The Monte Carlo code MCNPX has been utilized to calculate the effective delayed neutron fraction and reactivity by using the area-ratio method. The effective delayed neutron fraction eff has been calculated with the fission probability method proposed by Meulekamp and van der Marck. MCNPX was used to calculate separately the fission probability of the delayed and the prompt neutrons by using th...

This study explores how the metal materials of the applicator influence the dose distribution when performing brachytherapy for cervical cancer. A pinpoint ionization chamber, Monte Carlo code MCNPX, and treatment planning system are used to evaluate the dose distribution for a single Ir-192 source positioned in the tandem and ovoid. For dose distribution in water with the presence of the tande...

This paper presents the Monte Carlo simulation of the Positron Emission Tomography (PET) scanning technique using MCNPX code. The raw data generated by general MCNPX code contain a lot of unnecessary information for the image reconstruction process. This requires a large memory to store all this information. In order to reduce the needed memory, we introduce some modifications on the MCNPX code...

Secondary radiation in aircraft and spacecraft includes deuterons, tritons and helions. Two sets of fluence-to-effective dose conversion coefficients for isotropic exposure to these particles were compared: one used the particle and heavy ion transport code system (PHITS) radiation transport code coupled with the International Commission on Radiological Protection (ICRP) reference phantoms (PHI...

In the present work, the general purpose radiation transport MCNPX code (version 2.5.0) was used to evaluate the neutron fluence response matrix of the passive Bonner sphere spectrometer recently developed in our laboratory. The calculations were performed for an extended neutron incidence energy range (from 10−9 MeV to 1 GeV). Afterward, a sensitivity analysis of the main parameters affecting ...

This discussion paper is/has been under review for the journal Hydrology and Earth System Sciences (HESS). Please refer to the corresponding final paper in HESS if available. Abstract Soil moisture status in land surface models (LSMs) can be updated by assimilating cosmic-ray neutron intensity measured in air above the surface. This requires a fast and accurate model to calculate the neutron in...

Soil moisture status in land surface models (LSMs) can be updated by assimilating cosmic-ray neutron intensity measured in air above the surface. This requires a fast and accurate model to calculate the neutron intensity from the profiles of soil moisture modeled by the LSM. The existing Monte Carlo N-Particle eXtended (MCNPX) model is sufficiently accurate but too slow to be practical in the c...

Differential Die-Away Analysis (DDAA) is a very effective technique for detection of special nuclear material (SNM). It is based on fission neutrons that are detected with a time constant characteristic of the thermal neutron that created them. The presence of fast neutrons with this slow die-away time is a positive indication of the presence of SNM in the inspected cargo. Results are presented...

This paper presents dose calculation in proton therapy using Monte Carlo method and comparison with experimental data obtained at TOHOKU University’s cyclotron and isotope center in Japan. In this way, two Monte Carlo codes, FLUKA and MCNPX, has been employed to calculate percentage depth dose, lateral dose profiles, isodose curves and secondary particles production for proton pencil and broad ...