2015年 第32卷 第3期
2015, 32(3): 259-266.
doi: 10.11804/NuclPhysRev.32.03.259
摘要:
采用把重离子碰撞的动力学和统计衰变过程相结合的一个两步模型，再现了INDRA Collaborations 对入射能为35 AMeV40Ca+40Ca 和48Ca+48Ca 反应的实验结果。进而得到了反应碎块同位素分布的Isoscaling 参数α(Z) 和β(N)，约化对称能系数ζ(Z) 及与平均场中的对称能强度系数Cs 之间的关系。结果表明，Isoscaling 参数强烈依赖于系统的丰中子程度。随着质子数的增大，ζ(Z) 在动力学阶段呈现平缓趋势但在衰变之后呈现上升趋势，且该结果不依赖于所选取的反应系统。对称能效应在统计衰变过程之后的末级碎块分布中有明显表现。
A two-step model for combining the dynamical and statistical decay processes in heavy-ion collisions is used to reproduce the experimental results of the INDRA Collaborations on 40Ca+40Ca and 48Ca+48Ca reactions at 35 AMeV. We obtain the isoscaling parameters α(Z) and β(N) of isotopic distributions of the fragments, the reduced symmetry energy coefficient ζ(Z) and its dependence on the symmetry energy strength coefficient Cs in the mean field. Our results suggest that Isoscaling parameters strongly depend on the degree of neutron-rich. With the increasing atomic number, ζ(Z) represents a smoothly flat tendency during the dynamical process but shows the increasing tendency after decay, and such results are independent on the selected reaction systems. The effect of symmetry energy shows evidently in the isotopic distributions of fragments after statistical decay process.
采用把重离子碰撞的动力学和统计衰变过程相结合的一个两步模型，再现了INDRA Collaborations 对入射能为35 AMeV40Ca+40Ca 和48Ca+48Ca 反应的实验结果。进而得到了反应碎块同位素分布的Isoscaling 参数α(Z) 和β(N)，约化对称能系数ζ(Z) 及与平均场中的对称能强度系数Cs 之间的关系。结果表明，Isoscaling 参数强烈依赖于系统的丰中子程度。随着质子数的增大，ζ(Z) 在动力学阶段呈现平缓趋势但在衰变之后呈现上升趋势，且该结果不依赖于所选取的反应系统。对称能效应在统计衰变过程之后的末级碎块分布中有明显表现。
A two-step model for combining the dynamical and statistical decay processes in heavy-ion collisions is used to reproduce the experimental results of the INDRA Collaborations on 40Ca+40Ca and 48Ca+48Ca reactions at 35 AMeV. We obtain the isoscaling parameters α(Z) and β(N) of isotopic distributions of the fragments, the reduced symmetry energy coefficient ζ(Z) and its dependence on the symmetry energy strength coefficient Cs in the mean field. Our results suggest that Isoscaling parameters strongly depend on the degree of neutron-rich. With the increasing atomic number, ζ(Z) represents a smoothly flat tendency during the dynamical process but shows the increasing tendency after decay, and such results are independent on the selected reaction systems. The effect of symmetry energy shows evidently in the isotopic distributions of fragments after statistical decay process.
2015, 32(3): 267-273.
doi: 10.11804/NuclPhysRev.32.03.267
摘要:
利用UrQMD-3.3p1 模型模拟了在质心能量√sNN = 7.7, 11.5, 19.6, 27, 39 和62.4 GeV 的Au+Au 碰撞，在中心快度区域分析了质子，π+，K+ 以及它们相应的反粒子的椭圆流。分析了粒子与相应的反粒子的v2 差值随横动量pT 的变化。分析结果表明，在UrQMD 模型中在整个BES 能区K- 的v2 值大于K+ 的。在能区7.7 ~ 62.4GeV π+ 和π-的v2(pT) 值几乎相同。然而实验上在低能区7.7, 11.5 和19.6 GeV, 在所考察的pT 值范围内v2(π-)大于v2(π+)。能清楚看到在UrQMD模型中在整个BES 能区反质子的v2 大于质子的，这与实验结果相反。理论结果与实验数据相反，表明我们还需要不断深化对重离子碰撞的强耦合性和输运过程的非平衡性的理解。
利用UrQMD-3.3p1 模型模拟了在质心能量√sNN = 7.7, 11.5, 19.6, 27, 39 和62.4 GeV 的Au+Au 碰撞，在中心快度区域分析了质子，π+，K+ 以及它们相应的反粒子的椭圆流。分析了粒子与相应的反粒子的v2 差值随横动量pT 的变化。分析结果表明，在UrQMD 模型中在整个BES 能区K- 的v2 值大于K+ 的。在能区7.7 ~ 62.4GeV π+ 和π-的v2(pT) 值几乎相同。然而实验上在低能区7.7, 11.5 和19.6 GeV, 在所考察的pT 值范围内v2(π-)大于v2(π+)。能清楚看到在UrQMD模型中在整个BES 能区反质子的v2 大于质子的，这与实验结果相反。理论结果与实验数据相反，表明我们还需要不断深化对重离子碰撞的强耦合性和输运过程的非平衡性的理解。
2015, 32(3): 274-279.
doi: 10.11804/NuclPhysRev.32.03.274
摘要:
在日本东京大学CRIB 次级束装置上，用长气体靶开展了22Na+ α共振散射的厚靶实验研究。针对长气体靶实验中的两体运动学重构问题，提出了一套包括构建空间复杂几何关系、计算能量损失以及反应运动学的逐事件分析方法；对22Na+α共振散射的实验数据进行了重构分析，得到了Ec.m. = 4.2 ~ 5.4 MeV 区间22Na( α,α ) 的激发函数，从实验的激发函数中观测到了复合核26Al 5 个较为明显的共振峰。鉴于26Al 共振态的衰变模式比较复杂，本工作发现的26Al新共振态的能级性质有待进一步的理论分析。The 22Na+α resonant scattering is studied via a conventional thick target inverse kinematic method with an extended gas target. A data analysis method is proposed for the two-body reaction kinematic reconstruction, in which the spatial geometry, the reaction kinematics and the energy losses are considered. The experimental data of 22Na+ αresonant scattering have been thus reconstructed, and the excitation function is obtained in the energy interval of Ec.m. =4.2~5.4 MeV. Five resonant states in 26Al are observed in the experimental excitation function. Since several decay modes coexist for the observed 26Al resonant states, multi-channel theoretical analysis is thus needed to reveal their structure and decay features.
在日本东京大学CRIB 次级束装置上，用长气体靶开展了22Na+ α共振散射的厚靶实验研究。针对长气体靶实验中的两体运动学重构问题，提出了一套包括构建空间复杂几何关系、计算能量损失以及反应运动学的逐事件分析方法；对22Na+α共振散射的实验数据进行了重构分析，得到了Ec.m. = 4.2 ~ 5.4 MeV 区间22Na( α,α ) 的激发函数，从实验的激发函数中观测到了复合核26Al 5 个较为明显的共振峰。鉴于26Al 共振态的衰变模式比较复杂，本工作发现的26Al新共振态的能级性质有待进一步的理论分析。The 22Na+α resonant scattering is studied via a conventional thick target inverse kinematic method with an extended gas target. A data analysis method is proposed for the two-body reaction kinematic reconstruction, in which the spatial geometry, the reaction kinematics and the energy losses are considered. The experimental data of 22Na+ αresonant scattering have been thus reconstructed, and the excitation function is obtained in the energy interval of Ec.m. =4.2~5.4 MeV. Five resonant states in 26Al are observed in the experimental excitation function. Since several decay modes coexist for the observed 26Al resonant states, multi-channel theoretical analysis is thus needed to reveal their structure and decay features.
2015, 32(3): 280-285.
doi: 10.11804/NuclPhysRev.32.03.280
摘要:
在浦项中子装置(PNF) 的100 MeV电子直线加速器上利用透射法和飞行时间法测量了209Bi 的0.1~100 eV的中子全截面。文中对于实验装置特点、用吸收片法拟合本底、拟合中子飞行距离和时间零点的处理过程做了较为详细的描述。测量结果与以前发表的实验数据以及评价数据ENDF/B-VII.1 做了比较，比较结果符合得较好。
在浦项中子装置(PNF) 的100 MeV电子直线加速器上利用透射法和飞行时间法测量了209Bi 的0.1~100 eV的中子全截面。文中对于实验装置特点、用吸收片法拟合本底、拟合中子飞行距离和时间零点的处理过程做了较为详细的描述。测量结果与以前发表的实验数据以及评价数据ENDF/B-VII.1 做了比较，比较结果符合得较好。
2015, 32(3): 286-290.
doi: 10.11804/NuclPhysRev.32.03.286
摘要:
通过对宇宙线周期变化研究可以得到宇宙线产生和传播区域的重要信息，是宇宙线长期研究的重要热点问题。利用位于西藏羊八井(地磁截止刚度：14.1 GeV) 的中子监测器2006 至2011年的观测数据，研究宇宙线的太阳日周期变化。在对中子监测器观测数据进行气压修正后，通过Lomb-Scargle 傅立叶变换法对修正后的数据进行周期分析，发现宇宙线计数率存在超过地球公转运动Compton-Getting 效应的太阳日周期变化，该周期变化可能是地球公转效应和宇宙线传播物理过程调制效应以及剩余气象效应的叠加。计算分析了1 日周期信号的振幅和初相位随时间的变化，发现1 日周期变化的初相位存在较为明显的年周期变化规律，这可能是地球公转和自转合成运动的结果；1 日周期变化幅度在2010 年后出现增大趋势。这些结果对宇宙线周期变化和各向异性的研究具有重要参考意义。With the study of the cosmic rays' solar diurnal variation we can get the important information about Cosmic Ray's production and propagation. It's important issues of cosmic rays' studies. We analyze the temporal variation of cosmic rays rate observed with the Yangbajing neutron monitor during 2006 to 2011, and nd semidiurnal and diurnal period signals included in the rates of cosmic rays with vertical rigidity equal to 14.1 GV. We have checked the time dependence of the phase and the amplitude of semidiurnal and diurnal anisotropy, and nd that the phase of diurnal signal varies yearly, it could be a synthetic movement of the earth's rotation and revolution. The amplitude before 2010 is obvious smaller than that after 2010. These results are of great reference value for studying the anisotropy and time variation of cosmic rays.
通过对宇宙线周期变化研究可以得到宇宙线产生和传播区域的重要信息，是宇宙线长期研究的重要热点问题。利用位于西藏羊八井(地磁截止刚度：14.1 GeV) 的中子监测器2006 至2011年的观测数据，研究宇宙线的太阳日周期变化。在对中子监测器观测数据进行气压修正后，通过Lomb-Scargle 傅立叶变换法对修正后的数据进行周期分析，发现宇宙线计数率存在超过地球公转运动Compton-Getting 效应的太阳日周期变化，该周期变化可能是地球公转效应和宇宙线传播物理过程调制效应以及剩余气象效应的叠加。计算分析了1 日周期信号的振幅和初相位随时间的变化，发现1 日周期变化的初相位存在较为明显的年周期变化规律，这可能是地球公转和自转合成运动的结果；1 日周期变化幅度在2010 年后出现增大趋势。这些结果对宇宙线周期变化和各向异性的研究具有重要参考意义。With the study of the cosmic rays' solar diurnal variation we can get the important information about Cosmic Ray's production and propagation. It's important issues of cosmic rays' studies. We analyze the temporal variation of cosmic rays rate observed with the Yangbajing neutron monitor during 2006 to 2011, and nd semidiurnal and diurnal period signals included in the rates of cosmic rays with vertical rigidity equal to 14.1 GV. We have checked the time dependence of the phase and the amplitude of semidiurnal and diurnal anisotropy, and nd that the phase of diurnal signal varies yearly, it could be a synthetic movement of the earth's rotation and revolution. The amplitude before 2010 is obvious smaller than that after 2010. These results are of great reference value for studying the anisotropy and time variation of cosmic rays.
2015, 32(3): 291-295.
doi: 10.11804/NuclPhysRev.32.03.291
摘要:
高能重离子碰撞热核环境中J/ψ产额的压低被认为是夸克胶子等离子体生成的重要信号。研究冷核物质中各种核效应对J/ψ 形成过程的影响，是准确理解热核环境中核效应对J/ψ产额压低机制的重要途径。研究了质子-原子核碰撞J/ψ 产生过程中初态部分子分布函数的核效应、入射质子的能量损失效应、以及末态粲夸克对能量损失效应对J/ψ 粒子产额的压低作用，对质子-原子核碰撞J/ψ产生过程的微分截面比RFe/Be(xF)进行了领头阶的唯象分析，并与E866 实验数据中代表J/ψ粒子在靶核外产生的实验数据进行比较，获取了粲夸克对的能量损失值(3.81±1.71) GeV/fm。研究结果表明，部分子分布函数的核效应对截面比RFe=Be(xF) 的压低作用在xF > 0区域是随着xF 的增大而增大的；末态粲夸克对的能量损失效应是影响J= 粒子产额压低的重要核效应；当xF较大时(0:65≤xF≤0.92)，初态入射质子的能量损失效应在对微分截面比RFe/Be(xF)的压低中起了主要作用。J/ψ suppression observed in hot nuclear matter from heavy-ion collisions is considered as a most reliable signature for the formation of Quark-Gluon Plasma. The study about the nuclear effects on J/ψ production in cold nuclear matter provides an important tool for clarifying the conventional nuclear suppression mechanism in heavy-ion collisions. J/ψ suppression in p-A collisions is studied by considering the nuclear effects on parton distribution, the energy loss of beam proton in initial state, and the finial state energy loss of c¯c pair.The leading-order computations for J/ψ production cross-section ratios RFe=Be(xF) are presented and compared with the selected E866 experimental data with the J/ψ production occurring outside the nucleus, the obtained energy loss of the color octet is (3.81±1.71) GeV/fm. It is found that the nuclear suppression from the nuclear effects on the parton distribution functions becomes larger as the increase of xF in the range xF > 0，the J/ψ suppression on RFe/Be(xF) induced by the energy loss of color octet c¯c is an important nuclear effect, in the region 0:656xF 60:92, the energy loss of beam proton in initial state is the dominant mechanism which causes a reduction of the J/ψ yield.
高能重离子碰撞热核环境中J/ψ产额的压低被认为是夸克胶子等离子体生成的重要信号。研究冷核物质中各种核效应对J/ψ 形成过程的影响，是准确理解热核环境中核效应对J/ψ产额压低机制的重要途径。研究了质子-原子核碰撞J/ψ 产生过程中初态部分子分布函数的核效应、入射质子的能量损失效应、以及末态粲夸克对能量损失效应对J/ψ 粒子产额的压低作用，对质子-原子核碰撞J/ψ产生过程的微分截面比RFe/Be(xF)进行了领头阶的唯象分析，并与E866 实验数据中代表J/ψ粒子在靶核外产生的实验数据进行比较，获取了粲夸克对的能量损失值(3.81±1.71) GeV/fm。研究结果表明，部分子分布函数的核效应对截面比RFe=Be(xF) 的压低作用在xF > 0区域是随着xF 的增大而增大的；末态粲夸克对的能量损失效应是影响J= 粒子产额压低的重要核效应；当xF较大时(0:65≤xF≤0.92)，初态入射质子的能量损失效应在对微分截面比RFe/Be(xF)的压低中起了主要作用。J/ψ suppression observed in hot nuclear matter from heavy-ion collisions is considered as a most reliable signature for the formation of Quark-Gluon Plasma. The study about the nuclear effects on J/ψ production in cold nuclear matter provides an important tool for clarifying the conventional nuclear suppression mechanism in heavy-ion collisions. J/ψ suppression in p-A collisions is studied by considering the nuclear effects on parton distribution, the energy loss of beam proton in initial state, and the finial state energy loss of c¯c pair.The leading-order computations for J/ψ production cross-section ratios RFe=Be(xF) are presented and compared with the selected E866 experimental data with the J/ψ production occurring outside the nucleus, the obtained energy loss of the color octet is (3.81±1.71) GeV/fm. It is found that the nuclear suppression from the nuclear effects on the parton distribution functions becomes larger as the increase of xF in the range xF > 0，the J/ψ suppression on RFe/Be(xF) induced by the energy loss of color octet c¯c is an important nuclear effect, in the region 0:656xF 60:92, the energy loss of beam proton in initial state is the dominant mechanism which causes a reduction of the J/ψ yield.
2015, 32(3): 296-300.
doi: 10.11804/NuclPhysRev.32.03.296
摘要:
随机冷却是一种基于带宽反馈系统对束流振荡进行衰减的冷却方法，更适合冷却较大发射度和动量分散的次级粒子束，与电子冷却互补，可以得到更高品质的束流。兰州重离子研究装置(HIRFL) 目前处于冷却存储环的实验环随机冷却系统的设计和建造阶段。通过对横向Betatron 振荡的模拟，得到了提高系统带宽、增加探测器(Pick-up) 和冲击器(Kicker) 的个数、降低系统噪声温度等对缩短冷却时间和减小冷却平衡值的重要作用。同时，分析了较大的动量分散或较大的放大器增益对Betatron 振荡冷却过程产生的加热现象。Stochastic cooling, based on a feedback system, aims at damping the oscillation of particles. Stochastic cooling is more suitable to cool secondary beam with larger size and momentum spread, and it is therefore can be complemented with electron cooling, in order to obtain beam of higher quality. Stochastic cooling system is being designed and constructed on the experimental Cooling Storage Ring of HIRFL. By simulation of Betatron stochastic cooling, it is obtained that the importance for shortening the cooling time and reducing cooling equilibrium by improving bandwidth, increasing the numbers of pickup and kicker, and decreasing the system noises. Meanwhile, the heating during the cooling process caused by larger momentum spread or larger gain of amplifier is analyzed.
随机冷却是一种基于带宽反馈系统对束流振荡进行衰减的冷却方法，更适合冷却较大发射度和动量分散的次级粒子束，与电子冷却互补，可以得到更高品质的束流。兰州重离子研究装置(HIRFL) 目前处于冷却存储环的实验环随机冷却系统的设计和建造阶段。通过对横向Betatron 振荡的模拟，得到了提高系统带宽、增加探测器(Pick-up) 和冲击器(Kicker) 的个数、降低系统噪声温度等对缩短冷却时间和减小冷却平衡值的重要作用。同时，分析了较大的动量分散或较大的放大器增益对Betatron 振荡冷却过程产生的加热现象。Stochastic cooling, based on a feedback system, aims at damping the oscillation of particles. Stochastic cooling is more suitable to cool secondary beam with larger size and momentum spread, and it is therefore can be complemented with electron cooling, in order to obtain beam of higher quality. Stochastic cooling system is being designed and constructed on the experimental Cooling Storage Ring of HIRFL. By simulation of Betatron stochastic cooling, it is obtained that the importance for shortening the cooling time and reducing cooling equilibrium by improving bandwidth, increasing the numbers of pickup and kicker, and decreasing the system noises. Meanwhile, the heating during the cooling process caused by larger momentum spread or larger gain of amplifier is analyzed.
2015, 32(3): 301-305.
doi: 10.11804/NuclPhysRev.32.03.301
摘要:
中国科学院近代物理研究所医用重离子加速器(HIMM) 高频系统31.02 MHz回旋加速器谐振腔已完成设计加工和腔体的老炼，并投入正常运行。高频腔体的设计峰值Dee 电压要求达到70 kV，但是Dee 电压准确计算比较困难，可以通过CST 仿真软件对腔体进行模拟得到高频腔体的RP=Q0 值，结合输入到腔体的实际功率，计算出腔体的实际电压值。为了验证Dee 电压的准确性，在相同的腔体输入功率条件下，利用韧致辐射法测量腔体电压，测量结果与计算结果误差在0.6% 以内。The 31.02 MHz cyclotron RF system of Heavy Ion Medical Machine (HIMM) in IMP(Institute of Modern Physics, Chinese Academy of Sciences) has completed the design and commssioning，and now has already been put into operation. Its peak voltage requires 70 kV, but the precise calculation of the Dee voltage is still a difficulty problem, we can get the value Rp/Q0 of the cavity by CST simulation, and then combining the actual input power for cavity to calculate the real Dee voltage. In order to verify its accuracy, we use the bremsstrahlung method to test the cavity voltage under the condition of same input power. The error between test results and calculation is less than 0.6%.
中国科学院近代物理研究所医用重离子加速器(HIMM) 高频系统31.02 MHz回旋加速器谐振腔已完成设计加工和腔体的老炼，并投入正常运行。高频腔体的设计峰值Dee 电压要求达到70 kV，但是Dee 电压准确计算比较困难，可以通过CST 仿真软件对腔体进行模拟得到高频腔体的RP=Q0 值，结合输入到腔体的实际功率，计算出腔体的实际电压值。为了验证Dee 电压的准确性，在相同的腔体输入功率条件下，利用韧致辐射法测量腔体电压，测量结果与计算结果误差在0.6% 以内。The 31.02 MHz cyclotron RF system of Heavy Ion Medical Machine (HIMM) in IMP(Institute of Modern Physics, Chinese Academy of Sciences) has completed the design and commssioning，and now has already been put into operation. Its peak voltage requires 70 kV, but the precise calculation of the Dee voltage is still a difficulty problem, we can get the value Rp/Q0 of the cavity by CST simulation, and then combining the actual input power for cavity to calculate the real Dee voltage. In order to verify its accuracy, we use the bremsstrahlung method to test the cavity voltage under the condition of same input power. The error between test results and calculation is less than 0.6%.
2015, 32(3): 305-309.
doi: 10.11804/NuclPhysRev.32.03.305
摘要:
设计了用于ADS注入器Ⅱ超导腔的低温恒温器控制系统。采用了基于EPICS 的分布式控制系统架构，以PLC 和串口服务器等为核心控制硬件，用PID 算法实现了恒温器内氦压和液氦量的自动控制，压力控制精度约为100 Pa，液氦高度误差约10 mm。利用EPICS 和LabVIEW 在局域网发布过程数据，实现了操作员界面对低温恒温器分布式系统的统一管理，控制系统设计性能满足使用需求，已经在ADS注入器Ⅱ超导高频腔水平测试中发挥了重要作用。Cryogenic module provides important low temperature environment for half wave resonance superconducting cavity in C-ADS injector Ⅱ, to ensure the effective operation of cryogenic module, a remote control system which is based on the physical and experimental industrial control systems (EPICS) is introduced in this paper. PLC and serial port server are used as field controllers. Host computer runs EPICS and LabVIEW which are capable of getting and releasing data in local area net. Operators manage all the equipments through a CSS interface which is linked to local area net. The control system which is simple structure and reliable work, has played an important role in the level test of HWR superconducting cavity.
设计了用于ADS注入器Ⅱ超导腔的低温恒温器控制系统。采用了基于EPICS 的分布式控制系统架构，以PLC 和串口服务器等为核心控制硬件，用PID 算法实现了恒温器内氦压和液氦量的自动控制，压力控制精度约为100 Pa，液氦高度误差约10 mm。利用EPICS 和LabVIEW 在局域网发布过程数据，实现了操作员界面对低温恒温器分布式系统的统一管理，控制系统设计性能满足使用需求，已经在ADS注入器Ⅱ超导高频腔水平测试中发挥了重要作用。Cryogenic module provides important low temperature environment for half wave resonance superconducting cavity in C-ADS injector Ⅱ, to ensure the effective operation of cryogenic module, a remote control system which is based on the physical and experimental industrial control systems (EPICS) is introduced in this paper. PLC and serial port server are used as field controllers. Host computer runs EPICS and LabVIEW which are capable of getting and releasing data in local area net. Operators manage all the equipments through a CSS interface which is linked to local area net. The control system which is simple structure and reliable work, has played an important role in the level test of HWR superconducting cavity.
2015, 32(3): 310-317.
doi: 10.11804/NuclPhysRev.32.03.310
摘要:
采用分子镀方法研究了异丙醇-硝酸体系中两极间距离、电流密度、加入HNO3的量和分子镀持续时间对镀层性能和电沉积效率的影响，确定了制备Tb，Dy 和Ho 靶的最佳工艺条件。同时也探索了在异丁醇-硝酸体系中，分子镀持续时间和电流密度对Tb 靶电沉积效率的影响。因Tb，Dy 和Ho 三种元素化学性质相近，故采用了相同的工艺条件： 两极间最优距离为15 mm，电流密度为5.7 mA/cm2，加入0.1mol/L HNO3 400 L，分子镀时间为1 h。用分光光度法测得各靶的沉积效率均高于85%；利用扫描电子显微镜(SEM)对部分靶的表面形貌分析后发现靶面结构均匀致密；利用能谱仪(EDS) 对靶子进行了定性和半定量分析；利用红外光谱法对靶膜化学成分进行了分析，发现靶膜成分结构复杂，不是由一种化合物组成。目前制得的Tb 靶和Ho 靶已用于中国科学院近代物理研究所加速器SFC 低能核化学终端上，利用19F 束流轰击，分别产生了W和Os 的短寿命同位素，从而成功完成了Sg(Z =106) 和Hs(Z =108) 的模型试验。Preparation of Tb, Dy and Ho targets from the mixture of isopropanol and nitricacid solution are studied by using molecular plating technique. To determine the optimum conditions for the deposition process,the effect of distance between the two electrodes, current density, volume of 0.1 mol/L nitric acid, deposition time on the quality and electrodeposition yield of the target films are investigated individually. Preparation of Tb targets from the mixture of isobutylalcohol and nitricacid solution are also studied by using molecular plating technique. Depending on the similar chemical properties of Tb, Dy and Ho, the same process conditions are used.The suitable distance between the two electrodes is 15 mm. The current density is 5.7 mA/ cm2. The volume of nitric acid (0.1 mol/L) is 400 L. With the spectrophotometry method, the electrodeposition yields for all the targets prepared are found to be higher than 85% after one hour’s deposition. The morphological structure of some targets are characterized by scanning electron microscope (SEM) and it can be seen that the surface of the targets are uniform and intact. With EDS method, the composition of some targets are found to be very pure. The chemical structure of the targets are analyzed by Infrared Spectroscopy. It is found that the chemical structure of the targets are complex and the target membrane is not composed by only one compound. Short lived isotopes of W and Os were produced from natural Tb and Ho targets bombarded by 19F beam at the SFC low energy radiochemical terminal of Institute of Modern Physics, Chinese Academy of Sciences, respectively,and were successfully applied in the model experiment of Sg (Z =106) and Hs (Z =108).
采用分子镀方法研究了异丙醇-硝酸体系中两极间距离、电流密度、加入HNO3的量和分子镀持续时间对镀层性能和电沉积效率的影响，确定了制备Tb，Dy 和Ho 靶的最佳工艺条件。同时也探索了在异丁醇-硝酸体系中，分子镀持续时间和电流密度对Tb 靶电沉积效率的影响。因Tb，Dy 和Ho 三种元素化学性质相近，故采用了相同的工艺条件： 两极间最优距离为15 mm，电流密度为5.7 mA/cm2，加入0.1mol/L HNO3 400 L，分子镀时间为1 h。用分光光度法测得各靶的沉积效率均高于85%；利用扫描电子显微镜(SEM)对部分靶的表面形貌分析后发现靶面结构均匀致密；利用能谱仪(EDS) 对靶子进行了定性和半定量分析；利用红外光谱法对靶膜化学成分进行了分析，发现靶膜成分结构复杂，不是由一种化合物组成。目前制得的Tb 靶和Ho 靶已用于中国科学院近代物理研究所加速器SFC 低能核化学终端上，利用19F 束流轰击，分别产生了W和Os 的短寿命同位素，从而成功完成了Sg(Z =106) 和Hs(Z =108) 的模型试验。Preparation of Tb, Dy and Ho targets from the mixture of isopropanol and nitricacid solution are studied by using molecular plating technique. To determine the optimum conditions for the deposition process,the effect of distance between the two electrodes, current density, volume of 0.1 mol/L nitric acid, deposition time on the quality and electrodeposition yield of the target films are investigated individually. Preparation of Tb targets from the mixture of isobutylalcohol and nitricacid solution are also studied by using molecular plating technique. Depending on the similar chemical properties of Tb, Dy and Ho, the same process conditions are used.The suitable distance between the two electrodes is 15 mm. The current density is 5.7 mA/ cm2. The volume of nitric acid (0.1 mol/L) is 400 L. With the spectrophotometry method, the electrodeposition yields for all the targets prepared are found to be higher than 85% after one hour’s deposition. The morphological structure of some targets are characterized by scanning electron microscope (SEM) and it can be seen that the surface of the targets are uniform and intact. With EDS method, the composition of some targets are found to be very pure. The chemical structure of the targets are analyzed by Infrared Spectroscopy. It is found that the chemical structure of the targets are complex and the target membrane is not composed by only one compound. Short lived isotopes of W and Os were produced from natural Tb and Ho targets bombarded by 19F beam at the SFC low energy radiochemical terminal of Institute of Modern Physics, Chinese Academy of Sciences, respectively,and were successfully applied in the model experiment of Sg (Z =106) and Hs (Z =108).
2015, 32(3): 318-322.
doi: 10.11804/NuclPhysRev.32.03.318
摘要:
在国内首次采用高强度窄脉冲DPF中子源，采用直照法测量零功率堆瞬发中子时间常数α。由于外中子源本底太强，导致直照中子和散射中子产生的干扰信号比测量信号高三个量级。为有效地抑制外本底，针对不同能量的干扰中子，采用不同材料进行屏蔽。通过数值模拟的方法优化辐射屏蔽体设计，在屏蔽中子的同时也对散射γ 进行了有效屏蔽，使测量信噪比达到了7.5:1，并与实验结果相符合，实验中所采用的新型无机晶体也有效抑制了中子本底。The value of prompt neutron multiplication, α, is measured under the condition of using a denser plasma focus(DPF) neutron-source irradiating zero power assembly for the first time in China. The acquired signal is lower three orders of magnitudes than that of the noise caused by direct and scattered neutrons from the extra-high-intensity neutron-source. Using different kinds of material to decrease the noise caused by neutron with different kinds of energies, an optimized design for radiation shielding is developed by the method of numerical simulation to suppress noise signal. Both neutron and γ-ray are shielded simultaneously. The Signal/Noise Ratio (SNR) with the optimal design was up to 7.5:1 and was consistent with the experimental results. The noise of neutron is decreased effectively by the new kind of unorganic crystals used.
在国内首次采用高强度窄脉冲DPF中子源，采用直照法测量零功率堆瞬发中子时间常数α。由于外中子源本底太强，导致直照中子和散射中子产生的干扰信号比测量信号高三个量级。为有效地抑制外本底，针对不同能量的干扰中子，采用不同材料进行屏蔽。通过数值模拟的方法优化辐射屏蔽体设计，在屏蔽中子的同时也对散射γ 进行了有效屏蔽，使测量信噪比达到了7.5:1，并与实验结果相符合，实验中所采用的新型无机晶体也有效抑制了中子本底。The value of prompt neutron multiplication, α, is measured under the condition of using a denser plasma focus(DPF) neutron-source irradiating zero power assembly for the first time in China. The acquired signal is lower three orders of magnitudes than that of the noise caused by direct and scattered neutrons from the extra-high-intensity neutron-source. Using different kinds of material to decrease the noise caused by neutron with different kinds of energies, an optimized design for radiation shielding is developed by the method of numerical simulation to suppress noise signal. Both neutron and γ-ray are shielded simultaneously. The Signal/Noise Ratio (SNR) with the optimal design was up to 7.5:1 and was consistent with the experimental results. The noise of neutron is decreased effectively by the new kind of unorganic crystals used.
2015, 32(3): 323-329.
doi: 10.11804/NuclPhysRev.32.03.323
摘要:
近年来，国际社会对核材料保护、控制和衡算日益加强。对不明材料损失量(MUF) 的关注逐渐提升。铀材料质量不确定性测量在估算铀材料生产量中扮演重要角色。由于铀材料自发裂变相对较弱，主动中子多重性法被应用于估算铀材料质量。通过拟合对不同系列铀金属壳的数值模拟结果，获得了描述铀材料质量与主动中子多重性特征之间的算法和参数。得到的关系表明，可以通过分析不同重数中子多重性探测结果获得铀部件的质量。对不同探测条件下的模拟结果的定量分析，确定了探测系统设置对铀质量估算的影响，以及认知不确定性和随机不确定在估算过程中传播对质量估算的影响。对不确定度的分析获得了本文模拟采用的探测系统的最佳源强和探测时间窗设置，在此设置下，质量估算的不确定性最小。Recently, the international society pays more and more attention to nuclear material protection,control and accounting. The focus on the material unaccounted for (MUF) is enhanced. The uncertainty assessment of uranium mass measurement plays an essential role in estimating the production of uranium. Due to the relatively weak radioactivity of uranium, the active neutron multiplicity counting (ANMC) method is usually applied to assess the mass of uranium material. In this paper, the relations and parameters between the masses of the uranium objects and the features of the ANMCs are formulated by fitting the simulated results of different sets of uranium shells. The result indicates that,each mass of the objects could be obtained by analyzing the ANMCs of different orders. In order to study the effects of the detection system settings on the mass estimation, the propagation of the aleatoric and epistemic uncertainty of the method is quantitatively studied by the simulations with different detection onditions. The optimized settings of source intensity and detection coincidence gate width, which result in the minimal uncertainty of the mass estimation, are obtained for the simulated detection system.
近年来，国际社会对核材料保护、控制和衡算日益加强。对不明材料损失量(MUF) 的关注逐渐提升。铀材料质量不确定性测量在估算铀材料生产量中扮演重要角色。由于铀材料自发裂变相对较弱，主动中子多重性法被应用于估算铀材料质量。通过拟合对不同系列铀金属壳的数值模拟结果，获得了描述铀材料质量与主动中子多重性特征之间的算法和参数。得到的关系表明，可以通过分析不同重数中子多重性探测结果获得铀部件的质量。对不同探测条件下的模拟结果的定量分析，确定了探测系统设置对铀质量估算的影响，以及认知不确定性和随机不确定在估算过程中传播对质量估算的影响。对不确定度的分析获得了本文模拟采用的探测系统的最佳源强和探测时间窗设置，在此设置下，质量估算的不确定性最小。Recently, the international society pays more and more attention to nuclear material protection,control and accounting. The focus on the material unaccounted for (MUF) is enhanced. The uncertainty assessment of uranium mass measurement plays an essential role in estimating the production of uranium. Due to the relatively weak radioactivity of uranium, the active neutron multiplicity counting (ANMC) method is usually applied to assess the mass of uranium material. In this paper, the relations and parameters between the masses of the uranium objects and the features of the ANMCs are formulated by fitting the simulated results of different sets of uranium shells. The result indicates that,each mass of the objects could be obtained by analyzing the ANMCs of different orders. In order to study the effects of the detection system settings on the mass estimation, the propagation of the aleatoric and epistemic uncertainty of the method is quantitatively studied by the simulations with different detection onditions. The optimized settings of source intensity and detection coincidence gate width, which result in the minimal uncertainty of the mass estimation, are obtained for the simulated detection system.
2015, 32(3): 330-334.
doi: 10.11804/NuclPhysRev.32.03.330
摘要:
波移光纤是闪烁体中子探测器的重要组成部分，其性能参数——光衰减长度、光损失率和光吸收重发射效率等将直接影响探测器的性能。本研究利用一套光纤性能测试试验装置，系统地研究了BCF91A 型波移光纤的光传输性能。结果表明：BCF-91A 型波移光纤光衰减长度为(1485) cm，吸收重发射效率约为5.6%；当光纤转弯半径为20 mm，长度为1.1 m时，其性能可以满足闪烁体中子探测器要求；BCF-91A 型波移光纤是很好的光纤候选材料.The position-sensitive scintillator neutron detector (SSND) with high efficiency, high resolution and high n/ discriminate ability etc., is developed to replace the traditional 3He neutron detector. The wave-length shifting fibers (WLSF) are used in SSND. The performances of BCF-91A type WLSF, such as attenuation length, bend loss and lights transportation ability etc., are studied in this paper. The attenuation length is (1485) cm.The lights transportation ability is about 5.6%. When the length of WLSF is 1.1 m, the bend radius is 20 mm,the photon number N transferred by the fiber meet the demand of SSND. According to the result, BCF-91A type WLSF is a good candidate for SSND.
波移光纤是闪烁体中子探测器的重要组成部分，其性能参数——光衰减长度、光损失率和光吸收重发射效率等将直接影响探测器的性能。本研究利用一套光纤性能测试试验装置，系统地研究了BCF91A 型波移光纤的光传输性能。结果表明：BCF-91A 型波移光纤光衰减长度为(1485) cm，吸收重发射效率约为5.6%；当光纤转弯半径为20 mm，长度为1.1 m时，其性能可以满足闪烁体中子探测器要求；BCF-91A 型波移光纤是很好的光纤候选材料.The position-sensitive scintillator neutron detector (SSND) with high efficiency, high resolution and high n/ discriminate ability etc., is developed to replace the traditional 3He neutron detector. The wave-length shifting fibers (WLSF) are used in SSND. The performances of BCF-91A type WLSF, such as attenuation length, bend loss and lights transportation ability etc., are studied in this paper. The attenuation length is (1485) cm.The lights transportation ability is about 5.6%. When the length of WLSF is 1.1 m, the bend radius is 20 mm,the photon number N transferred by the fiber meet the demand of SSND. According to the result, BCF-91A type WLSF is a good candidate for SSND.
2015, 32(3): 335-340.
doi: 10.11804/NuclPhysRev.32.03.335
摘要:
GEM探测器的供电一般采用电阻链分压供电模式和多路分立供电模式，在低通量X射线下测量时区别不大，但是在高通量X射线时，电阻链分压供电模式会带来饱和效应引起工作电压的变化，造成探测器工作不稳定。本研究在高通量X 射线照射下，研究了有效面积为100 mm100 mm三层级联GEM探测器的有效增益(稳定性) 与不同高压供电模式的关系。通过测量不同分压电阻值(1, 2, 5 到30 MΩ)的实验研究，发现随着X 射线通量的增加，在电阻链分压供电模式下，出现了GEM探测器感应电极的读出电流饱和趋势，分析了可能导致饱和效应出现的原因。结果表明，当入射X射线在探测器上的有效吸收剂量不断增加时，电阻链供电模式需要调整分压单元电阻值，或者采用多路分立供电模式，从而避免因饱和效应引起的GEM探测器有效增益的变化，实现探测器稳定的工作状态。There are two methods of the HV power supply for the GEM detector. One is a HV channel divided by the resistive chain and the other is the several separate HV channels. In the smaller dose rate of X-ray, all of the methods are similar. When the dose rate increases, the resistive chain-dividing mode has more obvious saturation effect and the working voltage of the GEM detector is unstable. In the paper, a GEM detector with an effective area of 100 mm100 mm has been studied in the high dose rate using X-tube. The unit values in the divider resistance chain are set to 1, 2, 5 and 30 MΩ respectively in the test. With the resistive chain-dividing mode, the readout current of the GEM detector’s anode tends to saturate when the dose rate of X-ray increases,and the reasons of the saturation effect are analyzed. The results indicate that the effective absorbed dose of X-ray by the triple GEMs detector reaches to the pecific value and the divider resistance needs to re-select, even the several separate HV channels mode should be considered. It will keep the constant of the working voltage of the GEM detector without the saturation effect and gain variation and the performance of GEM detector is stable.
GEM探测器的供电一般采用电阻链分压供电模式和多路分立供电模式，在低通量X射线下测量时区别不大，但是在高通量X射线时，电阻链分压供电模式会带来饱和效应引起工作电压的变化，造成探测器工作不稳定。本研究在高通量X 射线照射下，研究了有效面积为100 mm100 mm三层级联GEM探测器的有效增益(稳定性) 与不同高压供电模式的关系。通过测量不同分压电阻值(1, 2, 5 到30 MΩ)的实验研究，发现随着X 射线通量的增加，在电阻链分压供电模式下，出现了GEM探测器感应电极的读出电流饱和趋势，分析了可能导致饱和效应出现的原因。结果表明，当入射X射线在探测器上的有效吸收剂量不断增加时，电阻链供电模式需要调整分压单元电阻值，或者采用多路分立供电模式，从而避免因饱和效应引起的GEM探测器有效增益的变化，实现探测器稳定的工作状态。There are two methods of the HV power supply for the GEM detector. One is a HV channel divided by the resistive chain and the other is the several separate HV channels. In the smaller dose rate of X-ray, all of the methods are similar. When the dose rate increases, the resistive chain-dividing mode has more obvious saturation effect and the working voltage of the GEM detector is unstable. In the paper, a GEM detector with an effective area of 100 mm100 mm has been studied in the high dose rate using X-tube. The unit values in the divider resistance chain are set to 1, 2, 5 and 30 MΩ respectively in the test. With the resistive chain-dividing mode, the readout current of the GEM detector’s anode tends to saturate when the dose rate of X-ray increases,and the reasons of the saturation effect are analyzed. The results indicate that the effective absorbed dose of X-ray by the triple GEMs detector reaches to the pecific value and the divider resistance needs to re-select, even the several separate HV channels mode should be considered. It will keep the constant of the working voltage of the GEM detector without the saturation effect and gain variation and the performance of GEM detector is stable.
2015, 32(3): 341-346.
doi: 10.11804/NuclPhysRev.32.03.341
摘要:
彭宁阱是用于直接测量原子核质量的精确设备。为了保证彭宁阱的测量精度，需在阱中心产生精准的四极静电场，而四极静电场是通过对彭宁阱的核心电极施加合适的电压产生的。采用公式推导法和最小二乘法两种方法计算得到了LPT核心电极需加电压幅值。对于公式推导法，电压值完全从理论出发，经公式推导后计算得到；最小二乘法的出发点是使取样偏差的平方和最小，且通过仿真模拟考虑了电极的实际几何形状。由这两种方法得到的非四极项系数C4 和C6，可用于估算因偏离理想四极电场所产生的实验误差。虽然这两种方法的出发点不同，但都可以在阱中心产生需要的四极电场。Penning trap mass spectrometry is one of the direct methods and maybe the most accurate tool for atomic mass measurements. The quadrupole electric eld produced in the trap should be very accurate in order to ensure the precision of measurements. The optimal amplitudes for the key electrodes of the Lanzhou Penning Trap(LPT) have been calculated by two methods|formula derivation and least-squares tting. For formula derivation method, the optimal values are based on the theory and deduced from the formulas. Least-squares tting method is to minimize the quadratic sum of sampling deviations, where the actual geometry of the electrodes has been considered by the simulation. The obtained C4 and C6 values can be used to estimate the experimental error produced by the deviation from the ideal quadrupole electric eld. The expected quadrupole electric led could be gotten by both methods.
彭宁阱是用于直接测量原子核质量的精确设备。为了保证彭宁阱的测量精度，需在阱中心产生精准的四极静电场，而四极静电场是通过对彭宁阱的核心电极施加合适的电压产生的。采用公式推导法和最小二乘法两种方法计算得到了LPT核心电极需加电压幅值。对于公式推导法，电压值完全从理论出发，经公式推导后计算得到；最小二乘法的出发点是使取样偏差的平方和最小，且通过仿真模拟考虑了电极的实际几何形状。由这两种方法得到的非四极项系数C4 和C6，可用于估算因偏离理想四极电场所产生的实验误差。虽然这两种方法的出发点不同，但都可以在阱中心产生需要的四极电场。Penning trap mass spectrometry is one of the direct methods and maybe the most accurate tool for atomic mass measurements. The quadrupole electric eld produced in the trap should be very accurate in order to ensure the precision of measurements. The optimal amplitudes for the key electrodes of the Lanzhou Penning Trap(LPT) have been calculated by two methods|formula derivation and least-squares tting. For formula derivation method, the optimal values are based on the theory and deduced from the formulas. Least-squares tting method is to minimize the quadratic sum of sampling deviations, where the actual geometry of the electrodes has been considered by the simulation. The obtained C4 and C6 values can be used to estimate the experimental error produced by the deviation from the ideal quadrupole electric eld. The expected quadrupole electric led could be gotten by both methods.
2015, 32(3): 347-352.
doi: 10.11804/NuclPhysRev.32.03.347
摘要:
与传统的铁素体钢相比，氧化物弥散强化(ODS) 的铁素体钢具有更优的耐高温和抗辐照性能，近年来成为先进核能装置重要的候选结构材料。在HIRFL 的扇聚焦型回旋加速器(SFC) 材料辐照终端，对一种氧化物弥散强化(ODS) 铁素体钢MA956 进行了高能Ne 离子辐照实验，旨在研究级联碰撞损伤和惰性气体原子注入条件下该材料力学性能的变化。利用辐照终端的能量衰减装置将SFC出口123.4 MeV的离子能量分解为介于38.5~121.0 MeV之间的30 个入射能量值，并通过双面辐照在厚度60 μm的样品中均匀产生了损伤。辐照剂量为9x1016 ions/cm2，在样品中的平均位移损伤为0.7 dpa，注入的Ne原子浓度为350 appm。辐照期间样品温度保持在440 ℃附近。对辐照前后的样品分别在室温和500 ℃下进行了小冲杆试验(Small-punchTest)，获得了辐照前后样品的加载位移曲线，由此得到该辐照条件下样品的延性损失为18%~26%。通过扫描电子显微镜观察了断口形貌和厚度变化，估算了样品的等效断裂应变和断裂韧性。结果表明，MA956 钢经过高能Ne离子辐照后等延伸率减小,断裂韧性降低，样品发生了一定的脆化。透射电镜结果说明氧化物弥散相界面处微空洞的形成可能是导致脆化的原因。Oxide dispersion strengthened (ODS) ferritic steels have better high-temperature creep rupture strength and higher irradiation resistance than conventional ferritic steels, and show high prominence of application in advance nuclear reactors. Their stability under high-dose radiation conditions needs to be clarified. In the present study, a commercial ODS ferritic steel MA956 were irradiated with high 20Ne ions at a terminal chamber of the Sector-focused Cyclotron (SFC) at HIRFL (Heavy-ion Research Facility in Lanzhou). With the energy gradient degrader of the irradiation chamber, the primary energy (123.4 MeV) of the Ne-ion was dispersed into 30 different energies between 38.5~ 121.0 MeV, which resulted in a plateau distribution of lattice damage in the specimens. The specimens were irradiated from both sides so that the whole 60 m thickness was nearly uniformly damaged. The specimen temperature was maintained around 440 ℃ during the irradiation. The irradiation dose is about 9x1016 ions/cm2, corresponding to a damage level of 0.7 dpa and a Ne concentration of 350 appm. The specimens before and after irradiation were tested with the Small-punch Test technique, at room temperature and 500 ℃, respectively. The fracture morphology was observed by scanning electron microscopy.The results show that MA956 underwent some loss of ductility and fracture toughness after the irradiation with high-energy 20Ne ions. It may be ascribed to the formation of nano-scale cavities at the oxides/matrix interfaces
in the ODS steel specimens under irradiation .
与传统的铁素体钢相比，氧化物弥散强化(ODS) 的铁素体钢具有更优的耐高温和抗辐照性能，近年来成为先进核能装置重要的候选结构材料。在HIRFL 的扇聚焦型回旋加速器(SFC) 材料辐照终端，对一种氧化物弥散强化(ODS) 铁素体钢MA956 进行了高能Ne 离子辐照实验，旨在研究级联碰撞损伤和惰性气体原子注入条件下该材料力学性能的变化。利用辐照终端的能量衰减装置将SFC出口123.4 MeV的离子能量分解为介于38.5~121.0 MeV之间的30 个入射能量值，并通过双面辐照在厚度60 μm的样品中均匀产生了损伤。辐照剂量为9x1016 ions/cm2，在样品中的平均位移损伤为0.7 dpa，注入的Ne原子浓度为350 appm。辐照期间样品温度保持在440 ℃附近。对辐照前后的样品分别在室温和500 ℃下进行了小冲杆试验(Small-punchTest)，获得了辐照前后样品的加载位移曲线，由此得到该辐照条件下样品的延性损失为18%~26%。通过扫描电子显微镜观察了断口形貌和厚度变化，估算了样品的等效断裂应变和断裂韧性。结果表明，MA956 钢经过高能Ne离子辐照后等延伸率减小,断裂韧性降低，样品发生了一定的脆化。透射电镜结果说明氧化物弥散相界面处微空洞的形成可能是导致脆化的原因。Oxide dispersion strengthened (ODS) ferritic steels have better high-temperature creep rupture strength and higher irradiation resistance than conventional ferritic steels, and show high prominence of application in advance nuclear reactors. Their stability under high-dose radiation conditions needs to be clarified. In the present study, a commercial ODS ferritic steel MA956 were irradiated with high 20Ne ions at a terminal chamber of the Sector-focused Cyclotron (SFC) at HIRFL (Heavy-ion Research Facility in Lanzhou). With the energy gradient degrader of the irradiation chamber, the primary energy (123.4 MeV) of the Ne-ion was dispersed into 30 different energies between 38.5~ 121.0 MeV, which resulted in a plateau distribution of lattice damage in the specimens. The specimens were irradiated from both sides so that the whole 60 m thickness was nearly uniformly damaged. The specimen temperature was maintained around 440 ℃ during the irradiation. The irradiation dose is about 9x1016 ions/cm2, corresponding to a damage level of 0.7 dpa and a Ne concentration of 350 appm. The specimens before and after irradiation were tested with the Small-punch Test technique, at room temperature and 500 ℃, respectively. The fracture morphology was observed by scanning electron microscopy.The results show that MA956 underwent some loss of ductility and fracture toughness after the irradiation with high-energy 20Ne ions. It may be ascribed to the formation of nano-scale cavities at the oxides/matrix interfaces
in the ODS steel specimens under irradiation .
2015, 32(3): 353-357.
doi: 10.11804/NuclPhysRev.32.03.353
摘要:
宇航半导体器件运行在一个复杂的空间辐射环境中，质子是空间辐射环境中粒子的重要组成部分，因而质子在半导体器件中导致的辐射效应一直受到国内外的关注。利用兰州重离子加速器(Heavy Ion Research Facility In Lanzhou) 加速出的H2 分子打靶产生能量为10 MeV 的质子，研究了特征尺寸为0.5/0.35/0.15 μm体硅和绝缘体上硅(SOI) 工艺静态随机存储器(SRAM) 的质子单粒子翻转敏感性，这也是首次在该装置上开展的质子单粒子翻转实验研究。实验结果表明特征尺寸为亚微米的SOI 工艺SRAM器件对质子单粒子翻转不敏感，但随着器件特征尺寸的减小和工作电压的降低，SOI 工艺SRAM器件对质子单粒子翻转越来越敏感；特征尺寸为深亚微米的体硅工艺SRAM器件单粒子翻转截面随入射质子能量变化明显，存在发生翻转的质子能量阈值，CREME-MC模拟结果表明质子在深亚微米的体硅工艺SRAM器件中通过质子核反应导致单粒子翻转。Microelectronic devices are used in a harsh radiation environment for space missions. Among all the reliability issues concerned, proton induced single event upset (SEU) is becoming more and more noticeable for semiconductor components exposed on space. In this work, an experimental research of SEU induced by 10 MeV proton for static random access memory (SRAM) of 0.5, 0.35 and 0.15 m feature size is carried out on HeavyIon Research Facility in Lanzhou for the rst time. The experimental results show that proton induced SEUs in submicron and deep-submicron (SRAMs) are dominated by secondary ions generated by proton nuclear reaction events. The silicon-on-insulator SRAMs characters natural radiation-hardened SEU by proton. For the deep-submicron bulk-silicon technology SRAM, the proton SEU cross section is closely related to the proton energy and there is a threshold energy for the SEU occurrence by proton indirect ionization. CREME-MC simulation indicates that the SEU events in deep-submicron SRAM are induced by the proton nuclear reaction.
宇航半导体器件运行在一个复杂的空间辐射环境中，质子是空间辐射环境中粒子的重要组成部分，因而质子在半导体器件中导致的辐射效应一直受到国内外的关注。利用兰州重离子加速器(Heavy Ion Research Facility In Lanzhou) 加速出的H2 分子打靶产生能量为10 MeV 的质子，研究了特征尺寸为0.5/0.35/0.15 μm体硅和绝缘体上硅(SOI) 工艺静态随机存储器(SRAM) 的质子单粒子翻转敏感性，这也是首次在该装置上开展的质子单粒子翻转实验研究。实验结果表明特征尺寸为亚微米的SOI 工艺SRAM器件对质子单粒子翻转不敏感，但随着器件特征尺寸的减小和工作电压的降低，SOI 工艺SRAM器件对质子单粒子翻转越来越敏感；特征尺寸为深亚微米的体硅工艺SRAM器件单粒子翻转截面随入射质子能量变化明显，存在发生翻转的质子能量阈值，CREME-MC模拟结果表明质子在深亚微米的体硅工艺SRAM器件中通过质子核反应导致单粒子翻转。Microelectronic devices are used in a harsh radiation environment for space missions. Among all the reliability issues concerned, proton induced single event upset (SEU) is becoming more and more noticeable for semiconductor components exposed on space. In this work, an experimental research of SEU induced by 10 MeV proton for static random access memory (SRAM) of 0.5, 0.35 and 0.15 m feature size is carried out on HeavyIon Research Facility in Lanzhou for the rst time. The experimental results show that proton induced SEUs in submicron and deep-submicron (SRAMs) are dominated by secondary ions generated by proton nuclear reaction events. The silicon-on-insulator SRAMs characters natural radiation-hardened SEU by proton. For the deep-submicron bulk-silicon technology SRAM, the proton SEU cross section is closely related to the proton energy and there is a threshold energy for the SEU occurrence by proton indirect ionization. CREME-MC simulation indicates that the SEU events in deep-submicron SRAM are induced by the proton nuclear reaction.
2015, 32(3): 358-362.
doi: 10.11804/NuclPhysRev.32.03.358
摘要:
在空间离子探测过程中，太阳紫外光也会进入探测器产生光污染信号。为了考察它对离子探测的影响，搭建了一套模拟太阳紫外光污染的地面测试系统，并对自主研制的空间低能离子探测器原理样机进行了紫外响应测试。实验结果表明：沿水平方向进入分析器的紫外光响应可以忽略，而以一定倾斜角进入分析器的紫外光响应计数率约为102~ 103 s−1。根据测试结果，估算出探测器对太阳紫外光的抑制率约为10−8，分析了紫外光污染对探测空间低能离子如质子和 粒子的影响。对于质子，由于其通量大，紫外光的影响不大。而对于通量较小的 粒子，紫外光的影响较大，需要进一步采取有效措施进行抑制。此外，本测试系统可以推广到其它空间粒子探测器的太阳紫外光污染的地面模拟测试。In the detection of space ions, solar ultraviolet (UV) can also enter the detector and generate a noise to the signal of ions. A testing system on the ground is built to test the UV response of detector. Experiments on a home-made principle prototype of space low-energy ion detector are carried out by using this system. The results show that the response of detector to the UV entering the electrostatic analyzer along the horizontal direction can be negligible and counts of the response to the UV along a bias direction are about 102 ~103 s−1. According to the measured results, the UV suppression ratio is estimated to be about 10−8 and the inuence of solar UV on the detection of space low-energy ions such as proton and alpha particle has been analyzed. For proton, the inuence is insigni cant due to its high ux. But for the low ux alpha particle, the inuence of solar UV is noticeable and further rejection is needed. In addition, this system can also be applied to test the UV response of other space particle detectors.
在空间离子探测过程中，太阳紫外光也会进入探测器产生光污染信号。为了考察它对离子探测的影响，搭建了一套模拟太阳紫外光污染的地面测试系统，并对自主研制的空间低能离子探测器原理样机进行了紫外响应测试。实验结果表明：沿水平方向进入分析器的紫外光响应可以忽略，而以一定倾斜角进入分析器的紫外光响应计数率约为102~ 103 s−1。根据测试结果，估算出探测器对太阳紫外光的抑制率约为10−8，分析了紫外光污染对探测空间低能离子如质子和 粒子的影响。对于质子，由于其通量大，紫外光的影响不大。而对于通量较小的 粒子，紫外光的影响较大，需要进一步采取有效措施进行抑制。此外，本测试系统可以推广到其它空间粒子探测器的太阳紫外光污染的地面模拟测试。In the detection of space ions, solar ultraviolet (UV) can also enter the detector and generate a noise to the signal of ions. A testing system on the ground is built to test the UV response of detector. Experiments on a home-made principle prototype of space low-energy ion detector are carried out by using this system. The results show that the response of detector to the UV entering the electrostatic analyzer along the horizontal direction can be negligible and counts of the response to the UV along a bias direction are about 102 ~103 s−1. According to the measured results, the UV suppression ratio is estimated to be about 10−8 and the inuence of solar UV on the detection of space low-energy ions such as proton and alpha particle has been analyzed. For proton, the inuence is insigni cant due to its high ux. But for the low ux alpha particle, the inuence of solar UV is noticeable and further rejection is needed. In addition, this system can also be applied to test the UV response of other space particle detectors.
2015, 32(3): 363-367.
doi: 10.11804/NuclPhysRev.32.03.363
摘要:
为了研究磁共振引导放射治疗对剂量分布的影响，采用蒙特卡罗方法研究了横向均匀磁场对6 MV光子束在4种不同人体组织材料与空气界面处因电子回转效应导致剂量分布的改变。模拟显示，对于电离能相近的几种材料，磁场对剂量分布扰动的差别较小，而且电离能较大的材料，这种扰动明显变小。结果表明，磁场的引入会影响光子束原有的剂量分布，且这种影响与材料的电离能有关。这意味着虽然磁共振引导放射治疗可以增强靶向精度，提高治疗效果，但磁场会导致光子束剂量分布的改变，且不同的组织这种改变也不相同，这将为相应的剂量算法研究带来了新的挑战。A Monte Carlo code was used to study the discrepancy resulted from the emergence of magnetic field in MRI guided radiotherapy. In this work, four different tissue phantoms with magnetic field and 6 MV photon were studied, and the dose distributions at the interface of phantom-air were evaluated. It is found that the differences of the dose perturbation are small between the materials with similar ionization energy. However, the dose perturbation decreased significantly for the material with high ionization energy. The results of this study demonstrate that magnetic field will change the dose distribution of photon beam and the dose perturbation associated with ionization energy of materials. It means that magnetic resonance imaging guided radiotherapy can enhance the target accuracy, but the magnetic field will change the dose distribution of photon beam, and the perturbation was not the same for the different materials of human tissue, it has brought new challenges for the research of dose algorithm.
为了研究磁共振引导放射治疗对剂量分布的影响，采用蒙特卡罗方法研究了横向均匀磁场对6 MV光子束在4种不同人体组织材料与空气界面处因电子回转效应导致剂量分布的改变。模拟显示，对于电离能相近的几种材料，磁场对剂量分布扰动的差别较小，而且电离能较大的材料，这种扰动明显变小。结果表明，磁场的引入会影响光子束原有的剂量分布，且这种影响与材料的电离能有关。这意味着虽然磁共振引导放射治疗可以增强靶向精度，提高治疗效果，但磁场会导致光子束剂量分布的改变，且不同的组织这种改变也不相同，这将为相应的剂量算法研究带来了新的挑战。A Monte Carlo code was used to study the discrepancy resulted from the emergence of magnetic field in MRI guided radiotherapy. In this work, four different tissue phantoms with magnetic field and 6 MV photon were studied, and the dose distributions at the interface of phantom-air were evaluated. It is found that the differences of the dose perturbation are small between the materials with similar ionization energy. However, the dose perturbation decreased significantly for the material with high ionization energy. The results of this study demonstrate that magnetic field will change the dose distribution of photon beam and the dose perturbation associated with ionization energy of materials. It means that magnetic resonance imaging guided radiotherapy can enhance the target accuracy, but the magnetic field will change the dose distribution of photon beam, and the perturbation was not the same for the different materials of human tissue, it has brought new challenges for the research of dose algorithm.
2015, 32(3): 368-374.
doi: 10.11804/NuclPhysRev.32.03.368
摘要:
核反应R矩阵理论是研究轻核反应以及中重和重核共振能区核反应的重要理论方法。包含能级矩阵非对角元贡献的完全R矩阵理论在理论上比较严格。根据不同的假定和近似得到不同的R矩阵计算方法。新编的R矩阵程序FDRR包含了4种计算方法，包括约化道多能级Breit-Wigner 方法、完全约化R矩阵方法、非对角化能级位移约化R矩阵方法及对角化能级位移约化R矩阵方法。可计算轻核各种两体反应道的截面、角分布。利用FDRR程序对n+6Li 反应20 MeV以下能区进行理论分析和计算，理论计算结果与实验数据进行了比较分析，理论计算得到的截面和角分布与实验数据符合得很好。R-matrix theory is an important theory of light, medium and heavy mass nuclide nuclear reaction in the resonance energy range. Full R-matrix formalism contains the un-diagonal element of energy levels matrix and it is rigorous in theory. Because of different assumptions and approximations, many kinds of R-matrix methods are obtained. The new R-matrix code FDRR is presented and includes 4 kinds of R-matrix methods, reduced multi-level Breit-Wigner R-matrix method, full reduced R-matrix method, un-diagonal energy shift reduced Rmatrixn method, and diagonal energy shift reduced R-matrix method. It can be used for calculating integral cross sections and angular distributions of 2-bodies reactions. The cross sections and angular distributions of n+6Li reaction are calculated and analyzed by FDRR code below 20 MeV. The calculation results are compared with the experimental data, and the cross sections and angular distributions are in good agreement with experimental data.
核反应R矩阵理论是研究轻核反应以及中重和重核共振能区核反应的重要理论方法。包含能级矩阵非对角元贡献的完全R矩阵理论在理论上比较严格。根据不同的假定和近似得到不同的R矩阵计算方法。新编的R矩阵程序FDRR包含了4种计算方法，包括约化道多能级Breit-Wigner 方法、完全约化R矩阵方法、非对角化能级位移约化R矩阵方法及对角化能级位移约化R矩阵方法。可计算轻核各种两体反应道的截面、角分布。利用FDRR程序对n+6Li 反应20 MeV以下能区进行理论分析和计算，理论计算结果与实验数据进行了比较分析，理论计算得到的截面和角分布与实验数据符合得很好。R-matrix theory is an important theory of light, medium and heavy mass nuclide nuclear reaction in the resonance energy range. Full R-matrix formalism contains the un-diagonal element of energy levels matrix and it is rigorous in theory. Because of different assumptions and approximations, many kinds of R-matrix methods are obtained. The new R-matrix code FDRR is presented and includes 4 kinds of R-matrix methods, reduced multi-level Breit-Wigner R-matrix method, full reduced R-matrix method, un-diagonal energy shift reduced Rmatrixn method, and diagonal energy shift reduced R-matrix method. It can be used for calculating integral cross sections and angular distributions of 2-bodies reactions. The cross sections and angular distributions of n+6Li reaction are calculated and analyzed by FDRR code below 20 MeV. The calculation results are compared with the experimental data, and the cross sections and angular distributions are in good agreement with experimental data.
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