CORRECTION OF INFLUENCE OF SUBSTRATE ON MEASUREMENT OF INNER SHELL IONIZATION CROSS SECTIONS

The energy spectra of reflected electrons from the substrates of targets have been calculated by the bipartion model of electron transport,the contributions of the inner shell ionization events produced by the reflected electrons from the substrates in the targets to the x-ray counting in a Si(Li) detector have been estimated.It has been confirmed that,by such correction to the measured data.the experimental results of inner shell ionization cross sections by electron impact with fine precision may be obtained under the conditio of thick substrate.     

Measurement of 8—25keV electron impact K—shell ionization cross sections of Cu and Co elements

The influence of substrate of thin targets on ionization cross sections has been corrected by a new method based upon the bipartition model of electron transport.The measured cross sections for Cu element are in good agreement with existing experimental data and those produced by the empirical formula of Green and Cosslett.Cross sections for Co element are measured for the first time.     

MEASUREMENTS OF TOTAL CROSS SECTIONS FOR K—SHELL IONIZATION BY ELECTRON BOMBARDMENT

Cross sections for K-shell ionization have been measured at electron energies of 0.1-0.40MeV for Cu and Sn,and of 0.30MeV for Ag.The present results have been compared with theoretical calculations and previously reported experimental values.A great deal of experimental and theoretical work has been devoted in recent years to the study of the ionization cross sections of atoms or ions by electron impact^[1-3],The importance of an accurate evaluation of these cross sections is evidenced by the wide variety of physical phenomana,the interpretations of which demand a knowledge of reaction rates for ionization by electron impact.Examples of such phenomena arise in the field of plamsa physics,in study of stellar atomospheres and the solar corona,in studies of gas discharges and of the passage of shock waves through gases,and in astrophysics.     

Preliminary Measurement of the K-Shell Ionization Cross Sections of Ti by Positron Impact in the Low Energy Region

Measurements were performed of K-shell ionization cross sections of Ti element by 10～30 keV positron impact using the thick-target method. The effects of multiple scattering of incident positron and from bremsstrahlung photons and annihilation photons with the thick-target method are discussed with the Monte Carlo code PENELOPE. Meanwhile, the Monte Carlo method is also applied to determine the detection efficiencies of X-and γ-ray detectors. Our experimental K-shell ionization cross sections for Ti element are compared with the distorted-wave Born approximation (DWBA) theoretical predictions, and it is found that the agreement of the experimental data and theoretical values is good and this indicates that the experimental method adopted in this study is applicable.     

Evaluation of Cross Sections for Neutron Monitor Reactions ~(169)Tm(n,xn)~(168, 167, 166, 165)Tm from Threshold to 100 MeV

The cross sections for ~(169)Tm(n,xn)~(168,167,166,165)Tm reactions in intermediate energy region are useful for neutron field monitor, safety design consideration and material damage research for fusion material irradiation test and the radioactivities induced in components of accelerator. The evaluation of activation cross sections of (n,2n) reaction for ~(169)Tm has been performed below 20 MeV. In our evaluation, the identification and correction have been made to the differences and discrepancies among the existing activation cross sections from different laboratories to obtain more accurate da     

NONSTATISTICAL EFFECTS IN THE RADIATIVE NEUTRON CAPTURE IN THE ENERGY REGION FROM 10 keV TO 3 MeV

Three nonstatistical effects in the radiative neutron capture-the capture in theshape-elastic channels,the capture in the compound-elastic channels and the capture inthe compound inelastic channels-have been considered and Hauser-Feshbach formulaswith the width fluctuation correction have been used for the compound statistical processesin the theoretical calculations of the average radiative capture cross sections systematicallyfor the 26 nuclides in the nucleus region from ~(23)Na to ~(208)Pb at the neutron incident energyregion from 10 keV to 3 MeV.The purpose of this calculation is to examine the numeri-cal relations of the reaction cross sections of the three nonstutistical effects,as well as thechanging in the ratio of the cross section of the nonstutistical effects to the total radiativecapture cross section with the mass number.     

Cross Section Measurement of ~(64)Zn(n,p)~(64)Cu Reaction from 4 to 7 MeV

Introduction In the areas of activation and neutron scattering cross sections, there are still deficiencies in the nuclear database. Activation cross sections were found to be unsatisfactory in 83 of the 183 reactions reviewed. The excitation curve for ~(64)Zn(n,p)~(64)Cu reaction has been measured from threshold to 10 MeV by different authors. All of these measured cross sections are not in very good agreement with each other. To clarify the discrepancy it is necessary to measure the cross sections for ~(64)Zn(n,p)~(64)Cu reaction once again.     

Simultaneous Evaluation

Two kinds of simultaneous evaluation programs have been developed:one for different cross sections of a nuclide for their self-consistence and anotherfor cross sections and their ratios of different nuclides,which are correlative inthe measuring,e.g.one taken as the standard of another or two cross sections     

Calculations of n+~(112,120)Sn Reactions in the Energy Region up to 20 MeV

A set of optimal neutron optical potential parameter is obtained based on experimental data of total, nonelastic, elastic scattering cross sections and elastic scattering distribution. All cross sections of neutron induced reaction, γ-ray produced cross sections, angular distribution, energy spectrum and double differential cross sections are calculated and analyzed for n+112 120Sn at incident neutron energies below 20 MeV. All experimental data are taken from EXFOR library and other evaluated data from JENDL-3.     

L X-ray Production in Au, Nb, Cd,Fe and Taby 20-45 MeV Oxygen Ions

L X-ray production cross sections have been measured for solid targets of Au, Nb, Cd, Fe and Ta for 20-45 MeV O^5＋ ions. In heavy-ion-atom collisions, an inner shell vacancy is produced due to the direct ionization （DI） as well as from the electron capture （EC） by an ionic projectile. The experiment was performed with the HI-13 model tandem accelerator in CIAE. The carbon beam having energies 20-45MeV with charge states 4＋,     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.