2015年 第32卷 第1期
2015, 32(1): 1-23.
doi: 10.11804/NuclPhysRev.32.01.001
摘要:
基于Ru (Z = 44) 丰中子同位素中存在最大三轴形变的理论预言和实验证据，综述了近年来Rh (Z = 45),Pd (Z =46), Ag (Z =47), Cd (Z =48)(质子数Z 位于Ru，Z =44 之上)及Zr (Z =40), Nb (Z =41), Mo (Z =42),Tc (Z =43)(质子数Z 位于Ru，Z =44 之下) 的A~ (100~126) 丰中子同位素中关于三轴形变的形状变迁和形状共存系统性研究的重要进展。252Cf 自发裂变瞬发 射线-- 三重符合、特别是新建立的--- 四重符合数据的系统观测和研究，在Ru, Pd, Cd 和Nb 丰中子同位素中显著扩展或首次观测到了一系列能带，为这个核区原子核形状的研究提供了新的、重要的实验数据。联系此前报道的有关进展，使用PES, TRS, PSM, CCCSM 和SCTAC 理论模型计算拟合新的实验数据，在该核区沿同中素和同位素链，并随自旋和激发能变化各自由度，跟踪原子核形状渐进变化，获得了新的系统性研究成果，显著扩展和深化了人们对原子核形状变迁和形状共存的认知。对于Ru 及其上的Rh (Z = 45), Pd (Z = 46), Ag (Z = 47) 和Cd (Z = 48) 丰中子同位素的研究表明：Rh 丰中子核具有比最大值稍小的三轴形变，γ = 28°，并在103{106Rh 同位素链上鉴别出了手征对称破缺；在三轴形变核112Ru和114Pd(N = 68)中发现了三轴原子核的摆动运动，该摆动运动也可能在114Ru (N = 70)中存在；观察到了从具有最大三轴形变的110,112Ru 中手征破缺到稍小三轴形变的112,114,116Pd 中扰动的手征破缺的过渡；在较软的Ag 核中观察到了丰富的谱学结构，在104,105Ag 中鉴别出了可能的手征对称破缺，在较重的115,117Ag 中提出了趋于三轴形变的软度；具有小形变的Cd核的能级结构被解释为准粒子耦合、准转动和软三轴形变；最近的库伦激发的研究提供了Z = 50, N = 82满壳附近122,124,126Cd 核中出现核集体性的实验和理论证据；上述研究成果展现出从Ru中的最大三轴形变(γ=30°，三轴形变极小增益为0.67 MeV), 经具有大三轴形变的Rh核γ=28°)，到Pd核中的稍小、但稳定于中等自旋到高自旋区的三轴形变(γ~41°,三轴形变极小增益为0.32 MeV)，再经Ag核中的软度，最后到具有很小形变、但仍出现集体性质、包括软三轴形变的Cd核的过渡。对于Pd核转动带交叉系统性的研究揭示了其第一带交叉(νh11/2)2 中子转动顺排的上行驱动，和第二带交叉(πg9/2)2质子转动顺排的下行驱动效应，成功地解释了114Pd 中的三轴摆动运动，并给出了110-118Pd同位素链中理论早已预言、而比早期理论预言更为完整准确的形状渐进变迁和形状共存的图像。根据该核区的系统研究，发现最大三轴形变出现在112Ru，而在相邻的偶Z(Pd)同位素链，三轴形变极小的中心在114Pd, 两者均为N = 68。上述系统性研究沿相邻的Ru和Pd偶Z同位素链，在N =68同中素中鉴别出最大三轴形变，均比理论预言的108Ru 和110Pd 多4个中子。在Z值位于Ru (Z = 44) 之下的Zr (Z = 40), Nb (Z = 41), Mo (Z = 42) and Tc (Z = 43) 丰中子同位素中，Y和Zr核具有很强的轴对称四极形变，而在较重的Zr同位素中出现了自由度；较重的Nb核(A = 104~106) 基态具有中等程度的软三轴形变和强四极形变，随着自旋和激发能的增加，过渡到接近于轴对称的强四极形变；而较轻的Nb核(A≤103) 基态均接近轴对称形状；在Nb同位素链上基态由球形到强四极形变的形状突变发生在100Nb(N = 59)，在100-106Nb同位素链中基态的软三轴形变随中子数增加而增加；在Nb核中还观察到关于软三轴形变的形状共存；Mo核具有大的三轴形变，观察到了振动和手征对称破缺；Tc核具有比最大值稍小的三轴形变，γ=26°，并观察到了手征对称破缺。质子数Z从41到48的A~(100~126)丰中子同位素，特别是Pd和Nb 同位素，呈现出关于三轴形变的过渡特征。This paper reviews the systematic investigations and understanding for the shape transitions and coexistence with regard to triaxial deformations in A s 100 to 126 neutron-rich Rh (Z = 45), Pd (Z = 46), Ag (Z = 47), Cd (Z = 48) and Zr (Z = 40), Nb (Z = 41), Mo (Z = 42), Tc (Z = 43) isotopes with Z beyond and below Ru (Z = 44), respectively, in Ru the maximal triaxial deformation having been predicted and deduced. The recent measurements and studies of prompt triple- and four-fold, γ-γ-γ and γ-γ-γ-γ, coincidence data from the spontaneous fission of 252Cf using Gammasphere have yielded considerable expansion and extension or first observation of the bands in Ru, Pd, Cd, and Nb isotopes,which provided important data for the studies of nuclear shapes in this region. Combined with previous investigations, recent systematic studies of the new data well reproduced by PES, TRS, PSM, CCCSM and SCTAC model calculations have traced shape changes along the isotonic and isotopic chains, respectively,and with changing excitations/spins as well, significantly expanding our knowledge of shape transitions/coexistence in nuclei.For the neutron-rich Ru and beyond, Rh, Pd, Ag and Cd isotopes, triaxial deformations γ= 28°,slightly smaller than the maximal value, were deduced in Rh (Z = 45) isotopes, with chiral symmetry breaking proposed in 103-106Rh; onset of wobbling motions were identified in 112Ru and 114Pd (N =68),and probably also in 114Ru (N =70); evolution from chiral symmetry breaking in 110,112Ru with maximal triaxial deformations to disturbed chirality in 112,114,116Pd with less pronounced triaxial deformations was proposed; rich nuclear structure was proposed in soft Ag isotopes with possible chiral doubling structure suggested in 104,105Ag, and softness towards triaxial deformation proposed in heavier 115,117Ag;quasi-particle couplings, quasi-rotations and soft triaxiality were suggested in Cd (Z =48) isotopes with small deformations; onset of collectivity was recently suggested in 122,124,126Cd in the vicinity of Z =50 and N = 82 closed shells by studies of Coulomb excitations; shape evolutions from maximal triaxial deformations in Ru (γ=30°, with triaxial minimum energy gain of 0.67 MeV), through Rh with large triaxial deformations ( γ=28°), to less pronounced triaxiality in Pd (with triaxial minimum energy gain of 0.32 MeV), then soft triaxiality in Ag, and finally to slightly deformed Cd isotopes but with emergence of collectivity and soft triaxiality were proposed. The systematic studies of the band crossings in Pd revealed up-rising drivings of the first band crossings caused by (νh11/2)2 and down-sloping drivings of the second band crossings by (πg9/2)2, explained the onset of wobbling motions in 114Pd,and showed a long-sought picture of shape evolution and coexistence in the Pd isotopic chain which is more complete but complex than earlier predictions. Based on the systematic studies in the mass region,maximal triaxial deformation is found to be reached in 112Ru and less-pronounced triaxiality centered at 114Pd, both for N =68, four neutrons more than predicted in earlier theoretical calculations.In the neutron-rich Zr (Z =40), Nb (Z =41), Mo (Z =42) and Tc (Z =43) isotopes with Z just below Ru, large quadrupole deformations of axially symmetric shapes were deduced in Y and Zr isotopes, with emergence of the degree of freedom having been suggested for heavier Zr isotopes; medium triaxial deformations were deduced for the ground states of heavier (A > 104) Nb isotopes, and, with increasing excitations and spins, evolution from medium triaxial deformations with strong quadrupole deformations at ground states to nearly axially-symmetric shapes were deduced; light Nb isotopes (A6103) have near axially-symmetric shapes with strong quadrupole deformations; combining with the identification of onset of strong quadrupole deformation at 100Nb in the Nb isotopic chain, an increase of soft triaxiality with increasing neutron number was proposed in 100-106Nb. Shape coexistence with regard to soft triaxiality is also proposed in Nb isotopes; large triaxial deformations, vibrations and chiral doublets were proposed in Mo isotopes; chiral doubling and large triaxial deformations (γ ~26°) slightly smaller than the maximal triaxiality were suggested in Tc isotopes.The neutron-rich nuclei with Z ranging from 41 through 48 and A ~100 to 126, especially the Pd and Nb isotopes are thus found to be transitional nuclei with regard to triaxiality.
基于Ru (Z = 44) 丰中子同位素中存在最大三轴形变的理论预言和实验证据，综述了近年来Rh (Z = 45),Pd (Z =46), Ag (Z =47), Cd (Z =48)(质子数Z 位于Ru，Z =44 之上)及Zr (Z =40), Nb (Z =41), Mo (Z =42),Tc (Z =43)(质子数Z 位于Ru，Z =44 之下) 的A~ (100~126) 丰中子同位素中关于三轴形变的形状变迁和形状共存系统性研究的重要进展。252Cf 自发裂变瞬发 射线-- 三重符合、特别是新建立的--- 四重符合数据的系统观测和研究，在Ru, Pd, Cd 和Nb 丰中子同位素中显著扩展或首次观测到了一系列能带，为这个核区原子核形状的研究提供了新的、重要的实验数据。联系此前报道的有关进展，使用PES, TRS, PSM, CCCSM 和SCTAC 理论模型计算拟合新的实验数据，在该核区沿同中素和同位素链，并随自旋和激发能变化各自由度，跟踪原子核形状渐进变化，获得了新的系统性研究成果，显著扩展和深化了人们对原子核形状变迁和形状共存的认知。对于Ru 及其上的Rh (Z = 45), Pd (Z = 46), Ag (Z = 47) 和Cd (Z = 48) 丰中子同位素的研究表明：Rh 丰中子核具有比最大值稍小的三轴形变，γ = 28°，并在103{106Rh 同位素链上鉴别出了手征对称破缺；在三轴形变核112Ru和114Pd(N = 68)中发现了三轴原子核的摆动运动，该摆动运动也可能在114Ru (N = 70)中存在；观察到了从具有最大三轴形变的110,112Ru 中手征破缺到稍小三轴形变的112,114,116Pd 中扰动的手征破缺的过渡；在较软的Ag 核中观察到了丰富的谱学结构，在104,105Ag 中鉴别出了可能的手征对称破缺，在较重的115,117Ag 中提出了趋于三轴形变的软度；具有小形变的Cd核的能级结构被解释为准粒子耦合、准转动和软三轴形变；最近的库伦激发的研究提供了Z = 50, N = 82满壳附近122,124,126Cd 核中出现核集体性的实验和理论证据；上述研究成果展现出从Ru中的最大三轴形变(γ=30°，三轴形变极小增益为0.67 MeV), 经具有大三轴形变的Rh核γ=28°)，到Pd核中的稍小、但稳定于中等自旋到高自旋区的三轴形变(γ~41°,三轴形变极小增益为0.32 MeV)，再经Ag核中的软度，最后到具有很小形变、但仍出现集体性质、包括软三轴形变的Cd核的过渡。对于Pd核转动带交叉系统性的研究揭示了其第一带交叉(νh11/2)2 中子转动顺排的上行驱动，和第二带交叉(πg9/2)2质子转动顺排的下行驱动效应，成功地解释了114Pd 中的三轴摆动运动，并给出了110-118Pd同位素链中理论早已预言、而比早期理论预言更为完整准确的形状渐进变迁和形状共存的图像。根据该核区的系统研究，发现最大三轴形变出现在112Ru，而在相邻的偶Z(Pd)同位素链，三轴形变极小的中心在114Pd, 两者均为N = 68。上述系统性研究沿相邻的Ru和Pd偶Z同位素链，在N =68同中素中鉴别出最大三轴形变，均比理论预言的108Ru 和110Pd 多4个中子。在Z值位于Ru (Z = 44) 之下的Zr (Z = 40), Nb (Z = 41), Mo (Z = 42) and Tc (Z = 43) 丰中子同位素中，Y和Zr核具有很强的轴对称四极形变，而在较重的Zr同位素中出现了自由度；较重的Nb核(A = 104~106) 基态具有中等程度的软三轴形变和强四极形变，随着自旋和激发能的增加，过渡到接近于轴对称的强四极形变；而较轻的Nb核(A≤103) 基态均接近轴对称形状；在Nb同位素链上基态由球形到强四极形变的形状突变发生在100Nb(N = 59)，在100-106Nb同位素链中基态的软三轴形变随中子数增加而增加；在Nb核中还观察到关于软三轴形变的形状共存；Mo核具有大的三轴形变，观察到了振动和手征对称破缺；Tc核具有比最大值稍小的三轴形变，γ=26°，并观察到了手征对称破缺。质子数Z从41到48的A~(100~126)丰中子同位素，特别是Pd和Nb 同位素，呈现出关于三轴形变的过渡特征。This paper reviews the systematic investigations and understanding for the shape transitions and coexistence with regard to triaxial deformations in A s 100 to 126 neutron-rich Rh (Z = 45), Pd (Z = 46), Ag (Z = 47), Cd (Z = 48) and Zr (Z = 40), Nb (Z = 41), Mo (Z = 42), Tc (Z = 43) isotopes with Z beyond and below Ru (Z = 44), respectively, in Ru the maximal triaxial deformation having been predicted and deduced. The recent measurements and studies of prompt triple- and four-fold, γ-γ-γ and γ-γ-γ-γ, coincidence data from the spontaneous fission of 252Cf using Gammasphere have yielded considerable expansion and extension or first observation of the bands in Ru, Pd, Cd, and Nb isotopes,which provided important data for the studies of nuclear shapes in this region. Combined with previous investigations, recent systematic studies of the new data well reproduced by PES, TRS, PSM, CCCSM and SCTAC model calculations have traced shape changes along the isotonic and isotopic chains, respectively,and with changing excitations/spins as well, significantly expanding our knowledge of shape transitions/coexistence in nuclei.For the neutron-rich Ru and beyond, Rh, Pd, Ag and Cd isotopes, triaxial deformations γ= 28°,slightly smaller than the maximal value, were deduced in Rh (Z = 45) isotopes, with chiral symmetry breaking proposed in 103-106Rh; onset of wobbling motions were identified in 112Ru and 114Pd (N =68),and probably also in 114Ru (N =70); evolution from chiral symmetry breaking in 110,112Ru with maximal triaxial deformations to disturbed chirality in 112,114,116Pd with less pronounced triaxial deformations was proposed; rich nuclear structure was proposed in soft Ag isotopes with possible chiral doubling structure suggested in 104,105Ag, and softness towards triaxial deformation proposed in heavier 115,117Ag;quasi-particle couplings, quasi-rotations and soft triaxiality were suggested in Cd (Z =48) isotopes with small deformations; onset of collectivity was recently suggested in 122,124,126Cd in the vicinity of Z =50 and N = 82 closed shells by studies of Coulomb excitations; shape evolutions from maximal triaxial deformations in Ru (γ=30°, with triaxial minimum energy gain of 0.67 MeV), through Rh with large triaxial deformations ( γ=28°), to less pronounced triaxiality in Pd (with triaxial minimum energy gain of 0.32 MeV), then soft triaxiality in Ag, and finally to slightly deformed Cd isotopes but with emergence of collectivity and soft triaxiality were proposed. The systematic studies of the band crossings in Pd revealed up-rising drivings of the first band crossings caused by (νh11/2)2 and down-sloping drivings of the second band crossings by (πg9/2)2, explained the onset of wobbling motions in 114Pd,and showed a long-sought picture of shape evolution and coexistence in the Pd isotopic chain which is more complete but complex than earlier predictions. Based on the systematic studies in the mass region,maximal triaxial deformation is found to be reached in 112Ru and less-pronounced triaxiality centered at 114Pd, both for N =68, four neutrons more than predicted in earlier theoretical calculations.In the neutron-rich Zr (Z =40), Nb (Z =41), Mo (Z =42) and Tc (Z =43) isotopes with Z just below Ru, large quadrupole deformations of axially symmetric shapes were deduced in Y and Zr isotopes, with emergence of the degree of freedom having been suggested for heavier Zr isotopes; medium triaxial deformations were deduced for the ground states of heavier (A > 104) Nb isotopes, and, with increasing excitations and spins, evolution from medium triaxial deformations with strong quadrupole deformations at ground states to nearly axially-symmetric shapes were deduced; light Nb isotopes (A6103) have near axially-symmetric shapes with strong quadrupole deformations; combining with the identification of onset of strong quadrupole deformation at 100Nb in the Nb isotopic chain, an increase of soft triaxiality with increasing neutron number was proposed in 100-106Nb. Shape coexistence with regard to soft triaxiality is also proposed in Nb isotopes; large triaxial deformations, vibrations and chiral doublets were proposed in Mo isotopes; chiral doubling and large triaxial deformations (γ ~26°) slightly smaller than the maximal triaxiality were suggested in Tc isotopes.The neutron-rich nuclei with Z ranging from 41 through 48 and A ~100 to 126, especially the Pd and Nb isotopes are thus found to be transitional nuclei with regard to triaxiality.
2015, 32(1): 24-29.
doi: 10.11804/NuclPhysRev.32.01.024
摘要:
和中高能重离子碰撞相比，低能重离子碰撞中的弹靶结构效应起着更为重要的作用，因此要求输运模型能够对核的基态性质给出更合理的描述。利用扩展的量子分子动力学(EQMD) 模型计算了从轻到重不同质量区不同同位素链的结合能及方均根半径等基态性质，并与实验值进行了比较，发现EQMD模型不仅能够非常好地重现稳定核的基态性质，而且能够合理地描述远离 稳定线核的基态结合能，因此相比于IQMD，CoMD，ImQMD等其他QMD版本，EQMD模型对初始化核稳定性的描述也有了极大改善。这为利用微观动力学模型研究弱束缚核在低能区引起的弹性散射、熔合、转移及破裂等反应机制提供了基础。The structure effects of project and target in heavy ion collision at low energy is more important compared with the effects at high energy, which requires the transport model to describe the ground properties of nuclei more reasonably. In this paper, we carry out calculations of the ground state properties, such as binding energy and root mean square radius, of different isotope chains from light to heavy mass region by an extended quantum molecular dynamics (EQMD) model and compare the results with data. It is found that the EQMD model not only can reproduce ground state properties of stable nuclei very well, but also can reasonably describe the ground state binding energy of nuclei far from βstability line. Compared with other versions of QMD, EQMD model greatly improves the description of the stability of initialized nuclei. Recent investigations would serve as a starting basis for studying the reaction mechanisms of elastic scattering, fusion, transfer and breakup induced by weakly bound nuclei by the microscopic dynamical model.
和中高能重离子碰撞相比，低能重离子碰撞中的弹靶结构效应起着更为重要的作用，因此要求输运模型能够对核的基态性质给出更合理的描述。利用扩展的量子分子动力学(EQMD) 模型计算了从轻到重不同质量区不同同位素链的结合能及方均根半径等基态性质，并与实验值进行了比较，发现EQMD模型不仅能够非常好地重现稳定核的基态性质，而且能够合理地描述远离 稳定线核的基态结合能，因此相比于IQMD，CoMD，ImQMD等其他QMD版本，EQMD模型对初始化核稳定性的描述也有了极大改善。这为利用微观动力学模型研究弱束缚核在低能区引起的弹性散射、熔合、转移及破裂等反应机制提供了基础。The structure effects of project and target in heavy ion collision at low energy is more important compared with the effects at high energy, which requires the transport model to describe the ground properties of nuclei more reasonably. In this paper, we carry out calculations of the ground state properties, such as binding energy and root mean square radius, of different isotope chains from light to heavy mass region by an extended quantum molecular dynamics (EQMD) model and compare the results with data. It is found that the EQMD model not only can reproduce ground state properties of stable nuclei very well, but also can reasonably describe the ground state binding energy of nuclei far from βstability line. Compared with other versions of QMD, EQMD model greatly improves the description of the stability of initialized nuclei. Recent investigations would serve as a starting basis for studying the reaction mechanisms of elastic scattering, fusion, transfer and breakup induced by weakly bound nuclei by the microscopic dynamical model.
2015, 32(1): 30-35.
doi: 10.11804/NuclPhysRev.32.01.030
摘要:
研究了15 MeV/u 197Au+197Au 体系三裂变反应过程中体系的集体运动动能、核-核相互作用势、集体运动总动能以及核子激发能的演化过程，并讨论了该反应过程的能量耗散问题。通过与两裂变时体系总动能εtot 和Θc.m.:关联图作对比，初步得出三裂变反应体系的第一次裂变是极端深度非弹性散射过程；进一步分析了三裂变与两裂变反应体系总动能与碰撞参数的关系，发现小碰撞参数下两裂变比三裂变反应耗散的能量多大约150 MeV，大碰撞参数下三裂变比两裂变反应多消耗300 MeV。We studied the evolution of the collective motion, interaction potential, the total kinetic and excitation energies in ternary ssions of 197Au +197Au system at 15 Mev/u, and discussed energy dissipation of this reaction. Through the comparison with energy-angle correlation data in binary ssions, we preliminarily concluded that the rst ssion of ternary ssion was an extreme deep-inelastic process. We further analyzed the correlation of the total kinetic energy with impact parameters in both binary and ternary reactions, and found that the total energy of binary reactions systems was lost about 150 MeV more than ternary ssion with small impact parameters, and with larger impact parameters the total energy of ternary reactions were lost 300 MeV more than binary reactions.
研究了15 MeV/u 197Au+197Au 体系三裂变反应过程中体系的集体运动动能、核-核相互作用势、集体运动总动能以及核子激发能的演化过程，并讨论了该反应过程的能量耗散问题。通过与两裂变时体系总动能εtot 和Θc.m.:关联图作对比，初步得出三裂变反应体系的第一次裂变是极端深度非弹性散射过程；进一步分析了三裂变与两裂变反应体系总动能与碰撞参数的关系，发现小碰撞参数下两裂变比三裂变反应耗散的能量多大约150 MeV，大碰撞参数下三裂变比两裂变反应多消耗300 MeV。We studied the evolution of the collective motion, interaction potential, the total kinetic and excitation energies in ternary ssions of 197Au +197Au system at 15 Mev/u, and discussed energy dissipation of this reaction. Through the comparison with energy-angle correlation data in binary ssions, we preliminarily concluded that the rst ssion of ternary ssion was an extreme deep-inelastic process. We further analyzed the correlation of the total kinetic energy with impact parameters in both binary and ternary reactions, and found that the total energy of binary reactions systems was lost about 150 MeV more than ternary ssion with small impact parameters, and with larger impact parameters the total energy of ternary reactions were lost 300 MeV more than binary reactions.
2015, 32(1): 36-43.
doi: 10.11804/NuclPhysRev.32.01.036
摘要:
运用改进的量子分子动力学(ImQMD)模型嫁接GEMINI统计衰变模型对波包宽度与弹核碎裂反应截面之间的关系进行了理论分析，分析了不同的波包宽度对400 AMeV 36Ar+C，20Ne与C，Al，Cu，Sn弹核碎裂反应截面的影响，分析了同位素36Ar，40Ar与Al反应在不同的波包宽度下的同位素分布。分析结果表明：波包宽度的选择影响着弹核碎裂的反应截面，并且与核反应体系有关。当σ2r = 2 fm2时的计算结果与实验结果一致；而σr =(0.88+0.09 A1/3) fm的计算结果与体系有很大的关系，对弹核碎裂的反应截面影响明显。不的波包宽度对丰中子核40Ar的弹核碎裂反应截面的影响要小于对36Ar的弹核碎裂反应截面的影响，而且随体系分布的波包宽度计算的同位素要比σ2r =2 fm2时计算的同位素多。The relations between wave packet width and projectile fragmentation cross sections are studied in theory by using the improved quantum molecular dynamics (ImQMD) and GEMINI models. The effect of different wave packet width for projectile fragmentation cross sections is analyzed for the reaction 36Ar on C, 20Ne on C, Al, Cu, Sn at 400 AMeV, the isotope distributions with different wave packet width are studied for reactions 36Ar, 40Ar on Al. The results show that the projectile fragmentation cross sections are affected by the choice of the wave packet width, and are related to the system of nuclear reaction. The calculation results of σ2r =2 fm2are in agreement with the experimental results, but the results of σr = (0.88+0.09A1/3) fm have a strong relation with reaction system and the projectile fragmentation cross sections are affected obviously. The influence of wave packet width for 40Ar projectile fragmentation cross sections is smaller than that for 36Ar.Moreover isotope distributions with system-size-dependent wave packet width are larger than with σ2r =2 fm2.
运用改进的量子分子动力学(ImQMD)模型嫁接GEMINI统计衰变模型对波包宽度与弹核碎裂反应截面之间的关系进行了理论分析，分析了不同的波包宽度对400 AMeV 36Ar+C，20Ne与C，Al，Cu，Sn弹核碎裂反应截面的影响，分析了同位素36Ar，40Ar与Al反应在不同的波包宽度下的同位素分布。分析结果表明：波包宽度的选择影响着弹核碎裂的反应截面，并且与核反应体系有关。当σ2r = 2 fm2时的计算结果与实验结果一致；而σr =(0.88+0.09 A1/3) fm的计算结果与体系有很大的关系，对弹核碎裂的反应截面影响明显。不的波包宽度对丰中子核40Ar的弹核碎裂反应截面的影响要小于对36Ar的弹核碎裂反应截面的影响，而且随体系分布的波包宽度计算的同位素要比σ2r =2 fm2时计算的同位素多。The relations between wave packet width and projectile fragmentation cross sections are studied in theory by using the improved quantum molecular dynamics (ImQMD) and GEMINI models. The effect of different wave packet width for projectile fragmentation cross sections is analyzed for the reaction 36Ar on C, 20Ne on C, Al, Cu, Sn at 400 AMeV, the isotope distributions with different wave packet width are studied for reactions 36Ar, 40Ar on Al. The results show that the projectile fragmentation cross sections are affected by the choice of the wave packet width, and are related to the system of nuclear reaction. The calculation results of σ2r =2 fm2are in agreement with the experimental results, but the results of σr = (0.88+0.09A1/3) fm have a strong relation with reaction system and the projectile fragmentation cross sections are affected obviously. The influence of wave packet width for 40Ar projectile fragmentation cross sections is smaller than that for 36Ar.Moreover isotope distributions with system-size-dependent wave packet width are larger than with σ2r =2 fm2.
2015, 32(1): 44-49.
doi: 10.11804/NuclPhysRev.32.01.044
摘要:
最近Diakonov考虑了大Nc平均场近似下重子共振态谱的海夸克效应并提出重子共振态谱的集体激发理论，该理论恰好是SU(6) 夸克模型的一种推广。检查了Diakonov重子谱理论中介子张量势的物理含义并给出重子共振态谱公式参数的数值优化。发现，重子共振态谱公式能够与2 GeV以下重子谱良好吻合。Recently, Diakonov considered the sea quark effect of baryon resonance spectrum in the large Nc mean field approximation and put forward the collective excitation theory of baryon resonance spectrum, which is an extension of the SU(6) quark model. In this paper we examine the implications of the meson tensor potential of the Diakonov’s baryon spectrum theory and provide a numerical optimization of the parameters in the baryon resonance spectrum formula. The resulted baryon resonance spectrum formula is in good agreement with the spectra data below 2 GeV.
最近Diakonov考虑了大Nc平均场近似下重子共振态谱的海夸克效应并提出重子共振态谱的集体激发理论，该理论恰好是SU(6) 夸克模型的一种推广。检查了Diakonov重子谱理论中介子张量势的物理含义并给出重子共振态谱公式参数的数值优化。发现，重子共振态谱公式能够与2 GeV以下重子谱良好吻合。Recently, Diakonov considered the sea quark effect of baryon resonance spectrum in the large Nc mean field approximation and put forward the collective excitation theory of baryon resonance spectrum, which is an extension of the SU(6) quark model. In this paper we examine the implications of the meson tensor potential of the Diakonov’s baryon spectrum theory and provide a numerical optimization of the parameters in the baryon resonance spectrum formula. The resulted baryon resonance spectrum formula is in good agreement with the spectra data below 2 GeV.
2015, 32(1): 50-53.
doi: 10.11804/NuclPhysRev.32.01.050
摘要:
采用多粒子跟踪程序BEAMPATH 对SSC-LINAC 重离子RFQ 直线加速器进行动力学模拟，分别对RFQ 的接受度、高频特性、束流稳定性、空间电荷效应等进行了分析。该RFQ具有很大的纵向接受度，有利于束流在RFQ中的传输；高频特性研究表明，翼间电压设定在理论值以上时，该RFQ都能保持较好的束流特性；束流稳定性分析结果表明，该RFQ具有很大的束流失配容忍度；空间电荷效应研究表明，当束流强度低于0.5 mA时，束流传输不受影响。综合研究结果表明，53.667 MHz重离子RFQ具有较好的动力学特性，满足SSC-LINAC直线加速器的设计要求。The RFQ beam dynamics of a heavy ion linac was investigated in this paper and the BEAMPATH code was employed in this study. The main research was focused on the beam performances depending on longitudinal acceptance, RF properties, beam instability and space charge effect. The RFQ has large longitudinal acceptance in design, which brings the beam performances well. In the RF parameter study, the beam can keep good transmission in the acceleration even the vane voltage is larger than the theoretical value. It is also shown that the RFQ has a large robustness for the mismatch of the input beam by the analysis of the beam instability.Furthermore, the beam evolution is independent on the space charge effect when the beam current is less than 0.5 emA. The preliminary analysis of the beam dynamics shows that the 53.667 MHz heavy ion RFQ has a promising performance, which meets the requirements of SSC-LINAC.
采用多粒子跟踪程序BEAMPATH 对SSC-LINAC 重离子RFQ 直线加速器进行动力学模拟，分别对RFQ 的接受度、高频特性、束流稳定性、空间电荷效应等进行了分析。该RFQ具有很大的纵向接受度，有利于束流在RFQ中的传输；高频特性研究表明，翼间电压设定在理论值以上时，该RFQ都能保持较好的束流特性；束流稳定性分析结果表明，该RFQ具有很大的束流失配容忍度；空间电荷效应研究表明，当束流强度低于0.5 mA时，束流传输不受影响。综合研究结果表明，53.667 MHz重离子RFQ具有较好的动力学特性，满足SSC-LINAC直线加速器的设计要求。The RFQ beam dynamics of a heavy ion linac was investigated in this paper and the BEAMPATH code was employed in this study. The main research was focused on the beam performances depending on longitudinal acceptance, RF properties, beam instability and space charge effect. The RFQ has large longitudinal acceptance in design, which brings the beam performances well. In the RF parameter study, the beam can keep good transmission in the acceleration even the vane voltage is larger than the theoretical value. It is also shown that the RFQ has a large robustness for the mismatch of the input beam by the analysis of the beam instability.Furthermore, the beam evolution is independent on the space charge effect when the beam current is less than 0.5 emA. The preliminary analysis of the beam dynamics shows that the 53.667 MHz heavy ion RFQ has a promising performance, which meets the requirements of SSC-LINAC.
2015, 32(1): 54-58.
doi: 10.11804/NuclPhysRev.32.01.054
摘要:
中国科学院近代物理研究所设计的工作频率为325 MHz、最优β为0.52 的双柱超导Spoke 腔的电磁已经完成。详细地描述了Spoke 基部横截面形状和大小对腔体射频性能的影响，采用了跑道形来取代通常的圆形Spoke 基部截面。从归一化峰值电磁场和分路阻抗两方面出发，比较了横截面为横向跑道和纵向跑道的Spoke 基部。Spoke 基部横截面的形状为横向跑道时能得到较好的射频参数，满足中国ADS(C-ADS) 的工程需求。最后利用CST 粒子工作室对得到的腔体进行了二次电子倍增分析，在工作电压附近不存在二次电子倍增，验证了该腔体形状的可行性。The EM design of a 325 MHz β= 0.52 superconducting double Spoke cavity has been finished at Institute of Modern Physics (IMP), Chinese Academy of Sciences(CAS). In this paper, the optimization of the Spoke base is described in detail. The goal is to minimize the peak surface field and maximize the shunt impedance. The common cylinder is replaced by the racetrack shape for the Spoke base. The transverse racetrack Spoke base can offer a better RF property than the longitudinal racetrack Spoke base, which meet the requirement of the C-ADS. The simulation of multipactor finished by CST Particle Studio is also presented, which gives a promising result that there is no multipactor around working voltage.
中国科学院近代物理研究所设计的工作频率为325 MHz、最优β为0.52 的双柱超导Spoke 腔的电磁已经完成。详细地描述了Spoke 基部横截面形状和大小对腔体射频性能的影响，采用了跑道形来取代通常的圆形Spoke 基部截面。从归一化峰值电磁场和分路阻抗两方面出发，比较了横截面为横向跑道和纵向跑道的Spoke 基部。Spoke 基部横截面的形状为横向跑道时能得到较好的射频参数，满足中国ADS(C-ADS) 的工程需求。最后利用CST 粒子工作室对得到的腔体进行了二次电子倍增分析，在工作电压附近不存在二次电子倍增，验证了该腔体形状的可行性。The EM design of a 325 MHz β= 0.52 superconducting double Spoke cavity has been finished at Institute of Modern Physics (IMP), Chinese Academy of Sciences(CAS). In this paper, the optimization of the Spoke base is described in detail. The goal is to minimize the peak surface field and maximize the shunt impedance. The common cylinder is replaced by the racetrack shape for the Spoke base. The transverse racetrack Spoke base can offer a better RF property than the longitudinal racetrack Spoke base, which meet the requirement of the C-ADS. The simulation of multipactor finished by CST Particle Studio is also presented, which gives a promising result that there is no multipactor around working voltage.
2015, 32(1): 59-62.
doi: 10.11804/NuclPhysRev.32.01.059
摘要:
设计并实现了近代物理研究所激光离子源双脉冲打靶方案以产生高电荷态离子束。从Nd:YAG激光器输出的激光束经过一对分光棱镜的分束-合束，通过改变两束光的光程差，得到有一定时间延迟的双激光脉冲。利用四分之一玻片，双脉冲的能量比值可以在3:8~8:3之间连续调节。为了验证该方案的可行性，对C靶进行了初步实验。实验结果发现，与以往单脉冲打靶方案对比，双脉冲方案在离子束的脉冲时间结构和电荷态分布有所不同。但是，导致这些差异的机理和实验的优化还尚需要进一步研究。A double-pulse laser irradiating scheme has been designed and established for the production of highly charged ion beams at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The laser beam output by a Nd:YAG laser is split and combined by a double of beam splitters, between which the split laser beams are transmitted along different optical paths to get certain time delay between each other. With the help of a quarter-wave plate before the first splitter, the energy ratio between the two laser pulses can be adjusted between 3:8 to 8:3. To testify its feasibility, a preliminary experiment was carried out with the new-developed double-pulse irradiating scheme to produce highly charged carbon ions. Comparing the results with those got from the previous single-pulse irradiating scheme, the differences in the time structure and Charge State Distribution (CSD) of the ion pulse were observed, but its mechanisms and optimization require further studies.
设计并实现了近代物理研究所激光离子源双脉冲打靶方案以产生高电荷态离子束。从Nd:YAG激光器输出的激光束经过一对分光棱镜的分束-合束，通过改变两束光的光程差，得到有一定时间延迟的双激光脉冲。利用四分之一玻片，双脉冲的能量比值可以在3:8~8:3之间连续调节。为了验证该方案的可行性，对C靶进行了初步实验。实验结果发现，与以往单脉冲打靶方案对比，双脉冲方案在离子束的脉冲时间结构和电荷态分布有所不同。但是，导致这些差异的机理和实验的优化还尚需要进一步研究。A double-pulse laser irradiating scheme has been designed and established for the production of highly charged ion beams at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The laser beam output by a Nd:YAG laser is split and combined by a double of beam splitters, between which the split laser beams are transmitted along different optical paths to get certain time delay between each other. With the help of a quarter-wave plate before the first splitter, the energy ratio between the two laser pulses can be adjusted between 3:8 to 8:3. To testify its feasibility, a preliminary experiment was carried out with the new-developed double-pulse irradiating scheme to produce highly charged carbon ions. Comparing the results with those got from the previous single-pulse irradiating scheme, the differences in the time structure and Charge State Distribution (CSD) of the ion pulse were observed, but its mechanisms and optimization require further studies.
2015, 32(1): 63-68.
doi: 10.11804/NuclPhysRev.32.01.063
摘要:
兰州重离子加速器冷却储存环(HIRFL-CSR)现有的Kicker踢轨控制系统为多板结构，需要安装多个控制软件对其进行参数配置，系统的时间分辨率为5 ns；新研制的踢轨控制系统采用单板结构，将系统的时间分辨率提高至2.5 ns。界面设计采用流行的浏览器/服务器模式，在嵌入式系统中移植Boa Web服务器，用来实现浏览器和底层硬件的通信，操作人员通过浏览器即可对Kicker控制系统各项参数进行配置。实验验证，该软件系统具有免安装、操作简单、易于与其他软件系统集成的优点，能够满足踢轨控制系统的需要。The existed Kicker Control System for HIRFL-CSR in Lanzhou is multi-board and many software interfaces have been installed to have the parameters to be con gurated. The time resolution for the beam to be identi ed is 5 ns. The newly designed Kicker Control System is designed with single-board architecture and raises the system time resolution to 2.5 ns. The B/S model has been applied to upgrade the software interface.In order to realize the target, we use the browser to communicate with hardware for the purpose of con guring the controller, the Boa web server has been transplanted into embedded system. The experiments showed that this software system is easy to use and integrate with other control system, without setup process, and is of great research value and popularization.
兰州重离子加速器冷却储存环(HIRFL-CSR)现有的Kicker踢轨控制系统为多板结构，需要安装多个控制软件对其进行参数配置，系统的时间分辨率为5 ns；新研制的踢轨控制系统采用单板结构，将系统的时间分辨率提高至2.5 ns。界面设计采用流行的浏览器/服务器模式，在嵌入式系统中移植Boa Web服务器，用来实现浏览器和底层硬件的通信，操作人员通过浏览器即可对Kicker控制系统各项参数进行配置。实验验证，该软件系统具有免安装、操作简单、易于与其他软件系统集成的优点，能够满足踢轨控制系统的需要。The existed Kicker Control System for HIRFL-CSR in Lanzhou is multi-board and many software interfaces have been installed to have the parameters to be con gurated. The time resolution for the beam to be identi ed is 5 ns. The newly designed Kicker Control System is designed with single-board architecture and raises the system time resolution to 2.5 ns. The B/S model has been applied to upgrade the software interface.In order to realize the target, we use the browser to communicate with hardware for the purpose of con guring the controller, the Boa web server has been transplanted into embedded system. The experiments showed that this software system is easy to use and integrate with other control system, without setup process, and is of great research value and popularization.
2015, 32(1): 69-72.
doi: 10.11804/NuclPhysRev.32.01.069
摘要:
利用水热法生长的N型优质ZnO晶体材料蒸镀了Au、Ag、Al金属，制备出金属-半导体-金属型(MSM)ZnO紫外探测器，测试了五种接触类型的ZnO紫外探测器(Au-ZnO-Au、Ag-ZnO-Ag、Au-ZnO-Al、Ag-ZnO-Al、Al-ZnO-Al)在365nm紫外光光照前后的I-V特性曲线。实验表明Au-ZnO-Au 型、Ag-ZnO-Ag型的探测器的光电流是暗电流的100 万倍，因此，Au-ZnO-Au型、Ag-ZnO-Ag型的ZnO紫外探测器性能比Au-ZnO-Al、Ag-ZnO-Al、Al-ZnO-Al型的优越。ZnO材料的电阻率对ZnO紫外探测器的光电流有较大的影响。在相同偏压下，电阻率越大，探测器的光电流越小。ZnO ultraviolet(UV) detectors with Metal-Semiconductor-Metal(MSM) structure were fabricated by the vacuum evaporation of Au, Ag, and Al on the n-type ZnO single crystal, which was grown with hydrothermal synthesis method. Five types of MSM ZnO detectors(Au-ZnO-Au, Ag-ZnO-Ag, Au-ZnO-Al, Ag-ZnO-Al,Al-ZnO-Al) were illuminated with 365 nm UV light respectively, and their corresponding I-V(Current-Voltage) characteristics were measured. The UV photocurrent values for Au-ZnO-Au and Ag-ZnO-Ag detectors were 1x106 times than their dark current values, and these facts imply that the Au-ZnO-Au and Ag-ZnO-Ag detectors were rather good UV detectors compared to Au-ZnO-Al, Ag-ZnO-Al, Al-ZnO-Al detectors. The photocurrent of the MSM ZnO detectors was also sensitive to the cubic resistance of the ZnO crystal. And it’s found that the higher resistance rate the ZnO crystal the smaller photocurrent value the detector under the same working voltage.
利用水热法生长的N型优质ZnO晶体材料蒸镀了Au、Ag、Al金属，制备出金属-半导体-金属型(MSM)ZnO紫外探测器，测试了五种接触类型的ZnO紫外探测器(Au-ZnO-Au、Ag-ZnO-Ag、Au-ZnO-Al、Ag-ZnO-Al、Al-ZnO-Al)在365nm紫外光光照前后的I-V特性曲线。实验表明Au-ZnO-Au 型、Ag-ZnO-Ag型的探测器的光电流是暗电流的100 万倍，因此，Au-ZnO-Au型、Ag-ZnO-Ag型的ZnO紫外探测器性能比Au-ZnO-Al、Ag-ZnO-Al、Al-ZnO-Al型的优越。ZnO材料的电阻率对ZnO紫外探测器的光电流有较大的影响。在相同偏压下，电阻率越大，探测器的光电流越小。ZnO ultraviolet(UV) detectors with Metal-Semiconductor-Metal(MSM) structure were fabricated by the vacuum evaporation of Au, Ag, and Al on the n-type ZnO single crystal, which was grown with hydrothermal synthesis method. Five types of MSM ZnO detectors(Au-ZnO-Au, Ag-ZnO-Ag, Au-ZnO-Al, Ag-ZnO-Al,Al-ZnO-Al) were illuminated with 365 nm UV light respectively, and their corresponding I-V(Current-Voltage) characteristics were measured. The UV photocurrent values for Au-ZnO-Au and Ag-ZnO-Ag detectors were 1x106 times than their dark current values, and these facts imply that the Au-ZnO-Au and Ag-ZnO-Ag detectors were rather good UV detectors compared to Au-ZnO-Al, Ag-ZnO-Al, Al-ZnO-Al detectors. The photocurrent of the MSM ZnO detectors was also sensitive to the cubic resistance of the ZnO crystal. And it’s found that the higher resistance rate the ZnO crystal the smaller photocurrent value the detector under the same working voltage.
2015, 32(1): 73-79.
doi: 10.11804/NuclPhysRev.32.01.073
摘要:
介绍了一种基于PXI总线的高精度、多通道定标器。可测量脉冲信号的最高重复频率为100 MHz，最高计数可达240。定标器有2种工作模式：定时计数模式和精确触发测量模式。定时计数模式工作在低计数率下(s 1 MHz)；精确触发测量模式可以工作在高计数率下(~ 100 MHz)，可以满足兰州反应显微成像谱仪实验中对定标器的要求。基于可编程逻辑器件FPGA进行设计，使之变得灵活，方便进行升级和改造。This article introduces a high resolution and multi-channel scaler based on PXI-3U standard. The maximum repetition frequency of the input signal is 100 MHz, with a counting scale up to 240. This scaler is able to operate in two working modes: counting within a certain time period or between two adjacent input trigger signals. The rst mode is designed for a low counting rate (~ 1 MHz), while the second mode for a high rate ( 100 MHz). Test results indicate that this scaler has a good performance, beyond the application requirement in the experiment of the reaction microscope at Lanzhou (ReMiLa). Besides, with the application of Field Programmable Gate Array (FPGA), this scaler module is exible and convenient to be upgrade in future.
介绍了一种基于PXI总线的高精度、多通道定标器。可测量脉冲信号的最高重复频率为100 MHz，最高计数可达240。定标器有2种工作模式：定时计数模式和精确触发测量模式。定时计数模式工作在低计数率下(s 1 MHz)；精确触发测量模式可以工作在高计数率下(~ 100 MHz)，可以满足兰州反应显微成像谱仪实验中对定标器的要求。基于可编程逻辑器件FPGA进行设计，使之变得灵活，方便进行升级和改造。This article introduces a high resolution and multi-channel scaler based on PXI-3U standard. The maximum repetition frequency of the input signal is 100 MHz, with a counting scale up to 240. This scaler is able to operate in two working modes: counting within a certain time period or between two adjacent input trigger signals. The rst mode is designed for a low counting rate (~ 1 MHz), while the second mode for a high rate ( 100 MHz). Test results indicate that this scaler has a good performance, beyond the application requirement in the experiment of the reaction microscope at Lanzhou (ReMiLa). Besides, with the application of Field Programmable Gate Array (FPGA), this scaler module is exible and convenient to be upgrade in future.
2015, 32(1): 80-83.
doi: 10.11804/NuclPhysRev.32.01.080
摘要:
为了评估弹核碎裂反应在碳离子肿瘤治疗中产生的影响，中国科学院近代物理研究所建立了一套探测器系统用来测量相关反应产物。这套探测系统包括起始探测器、水靶系统、带电粒子鉴别系统和中子测量系统。利用中国科学院近代物理研究所250 MeV/u 12C6+ 束打50 mm水靶的实验在束测试了这套系统的性能。实验结果表明，通过ΔE-E 和TOF-ΔE 两种粒子鉴别方法这套探测系统清楚地区分了H，He，Li，Be，B和C 等元素。通过计算不同Z 值带电碎片的微分截面得到了这些带电碎片(本工作给出元素H 和He)相应的角分布。这套探测系统中的带电粒子测量系统性能达到了设计的预期目标。For estimating the influence of the projectile breakup reaction on carbon ion tumour therapy, a detector system was built by IMP(Institute of Modern Physics), Chinese Academy of Sciences(CAS), and used to detect the results of the reaction. The system is composed of start detector, water target system, charged fragments detector system and neutron detector system. The performance of the detector system was tested in the experiment of 5 cm thick water target bombarded by 250 MeV/u carbon beam. The results reveal that the charged fragments, such as elements H, He, Li, Be, B and C, were identified clearly by ΔE-E and ΔE-TOF techniques. The angular distributions of some charged fragments were obtained by calculating the charge-changing cross-sections of the fragments(e.g. elements H and He isotopes in our work). The test results prove that the charged fragment detector system achieves the design aim.
为了评估弹核碎裂反应在碳离子肿瘤治疗中产生的影响，中国科学院近代物理研究所建立了一套探测器系统用来测量相关反应产物。这套探测系统包括起始探测器、水靶系统、带电粒子鉴别系统和中子测量系统。利用中国科学院近代物理研究所250 MeV/u 12C6+ 束打50 mm水靶的实验在束测试了这套系统的性能。实验结果表明，通过ΔE-E 和TOF-ΔE 两种粒子鉴别方法这套探测系统清楚地区分了H，He，Li，Be，B和C 等元素。通过计算不同Z 值带电碎片的微分截面得到了这些带电碎片(本工作给出元素H 和He)相应的角分布。这套探测系统中的带电粒子测量系统性能达到了设计的预期目标。For estimating the influence of the projectile breakup reaction on carbon ion tumour therapy, a detector system was built by IMP(Institute of Modern Physics), Chinese Academy of Sciences(CAS), and used to detect the results of the reaction. The system is composed of start detector, water target system, charged fragments detector system and neutron detector system. The performance of the detector system was tested in the experiment of 5 cm thick water target bombarded by 250 MeV/u carbon beam. The results reveal that the charged fragments, such as elements H, He, Li, Be, B and C, were identified clearly by ΔE-E and ΔE-TOF techniques. The angular distributions of some charged fragments were obtained by calculating the charge-changing cross-sections of the fragments(e.g. elements H and He isotopes in our work). The test results prove that the charged fragment detector system achieves the design aim.
2015, 32(1): 84-88.
doi: 10.11804/NuclPhysRev.32.01.084
摘要:
运用MCNP5程序，建立了基于MIRD数字体模的肺部γ内污染模型以及NaI(Tl)探测器模型，模拟计算了NaI(Tl)探测器对基于MIRD数字体模的肺部γ内污染的探测效率，获得了在多种空间位置上对沉积在肺部的9 种能量 射线的探测效率。模拟结果表明，在不同位置的探测效率并不完全符合人体肺部的解剖学结构，在右下肺位置可获得最高的探测效率，左下肺次之，左上肺最低。在探测器位置固定的情况下，探测效率随能量的增加，有先增高后降低的现象。In order to obtain detection efficiencies of nine kinds of gamma rays emitted by isotopes deposited in lungs at various measurement geometry, Monte Carlo N-Particle Transport Code 5 (MCNP5) has been employed to for calculation. The results show that the detection efficiency in different locations of lung is not completely accord with human body’s anatomy structure. The efficiency decreases gradually from lower-right lung, to lowerleft lung, and then to upper-left lung. When the location of detector is fixed, with the increase of energy, the
detection efficiency rises up firstly and then falls down.
运用MCNP5程序，建立了基于MIRD数字体模的肺部γ内污染模型以及NaI(Tl)探测器模型，模拟计算了NaI(Tl)探测器对基于MIRD数字体模的肺部γ内污染的探测效率，获得了在多种空间位置上对沉积在肺部的9 种能量 射线的探测效率。模拟结果表明，在不同位置的探测效率并不完全符合人体肺部的解剖学结构，在右下肺位置可获得最高的探测效率，左下肺次之，左上肺最低。在探测器位置固定的情况下，探测效率随能量的增加，有先增高后降低的现象。In order to obtain detection efficiencies of nine kinds of gamma rays emitted by isotopes deposited in lungs at various measurement geometry, Monte Carlo N-Particle Transport Code 5 (MCNP5) has been employed to for calculation. The results show that the detection efficiency in different locations of lung is not completely accord with human body’s anatomy structure. The efficiency decreases gradually from lower-right lung, to lowerleft lung, and then to upper-left lung. When the location of detector is fixed, with the increase of energy, the
detection efficiency rises up firstly and then falls down.
2015, 32(1): 89-94.
doi: 10.11804/NuclPhysRev.32.01.089
摘要:
用修饰的库仑波(MCB)模型计算入射能量2 MeV/amu裸碳离子碰撞氦单电离的全微分截面,并将计算结果与相应的实验数据和其他理论结果进行比较，发现MCB理论在较小的电离电子能量和较大的动量转移条件下与实验结果符合得很好，在动量转移比较小时MCB理论结果binary峰的位置向大角方向发生了偏移。MCB理论和3CW(三体库仑波)理论相似，他们都比3DW-EIS(三体扭曲波程函初态近似)理论符合的好，说明了在微扰势中被动离子与入射粒子的相互作用是不可忽略的。与3CW理论相比，MCB模型在初态波函数和相互作用势中加入扭曲效应，比较发现扭曲效应会影响全微分截面的大小，但影响不是很明显。The modified coulomb born (MCB) model is applied to study the single ionization of helium by 2 MeV/amu C6+ ion. The fully differential cross sections are presented for a variety of momentum transfers and ejected-electron energies in the scattering plane. The MCB results are compared with the experimental data and other theoretical predictions. We find that the MCB results are similar to the 3CW (three-body coulomb wave) results and they are superior to the 3DW-EIS (three-body distorted wave-eikonal initial state) results. It turns out that the treatment of the passive electron is very important for the results and distorting effects are not obvious.
用修饰的库仑波(MCB)模型计算入射能量2 MeV/amu裸碳离子碰撞氦单电离的全微分截面,并将计算结果与相应的实验数据和其他理论结果进行比较，发现MCB理论在较小的电离电子能量和较大的动量转移条件下与实验结果符合得很好，在动量转移比较小时MCB理论结果binary峰的位置向大角方向发生了偏移。MCB理论和3CW(三体库仑波)理论相似，他们都比3DW-EIS(三体扭曲波程函初态近似)理论符合的好，说明了在微扰势中被动离子与入射粒子的相互作用是不可忽略的。与3CW理论相比，MCB模型在初态波函数和相互作用势中加入扭曲效应，比较发现扭曲效应会影响全微分截面的大小，但影响不是很明显。The modified coulomb born (MCB) model is applied to study the single ionization of helium by 2 MeV/amu C6+ ion. The fully differential cross sections are presented for a variety of momentum transfers and ejected-electron energies in the scattering plane. The MCB results are compared with the experimental data and other theoretical predictions. We find that the MCB results are similar to the 3CW (three-body coulomb wave) results and they are superior to the 3DW-EIS (three-body distorted wave-eikonal initial state) results. It turns out that the treatment of the passive electron is very important for the results and distorting effects are not obvious.
2015, 32(1): 95-99.
doi: 10.11804/NuclPhysRev.32.01.095
摘要:
研究了氧化物弥散强化(ODS) 的3 种铁素体钢，包括： 19Cr-3.5Al ODS钢(MA956)，16Cr-0.1TiODS和16Cr-0.1Zr ODS铁素体钢，在多能量的氦离子和MeV能量级的Bi、Xe 离子辐照条件下的硬化效应。获得了辐照硬化与原子离位损伤水平(dpa)、He 注入浓度的关系。结果表明，材料的硬度在低剂量范围会随着辐照剂量迅速增加，而在高剂量范围材料的硬度逐渐趋于饱和，可以用1/2 次的幂函数拟合辐照硬化与离位损伤水平之间的关系。不同入射离子——Bi离子和Xe离子都会引起ODS 钢的硬化，而氦离子还会在材料中聚集导致氦泡的形成，造成更加明显的硬化。实验证明，Ti 或Zr 掺杂的16Cr-ODS 铁素体钢较19Cr-3.5AlODS钢具有更强的抗辐照硬化能力，原因可归于其含有更高数密度的细小氧化物粒子——能够有效俘获点缺陷和氦原子，从而有效抑制晶粒内部和晶界出缺陷的长大。The present work investigates the irradiation hardening of ODS ferritic steels after multi-energy Heion implantation, or energetic Bi-ion and Xe-ion irradiation, to get an understanding of dependence of irradiationhardening on atomic displacement damage and gas accumulation. Three kinds of high-Cr ODS ferritic steels including the commercial MA956 (19Cr-3.5Al), the 16Cr-0.1Ti and the 16Cr-0.1Zr ODS ferritic steels were used.The results show that the hardness increases rapidly at the lower doses but tends to saturate at the higher dose.An 1/2-power law dependence on dpa value is obtained. Helium implantation contributes significantly to the irradiation hardening, possibly due to the impediment of the motion dislocations by helium bubbles. 16Cr-ODS (Ti or Zr added) ferritic which contains finer oxide particles in higher number density shows higher resistance to irradiation hardening than the MA056.
研究了氧化物弥散强化(ODS) 的3 种铁素体钢，包括： 19Cr-3.5Al ODS钢(MA956)，16Cr-0.1TiODS和16Cr-0.1Zr ODS铁素体钢，在多能量的氦离子和MeV能量级的Bi、Xe 离子辐照条件下的硬化效应。获得了辐照硬化与原子离位损伤水平(dpa)、He 注入浓度的关系。结果表明，材料的硬度在低剂量范围会随着辐照剂量迅速增加，而在高剂量范围材料的硬度逐渐趋于饱和，可以用1/2 次的幂函数拟合辐照硬化与离位损伤水平之间的关系。不同入射离子——Bi离子和Xe离子都会引起ODS 钢的硬化，而氦离子还会在材料中聚集导致氦泡的形成，造成更加明显的硬化。实验证明，Ti 或Zr 掺杂的16Cr-ODS 铁素体钢较19Cr-3.5AlODS钢具有更强的抗辐照硬化能力，原因可归于其含有更高数密度的细小氧化物粒子——能够有效俘获点缺陷和氦原子，从而有效抑制晶粒内部和晶界出缺陷的长大。The present work investigates the irradiation hardening of ODS ferritic steels after multi-energy Heion implantation, or energetic Bi-ion and Xe-ion irradiation, to get an understanding of dependence of irradiationhardening on atomic displacement damage and gas accumulation. Three kinds of high-Cr ODS ferritic steels including the commercial MA956 (19Cr-3.5Al), the 16Cr-0.1Ti and the 16Cr-0.1Zr ODS ferritic steels were used.The results show that the hardness increases rapidly at the lower doses but tends to saturate at the higher dose.An 1/2-power law dependence on dpa value is obtained. Helium implantation contributes significantly to the irradiation hardening, possibly due to the impediment of the motion dislocations by helium bubbles. 16Cr-ODS (Ti or Zr added) ferritic which contains finer oxide particles in higher number density shows higher resistance to irradiation hardening than the MA056.
2015, 32(1): 100-104.
doi: 10.11804/NuclPhysRev.32.01.100
摘要:
LET 作为一个传统的工程参量，并不能完全满足单粒子翻转数据表征的需要，而且也不能直接地反映核反应的一些特性(包括核反应概率与次级粒子)，因此研究了重离子与器件作用过程中核反应对单粒子翻转的影响。基于蒙特卡罗模拟与深入的分析，本研究对比了在直接电离与考虑核反应两种模式下的模拟结果。在模拟中，利用不同的重离子表征了核反应在单粒子翻转发生中所起的作用。结果显示，核反应对单粒子翻转截面的贡献依赖于离子的能量，并呈现非单调的变化关系。基于模拟的结果，建议用重离子核反应引起单粒子翻转的最恶劣情况来预估空间单粒子翻转率。This work investigates the effect of nuclear reactions resulting from the interaction of heavyion with the specific devices on single event upset (SEU), since the traditional application of linear energy transfer (LET) as an engineering metric may be unsatisfied on SEU characterization or has no ability to directly present the property of nuclear reaction (including its probability and secondary ions). Using Monte Carlo simulation and in-depth analysis, this study provides a powerful comparison between direct ionization processes and the one within nuclear reactions. The different heavy ions have been applied in simulation to characterize the role of nuclear reactions in SEU occurrence. The results show that the contribution of heavy-ion nuclear reactions to SEU cross section depends on ion energy with a nonmonotonic relationship. Based on the simulated results, suggestions were put forward that the worst case of SEU occurrence induced by heavy-ion nuclear reactions should be considered to predict the on-orbit SEU rate.
LET 作为一个传统的工程参量，并不能完全满足单粒子翻转数据表征的需要，而且也不能直接地反映核反应的一些特性(包括核反应概率与次级粒子)，因此研究了重离子与器件作用过程中核反应对单粒子翻转的影响。基于蒙特卡罗模拟与深入的分析，本研究对比了在直接电离与考虑核反应两种模式下的模拟结果。在模拟中，利用不同的重离子表征了核反应在单粒子翻转发生中所起的作用。结果显示，核反应对单粒子翻转截面的贡献依赖于离子的能量，并呈现非单调的变化关系。基于模拟的结果，建议用重离子核反应引起单粒子翻转的最恶劣情况来预估空间单粒子翻转率。This work investigates the effect of nuclear reactions resulting from the interaction of heavyion with the specific devices on single event upset (SEU), since the traditional application of linear energy transfer (LET) as an engineering metric may be unsatisfied on SEU characterization or has no ability to directly present the property of nuclear reaction (including its probability and secondary ions). Using Monte Carlo simulation and in-depth analysis, this study provides a powerful comparison between direct ionization processes and the one within nuclear reactions. The different heavy ions have been applied in simulation to characterize the role of nuclear reactions in SEU occurrence. The results show that the contribution of heavy-ion nuclear reactions to SEU cross section depends on ion energy with a nonmonotonic relationship. Based on the simulated results, suggestions were put forward that the worst case of SEU occurrence induced by heavy-ion nuclear reactions should be considered to predict the on-orbit SEU rate.
2015, 32(1): 105-109.
doi: 10.11804/NuclPhysRev.32.01.105
摘要:
重离子辐射具有独特的深度剂量分布和较高的相对生物学效应，被认为是理想的放疗手段。重离子的生物学效应在径迹形成过程中由多个物理参量共同决定，而这些物理参量和离子入射深度紧密相关，因此明确离子不同入射深度的生物学效应对重离子肿瘤放疗方案的设计和优化有着重要的理论和应用价值。使用兰州重离子研究装置HIRFL-CSRe 终端的碳离子束作为辐射源，以活体模式动物线虫作为实验对象，以线虫生殖细胞的凋亡水平作为生物学检测终点，研究了10 和20 Gy 碳离子辐射在辐射的入口、坪区和峰区的当代生物学效应和对后代个体基因组不稳定性的影响。结果表明：10 和20 Gy 碳离子辐射在三个不同的辐照区域内均显著增加了辐射当代的线虫生殖腺细胞的凋亡水平，并表现出一定的辐射区域和辐射剂量依赖性。同时，辐射诱导的后代个体基因组不稳定性也表现出一定的辐射区域和辐射剂量相关性。Heavy ion irradiation is a perfect means in radio-therapy due to its special depth dose distribution and high relative biological effects. The biological effects of heavy ion irradiation are determined by some major physical parameters, and vary along the tracks of heavy ions. Therefore, it is very significant for the tumor radio-therapy to investigate the biological effects along whole range of heavy ion radiation. In the present study, Caenorhabditis elegans, a model in vivo, was irradiated by carbon ion beams from HCRFL-CSRe, The level of germ cell apoptosis of worms was used as a checking endpoint for DNA damage, the effects of carbon irradiation located in the entrance, plateau and peak regions on the genomic instability of the irradiated worm and their progeny were detected. The results showed that the 10 and 20 Gy of carbon ion radiations led to the increased germ cell apoptosis in irradiated worms and these effects depend on the worm location along the range of carbon ions and the irradiation dosage. The results also suggested that heavy ion irradiation induced the up-regulated genomic instability in their progeny, and might be related to both the irradiation dose and the irradiated location.
重离子辐射具有独特的深度剂量分布和较高的相对生物学效应，被认为是理想的放疗手段。重离子的生物学效应在径迹形成过程中由多个物理参量共同决定，而这些物理参量和离子入射深度紧密相关，因此明确离子不同入射深度的生物学效应对重离子肿瘤放疗方案的设计和优化有着重要的理论和应用价值。使用兰州重离子研究装置HIRFL-CSRe 终端的碳离子束作为辐射源，以活体模式动物线虫作为实验对象，以线虫生殖细胞的凋亡水平作为生物学检测终点，研究了10 和20 Gy 碳离子辐射在辐射的入口、坪区和峰区的当代生物学效应和对后代个体基因组不稳定性的影响。结果表明：10 和20 Gy 碳离子辐射在三个不同的辐照区域内均显著增加了辐射当代的线虫生殖腺细胞的凋亡水平，并表现出一定的辐射区域和辐射剂量依赖性。同时，辐射诱导的后代个体基因组不稳定性也表现出一定的辐射区域和辐射剂量相关性。Heavy ion irradiation is a perfect means in radio-therapy due to its special depth dose distribution and high relative biological effects. The biological effects of heavy ion irradiation are determined by some major physical parameters, and vary along the tracks of heavy ions. Therefore, it is very significant for the tumor radio-therapy to investigate the biological effects along whole range of heavy ion radiation. In the present study, Caenorhabditis elegans, a model in vivo, was irradiated by carbon ion beams from HCRFL-CSRe, The level of germ cell apoptosis of worms was used as a checking endpoint for DNA damage, the effects of carbon irradiation located in the entrance, plateau and peak regions on the genomic instability of the irradiated worm and their progeny were detected. The results showed that the 10 and 20 Gy of carbon ion radiations led to the increased germ cell apoptosis in irradiated worms and these effects depend on the worm location along the range of carbon ions and the irradiation dosage. The results also suggested that heavy ion irradiation induced the up-regulated genomic instability in their progeny, and might be related to both the irradiation dose and the irradiated location.
2015, 32(1): 110-114.
doi: 10.11804/NuclPhysRev.32.01.110
摘要:
采用高传能线密度(LET) 重离子辐照人胃癌SGC7901 细胞，应用流式细胞技术、蛋白质印迹法(Western blot) 及反转录聚合酶链式反应(RT-PCR) 观察重离子诱导人胃癌SGC7901 细胞周期、凋亡和MSH2 表达状况。结果表明： 与对照组相比，SGC7901 细胞在辐射后72 h G2/M 期所占细胞比率(33.26±0.08) 和凋亡率(24.16±0.64) 均达到峰值，且呈时间依赖性增加；经重离子照射后，DNA错配修复基因MSH2 mRNA 和蛋白表达水平在6 h 最高。结果提示：重离子在体外诱导SGC7901 细胞周期阻滞和凋亡，且具有显著的时间依赖性效应；重离子在一定剂量和时间下，诱导了SGC7901 细胞MSH2 基因表达。DNA错配修复基因MSH2 可能参与了重离子辐照诱导胃癌细胞DNA损伤的修复应答。Human gastric cancer cell SGC7901 were irradiated with high linear energy transfer (LET) carbon ion. Apoptotic cells after irradiation were analyzed by flow cytometry and expression of MSH2 genes in the irradiated cells was detected by western blot and RT-PCR assay. Compared with the control group, we found that the number of G2/M (33.26±0.08) or apoptosis (24.16±0.64) of SGC7901 cells reached a maximum after irradiation at 72 h in a dose dependent manner. And heavy ion irradiation efficiently up-regulated the expression of MSH2 gene at 4.0 Gy after being irradiated 6 h. These results imply that heavy ion beam could induce cell apoptosis and cell cycle arrest in time-dependent manners. Furthermore, expression of MSH2 genes activated by carbon ion irradiation suggests that DNA mismatch repair gene MSH2 might be involved in DNA repair pathways.
采用高传能线密度(LET) 重离子辐照人胃癌SGC7901 细胞，应用流式细胞技术、蛋白质印迹法(Western blot) 及反转录聚合酶链式反应(RT-PCR) 观察重离子诱导人胃癌SGC7901 细胞周期、凋亡和MSH2 表达状况。结果表明： 与对照组相比，SGC7901 细胞在辐射后72 h G2/M 期所占细胞比率(33.26±0.08) 和凋亡率(24.16±0.64) 均达到峰值，且呈时间依赖性增加；经重离子照射后，DNA错配修复基因MSH2 mRNA 和蛋白表达水平在6 h 最高。结果提示：重离子在体外诱导SGC7901 细胞周期阻滞和凋亡，且具有显著的时间依赖性效应；重离子在一定剂量和时间下，诱导了SGC7901 细胞MSH2 基因表达。DNA错配修复基因MSH2 可能参与了重离子辐照诱导胃癌细胞DNA损伤的修复应答。Human gastric cancer cell SGC7901 were irradiated with high linear energy transfer (LET) carbon ion. Apoptotic cells after irradiation were analyzed by flow cytometry and expression of MSH2 genes in the irradiated cells was detected by western blot and RT-PCR assay. Compared with the control group, we found that the number of G2/M (33.26±0.08) or apoptosis (24.16±0.64) of SGC7901 cells reached a maximum after irradiation at 72 h in a dose dependent manner. And heavy ion irradiation efficiently up-regulated the expression of MSH2 gene at 4.0 Gy after being irradiated 6 h. These results imply that heavy ion beam could induce cell apoptosis and cell cycle arrest in time-dependent manners. Furthermore, expression of MSH2 genes activated by carbon ion irradiation suggests that DNA mismatch repair gene MSH2 might be involved in DNA repair pathways.
2015, 32(1): 115-120.
doi: 10.11804/NuclPhysRev.32.01.115
摘要:
为阐述分野照射治疗方式应用于中国科学院近代物理研究所(IMP) 肿瘤重离子临床治疗试验研究的理论基础，利用Monte Carlo (MC) 软件包Gate/Geant4 模拟计算了碳离子束分野照射分衔接处的横向剂量分布，得到了患者摆位误差±1.0 mm范围内的横向剂量分布和分野衔接处中心剂量随分野间距的变化关系，计算了分野间距5.0 mm的横向剂量分布。将分野间距5.0 mm的分野照射与整野照射的MC结果进行比较，发现：在靶区范围内两者模拟的剂量偏差在6.8% 以内，符合程度较好，并提出了在患者定位精确度较高的情况下(即患者治疗体位摆位误差在±1.0 mm范围) 解决分野衔接处剂量热点问题的可行方法，从而较大幅度地提高了分野照射时靶区范围内的剂量均匀性。To characterize the theoretical basis of eld patching technique in carbon ion beam therapy, Monte Carlo software package Gate/Geant4 was used to simulate the lateral dose distribution of matched elds. The lateral dose distribution of the matched elds within 1.0 millimeter of patient positioning error and the relationship between the central dose of the matched elds and the eld patching gap were obtained. Moreover, the lateral dose pro le of eld patching irradiation with 5.0 mm gap was simulated. While comparing the lateral dose distribution of eld patching irradiation with 5.0 mm gap with the undivided eld irradiation, a good agreement between both results with a maximum dose deviation of 6.8% was observed within the target volume.Hence a feasible method for solving the issue of dose hotspots during eld patching under the condition of higher patient positioning accuracies (patient positioning error within 1.0 millimeter) was proposed and the dose homogeneit within the target volume could be greatly improved when eld patching technique is adopted in carbon ion beam therapy.
为阐述分野照射治疗方式应用于中国科学院近代物理研究所(IMP) 肿瘤重离子临床治疗试验研究的理论基础，利用Monte Carlo (MC) 软件包Gate/Geant4 模拟计算了碳离子束分野照射分衔接处的横向剂量分布，得到了患者摆位误差±1.0 mm范围内的横向剂量分布和分野衔接处中心剂量随分野间距的变化关系，计算了分野间距5.0 mm的横向剂量分布。将分野间距5.0 mm的分野照射与整野照射的MC结果进行比较，发现：在靶区范围内两者模拟的剂量偏差在6.8% 以内，符合程度较好，并提出了在患者定位精确度较高的情况下(即患者治疗体位摆位误差在±1.0 mm范围) 解决分野衔接处剂量热点问题的可行方法，从而较大幅度地提高了分野照射时靶区范围内的剂量均匀性。To characterize the theoretical basis of eld patching technique in carbon ion beam therapy, Monte Carlo software package Gate/Geant4 was used to simulate the lateral dose distribution of matched elds. The lateral dose distribution of the matched elds within 1.0 millimeter of patient positioning error and the relationship between the central dose of the matched elds and the eld patching gap were obtained. Moreover, the lateral dose pro le of eld patching irradiation with 5.0 mm gap was simulated. While comparing the lateral dose distribution of eld patching irradiation with 5.0 mm gap with the undivided eld irradiation, a good agreement between both results with a maximum dose deviation of 6.8% was observed within the target volume.Hence a feasible method for solving the issue of dose hotspots during eld patching under the condition of higher patient positioning accuracies (patient positioning error within 1.0 millimeter) was proposed and the dose homogeneit within the target volume could be greatly improved when eld patching technique is adopted in carbon ion beam therapy.
2015, 32(1): 121-127.
doi: 10.11804/NuclPhysRev.32.01.121
摘要:
为满足核工程对核数据的需求，对20 MeV以下65Cu(n, p)65Ni 反应截面的实验数据进行了分析和评价，包括实验数据的收集、修正、选取、归一、误差调整和数据处理，在分析实验误差特别是关联误差的基础上构造了每家数据的协方差矩阵，最后利用样条拟合程序SPCC给出了评价截面数据和实验数据的协方差矩阵。评价不仅考虑了实验数据的误差，还考虑了数据间的相关性。To meet the needs for nuclear data engineering, the experimental data of the 65Cu(n, p)65Ni cross section below 20 MeV were analyzed and evaluated.The evaluation procedure includes the experimental data collection, correction, selection, normalization, error adjustment and data processing, especially the covariance matrix for each experimental data is constructed with the information on experimental errors and correlation errors. The evaluation cross section data and the corresponding covariance matrices were given using the spline fitting procedure SPCC. The evaluation work was done with the consideration of not only the experimental errors but also the correlation of data.
为满足核工程对核数据的需求，对20 MeV以下65Cu(n, p)65Ni 反应截面的实验数据进行了分析和评价，包括实验数据的收集、修正、选取、归一、误差调整和数据处理，在分析实验误差特别是关联误差的基础上构造了每家数据的协方差矩阵，最后利用样条拟合程序SPCC给出了评价截面数据和实验数据的协方差矩阵。评价不仅考虑了实验数据的误差，还考虑了数据间的相关性。To meet the needs for nuclear data engineering, the experimental data of the 65Cu(n, p)65Ni cross section below 20 MeV were analyzed and evaluated.The evaluation procedure includes the experimental data collection, correction, selection, normalization, error adjustment and data processing, especially the covariance matrix for each experimental data is constructed with the information on experimental errors and correlation errors. The evaluation cross section data and the corresponding covariance matrices were given using the spline fitting procedure SPCC. The evaluation work was done with the consideration of not only the experimental errors but also the correlation of data.
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