Slow Positron Beam (PB) is an important device in the study of positron physics andtechniques, especially in material research. For the purpose of conceptual designing a PB system, we have simulated a PB system with the parameters of an existing system – SPONSOR, using SIMION software. The simulation results have been compared with the SPONSOR published results. The effect of magnetic field in controlling beam trajectory has been investigated in the preaccelerated and accelerated stages. The simulation results of using steering coils to adjust the beam trajectory are also presented in this report.

The slow positron beam system is an important device in the study of positron physics and techniques, especially in materials research. This paper presents obtained results in studying and applying a charged particles trajectory simulation program – Simion for building feasible design models for the system. The built models with different designs based on reference designs of some typical systems include a straight-shaped model, a 500 bent-shaped model and a 900 bent-shaped model. Some positron beam trajectory calculation tests have been performed for comparison between the models. From the tests, the 500 bent-shaped model has been proposed as a conceptual design for building a real slow positron beam system in the future in Vietnam.

Anadara antiquata belongs to the Mollusca phylum, class Bivalvia, distributed in the coastal areas of Vietnam, with high nutritional and economic value. This study focused on the morphological characteristics and genetic diversity of A. antiquata in six regions of central Vietnam (Da Nang, Quang Nam, Phu Yen, Nha Trang, Binh Thuan and Thanh Hoa). The analysis of morphology of A. antiquata had the following results: shell width (SW: 41.45 mm), shell length (SL: 22.54 mm), right shell height (HRV: 29.27 mm), height left sheath (Coach: 28.49 mm), ligament length (LL: 25.74 mm), right trochanteric cavity depth (UHR: 7.90 mm), left trochanteric space depth (UHL: 8, 33 mm), right case symmetry (SRV: 8.58 mm) and left case symmetry (SLV: 8.41 mm). The mean shell volume (SV) and shell cavity volume (DSWT) were 4.45 ml and 11.11 ml, respectively. The average dry peel weight was 11.17 g. Genetic diversity showed that the 8 random primers used to analyze DNA polymorphisms of 41 A. antiquata had 87 amplified polymorphic DNA bands.

The theoretical study of the positron annihilation in complex material such as zeolite is greatly significant to support and increase the accuracy analysis of the material structure from the experimental data of the positron annihilation. The mordenite zeolite is a big and complicated structure consisting of channels and cavities. The analysis of the mordenite structure is studied by the PALS so depending on the selection of the positron lifetime components of the positron annihilation spectra fitting methods. Therefore, these positron life times in on TO4, Na, Ca, K, Fe, H2O and the rings which form the channels and cavities are sophisticatedly studied by the DFT calculation using Ab-initio. The mordenite and modified mordenite zeolite structures are precisely analyzed, and the physical behaviors of the positron in these are more understood by these theoretical results.