Chemical elements in a sample were excited by radioactive isotope sources (Fe55, H3-Zr and Am241) or X-ray tube (gold target and silver target). In the process, some characteristic X-rays were emitted unique to each element. Energy and the net peak area of characteristic X-ray were measured by Si detector and Amptek DppMCA spectra analysis software. From there, the composition and concentration of interested elements could be determined.
Illustrated figures and results
Figure 1.Configuration of XRF system
X-ray fluorescence spectrum was recorded during excited sample. Experimental results such as energy and the net peak area of characteristic X-ray were measured by Si detector and Amptek DppMCA spectra analysis software.
Figure 2.Spectrum of X-ray tube with silver target
Figure 3.Spectrum of X-ray tube with silver target and copper filter
Figure 4.X-ray fluorescence spectrum of A1 geological sample
In this field, several type of accidents of a nuclear power plant (NPP) are assumed, using simulation software, physical parameters in nuclear reactor, in turbine building and outside are investigated. The interested parameters are reactivity, neutron flux, fuel temperature, radioactive isotopes, thermal power output, steam temperature, pressure, flow, boron, water level, etc. This study is purposed to teaching and training for students and also for research. We have several simulation toolkits of PCTRAN, BWR, WWER-1000, CANDU, etc. This package is supported by International Atomic Energy Agency (IAEA).
Fig. 1. Schematic diagram of a nuclear power plant (NPP), Pressurized Water Reactor
Fig. 2. Simulation interface of PCTRAN – 2 Loop, Pressurized Water Reactor (PWR)
Fig. 3 Simulation interface of WWER-1000
In the field of Medical Simulation, MCNP5 and MCNPX programs developed by Los Alamos National Laboratory to simulate the radiation machines such as the head of accelerator, X-rays tube, cyclotron...are used. From these models, the characteristics of emitted radiation: the energy spectrum, the percentage depth dose, the off-axis dose, calculating the absorbed dose in the tumour in the simple cases, the dose distribution inside and outside the room...are evaluated. The radiation safety for technician and people arround outside the room are also investigated.
In this field, using the Monte Carlo simulation softwares such as MCNP, GEANT4, PENELOPE, or self-writing codes to evaluate the characteristics of the spectrometer, calculate the radiation dose from sources of radionuclides, accelerators, nuclear reactors, equipments for medical diagnostic or radiation therapy, assess radiation safety, design radiometer system.
The relevant works are published as:
- Evaluation of dose distribution from a linear accelerator at Cho Ray Hospital by MCNP5,
- Optimal design for gamma scattering measurements by MCNP5,
- Assessment of shielding safety in diagnostic radiology room using MCNP5 code,
Study the effect of secondary scattering to the total efficiency by using MCNP code,
- Simulation for Leksell Gamma Knife radiosurgery device using MCNP5,
- Simulation for cyclotron accelerator at Cho Ray Hospital by MCNPX,
- Survey for matrix and density effects on peak efficiency of spectrometer with HPGe detector by MCNP code,
- Simulation for Shell Model by SMMC methods,
- Develop a program of simulating the full energy peak efficiency using the HPGe detector,
- Develop a program of simulating photon-electron transport by Monte Carlo method,
- Survey for the dose distribution in diagnostic radiology room using MCNP code,
- Study on the shielding material in diagnostic radiology room with MCNP code,
- Simulation of muon lifetime by Geant4 code,
- Design of cosmic background shielding using Geant4,
- Survey for the distribution of the scattering gamma using NaI(Tl) detector by Geant4 code.
- Study on the effect of non-linear response to the energy resolution of the plastic scintillation detector using Geant4.
Positron annihilation is widely applied to study the material structure. The positron annihilation research group in Nuclear physics and Nuclear engineering Dept. is developing an theoretical approximation model of positron annihilating in material. This model is based on DFT - Density Functional Theory and VQMC – Variational Quantum Monte Carlo method which is performed to get the pseudo ground state of positron binding to atom or molecule in material. This is a many-particle system which is reduced to single particle system by Kohn – Sham approximation. In this model, the many particle interactions are included in the correlation function – Jastrow function. The model has been carrying out to materials such as ZnO, CuO, and TiO2.
