The application of keV ion beam in life science started in China several decades ago. In 1986, researchers initially studied the mutagenic effect of ion beam, and successfully applied it to plant breeding. Nowadays, i...The application of keV ion beam in life science started in China several decades ago. In 1986, researchers initially studied the mutagenic effect of ion beam, and successfully applied it to plant breeding. Nowadays, ion beam implantation technique has been extensively applied to many biological fields. This paper mainly introduces one of its important applications: genetic transformation mediated by keV ion beam.展开更多
External filtered neutron beams have been developed at the horizontal radial channels No. 4 of Dalat research reactor. In the material composition of the neutron filters, the primary material components of Iron, Alumi...External filtered neutron beams have been developed at the horizontal radial channels No. 4 of Dalat research reactor. In the material composition of the neutron filters, the primary material components of Iron, Aluminum, Nickel and Vanadium are used to obtain the mono-energetic neutron beams of 24 and 59 keV, with low level of Gamma and slow neutron background. A computer code and Monte-Carlo simulation technique were applied to optimize the filter configurations and to deduce the neutron energy distributions in the filtered beams. A hydrogen-filled proton recoil detector and the activation method with Gold foils were used to measure the neutron energy spectrum and flux of each beam at sample position. The results of experimental neutron fluxes are 6.1 × 105 and 5.3 × 105 n/cm2/s for 24 and 59 keV beams, respectively.展开更多
Background In this study,three sample detectors have been prepared by using cerium-activated YAG nanoscintillator(Y_(3)Al_(5)O_(12):Ce^(3+))synthesized by sol-gel method and heat-treat at 900°C for 2 h in differe...Background In this study,three sample detectors have been prepared by using cerium-activated YAG nanoscintillator(Y_(3)Al_(5)O_(12):Ce^(3+))synthesized by sol-gel method and heat-treat at 900°C for 2 h in different atmospheres such as vacuum,air and nitrogen.Purpose Many studies about YAG:Ce^(3+)single crystal have been carried out,but the material at the nanoscale remains not enough understood.The objective of the present paper is to investigate the effects of annealing atmosphere on the scintillation properties and identify the suitable atmosphere that allow to design radiation detectors with high scintillation efficiency.Methods In order to accurately assess the scintillation properties,the nanoscintillator sample powders have been designed as a detector,in which,preparation operations such as surface homogenization and efficiency coupling with photomultiplier tube(PMT)window were developed.The study was performed usingγ-rays 662 keV released from137Cs radioactive source,the bi-alkali GDB-4FF PMT was used as a photodetector.Nuclear instrumentation chain was set up in order to collect the pulse height spectra,NaI:Tl single-crystal scintillator was used as a reference detector to estimate the scintillation light yield.The delayed coincidence method was used for measuring the scintillation decay time of nanoscintillator sample detectors.Results The sample detector annealed at vacuum atmosphere exhibits the best scintillation properties,the scintillation light yield was estimated to be 14,600±3400 ph/MeV and the fast component in the scintillation decay was 90 ns.Conclusion The vacuum is the suitable atmosphere which allows the development of radiation detectors with high scintillation efficiency.展开更多
The average binding energy of the dineutron virtual state was derived from the correlative spectrum of two protons in ^(2)H(d,^(2)p)^(2)n reaction,and from the p-p coincidence measurement the value is estimated to be ...The average binding energy of the dineutron virtual state was derived from the correlative spectrum of two protons in ^(2)H(d,^(2)p)^(2)n reaction,and from the p-p coincidence measurement the value is estimated to be about 210keV.展开更多
We present the result of an experimental search for a heavy neutrino admixture in the electron capture process.The 95%confidence level upper limits from 0.02 to 0.04 are set for the mixing strength of heavy neutrinos ...We present the result of an experimental search for a heavy neutrino admixture in the electron capture process.The 95%confidence level upper limits from 0.02 to 0.04 are set for the mixing strength of heavy neutrinos in the neutrino mass range of 30keV to 90keV.展开更多
The mass of 40 Ti has been determined by using the isobaric multiplet mass equation method. The experimental data of the 40Tiβ-decay were used to determine the level of the isospin analogue state of^( 40)Sc. The grou...The mass of 40 Ti has been determined by using the isobaric multiplet mass equation method. The experimental data of the 40Tiβ-decay were used to determine the level of the isospin analogue state of^( 40)Sc. The ground-state mass excess and the QEc value for 40 Ti were determined to be -9060 ± 12 keV and 11 466 ± 13keV, respectively.展开更多
Under 2keV Xe ion bombardment of a ^(63)Cu69.1^(65)Cu30.9 isotope mixture,isotope fractionation difference between small and large polar emission angles,δ(15°)-δ(75°),was calculated by use of a dynamic Mon...Under 2keV Xe ion bombardment of a ^(63)Cu69.1^(65)Cu30.9 isotope mixture,isotope fractionation difference between small and large polar emission angles,δ(15°)-δ(75°),was calculated by use of a dynamic Monte Carlo program.Calculation results show that δ(15°)-δ(75°) is large at both the zero fluence and the high fluence,then it minimizes at a low fluence of 1.6x 10^(15) ions/cm^(2) between two fluence limits.An important cause of this minimum is that the surface composition gradient of ^(63)Cu maximiles at the fluence of 1.6x10^(15) ions /cm^(2).展开更多
Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~...Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~C. Transmission electron microscopy （TEM） is used to characterize the size and morphology of He bubbles. With the increase of the implantation temperature, TEM observations indicate that bubbles increase in size and the proportion of ＇brick shaped＇ cuboid bubbles increases while the proportion of polyhedral bubbles decreases in both the steel samples. For the samples implanted at the same temperature, the average size of He bubbles in MNHS is smaller than that in T91. This might be due to the abundance of boundaries and precipitates in MNHS, which provide additional sites for the trapping of He atoms, thus reduce the susceptibility of MNHS to He embrittlement.展开更多
^(99)mTc is the most commonly used diagnostic medical radioisotope because of its short half-life(T1/2=6.01 h)and low β-energy(140.5 keV)[1].Generally,^(99)mTc is obtained from^(99)Mo decays by β-emission.
Monoenergetic peaks have been searched in the inclusive gamma ray spectrum from oPs decay.For axion massr 60keV to 970keV the 90%confidence level limits on the rabtio R of single gamma ray to three gamma ray decay fro...Monoenergetic peaks have been searched in the inclusive gamma ray spectrum from oPs decay.For axion massr 60keV to 970keV the 90%confidence level limits on the rabtio R of single gamma ray to three gamma ray decay from oPsr 6 ×10^(-4) to 6×10^(-5) without the assumption of the penetrating axions.展开更多
Gamma-gamma coincidence evidences are presented in this paper to confirm the existence of levels 3394.5keV and 3473.7keV in ^(140)Ce.The level 3520.8keV in ^(140)Ce should be discarded because of the identification of...Gamma-gamma coincidence evidences are presented in this paper to confirm the existence of levels 3394.5keV and 3473.7keV in ^(140)Ce.The level 3520.8keV in ^(140)Ce should be discarded because of the identification of the peak at 1924keV as a pure sum-peak of two strong gamma rays at 328kev and 1596keV.展开更多
The cross sections of electron capture for 3-10 keV proton traversing H_(2) were measured by using the‘growth rate’method.The experimental procedure is described.The experimental results are in good agreement with t...The cross sections of electron capture for 3-10 keV proton traversing H_(2) were measured by using the‘growth rate’method.The experimental procedure is described.The experimental results are in good agreement with the recommended data.展开更多
Several hundred keV fast neutron radiography(HKFNR)can be a complementary technique to common thermal neutron radiography(TNR)and several MeV fast neutron radiography(MFNR).We tested HKFNR on a 4.5 MV Van de Graaff ac...Several hundred keV fast neutron radiography(HKFNR)can be a complementary technique to common thermal neutron radiography(TNR)and several MeV fast neutron radiography(MFNR).We tested HKFNR on a 4.5 MV Van de Graaff accelerator,and the experimental results show that the spatial resolution of this technique is better than MFNR and close to TNR.Several hundred keV fast neutrons can penetrate some thermal neutron absorbers such as Cd,and it is feasible to investigate its use on some materials which are transparent to cold/thermal neutrons,such as aluminum,using this technique.展开更多
文摘The application of keV ion beam in life science started in China several decades ago. In 1986, researchers initially studied the mutagenic effect of ion beam, and successfully applied it to plant breeding. Nowadays, ion beam implantation technique has been extensively applied to many biological fields. This paper mainly introduces one of its important applications: genetic transformation mediated by keV ion beam.
文摘External filtered neutron beams have been developed at the horizontal radial channels No. 4 of Dalat research reactor. In the material composition of the neutron filters, the primary material components of Iron, Aluminum, Nickel and Vanadium are used to obtain the mono-energetic neutron beams of 24 and 59 keV, with low level of Gamma and slow neutron background. A computer code and Monte-Carlo simulation technique were applied to optimize the filter configurations and to deduce the neutron energy distributions in the filtered beams. A hydrogen-filled proton recoil detector and the activation method with Gold foils were used to measure the neutron energy spectrum and flux of each beam at sample position. The results of experimental neutron fluxes are 6.1 × 105 and 5.3 × 105 n/cm2/s for 24 and 59 keV beams, respectively.
文摘Background In this study,three sample detectors have been prepared by using cerium-activated YAG nanoscintillator(Y_(3)Al_(5)O_(12):Ce^(3+))synthesized by sol-gel method and heat-treat at 900°C for 2 h in different atmospheres such as vacuum,air and nitrogen.Purpose Many studies about YAG:Ce^(3+)single crystal have been carried out,but the material at the nanoscale remains not enough understood.The objective of the present paper is to investigate the effects of annealing atmosphere on the scintillation properties and identify the suitable atmosphere that allow to design radiation detectors with high scintillation efficiency.Methods In order to accurately assess the scintillation properties,the nanoscintillator sample powders have been designed as a detector,in which,preparation operations such as surface homogenization and efficiency coupling with photomultiplier tube(PMT)window were developed.The study was performed usingγ-rays 662 keV released from137Cs radioactive source,the bi-alkali GDB-4FF PMT was used as a photodetector.Nuclear instrumentation chain was set up in order to collect the pulse height spectra,NaI:Tl single-crystal scintillator was used as a reference detector to estimate the scintillation light yield.The delayed coincidence method was used for measuring the scintillation decay time of nanoscintillator sample detectors.Results The sample detector annealed at vacuum atmosphere exhibits the best scintillation properties,the scintillation light yield was estimated to be 14,600±3400 ph/MeV and the fast component in the scintillation decay was 90 ns.Conclusion The vacuum is the suitable atmosphere which allows the development of radiation detectors with high scintillation efficiency.
文摘The average binding energy of the dineutron virtual state was derived from the correlative spectrum of two protons in ^(2)H(d,^(2)p)^(2)n reaction,and from the p-p coincidence measurement the value is estimated to be about 210keV.
文摘We present the result of an experimental search for a heavy neutrino admixture in the electron capture process.The 95%confidence level upper limits from 0.02 to 0.04 are set for the mixing strength of heavy neutrinos in the neutrino mass range of 30keV to 90keV.
基金Supported by the National Natural Science Foundation of China for Distinguished Young Scholars under Grant No.10025524the Major State Basic Research Development Programme under contract No.G200077400the National Natural Science Foundation of China under Grant Nos.10045002,19735010 and 19935030,and the Nuclear Energy Development Fund.
文摘The mass of 40 Ti has been determined by using the isobaric multiplet mass equation method. The experimental data of the 40Tiβ-decay were used to determine the level of the isospin analogue state of^( 40)Sc. The ground-state mass excess and the QEc value for 40 Ti were determined to be -9060 ± 12 keV and 11 466 ± 13keV, respectively.
文摘Under 2keV Xe ion bombardment of a ^(63)Cu69.1^(65)Cu30.9 isotope mixture,isotope fractionation difference between small and large polar emission angles,δ(15°)-δ(75°),was calculated by use of a dynamic Monte Carlo program.Calculation results show that δ(15°)-δ(75°) is large at both the zero fluence and the high fluence,then it minimizes at a low fluence of 1.6x 10^(15) ions/cm^(2) between two fluence limits.An important cause of this minimum is that the surface composition gradient of ^(63)Cu maximiles at the fluence of 1.6x10^(15) ions /cm^(2).
基金Supported by the National Basic Research Program of China under Grant Nos 2010CB832902 and 91026002the National Natural Science Foundation of China under Grant No U1232121
文摘Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~C. Transmission electron microscopy （TEM） is used to characterize the size and morphology of He bubbles. With the increase of the implantation temperature, TEM observations indicate that bubbles increase in size and the proportion of ＇brick shaped＇ cuboid bubbles increases while the proportion of polyhedral bubbles decreases in both the steel samples. For the samples implanted at the same temperature, the average size of He bubbles in MNHS is smaller than that in T91. This might be due to the abundance of boundaries and precipitates in MNHS, which provide additional sites for the trapping of He atoms, thus reduce the susceptibility of MNHS to He embrittlement.
文摘^(99)mTc is the most commonly used diagnostic medical radioisotope because of its short half-life(T1/2=6.01 h)and low β-energy(140.5 keV)[1].Generally,^(99)mTc is obtained from^(99)Mo decays by β-emission.
文摘Monoenergetic peaks have been searched in the inclusive gamma ray spectrum from oPs decay.For axion massr 60keV to 970keV the 90%confidence level limits on the rabtio R of single gamma ray to three gamma ray decay from oPsr 6 ×10^(-4) to 6×10^(-5) without the assumption of the penetrating axions.
文摘Gamma-gamma coincidence evidences are presented in this paper to confirm the existence of levels 3394.5keV and 3473.7keV in ^(140)Ce.The level 3520.8keV in ^(140)Ce should be discarded because of the identification of the peak at 1924keV as a pure sum-peak of two strong gamma rays at 328kev and 1596keV.
基金Supported by the National Natural Science Foundation of China。
文摘The cross sections of electron capture for 3-10 keV proton traversing H_(2) were measured by using the‘growth rate’method.The experimental procedure is described.The experimental results are in good agreement with the recommended data.
基金Supported by the National Basic Research Program of China under Grant No 2010CB833106。
文摘Several hundred keV fast neutron radiography(HKFNR)can be a complementary technique to common thermal neutron radiography(TNR)and several MeV fast neutron radiography(MFNR).We tested HKFNR on a 4.5 MV Van de Graaff accelerator,and the experimental results show that the spatial resolution of this technique is better than MFNR and close to TNR.Several hundred keV fast neutrons can penetrate some thermal neutron absorbers such as Cd,and it is feasible to investigate its use on some materials which are transparent to cold/thermal neutrons,such as aluminum,using this technique.
