The cross sections of the 75As(n, γ)76As reaction were measured in the neutron energy range from 0.50 to 1.50 MeV by using the activation technique, Neutrons were produced via the T(p,n)3He reaction and the cross sections of the 197Au(n, γ)198 Au reaction were used to determine the absolute neutron flux. Present results are compared with existing measurements and evaluations.
Vol.12, No.3
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2001
3
Research article 01 Aug 2001
ZHANG Guo-Hui，SHI Zhao-Min，TANG Guo-You，CHEN Jin-Xiang，LU Han-Lin
keyword：75As；Neutron capture cross sections；Activation method；
Research article 01 Aug 2001
ZHOU Wen-Jie，HE Ze-Jun
The production of dileptons from the chemically equilibrating quark gluon plasma in the intermediate mass region has been studied. Comparing with the calculated results based on the thermodynamic equilibrium system of quark gluon plasma, it has been found that the quark phase of the chemically equilibrating system gives rise to an even larger enhancement of the dileptons production. Therefore, such an enhancement of dilepton production may signal the formation of quark gluon plasma.
keyword：Quark gluon plasma；Intermediate mass dilepton；Chemically equilibrating system；
Research article 01 Aug 2001
LIU Feng，WANG Yu-Gang，XUE Jian-Ming，WANG Si-Xue，ZHAO Wei-Jiang
A new detection method has been applied to study the penetration depth of low-energy heavy ions in botanic samples. Highly oriented pyrolytic graphite (HOPG) pieces were placed behind the target samples with certain thickness to receive energetic penetrated ions during the irradiation. After irradiation, statistic number density of protrusion-like damage induced by energetic penetrated ions can be obtained through scanning tunneling microscope (STM) observation on the surfaces of HOPG. The results of test indicate that the detection limit can be as low as 1.0×109 protrusions/cm2. With the method, the penetration depth of at least 60µm can be detected in kidney bean slices irradiated by N+ ions with dose of 0.3-3×1017ions/cm2.
keyword：Low energy ion irradiation；Transmission；Botanic slice；STM observation；HOPG (piece)；
Research article 01 Aug 2001
ZHAO Qing，ZHENG Yong-Zhen，Mo Zhi-Tao，TONG Hong-Hui，GENG Man
Specimens of Ti6AI4V alloy were implanted with nitrogen ions of 4×1018 cm-2 at temperatures from 100 to 600℃. Auger Electron Spectroscopy (AES), microhardness measurements and pin-on-disk wear testing, Scanning Electron Microscopy (SEM), and Glancing angle X-ray Diffraction (XRD) were utilized to evaluate the surface property improvements. The thickness of implanted layers increased by about an order of magnitude when the temperature was elevated from 100 to 600℃. Higher surface hardness and wear resistance were also obtained in the high temperature implantation. The XRD image showed the presence of nitrides of titanium at the implanted surface.
keyword：Ti6Al4V alloy；Anti-wearing；Plasma source ion implantation of Nitrogen；
Research article 01 Aug 2001
ZHANG Zhi-Bin，ZHANG Shi-Li，ZHU De-Zhang，XU Hong-Jie
Annealing behavior, at different annealing temperatures, of an ultrathin Mo layer located between a Ti film and Si substrate or deposited on the top of surface of a Ti film was investigated by Rutherford backscattering spectrometry (RBS), cross-sectional transmission electron microscopy (TEM) and energy dispersive X-ray spectrometry (EDS), In a Ti/Mo/Si structure, partially reacted film with layer structure of Ti-rich silicide/TiSi2/(Mo, Ti)Si2 on a Si substrate was formed after 550℃ annealing for 30min. The ratio of Mo to Ti in (Mo, Ti)Si2 layer decreases from near Si substrate upwards and becomes zero at about 20 nm away. In a Mo/Ti/Si structure, the surface Mo layer enhances the Si diffusion from the substrate during annealing. Mo bearing Ti rich silicide exists on the surface until 600℃ and then converts to (Mo. Ti)Si2 after 650℃ annealing, and the atomic ratio of Mo to Ti decreases from the top surface into Ti silicide film, and becomes zero at about 30 nm away from the surface. In both cases of interface Mo and surface Mo layer, the atomic ratio of Mo to Ti in the region of (Mo, Ti)Si2 was found to be very low, with an average value of less than 0.2. Low content of Mo in Mo containing ternary silicide leads easily to the formation of the stable phase of C54 (Mo, Ti)Si2, which acts as a template for the formation of C54 TiSi2 beneath when Mo is deposited on the surface.
keyword：Silicidation；TiSi2；(Mo,Ti)Si2；
Research article 01 Aug 2001
WANG Tie-Shan，DING Bao-Wei，WANG Zhi-Guo，ZHENG Shi-Kui，JIANG You-Rong，LI Wei-Jun
Titanium is one of the best hydrogen loading material. The predicted maximum loading ratio of hydrogen in titanium may reach to 2.0. In this work, a titanium layer on molybdenum substrate was deuterated with the atomic ratio X =21.6. The change of the surface topography and microstructure of the sample before and after loading was observed by using Scan Electron Microscopy (SEM). The surface segregation of the samples after deuteron bombardment was also observed. A fiuctuatingly-incrcasing trend of the deuterium density in titanium target was detected in the deuteron implantation experiments. which indicated a suddenly explosion (segregation) or fast diffusion of deuterium in the titanium. Significant amount of nitrogen contamination was found in the Ti2Hx sample by nuclear reaction analysis (NRA), which indicated that the Ti2Hx structure might have the feature to trap nitrogen from air. The nitrogen contamination in Ti2Hx significantly affects the increase of the atomic ratio X=2H/Ti.
keyword：Deuterated titanium (Ti2Hx)；Nuclear reaction analysis；Scan election microscopy；
Research article 01 Aug 2001
HUANG Wei，FU Yi-Bei，XU Yun-Shu，BIAN Zhi-Shang，HE Mei-Ying
The 60Co γ radiation effect on spherical open-porous polymethylphenylvinyl siloxane foam was studied in different atmospheres at room temperature. The physical and chemical behaviors of unirradiated and irradiated materials were studied by SEM, FTIR, TG (thermal gravity analysis), GC/MS(gas chromatography and mass spectroscopy), etc. The present results indicate that the yields of gas products increase linearly with the dose increasing, Furthermore, some changes in material's microscopic form, composition, structure and mechanical property were observed, but the maximum thermal decomposition temperature of the sample alters little and the dose gives no effect on it.
keyword：Polymethylphenylvinyl siloxane foam；γ-ray irradiation；Radiation crosslinking；Radiation degradation；
Research article 01 Aug 2001
ZU Jian-Hua，WANG Heng-Dong，YE Yin，QIU Shi-Long，YAO Si-De
High-density polyethylene (HDPE) films were irradiated by 60Co gamma ray with a dose of 100 kGy in air and then immersed in aqueous solution of acrylic acid (AA) and sodium styrene sulfonate (SSS) at different temperature. The effects of grafting conditions such as temperature, reaction time, Mohr's salt concentration, and total concentration of monomer on grafting yield were studied. Both grafting yield of AA and SSS onto HDPE respectively increases with total concentration of monomers. The highest grafting yield was observed at 3 mol/L monomers where the grafted PE swelled to the largest extent in the monomers mixture. The grafting yield increases with reaction time and then levels off. At higher temperature, the grafting yield decreases with Mohr's salt concentration, but increases at low temperature when Mohr's salt concentration is 0.083%. Which can be interpreted that in the presence of Fe2+ diperoxides and hydroperoxides may decompose at low temperature to form radical which can initiate the grafting. The physical and chemical properties of grafting films were also investigated.
keyword：High-density polyethylene；Preirradiation graft；Acrylic acid；Sodimn styrene sulfonate；
Research article 01 Aug 2001
ZHU Shi-Yang，HUANG Yi-Ping，WANG Jin，LI An-Zhen，Shen Shao-Qun，Bao Min-Hang
Piezoresistive pressure sensors with a twin-island structure were successfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline silicon overlayer of the SOI wafer and were totally isolated by the buried SiO2, the sensors are radiation-hard. The sensitivity and the linearity of the pressure sensors keep their original values after being irradiated by 60Go γ-rays up to 2.3×104 Gy (H2O). However, the offset voltage of the sensor has a slight drift, increasing with the radiation dose. The absolute walue of the offset voltage deviation depends on the pressure sensor itself. For comparison, corresponding polysilicon pressure sensors were fabricated using the similar process and irradiated at the same condition.
keyword：Total dose radiation；Pressure sensor；Silicon on insulator；
Research article 01 Aug 2001
QIU Zhi-Jun，LU Rong-Rong，GUO Pan-Lin，WANG Ji-Qing，QIU Hui-Yuan，LI Xiao-Lin，ZHU Jie-Qing，REINERT T，HEITMANN J，SPEMANN D，VOGT J，FLAGMEYER R H，BUTZ T
A nuclear microprobe with high spatial resolution and high analyti cal sensitivity was applied to analyze atmospheric aerosol at five monitoring sites in Shanghai city. Meantime, a new pattern recognition technique, which used the micro PIXE spectrum of a single aerosol particle as its fingerprint, was developed to identify the origin of the particle. The results showed that the major contributors to the atmosphere pollution were soil dust (31.6%), building dust (30.8%), and the next were vehicle exhaust (13.7%), metallurgic industry excrements (5.6%), oil combustion (5%) and coal combustion (2.3%). Besides these, about 10% of the particles could not be identified. Based on the cluster analysis of these particles, they could be divided into eight groups. By inference, they might belong to some sub-pollution sources from soil dust, building dust and metallurgic industry excrements. Moreover, some new pollution sources from tyres and chemical plants were also revealed.
keyword：Single aerosol particle analysis；Source apportionment；Nuclear microprobe；Pattern recognition technique；
Research article 01 Aug 2001
DAS H A
Analysis of rain-and fresh water for trace constituents is a manda tory part of environmental monitoring. This text gives a survey of neutron activation analysis (NAA) within the framework of current environmental water research pro grammes, based on the practice developed in co-operation with the Dutch Energy Research Centre at Petten (ECN). While the procedures reported in literature cover about thirty five elements, our routine procedures of instrumental neutron activation analysis (INAA) is limited to ten to fifteen elements. The use of some dedicated ra diochemical separations (RNAA) adds another six, some of which are speciated as well. Current contributions of NAA to water analysis center on determination and speciation of anionic trace elements, notably Br, I, As. and Se, on the assay of some ultra traces like Ag, Au and Hg and on validation.
keyword：INAA；RNAA；Elemental and speciation analysis of water；
Research article 01 Aug 2001
LENG Yong-Bin，ZHENG Li-Fang，SHEN Guo-Bao，LIU Song-Qiang
In the process of making preliminary design for the Shanghai Syn chrotron Radiation Facility (SSRF) control system, we designed and implemented the fieldbus DeviceNet for communication between IOCs (I/O Controller) and device controllers. DeviceNet, as an open network standard, provides application layer protocol (IOS/OSI layer 7) and thus can transparently connect devices and IOCs without any need for network programming. The application of the DeviceNet to the EPICS (Experimental Physics and Industrial Control System) based control system are described.
keyword：Control system；EPICS；DeviceNet；
