Vol.22,

DBPM system performance is determined by the design and implementation of beam position signal processing algorithm. In order to develop the system, a beam position signal processing algorithm is implemented on FPGA. The hardware is a PMC board ICS-1554A-002 (GE Corp.) with FPGA chip XC5VSX95T. This paper adopts quadrature frequency mixing to down convert high frequency signal to base. Different from conventional method, the mixing is implemented by CORDIC algorithm. The algorithm theory and implementation details are discussed in this paper. As the board contains no front end gain controller, this paper introduces a published patent-pending technique that has been adopted to realize the function in digital logic. The whole design is implemented with VHDL language. An on-line evaluation has been carried on SSRF (Shanghai Synchrotron Radiation Facility) storage ring. Results indicate that the system turn-by-turn data can measure the real beam movement accurately, and system resolution is 1.1 µm.

462

It was reported that the α-helix of protein molecules could be destroyed when they were exposed to the electromagnetic field (EMF) and finally the signal transduction could be affected. To study this effect, one signal molecule, insulin, was exposed to electromagnetic fields at different combinations of the field strength, repetition rate and exposure time. For the first time, structural biology approach was used to detect the EMF effect. The results of a series of measurements on the interaction of electromagnetic fields with insulin in vitro are described. Under our experimental conditions, no effects of electromagnetic field exposure were observed on the molecular conformation.

395

Terahertz time-domain spectroscopy (THz-TDS) was utilized to investigate the solid-state reaction between L(+)-Tartaric acid and sodium hydrogen carbonate. Solid sodium hydrogen L(+)-tartrate monohydrate was synthesized efficiently by mechanical grinding, which is particularly sustainable and environmentally benign. Distinct THz absorptions were observed for pure reactants and the proposed product. The reaction process could be clearly visualized by THz spectral patterns of the reaction mixtures at different grinding time. The observed results were further confirmed by synchrotron radiation X-ray powder diffraction (SRXRPD) and Fourier transform infrared (FT-IR) spectroscopy. The study demonstrates that THz-TDS is an effective novel tool to monitor solid-state reactions in pharmaceutical industry.

418

In conventional PET systems, the parallax error degrades image resolution and causes image distortion. To remedy this, a PET ring diameter has to be much larger than the required size of field of view (FOV), and therefore the cost goes up. Measurement of depth-of-interaction (DOI) information is effective to reduce the parallax error and improve the image quality. This study is aimed at developing a practical method to incorporate DOI information in PET sinogram generation and image reconstruction processes and evaluate its efficacy through Monte Carlo simulation. An animal PET system with 30-mm long LSO crystals and 2-mm DOI measurement accuracy was simulated and list-mode PET data were collected. A sinogram generation method was proposed to bin each coincidence event to the correct LOR location according to both incident crystal indices and DOI positions of the two annihilation photons. The sinograms were reconstructed with an iterative OSMAPEM (ordered subset maximum a posteriori expectation maximization) algorithm. Two phantoms (a rod source phantom and a Derenzo phantom) were simulated, and the benefits of DOI were investigated in terms of reconstructed source diameter (FWHM) and source positioning accuracy. The results demonstrate that the proposed method works well to incorporate DOI information in data processing, which not only overcomes the image distortion problem but also significantly improves image resolution and resolution uniformity and results in satisfactory image quality.

507

In this paper, energy loss of alpha particles in different vacuum levels is studied experimentally and via theoretical analysis. A better understanding of energy loss of α particle in vacuum will help detect more exact numbers of alpha particles. Two ²³⁹Pu sources are used to measure the energy loss of α particle crossing different vacuum levels (different air pressures). The experimental data are obtained from an instrument – PAM-100 developed by authors. The experimental results have shown that increasing vacuum levels will lead to more alpha residual energy but less energy loss. When the vacuum level reaches 0.04 MPa, alpha particles (²³⁹Pu, 5.115 MeV) will lose the energy of about 0.175 MeV with traversing 5 mm distance. Theoretical calculations have shown a good agreement with experimental results. This implies that the instrument has a high accuracy and could be applied in field work.

449

In this paper, fast neutron inactivation effects of Bacillus subtilis were investigated with fission fast neutrons from CFBR-II reactor of INPC (Institute of Nuclear Physics and Chemistry) and mono-energetic neutrons from the Van de Graaff accelerator at Peking University. The method for determining the absorbed dose in the Bacillus subtilis suspension contained in test tubes is introduced. The absorbed dose, on account of its dependence on the volume and the form of confined state, was determined by combined experiments and Monte Carlo method. Using the calculation results of absorbed dose, the fast neutron inactivation effects on Bacillus subtilis were studied. The survival rates and absorbed dose curve was constructed.

400

Proton exchange membranes (PEMs) were prepared in three steps: grafting of polystyrene onto PVDF powder using pre-irradiation graft polymerization technique, processing the grafted PVDF powder into membranes of around 50-μm thickness, and sulfonating them with cholorosulfonic acid to form poly(vinylidene fluoride)-g-poly(styrene sulfonic acid) membranes. Kinetics of the graft polymerization was studied. The existing of polystyrene side-chains in the grafted PVDF powders, and PSSA groups in PEMs, were proved by FT-IR. Properties of the PEMs, i.e. the ion exchange capacity, water uptake, proton conductivity, thermal property and oxidative stability, were characterized. Dependence of properties on the degree of grafting was investigated, too.

620

The internal radiation dose calculations based on Chinese models is important in nuclear medicine. Most of the existing models are based on the physical and anatomical data of Caucasian, whose anatomical structure and physiological parameters are quite different from the Chinese, may lead significant effect on internal radiation. Therefore, it is necessary to establish the model based on the Chinese ethnic characteristics, and applied to radiation dosimetry calculation. In this study, a voxel model was established based on the high resolution Visible Chinese Human (VCH). The transport procedure of photon and electron was simulated using the MCNPX Monte Carlo code. Absorbed fraction (AF) and specific absorbed fraction (SAF) were calculated and S-factors and mean absorbed doses for organs with ^99mTc located in liver were also obtained. In comparison with those of VIP-Man and MIRD models, discrepancies were found to be correlated with the racial and anatomical differences in organ mass and inter-organ distance. The internal dosimetry data based on other models that were used to apply to Chinese adult population are replaced with Chinese specific data. The obtained results provide a reference for nuclear medicine, such as dose verification after surgery and potential radiation evaluation for radionuclides in preclinical research, etc.

512

A novel zoledronic acid derivative, 1-hydroxy-2-(2-butyl-1H-imidazole-1-yl)-ethylidene-1,1- diphosphonic acid (BIDP), was synthesized and labeled with ⁹⁹Tc^m. The detailed kinetic study on the labeling reaction between BIDP and ⁹⁹Tc^m was carried out. The results indicated that the reaction rate constants k were 0.0258, 0.0268, 0.0305, 0.0323, 0.0351 and 0.0384 min^-1 at 0°C, 5°C, 10°C, 15°C, 20°C and 25°C, respectively. From the Arrhenius equation k=A·e^–Ea/(RT), the activation energy E_a of the labeling reaction was calculated to be 10.45 kJ/mol. And the correlation between k and temperature (T) was also deduced as ln k=–1258.8×(1/T)+0.9531. In addition, it was found that in order to get a high radiolabeling yield (RLY) (> 90%), the reaction temperature must be up to 12°C.

414

In this paper, a digitalizing board for readout of PMT signals in the prototype array of WCDA (water Cerenkov detector array) for LHAASO (Large high altitude air shower observatory) is designed. The prototype array is composed of 9 PMTs, including the pulse time and charge measurement from the PMTs, and clock generation and trigger decision. In the digitalizing board, FPGA reconfiguration and data readout via VME bus are implemented. Test results show that the performances meet well with the requirements of readout electronics. It has been installed in Yangbajing and tests with the prototype array and DAQ is ongoing.

424

A new method for three-dimensional simulation of the interaction between the gas and the solid around is developed. The effects of the gas on the thermal-mechanical behaviors within the surrounded solid are performed by replacing the internal gas with an equivalent solid in the modeling, which can make it convenient to simulate the thermal-mechanical coupling effects in the solid research objects with gases in them. The applied thermal expansion coefficient, Young's modulus and Poisson's ratio of the equivalent solid material are derived. A series of tests have been conducted; and the proposed equivalent solid method to simulate the gas effects is validated.

508