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1. chinaXiv:201703.00573 [pdf]

Correlation between Cu precipitates and irradiation defects in Fe-Cu model alloys investigated by Positron annihilation spectroscopy

Shuoxue Jin; Peng Zhang; Eryang Lu; Liping Guo; Baoyi Wang; Xingzhong Cao; ?
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

The correlation between Cu precipitates and vacancy-like defects in three Fe-Cu model alloys, Fe-0.15%Cu, Fe-0.3%Cu and Fe-0.6%Cu, irradiated at 400 °C with hydrogen ions at doses from 0.045 to 0.45 dpa, were revealed by positron annihilation spectroscopy. The formation of vacancy-like defects surrounded by tiny Cu precipitates induced the increment of the S and W parameters after irradiation. The peak value of the relative W parameter (ΔW/W), as the high momentum information on Cu precipitates, located in the track region and decreased with irradiation dose increased from 0.045 dpa to 0.45 dpa. The information on high momentum depended on the coverage fraction of the defects by Cu atoms. The effect of the irradiation dose, the irradiation depth and the Cu content on the Cu coverage fraction of the defects has been investigated in the present work

submitted time 2017-03-26 Hits2161Downloads1247 Comment 0

2. chinaXiv:201703.00571 [pdf]

Investigation of vacancy-type defects in helium irradiated FeCrNi alloy by slow positron beam

Eryang Lu; Xingzhong Cao; Shuoxue Jin; Peng Zhang; Chunxiong Zhang; Jing Yang; Yaru Wu; Liping Guo; Baoyi Wang; ?
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

The evolution of microstruture for Fe16.7Cr14.5Ni model alloy and 316 stainless steel irradiated with 140 keV He ions were studied by Positron annihilation spectroscopy. The fluences were 1016 and 5016 He ions/cm2. The irradiation temperature was room temperature and 573 K, respectively. The variation of S parameter-incident positron energy profile indicated that large amount of vacancy-type defects formed after He ion irradiation. Meanwhile, helium atoms deposited in bulk and certain amount of He-vacancy complexes were formed. The vacancy-type defects could be the major defects in track region and He-vacancy complexes would be the main defects in cascade region. The vacancy-type defects could migrate and aggregate to form vacancy clusters and even microvoids at elevated temperature irradiation. The diffusion mechanism of helium atoms might be changed at different irradiation temperature.

submitted time 2017-03-26 Hits2385Downloads1412 Comment 0

3. chinaXiv:201703.00570 [pdf]

Cu precipitates in hydrogen ion irradiated Fe-0.3%Cu alloy investigated by positron annihilation spectroscopy

Shuoxue Jin; Xingzhong Cao; Peng Zhang; Eryang LU; Liping Guo; RuiSheng Yu; Baoyi Wang
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

The formation of Cu precipitates in Fe-0.3%Cu binary model alloy after hydrogen ion irradiation at 400 was investigated by positron annihilation spectroscopy based on slow positron beam. In order to study the effect of elevated temperature for the Cu precipitates, the annealing treatment at 400 in Fe-0.3%Cu alloy was also investigated. The S-parameters of specimens increased with the irradiation dose increased, especially in the damage peak region. H+ implantation produced a large number of vacancy-type defects in Fe-0.3%Cu alloy. Compared to the unirradiated samples, the irradiated specimens show an overall major increase in W parameter values. Experimental results indicate that Cu precipitates formed easily under lower irradiation dose at elevated temperature. No obvious Cu precipitates formed when Fe-0.3%Cu alloy was annealed for 2h at 400 .

submitted time 2017-03-26 Hits1704Downloads1024 Comment 0

4. chinaXiv:201703.00529 [pdf]

The evolution of micro defects in He+ irradiated FeCrNi alloy during isochronal annealing

Eryang Lu; Xingzhong Cao; Shuoxue Jin; Chunxiong Zhang; Peng Zhang; Liping Guo; Te Zhu; Yihao Gong; Baoyi Wang; ?
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

In order to study the microstructural evolution of the He+ irradiated FeCrNi model alloy, 140 keV He+ ions were implanted into the specimen with the fluence of 1015 ions/cm2 at room temperature. Positron Annihilation Spectroscopy was used to characterize the evolution of micro defects during isochronal annealing between 423 K and 873 K. The decrease of the S parameter between 573 K and 623 K has been associated to the annihilation of vacancy clusters, which were not trapped by helium atom. While the decline of the S parameter between 773 K and 823 K in the damage region might be caused by the dissociation of HenVm clusters. The dissociated vacancy clusters were unstable and annihilated rapidly, which decreases the concentration of vacancy defects.

submitted time 2017-03-24 Hits1684Downloads962 Comment 0

5. chinaXiv:201609.00947 [pdf]

Measurement of the fluorescence quantum yield of bis-MSB

DING Xue-Feng; WEN Liang-Jian; ZHOU Xiang; DING Ya-Yun YE Xing-Chen; ZHOU Li2 LIU Meng-Chao; CAI Hao; CAO Jun
Subjects: Physics >> Nuclear Physics

The fluorescence quantum yield of bis-MSB, a widely used liquid scintillator wavelength shifter, was measured to study the photon absorption and re-emission processes in liquid scintillator. The re-emission process affects the photoelectron yield and distribution, especially in a large liquid scintillator detector, thus must be understood to optimize the liquid scintillator for good energy resolution and to precisely simulate the detector with Monte Carlo. In this study, solutions of different bis-MSB concentration were prepared for absorption and fluorescence emission measurements to cover a broad range of wavelengths. Harmane was used as a standard reference to obtain the absolution fluorescence quantum yield. For the first time we measured the fluorescence quantum yield of bis-MSB up to 430 nm as inputs required by Monte Carlo simulation, which is 0.926±0.053 at?λex?= 350 nm.

submitted time 2016-09-13 Hits1274Downloads702 Comment 0

6. chinaXiv:201609.00946 [pdf]

Preliminary study of light yield dependence on LAB liquid scintillator composition

YE Xing-Chen; YU Bo-Xiang; ZHOU Xiang; ZHAO Li; DING Ya-Yun; LIU Meng-Chao; DING Xue-Feng; ZHANG Xuan; JIE Quan-Lin; ZHOU Li; FANG Jian; CHEN Hai-Tao; HU Wei; NIU Shun-Li; YAN Jia-Qing; ZHAO Hang; HONG Dao-Jin
Subjects: Physics >> Nuclear Physics

Liquid scintillator (LS) will be adopted as the detector material in JUNO (Jiangmen Underground Neutrino Observatory). The energy resolution requirement of JUNO is 3%, which has never previously been reached. To achieve this energy resolution, the light yield of liquid scintillator is an important factor. PPO (the fluor) and bis-MSB (the wavelength shifter) are the two main materials dissolved in LAB. To study the influence of these two materials on the transmission of scintillation photons in LS, 25 and 12 cm-long quartz vessels were used in a light yield experiment. LS samples with different concentration of PPO and bis-MSB were tested. At these lengths, the light yield growth is not obvious when the concentration of PPO is higher than 4 g/L. The influence from bis-MSB becomes insignificant when its concentration is higher than 8 mg/L. This result could provide some useful suggestions for the JUNO LS.

submitted time 2016-09-13 Hits1761Downloads981 Comment 0

7. chinaXiv:201609.00903 [pdf]

Rayleigh scattering of linear alkylbenzene in large liquid scintillator detectors

Xiang Zhou; Qian Liu; Michael Wurm; Qingmin Zhang; Yayun Ding; Zhenyu Zhang; Yangheng Zheng; Li Zhou; Jun Cao; Yifang Wang
Subjects: Physics >> Nuclear Physics

Rayleigh scattering poses an intrinsic limit for the transparency of organic liquid scintillators. This work focuses on the Rayleigh scattering length of linear alkylbenzene (LAB), which will be used as the solvent of the liquid scintillator in the central detector of the Jiangmen Underground Neutrino Observatory. We investigate the anisotropy of the Rayleigh scattering in LAB, showing that the resulting Rayleigh scattering length will be significantly shorter than reported before. Given the same overall light attenuation, this will result in a more efficient transmission of photons through the scintillator, increasing the amount of light collected by the photosensors and thereby the energy resolution of the detector.

submitted time 2016-09-13 Hits1566Downloads871 Comment 0

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