of the battery.

In the present research, the increase of nuclear spin effects on the fission barrier was studied for different nuclei. Then, the deposited energy in the target was calculated using MCNPX CODE. Based on F7 tally, the released energies due to fission and the neutron production rate were measured for 238,240,242,244Pu, 242,244,246,248Cm and 252,254Cf isotopes. It was shown that by increasing the spin of nuclei from 4+ to 26+, the rate of neutron production for different isotopes also increases. The simulation results showed that the increase in the energy of incident neutrons is proportional to the increase in the spin of the target nucleus. At last, the mutual effect of increasing spin on the nuclear deformation was investigated which indicates a good agreement with the simulation results. One of the most important results of this work is that neutron collision with any energy increases the spin of nucleus. Finally, based on the comparison, it was found that the results of CNS (Cranked Nilsson-Strutinsky) CODE are confirmed with that of MCNPX.

In this study, distribution of dose rate around the nuclear gauge device MC-1DR which located in shahrekord university was simulated by MCNPX CODE and was compared whit the measured values. Due to the asymmetry of device and neutron and gamma source positions, the dose rates were determined at a distance of 5, 30 and 100 cm in different directions. Base on the complex geometry of the inside of device, there are discripency between measured and simulated results in the some points. In general, the values show when the gamma source is positioned in safe mode. The maximum and minimum of dose rate are in below and back of the device. Also, in the left side neutron dose and in the right side gamma dose is greatest. Finally, for safe operating one hour is at most recommended at a distance of 1m in compare with standard threshhold, 12mrem per day.

Background: The present study aimed to investigate the equivalent dose in vital organs, including heart and lung, due to secondary particles produced during breast proton therapy. Materials and Methods: The numerical ORNL female-phantom was improved and simulated using the Monte Carlo MCNPX CODE. The depth-dose profile of proton beams with different energies was simulated. The proper energy range of incident proton beams has been estimated in order to have the Bragg peaks inside the breast tissue. The equivalent dose of secondary particles, including neutron and photon in vital organs, were evaluated. The TALYS CODE was used to investigate the neutron and photon particles’ production cross-sections. Results: The results showed that for the proton energy range of 60-70 MeV, the Bragg peaks positioned inside the breast. The maximum dose of 0. 65 mSv/nA-p was in Heart-Left Ventricle due to neutrons production by incident 70 MeV protons. However, the maximum absorbed dose, due to the secondary particles, was less than 0. 0004% of proton equivalent dose at the Bragg peak. The maximum photons dose and the protons dose into the Heart-Left Ventricle were 8. 42 μ Sv/nA-p and 68. 08 μ Sv/nA-p, respectively, which were negligible compared to the proton equivalent dose at the Bragg peak. Conclusion: The results confirmed a noticeable lower dose in the heart and lungs for breast proton therapy, compared with the previously reported dose for breast radiotherapy using photon. Most of the dose absorbed by the organs is due to the secondary neutrons, but those are low enough to be neglected.

Gamma ray measurement in various research fields requires high efficient detectors. In photon dosimetry, NaI(Tl) scintillation detector as one of the inorganic scintillation detector is noticeable, due to have the high amount of light output. In this study, the basics determination of photon dosimetry for the NaI(Tl) scintillation detector utilizing the Monte Carlo CODE (MCNPX) and using different methods of dose calculation (tally F6, * F4, + F6 and * F8) is studied. Regularly, the output of a radiation detector (counting the number of pulses) cannot be used to determine the radiation dose value. Therefore, in this study the spectro-dosimetry method based on software method is used to find out the value of the conversion coefficients to convert the detector spectrum to the value of air karma. In this method, the radiation dosimetry response is obtained with use of the MCNPX CODE simulation. The response function of the NaI(Tl) 3"×3" scintillation detector for several specific gamma rays was determined and then the functions of energy dependent conversion coefficients for calculating the dose values were obtained. Finally, with comparison of the measured data and simulation calculations results it is shown that the proposed method has a high accuracy in photon dosimetry.

Using a dredger to remove mud and garbage accumulated in the river or sea docks is a common and important process. In order to monitor the condition of sediments on the sea bed, it is necessary to use an online measurement system for the concentration of transfer slurry from the floor to the surface. The nuclear-based systems have this important and operational capability to provide the possibility of online monitoring of the passing slurry by installing it on the pipeline without causing any disruption in the transfer process. The concentration measurement system of the cutter-suction dredger uses the combination of two nuclear and non-nuclear parts to measure the fluid parameters desired by the client, such as the volumetric and mass flow rate of the two-phase fluid and its components. In using hybrid systems for this purpose, basic conditions such as online measurement capability, non-physical, chemical or environmental interference in the passing flow, compatibility with the operational conditions of temperature, pressure, humidity and vibrations in the dredging site, measurement accuracy should be met and safety principles should be considered. In this study, using Monte Carlo simulation with MCNPX CODE, the effect of different geometrical and dimensional parameters of output gamma ray collimator on the accuracy of measuring the concentration of passing slurry was investigated, and with the considerations related to personnel radiation safety, the final optimal mode was proposed. The decrease in the placement depth of the horizontal spring inside the beam is associated with the simultaneous maximum of gradient and count statistics. In all of the mentioned situations, the opening of the conical beam-forming aperture has a higher sensitivity and resolution compared to a rectangular one.