Vol.24,

In this paper, in order to achieve the output signal processing of cavity beam position monitor (CBPM), we develop a digital intermediate frequency receiver architecture based signal processing system, which consists of radio frequency (RF) front end and high speed data acquisition board. The beam position resolution in the CBPM signal processing system is superior to 1 μm. Two signal processing algorithms, fast Fourier transform (FFT) and digital down converter (DDC), are evaluated offline using MATLAB platform, and both can be used to achieve, the CW input signal, position resolutions of 0.31 μm and 0.10 μm at –16 dBm. The DDC algorithm for its good compatibility is downloaded into the FPGA to realize online measurement, reaching the position resolution of 0.49 μm due to truncation error. The whole system works well and the performance meets design target.

383

The measurement of electron density is important for medical diagnosis and charged particle radiotherapy treatment planning. Traditionally, electron density is obtained by CT imaging using the relationship between CT-number and electron densities established beforehand. However, the measurement is not accurate due to the beam hardening effect. In this paper, we propose a simple and practical electron density acquisition method based on dual-energy CT technique. For each sample, the CT imaging is conducted using two selected X-ray energy from synchrotron radiation. A post-processing dual-energy reconstruction method is used. Linear attenuation coefficients of the scanned samples are obtained by FBP reconstruction. The effective atomic number and electron density are got by solving the dual-energy simultaneous equations. Different phantoms and breast tissues were scanned in this experimental study under 10 keV and 30 keV monochromatic X-rays. The distribution of effective atomic numbers and electron densities of the scanned phantoms were obtained by Dual-energy CT image reconstruction, which agrees well with the theoretical values. Compared with conventional methods, the measurement accuracy is greatly improved, and the measurement error is reduced to about 1%. This experimental study demonstrates that DECT imaging based on synchrotron radiation source is applicable to medical diagnosis for quantitative measurement with high accuracy.

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In this study, a series of porous intelligent hydrogels were synthesized by radiation exhibiting the lower critical solution temperature (LCST) and fast response involving a combination of N-isopropyl acrylamide as monomer, polyethylene glycol (PEG) as pore-forming agent and N,N-methylene-bis-acrylamide as crosslinking agent. The hydrogels were analyzed by Fourier transform infrared spectroscopy, and the influence of radiation doses on their swelling and thermal behaviors were studied. Their surface morphologies were examined by scanning electron microscopy. The results showed that PEG molecules only acted as pore-forming agent in the cross-linked polymerization. Their swelling ratios reduced with increasing radiation doses. The LCST was around 37°C, and varied little with the radiation doses. The frozen water content of PNIPAM/PEG₆₀₀₀ hydrogel reduced with increasing the radiation dose, and was greater than that of PNIPAM hydrogel at 15 kGy. Hydrogel macropores were prepared by PEG agent, and the hydrogels without PEG had a dense surface. The porous hydrogels are expected to be applied in the field of artificial intelligence material.

394

The concentration of the natural ultra-trace radionuclides ³⁶Cl and ²³⁶U in the uranium depended on the neutron flux. In this article, a method for measuring ³⁶Cl and ²³⁶U in the same uranium mineral with accelerator mass spectrometry was developed in China Institute of Atomic Energy, providing a protocol of the potential application of ²³⁶U in uranium mining, environmental, and geological research. The two samples were from Guangxi and Shanxi province, China, and their ratios ³⁶Cl/Cl and ²³⁶U/²³⁸U were measured. More experimental data conduced to understand the natural nuclides in the uranium mineral. We plan to conduct more efforts on the research.

387

In this paper, the natural rubber is chosen as the main constituents for the transition layer of all-steel load radial tyre, which is pre-vulcanized by 500-keV E-beam irradiation of up to 60 kGy. The results show that the green strength of transitional layer increases with the dose, reaching four times as much as the control (without irradiation) at 60 kGy. The final mechanical properties do not differ significantly from those of the control except that the aging and fatigue performance increased. However, thickness of the natural rubber transitional layer for an average single tyre can be reduced by 1 mm (or 1.5 kg) without obvious adverse effect on tyre performance.

458

The ^99mTc-3PRGD₂ targeted SPECT/CT scanning was of significance in detecting differentiated glioma. In this work, the diagnostic value of ^99mTc-3PRGD₂ scintigraphy in brain glioma was evaluated by the ten clinically verified brain glioma patients after obtaining informed consent. The patients first accepted X-ray imaging to localize the detecting regions before administrating with ^99mTc-3PRGD₂ at a mean radioactivity of 849±115 MBq via single intravenous bolus injection 2 h prior to SPECT/CT imaging. Tumor samples for detecting αvβ3 were collected by surgical operations two weeks after the scintigraphy. The results of CT and SPECT scanning were merged and compared. The correlation between tumor occupation (T/N ratio) and αvβ3 expression level were analyzed. The T/N ratios in brain glioma were proportionally correlated to αvβ3 positive cell percentage (R²=0.9253, p<0.05). This study primarily evaluated the clinical application of ^99mTc-3PRGD₂ SPECT scintigraphy on brain glioma. The more pathological types and detecting strategies covering a large amount of samples would aid to clarify the potentials.

381

This study was to determine the Semaphorin3B (SEMA3B) role in glioma cells responding to irradiation. Two glioma cell lines, which were used here was wild-type p53 (U-87MG), and the other was harboring mutated p53 (U-251). The SEMA3B mRNA could be detected in the two cell lines. The expression level of SEMA3B mRNA was higher in U-87MG cells than in U-251 cells, and increased with time in U-87MG cells after irradiation. Knockdown of SEMA3B expression by shRNA decreased the radiosensitivity of U-87MG cells, this may be associated with the increased G2 accumulation after irradiation. In addition, G2 accumulation after irradiation was enhanced in SEMA3B low-expressing U-87MG cells. These results showed that the SEMA3B was implicated in glioma cells responding to irradiation.

655

Gamma Ray Array Detector (GRAD) is one of external target facility subsystems in the Cooling Storage Ring on the Heavy Ion Research Facility at Lanzhou (HIRFL-CSR). The trigger subsystem of GRAD is required to make a fast L1 trigger decision with a fixed latency for the data acquisition. Because the hit signals from the detector are asynchronous with the local clock of the trigger system, a nondeterministic latency (the value changes between zero and one clock period) is generated when the synchronous receivers of the conventional trigger system process the hit signals. In this paper, an improved trigger logic based on a field-programmable gate array is developed, and comprised of zero-delay broadening circuits as receivers and an improved adding circuit designed for the new receivers. Software simulation and experimental measurement have been conducted. Comparison with the conventional trigger logic, the improved trigger logic has the advantage of eliminating the nondeterministic latency and reducing the total processing latency.

393

Experimental Advanced Superconducting Tokamak (EAST) is the fully superconducting Tokamak. The EAST magnet system comprises 16 D-shaped toroidal field coils and 14 poloidal field coils which are cooled by supercritical helium at 4.2 K and 3.8 K. The temperature of superconducting coils is measured by Cernox as a new type low-temperature sensor, and monitored during the cooling and operation. The helium temperature can offer reference for quench signal. In this paper, a technique for the weak temperature signal measurement of superconducting coils is introduced, and its weak voltage is extracted from the intrinsic noise of the amplifier by the low-noise instrumentation amplifier, filter circuit, and high-linearity analog optocoupler. The temperature detection circuit works accurately and safely whether in cooling or operating process. This technique is an effective for the temperature detection on the low-temperature superconducting coils.

368

FWHM calibration is one of the essential procedures in gamma-ray spectra analysis. Traditional method is time consumption and poor flexibility because of extra measurement on calibration source. This paper introduces an implicit calibration method based on symmetric zero-area conversion. The single peaks can be differentiated from doublets. Meanwhile, the extracted FWHM values can be applied in the fitting process. Various forms of calibration equations are introduced and compared with practical spectrum data under this method.

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