Boron neutron capture therapy(BNCT)is recognized as a precise binary targeted radiotherapy technique that effectively eliminates tumors through the^(10)B(n,α)^(7)Li nuclear reaction.Among various neutron sources,acce...Boron neutron capture therapy(BNCT)is recognized as a precise binary targeted radiotherapy technique that effectively eliminates tumors through the^(10)B(n,α)^(7)Li nuclear reaction.Among various neutron sources,accelerator-based sources have emerged as particularly promising for BNCT applications.The^(7)Li(p,n)^(7)Be reaction is highly regarded as a potential neutron source for BNCT,owing to its low threshold energy for the reaction,significant neutron yield,appropriate average neutron energy,and additional benefits.This study utilized Monte Carlo simulations to model the physical interactions within a lithium target subjected to proton bombardment,including neutron moderation by an MgF_(2)moderator and subsequent BNCT dose analysis using a Snyder head phantom.The study focused on calculating the yields of epithermal neutrons for various incident proton energies,finding an optimal energy at 2.7 MeV.Furthermore,the Snyder head phantom was employed in dose simulations to validate the effectiveness of this specific incident energy when utilizing a^(7)Li(p,n)^(7)Be neutron source for BNCT purposes.展开更多
According to the requirements of improving production of Am source used for smoke-sensitice fire alarm making, a method and equipment of its fast relative calibration have been developed. Six measuring equipments have...According to the requirements of improving production of Am source used for smoke-sensitice fire alarm making, a method and equipment of its fast relative calibration have been developed. Six measuring equipments have being successfully applied at production lines of 241Am fire alarm source and factories of automatic smoke-sensitive fire alarm making.展开更多
Several primary factors influencing the alpha energy spectrum of 241Am fire alarm source have been studied in order to get better alpha energy spectrum. The results show that the homogeneity and the thickness of metal...Several primary factors influencing the alpha energy spectrum of 241Am fire alarm source have been studied in order to get better alpha energy spectrum. The results show that the homogeneity and the thickness of metal surface coat and the size of active area of the source have considerable influence on the alpha energy spectrum of the source.展开更多
The safety performance of 241Am fire alarm sources made by using powder metallurgical technology has been preliminarily studied, so as to determine an allowable maximum energy limit value of the alpha particles outgoi...The safety performance of 241Am fire alarm sources made by using powder metallurgical technology has been preliminarily studied, so as to determine an allowable maximum energy limit value of the alpha particles outgoing from this kind of sources in light of radiation safety and the present technology. The yielded results show that 241Am leak has not been found when the peak energy of the alpha energy spectrum of this kind of sources is less than 4.96 MeV.展开更多
The energy-resolved neutron imaging spectrometer(ERNI)will be installed in 2022 according to the spectrometer construction plan of the China Spallation Neutron Source(CSNS).The instrument requires neutron detectors wi...The energy-resolved neutron imaging spectrometer(ERNI)will be installed in 2022 according to the spectrometer construction plan of the China Spallation Neutron Source(CSNS).The instrument requires neutron detectors with the coverage area of approximately 4 m^(2)in 5°-170°neutron diffraction angle.The neutron detection efficiency needs to be better than 40%at 1 A neutron wavelength.The spatial resolution should be better than 3 mm×50 mm in the horizontal and vertical directions respectively.We develop a one-dimensional scintillator neutron detector which is composed of the^(6)Li F/Zn S(Ag)scintillation screens,the wavelength-shifting fiber(WLSF)array,the silicon photomultipliers(Si PMs),and the self-designed application-specific integrated circuit(ASIC)readout electronics.The pixel size of the detector is designed as 3 mm×50 mm,and the neutron-sensitive area is 50 mm×200 mm.The performance of the detector prototype is measured using neutron beam 20#of the CSNS.The maximum counting rate of 247 k Hz,and the detection efficiency of63%at 1.59 A are obtained.The test results show that the performance of the detector fulfills the physical requirements of the ERNI under construction at the CSNS.展开更多
Sedimentation of fine-grained deposits on coastal zones and continental shelves are important because of the association with chemical pollutants, and the implication to the impact on biological processes, the stratig...Sedimentation of fine-grained deposits on coastal zones and continental shelves are important because of the association with chemical pollutants, and the implication to the impact on biological processes, the stratigraphic correlations, and changes in sedimentary environments. The Yellow Sea continental shelf receives large quantities of sediment from the Huanghe （Yellow） River. Unfortunately, little attention has been yet paid to the sedimentation on the shallow shelf and its features, and the vertical sediment flux in the area is poorly understood. In this study, nine cores were collected in northern Yellow Sea by the R/V Science 1 in September, 1998 and 1999 to examine the sedimentation rate, sediment flux and the provenance with ^210Pb analysis. The 2^210Pb activity profiles showed that the vertical sediment flux ranged from 0.06 to 1.18 g/cm^2·a in the region. In central part of the area, there was a patch of fine-grained mud, with the flux below 0.33 g/cm^2·a. Most profiles were featured in two-segment model. Differences in the profiles reflected spatial and temporal variations in hydrodynamic and sedimentary processes. In order to determine the provenance and sedimentary setting in the area, the geochemistry of Ca, Fe, Sr, Cu, Ti and Rb in 11 surficial sediment samples were studied, which showed that in the central northern Yellow Sea, the mud deposit was from multi-source but mainly from the Huanghe River.展开更多
The bond length of ^4HeH^＋ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of ^4HeH^＋ is 0.094±0.003nm. The bond length of ...The bond length of ^4HeH^＋ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of ^4HeH^＋ is 0.094±0.003nm. The bond length of ^4HeH^＋ obtained with our radio frequency （RF） ion source is larger than that obtained with a duoplasmatron ion source at Argonne National Laboratory （ANL）, but the bond lengths of H^＋2 and H^＋3obtained separately by ANL and by us with the two different ion sources are consistent with each other, which implies that there exists an ion source effect on the bond length of ^4HeH^＋. The main reason why the 4^4HeH^＋ bond lengths obtained by the two different ion sources are different is also discussed.展开更多
^57Fe Mossbauer spectroscopic study was carried out on the organic rich sedimentary samples collected at different depth intervals from newly drilled test well Chinnewala Tibba-1（CT-1） located in Jaisalmer Petrolife...^57Fe Mossbauer spectroscopic study was carried out on the organic rich sedimentary samples collected at different depth intervals from newly drilled test well Chinnewala Tibba-1（CT-1） located in Jaisalmer Petroliferous basin India. It is found that iron is mainly distributed in high spin Fe^3＋and Fe^2＋ state in clay minerals. The plot of Fe^2＋/（Fe^2＋＋ Fe^3＋） indicates the presence of poor redox conditions in the samples.Results obtained are also compared with those already reported in the literature. This comparison shows that there may exist a correlation between prospecting of the basin, the redox environment in sediments and the nature of iron bearing minerals distributed in the sedimentary sequence.展开更多
Adopting NaF+HNO3 as the reagent to immerse and decontaminate metal parts contaminated by241Am.The decontamintion technology are verified,and the results show that the DF of this technology for leadwork,aluminium and ...Adopting NaF+HNO3 as the reagent to immerse and decontaminate metal parts contaminated by241Am.The decontamintion technology are verified,and the results show that the DF of this technology for leadwork,aluminium and tool steels are more than 90% when decontamination time is 300-450 min,and the concenrtation of HNO3 and NaF are respectively 3%-5% and 0.1%-0.5%.展开更多
文摘Boron neutron capture therapy(BNCT)is recognized as a precise binary targeted radiotherapy technique that effectively eliminates tumors through the^(10)B(n,α)^(7)Li nuclear reaction.Among various neutron sources,accelerator-based sources have emerged as particularly promising for BNCT applications.The^(7)Li(p,n)^(7)Be reaction is highly regarded as a potential neutron source for BNCT,owing to its low threshold energy for the reaction,significant neutron yield,appropriate average neutron energy,and additional benefits.This study utilized Monte Carlo simulations to model the physical interactions within a lithium target subjected to proton bombardment,including neutron moderation by an MgF_(2)moderator and subsequent BNCT dose analysis using a Snyder head phantom.The study focused on calculating the yields of epithermal neutrons for various incident proton energies,finding an optimal energy at 2.7 MeV.Furthermore,the Snyder head phantom was employed in dose simulations to validate the effectiveness of this specific incident energy when utilizing a^(7)Li(p,n)^(7)Be neutron source for BNCT purposes.
文摘According to the requirements of improving production of Am source used for smoke-sensitice fire alarm making, a method and equipment of its fast relative calibration have been developed. Six measuring equipments have being successfully applied at production lines of 241Am fire alarm source and factories of automatic smoke-sensitive fire alarm making.
文摘Several primary factors influencing the alpha energy spectrum of 241Am fire alarm source have been studied in order to get better alpha energy spectrum. The results show that the homogeneity and the thickness of metal surface coat and the size of active area of the source have considerable influence on the alpha energy spectrum of the source.
文摘The safety performance of 241Am fire alarm sources made by using powder metallurgical technology has been preliminarily studied, so as to determine an allowable maximum energy limit value of the alpha particles outgoing from this kind of sources in light of radiation safety and the present technology. The yielded results show that 241Am leak has not been found when the peak energy of the alpha energy spectrum of this kind of sources is less than 4.96 MeV.
基金the National Natural Science Foundation of China(Grant Nos.11875273,U1832111,61964001,and 12275049)the Science Foundation of Guangdong Province of China(Grant No.2020B1515120025)+3 种基金the Neutron Physics Laboratory Funding of China Academy of Engineering Physics(Grant No.2018BC03)the General Project of Jiangxi Province Key Research and Development Program(Grant No.20212BBG73012)the Key Scientific Research Projects of Henan Higher Education Institutions(Grant Nos.23A490002 and 24A490001)the Engineering Research Center of Nuclear Technology Application(Grant No.HJSJYB2021-4)。
文摘The energy-resolved neutron imaging spectrometer(ERNI)will be installed in 2022 according to the spectrometer construction plan of the China Spallation Neutron Source(CSNS).The instrument requires neutron detectors with the coverage area of approximately 4 m^(2)in 5°-170°neutron diffraction angle.The neutron detection efficiency needs to be better than 40%at 1 A neutron wavelength.The spatial resolution should be better than 3 mm×50 mm in the horizontal and vertical directions respectively.We develop a one-dimensional scintillator neutron detector which is composed of the^(6)Li F/Zn S(Ag)scintillation screens,the wavelength-shifting fiber(WLSF)array,the silicon photomultipliers(Si PMs),and the self-designed application-specific integrated circuit(ASIC)readout electronics.The pixel size of the detector is designed as 3 mm×50 mm,and the neutron-sensitive area is 50 mm×200 mm.The performance of the detector prototype is measured using neutron beam 20#of the CSNS.The maximum counting rate of 247 k Hz,and the detection efficiency of63%at 1.59 A are obtained.The test results show that the performance of the detector fulfills the physical requirements of the ERNI under construction at the CSNS.
基金Supported by Qingdao Special Program for Outstanding Scientists (No.04-3-JJ-03), the "100 Talents Program" of the Chinese Academy of Sciences (CAS), the Knowledge Innovation Program of CAS (Nos. KZCX1-SW-01-08 and KZCX3-SW-214) and the NSF for Outstanding Young Scientists (Nos. 49925614 and 49725612), and the NSF of Shan-dong Province (No. H74990247).
文摘Sedimentation of fine-grained deposits on coastal zones and continental shelves are important because of the association with chemical pollutants, and the implication to the impact on biological processes, the stratigraphic correlations, and changes in sedimentary environments. The Yellow Sea continental shelf receives large quantities of sediment from the Huanghe （Yellow） River. Unfortunately, little attention has been yet paid to the sedimentation on the shallow shelf and its features, and the vertical sediment flux in the area is poorly understood. In this study, nine cores were collected in northern Yellow Sea by the R/V Science 1 in September, 1998 and 1999 to examine the sedimentation rate, sediment flux and the provenance with ^210Pb analysis. The 2^210Pb activity profiles showed that the vertical sediment flux ranged from 0.06 to 1.18 g/cm^2·a in the region. In central part of the area, there was a patch of fine-grained mud, with the flux below 0.33 g/cm^2·a. Most profiles were featured in two-segment model. Differences in the profiles reflected spatial and temporal variations in hydrodynamic and sedimentary processes. In order to determine the provenance and sedimentary setting in the area, the geochemistry of Ca, Fe, Sr, Cu, Ti and Rb in 11 surficial sediment samples were studied, which showed that in the central northern Yellow Sea, the mud deposit was from multi-source but mainly from the Huanghe River.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10175041 and 10375040）.
文摘The bond length of ^4HeH^＋ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of ^4HeH^＋ is 0.094±0.003nm. The bond length of ^4HeH^＋ obtained with our radio frequency （RF） ion source is larger than that obtained with a duoplasmatron ion source at Argonne National Laboratory （ANL）, but the bond lengths of H^＋2 and H^＋3obtained separately by ANL and by us with the two different ion sources are consistent with each other, which implies that there exists an ion source effect on the bond length of ^4HeH^＋. The main reason why the 4^4HeH^＋ bond lengths obtained by the two different ion sources are different is also discussed.
文摘^57Fe Mossbauer spectroscopic study was carried out on the organic rich sedimentary samples collected at different depth intervals from newly drilled test well Chinnewala Tibba-1（CT-1） located in Jaisalmer Petroliferous basin India. It is found that iron is mainly distributed in high spin Fe^3＋and Fe^2＋ state in clay minerals. The plot of Fe^2＋/（Fe^2＋＋ Fe^3＋） indicates the presence of poor redox conditions in the samples.Results obtained are also compared with those already reported in the literature. This comparison shows that there may exist a correlation between prospecting of the basin, the redox environment in sediments and the nature of iron bearing minerals distributed in the sedimentary sequence.
文摘Adopting NaF+HNO3 as the reagent to immerse and decontaminate metal parts contaminated by241Am.The decontamintion technology are verified,and the results show that the DF of this technology for leadwork,aluminium and tool steels are more than 90% when decontamination time is 300-450 min,and the concenrtation of HNO3 and NaF are respectively 3%-5% and 0.1%-0.5%.
