As a non-destructive testing technology,neutron imaging plays an important role in various fields,including material science,nuclear engineering,and fundamental science.An imaging detector with a neutron-sensitive ima...As a non-destructive testing technology,neutron imaging plays an important role in various fields,including material science,nuclear engineering,and fundamental science.An imaging detector with a neutron-sensitive image intensifier has been developed and demonstrated to achieve good spatial resolution and timing resolution.However,the influence of the working voltage on the performance of the neutron-sensitive imaging intensifier has not been studied.To optimize the performance of the neutron-sensitive image intensifier at different voltages,experiments have been performed at the China Spallation Neutron Source(CSNS)neutron beamline.The change in the light yield and imaging quality with different voltages has been acquired.It is shown that the image quality benefits from the high gain of the microchannel plate(MCP)and the high accelerating electric field between the MCP and the screen.Increasing the accelerating electric field is more effective than increasing the gain of MCPs for the improvement of the imaging quality.Increasing the total gain of the MCP stack can be realized more effectively by improving the gain of the standard MCP than that of the n MCP.These results offer a development direction for image intensifiers in the future.展开更多
The transport process of 12C ions in water was studied with SRIM code and Geant4 toolkit. The SRIM results indicate that the transverse diffusion of 12C ion beam causes distortion of energy deposit along the beam dire...The transport process of 12C ions in water was studied with SRIM code and Geant4 toolkit. The SRIM results indicate that the transverse diffusion of 12C ion beam causes distortion of energy deposit along the beam direction. The distortion becomes more notable as the transverse diffusion increases. The simulation results of Geant4 indicate that the influence of secondary fragments on energy deposit distribution would be the main factor causing the distortion in higher energy range. In the region adjacent to the beam line where the contribution from 12C ions domi- nates, the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary frag- ments exceed that of 12C. Among all the secondary fragments, the contributions of H, He and B ions are mostly notable. It is also found that some positron-emitting secondary fragments could be very useful for position emitting tomography （PET）.展开更多
An experiment for measuring the hyperon-related fission rate was carried out with the reaction 209^Bi（e, e＇K^＋）209^hPb at the Thomas Jefferson National Laboratory （Jlab）. In the experiment, the performance of th...An experiment for measuring the hyperon-related fission rate was carried out with the reaction 209^Bi（e, e＇K^＋）209^hPb at the Thomas Jefferson National Laboratory （Jlab）. In the experiment, the performance of the fission fragment detector （FFD） was dramaticlly crashed by the background particles in comparison with that during the test without beam. The scattering of the high intensity （500 nA） primary electrons was the dominant cause. Using the GEANT4 toolkit, this report simulates the experimental situation of the target chamber in which the FFD was located. The simulation results indicate that the background particles were dominantly （~ electrons, and protons and alpha particles were the important heavy background particles. The performance of the multi-wire proportional chambers （MWPCs） depends not only on the background-particle intensity but also the current density, which was also given by the simulation code. Furthermore, the measures to suppress the background particles were also investigated with the simulation code.展开更多
A common optical potential for 4He＋12C at intermediate bombarding energies, which is essential in analyzing exotic nuclei with 4He clusters, is obtained based on the Sao Paulo potential. Among systematic optical pote...A common optical potential for 4He＋12C at intermediate bombarding energies, which is essential in analyzing exotic nuclei with 4He clusters, is obtained based on the Sao Paulo potential. Among systematic optical potentials for 4He＋12 C, this potential has the merit of using a fixed imaginary part of the Woods Saxon form. By optical- model calculations, this potential reproduces the experimental elastic scattering angular distributions of a He＋12 C well within the energy range of 26A 60A MeV. It is also applied successfully in calculations of the breakup reactions of 6Li＋12 C and 6He＋12 C with a three-body continuum discretized coupled-channel method.展开更多
Experimental data analysis and simulation calculations were performed in order to evaluate the cross-talk rejection performance of a typical neutron detection array. For very closely packed scintillation bars, the CT ...Experimental data analysis and simulation calculations were performed in order to evaluate the cross-talk rejection performance of a typical neutron detection array. For very closely packed scintillation bars, the CT rejection may rely on the position relation between the two signals. The criteria ｜△x｜≤ 15 cm and ｜△y｜≤12 cm are currently proposed for a rejection rate higher than 90%. For signals coming from distanced bars, the energy conservation relationship can be applied to reject the CT events with a similar performance. In both cases the results of simulation agree very well with the experimental data, assuring their applicability to other detection systems and physics problems.展开更多
In the present research, we used the 17^Ne beam at 30.8 MeV/u to bombard the 43 mg/cm^2 12^C target and measured the angular correlations between the fragments and emitted proton. In the break-up reaction of 17^Ne, on...In the present research, we used the 17^Ne beam at 30.8 MeV/u to bombard the 43 mg/cm^2 12^C target and measured the angular correlations between the fragments and emitted proton. In the break-up reaction of 17^Ne, one-proton knockout would result in an unstable nu- cleus 16^F, which would further decay by the proton emission. The measured angular correlation between the 16^F momentum and the relative momentum of its decay products was compared with theoretical calculations and indicated that the valence proton in 17^Ne has the most probability to be situated in the s1/2 orbital with a small admixture of the d5/2 orbital. The present results suggest that 17^Ne has a halo structure.展开更多
A code has been developed to simulate the neutralization and grazing process of slow highly charged ion Xe^q＋ on Al（111） surface under the classical-over-the-barrier model. The image energy gain of Xeq＋ ions are c...A code has been developed to simulate the neutralization and grazing process of slow highly charged ion Xe^q＋ on Al（111） surface under the classical-over-the-barrier model. The image energy gain of Xeq＋ ions are calculated and compared with experiment data. The simulation results of image energy gain are in good agreement with the experiment data. Meanwhile, in the present work, the reflection coefficient of incident Xe^q＋ on Al（111） surface as a function of the incidence angle, energy and charge state is also studied.展开更多
The total energy loss of N^＋q ions （for v 〈 Bohr velocity） grazing on the Al（111） has been simulated without any ＇fit＇ parameter and compared with the experimental data. The energy loss due to the charge excha...The total energy loss of N^＋q ions （for v 〈 Bohr velocity） grazing on the Al（111） has been simulated without any ＇fit＇ parameter and compared with the experimental data. The energy loss due to the charge exchange, happening before the N^＋q hits the Al（111） surface, is studied. The present simulation shows that the energy loss strongly depends on the charge state of the projectile and the lattice orientation of Al（111） surface. The calculated total energy loss agrees with experimental data very well.展开更多
Differential cross sections for the quasi-elastic scattering of^16 C at 47.5 MeV/nucleon from ^12 C target are measured.Coupled-channels calculations are carried out and the optical potential parameters are obtained b...Differential cross sections for the quasi-elastic scattering of^16 C at 47.5 MeV/nucleon from ^12 C target are measured.Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.展开更多
基金Project supported by the National Key R&D Program of China (Grant Nos.2023YFC2206502 and 2021YFA1600703)the National Natural Science Foundation of China (Grant Nos.12175254 and 12227810)the Guangdong–Hong Kong–Macao Joint Laboratory for Neutron Scattering Science and Technology。
文摘As a non-destructive testing technology,neutron imaging plays an important role in various fields,including material science,nuclear engineering,and fundamental science.An imaging detector with a neutron-sensitive image intensifier has been developed and demonstrated to achieve good spatial resolution and timing resolution.However,the influence of the working voltage on the performance of the neutron-sensitive imaging intensifier has not been studied.To optimize the performance of the neutron-sensitive image intensifier at different voltages,experiments have been performed at the China Spallation Neutron Source(CSNS)neutron beamline.The change in the light yield and imaging quality with different voltages has been acquired.It is shown that the image quality benefits from the high gain of the microchannel plate(MCP)and the high accelerating electric field between the MCP and the screen.Increasing the accelerating electric field is more effective than increasing the gain of MCPs for the improvement of the imaging quality.Increasing the total gain of the MCP stack can be realized more effectively by improving the gain of the standard MCP than that of the n MCP.These results offer a development direction for image intensifiers in the future.
基金supported by the Fundamental Research Funds for the Central Universities of China(HEUCF101501)the Fundamental Research Funds of Harbin Engineering University of China(002150260713)
文摘The transport process of 12C ions in water was studied with SRIM code and Geant4 toolkit. The SRIM results indicate that the transverse diffusion of 12C ion beam causes distortion of energy deposit along the beam direction. The distortion becomes more notable as the transverse diffusion increases. The simulation results of Geant4 indicate that the influence of secondary fragments on energy deposit distribution would be the main factor causing the distortion in higher energy range. In the region adjacent to the beam line where the contribution from 12C ions domi- nates, the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary frag- ments exceed that of 12C. Among all the secondary fragments, the contributions of H, He and B ions are mostly notable. It is also found that some positron-emitting secondary fragments could be very useful for position emitting tomography （PET）.
基金supported by the Fundamental Research Funds for the Central Universities of China (No.HEUCF101501)the Fundamental Research Funds of Harbin Engineering University of China (No.002150260713)
文摘An experiment for measuring the hyperon-related fission rate was carried out with the reaction 209^Bi（e, e＇K^＋）209^hPb at the Thomas Jefferson National Laboratory （Jlab）. In the experiment, the performance of the fission fragment detector （FFD） was dramaticlly crashed by the background particles in comparison with that during the test without beam. The scattering of the high intensity （500 nA） primary electrons was the dominant cause. Using the GEANT4 toolkit, this report simulates the experimental situation of the target chamber in which the FFD was located. The simulation results indicate that the background particles were dominantly （~ electrons, and protons and alpha particles were the important heavy background particles. The performance of the multi-wire proportional chambers （MWPCs） depends not only on the background-particle intensity but also the current density, which was also given by the simulation code. Furthermore, the measures to suppress the background particles were also investigated with the simulation code.
基金Supported by the National Natural Science Foundation of China under Grant No 11205036the Fundamental Research Funds for the Central Universities of China under Grant No HEUCF101501
文摘A common optical potential for 4He＋12C at intermediate bombarding energies, which is essential in analyzing exotic nuclei with 4He clusters, is obtained based on the Sao Paulo potential. Among systematic optical potentials for 4He＋12 C, this potential has the merit of using a fixed imaginary part of the Woods Saxon form. By optical- model calculations, this potential reproduces the experimental elastic scattering angular distributions of a He＋12 C well within the energy range of 26A 60A MeV. It is also applied successfully in calculations of the breakup reactions of 6Li＋12 C and 6He＋12 C with a three-body continuum discretized coupled-channel method.
基金supported by the National Basic Research Program of China (No. 2007CB815002)the Fundamental Research Funds for the Central Universities of China (HEUCF101501)Harbin Engineering University of China (002150260713)
文摘Experimental data analysis and simulation calculations were performed in order to evaluate the cross-talk rejection performance of a typical neutron detection array. For very closely packed scintillation bars, the CT rejection may rely on the position relation between the two signals. The criteria ｜△x｜≤ 15 cm and ｜△y｜≤12 cm are currently proposed for a rejection rate higher than 90%. For signals coming from distanced bars, the energy conservation relationship can be applied to reject the CT events with a similar performance. In both cases the results of simulation agree very well with the experimental data, assuring their applicability to other detection systems and physics problems.
基金supported by National Natural Science Foundation of China (Nos.10775005,10735010,J0730316)Chinese Major State Basic Research Development Program (2007CB815002)
文摘In the present research, we used the 17^Ne beam at 30.8 MeV/u to bombard the 43 mg/cm^2 12^C target and measured the angular correlations between the fragments and emitted proton. In the break-up reaction of 17^Ne, one-proton knockout would result in an unstable nu- cleus 16^F, which would further decay by the proton emission. The measured angular correlation between the 16^F momentum and the relative momentum of its decay products was compared with theoretical calculations and indicated that the valence proton in 17^Ne has the most probability to be situated in the s1/2 orbital with a small admixture of the d5/2 orbital. The present results suggest that 17^Ne has a halo structure.
基金Project supported by the Research Fund for the Doctoral Program of Hlgher Education （Grant No 20030730004）, the National Natural Science Foundation of China （Grant No 10374039） and the Natural Science Foundation of Gansu Province, China （Grant No ZS031-A25-001-Z）.
文摘A code has been developed to simulate the neutralization and grazing process of slow highly charged ion Xe^q＋ on Al（111） surface under the classical-over-the-barrier model. The image energy gain of Xeq＋ ions are calculated and compared with experiment data. The simulation results of image energy gain are in good agreement with the experiment data. Meanwhile, in the present work, the reflection coefficient of incident Xe^q＋ on Al（111） surface as a function of the incidence angle, energy and charge state is also studied.
基金Project supported by the Research Fund for the Doctoral Program of Higher Education, China （Grant No 20030730004）, the National Natural Science Foundation of China （Grant No 10374039） and the Natural Science Foundation of Gansu Province, , China .（G_ra_nt N oZS031-A25-001-Z）.
文摘The total energy loss of N^＋q ions （for v 〈 Bohr velocity） grazing on the Al（111） has been simulated without any ＇fit＇ parameter and compared with the experimental data. The energy loss due to the charge exchange, happening before the N^＋q hits the Al（111） surface, is studied. The present simulation shows that the energy loss strongly depends on the charge state of the projectile and the lattice orientation of Al（111） surface. The calculated total energy loss agrees with experimental data very well.
基金Supported by the National Basic Research Program of China under Grant No 2007CB815002, the National Natural Science Foundation of China under Grant Nos 10405002, 10775003 and 10720003, the Found for Fostering Talents of Basic Science （NFFTBS） （J073316）.
文摘Differential cross sections for the quasi-elastic scattering of^16 C at 47.5 MeV/nucleon from ^12 C target are measured.Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.
