2019年 第36卷 第1期
2019, 36(1): 1-36.
doi: 10.11804/NuclPhysRev.36.01.001
摘要:
中子星结构一直是核物理、粒子物理和天体物理共同关注的热点难题，双中子星并合事件GW170817的发现更是掀起这一研究的高潮。致密物质的状态方程是决定中子星结构的关键输入量，但是到目前为止，高密度的核物质状态方程行为依然很难确定。如今国内外已有许多运行或规划的大型核实验装置和天文观测设备，有望帮助我们很快解开致密物质状态方程的谜团。本文系统地阐述了基于微观多体理论和唯象模型对脉冲星类天体状态方程的研究现状，也讨论了奇异相变和奇异物质。结合理论计算和核物理实验及天文观测数据，致密物质状态方程的研究已取得相当多进展，但是也面临不少挑战，比如从实验和观测数据提取状态方程信息时的模型依赖，中子星各部分模型的不自洽以及各种依赖热密物质复杂动力学性质的实验和观测量。随着LIGO即将再运行而发现更多双中子星甚至中子星-黑洞等并合事件，多信使天文观测可望最终揭开中子星结构之谜。
The matter state inside neutron stars (NSs) is an exciting problem in nuclear physics, particle physics and astrophysics. The equation of state (EOS) of NSs plays a crucial role in the present multimessenger astronomy, especially after the event of GW170817. Thanks to accruing studies with advanced telescopes and radioactive beam facilities, the unknown EOS of supranuclear matter could soon be understood. We review the current status of the EOS for pulsar-like compact objects, that have been studied with both microscopic many-body approaches and phenomenological models. The appearance of strange baryonic matter and strange quark matter are also discussed. We compare the theoretical predictions with different data coming from both nuclear physics experiments and astrophysical observations. Despite great progresses obtained in dense nuclear matter properties, there are various challenges ahead, such as the model dependence of the constraints extracted from either experimental or observational data, the lack of a consistent and rigorous many-body treatment of all parts of the star, the dependence of many observables on the turbulent dynamics of relevant hot dense system. As LIGO is about to run again and discover more NS merger events, multimessenger observations are expected to finally unravel the mystery of NS structure.
中子星结构一直是核物理、粒子物理和天体物理共同关注的热点难题，双中子星并合事件GW170817的发现更是掀起这一研究的高潮。致密物质的状态方程是决定中子星结构的关键输入量，但是到目前为止，高密度的核物质状态方程行为依然很难确定。如今国内外已有许多运行或规划的大型核实验装置和天文观测设备，有望帮助我们很快解开致密物质状态方程的谜团。本文系统地阐述了基于微观多体理论和唯象模型对脉冲星类天体状态方程的研究现状，也讨论了奇异相变和奇异物质。结合理论计算和核物理实验及天文观测数据，致密物质状态方程的研究已取得相当多进展，但是也面临不少挑战，比如从实验和观测数据提取状态方程信息时的模型依赖，中子星各部分模型的不自洽以及各种依赖热密物质复杂动力学性质的实验和观测量。随着LIGO即将再运行而发现更多双中子星甚至中子星-黑洞等并合事件，多信使天文观测可望最终揭开中子星结构之谜。
The matter state inside neutron stars (NSs) is an exciting problem in nuclear physics, particle physics and astrophysics. The equation of state (EOS) of NSs plays a crucial role in the present multimessenger astronomy, especially after the event of GW170817. Thanks to accruing studies with advanced telescopes and radioactive beam facilities, the unknown EOS of supranuclear matter could soon be understood. We review the current status of the EOS for pulsar-like compact objects, that have been studied with both microscopic many-body approaches and phenomenological models. The appearance of strange baryonic matter and strange quark matter are also discussed. We compare the theoretical predictions with different data coming from both nuclear physics experiments and astrophysical observations. Despite great progresses obtained in dense nuclear matter properties, there are various challenges ahead, such as the model dependence of the constraints extracted from either experimental or observational data, the lack of a consistent and rigorous many-body treatment of all parts of the star, the dependence of many observables on the turbulent dynamics of relevant hot dense system. As LIGO is about to run again and discover more NS merger events, multimessenger observations are expected to finally unravel the mystery of NS structure.
2019, 36(1): 37-42.
doi: 10.11804/NuclPhysRev.36.01.037
摘要:
14O （α，p）17F是天体X射线暴中重要的突破反应。本工作通过厚靶方法测量其逆反应1H （17F，α）14O的反应截面来研究这一关键反应。本实验工作是在日本东京大学原子核科学研究中心（CNS）的低能次级束流线（CRIB）上完成的，后续的扣除本底实验是在兰州放射性束流线（RIBLL1）上完成的。CRIB实验是通过2H （16O，n）17F转移反应产生17F次级束，经过CRIB分离提纯之后，利用该次级束轰击氢气靶。在氢气靶后布置了三套望远镜探测器系统，用以探测不同实验角度的反冲α粒子，在数据处理的过程中经过动力学重构后得到了1H （17F，α）14O反应在质心系能区Ec.m.=2.7~3.4 MeV的反应截面。实验结果在3 MeV以上的高能区与前人的薄靶实验数据是一致的，在低能区本工作获得了新的实验数据，倾向于支持干涉相消的理论预言结果。
The 14O(α, p)17F reaction is one of the important breakout reactions in type I X-ray burst. This work reported a new cross section measurement of its reverse reaction of 1H(17F,α)14O. The experiment was performed using the CNS radioactive ion beam separator (CRIB), located at the Center for Nuclear Study (CNS), the University of Tokyo. The sequent background measurement was carried out at Radioactive Beam Line in Lanzhou (RIBLL1). 17F beam was produced via the transfer reaction of 2H(16O, n)17F, subsequently separated and purified by CRIB and bombarded a thick hydrogen H2 gas target. The recoiling α particles were measured by three △E-E silicon telescopes at three different angles. The total cross sections of 1H(17F,α)14O have been derived at Ec.m.=2.7~3.4 MeV based on an isotropic angular distribution assumption. Our results are consistent with the previous ones in the energy region of Ec.m.>3 MeV, and we also obtained some new data in the low energy region, which partly support the destructive interference between the direct and resonant reaction mechanism predicted by the theory.
14O （α，p）17F是天体X射线暴中重要的突破反应。本工作通过厚靶方法测量其逆反应1H （17F，α）14O的反应截面来研究这一关键反应。本实验工作是在日本东京大学原子核科学研究中心（CNS）的低能次级束流线（CRIB）上完成的，后续的扣除本底实验是在兰州放射性束流线（RIBLL1）上完成的。CRIB实验是通过2H （16O，n）17F转移反应产生17F次级束，经过CRIB分离提纯之后，利用该次级束轰击氢气靶。在氢气靶后布置了三套望远镜探测器系统，用以探测不同实验角度的反冲α粒子，在数据处理的过程中经过动力学重构后得到了1H （17F，α）14O反应在质心系能区Ec.m.=2.7~3.4 MeV的反应截面。实验结果在3 MeV以上的高能区与前人的薄靶实验数据是一致的，在低能区本工作获得了新的实验数据，倾向于支持干涉相消的理论预言结果。
The 14O(α, p)17F reaction is one of the important breakout reactions in type I X-ray burst. This work reported a new cross section measurement of its reverse reaction of 1H(17F,α)14O. The experiment was performed using the CNS radioactive ion beam separator (CRIB), located at the Center for Nuclear Study (CNS), the University of Tokyo. The sequent background measurement was carried out at Radioactive Beam Line in Lanzhou (RIBLL1). 17F beam was produced via the transfer reaction of 2H(16O, n)17F, subsequently separated and purified by CRIB and bombarded a thick hydrogen H2 gas target. The recoiling α particles were measured by three △E-E silicon telescopes at three different angles. The total cross sections of 1H(17F,α)14O have been derived at Ec.m.=2.7~3.4 MeV based on an isotropic angular distribution assumption. Our results are consistent with the previous ones in the energy region of Ec.m.>3 MeV, and we also obtained some new data in the low energy region, which partly support the destructive interference between the direct and resonant reaction mechanism predicted by the theory.
2019, 36(1): 43-48.
doi: 10.11804/NuclPhysRev.36.01.043
摘要:
利用严格求解的Nilsson轴形变平均场加扩展对力模型，对Er和Yb同位素链基态形状（量子相）酷越进行了研究。通过该模型下能级比R02+/21+、奇偶能差、信息熵的计算，成功地再现了155-163Er和157-165Yb同位素相关物理量的形状（量子相）酷越行为。通过分析这些量随着四极形变参数和总体对力强度的变化过程，显示了这种酷越行为主要是由于对力强度与四极形变之间的竞争导致的，该结果揭示了本模型下的基态形状（量子相）酷越行为的来源。
Ground-state shape (phase) crossover in Er and Yb isotopes is manifested in the axially deformed Nilsson mean-field plus extended pairing model. The energy ratio R02+/21+, the odd-even mass differences and the information entropy are calculated under the present model, reproduce the shape (phase) crossover behaviors of these quantities in 155-163Er and 157-165Yb isotopes. From the analysis of these quantities as functions of the quadrupole deformation parameter and the overall pairing interaction strength, it is shown that the crossover is mainly driven by the competition between the pairing interaction and the quadrupole deformation, which thus provides the origin of the shape (phase) crossover in the present model.
利用严格求解的Nilsson轴形变平均场加扩展对力模型，对Er和Yb同位素链基态形状（量子相）酷越进行了研究。通过该模型下能级比R02+/21+、奇偶能差、信息熵的计算，成功地再现了155-163Er和157-165Yb同位素相关物理量的形状（量子相）酷越行为。通过分析这些量随着四极形变参数和总体对力强度的变化过程，显示了这种酷越行为主要是由于对力强度与四极形变之间的竞争导致的，该结果揭示了本模型下的基态形状（量子相）酷越行为的来源。
Ground-state shape (phase) crossover in Er and Yb isotopes is manifested in the axially deformed Nilsson mean-field plus extended pairing model. The energy ratio R02+/21+, the odd-even mass differences and the information entropy are calculated under the present model, reproduce the shape (phase) crossover behaviors of these quantities in 155-163Er and 157-165Yb isotopes. From the analysis of these quantities as functions of the quadrupole deformation parameter and the overall pairing interaction strength, it is shown that the crossover is mainly driven by the competition between the pairing interaction and the quadrupole deformation, which thus provides the origin of the shape (phase) crossover in the present model.
2019, 36(1): 49-54.
doi: 10.11804/NuclPhysRev.36.01.049
摘要:
在强流重离子加速器运行中，带电粒子与真空管道中的残余气体分子相互作用发生的电荷交换反应是影响重离子束流寿命的关键因素。这种电荷交换过程导致的束流损失将解吸出真空管壁上吸附的气体分子，进而引起真空压力的动态变化，将严重影响加速器的稳定运行和最终束流引出流强。中国科学院近代物理研究所将在广东省惠州市建造的强流重离子加速器装置（High Intensity heavy-ion AcceleratorFacility，简称HIAF）利用增强器（Booster Ring，简称BRing）提供束流流强高达2×1011 ppp的238U35+用于核物理及原子物理等实验研究。对强流重离子加速器BRing中238U35+束流发生电荷交换反应，损失一个电子成为238U36+的过程进行了追踪模拟，计算得到了U36+损失前的运动径迹和全环粒子损失位置分布，模拟结果显示U36+受到色散元件的影响，将集中损失在位于二极磁铁后的漂移节区域中。基于模拟结果，在束流损失位置处设计安装由低解吸率材料制作的准直器，优化设计后的准直效率高达95%以上；并模拟计算了有无准直器时真空压力和束流流强的变化，安装准直器后BRing的平均真空度变化小于10%，将确保BRing加速器的稳定运行。
During heavy ion accelerator operation, the charge exchange effect between ions and residual gas molecules is the key factor to influence beam lifetime. The charge exchange process has ions lost on the wall and leads to a dynamical vacuum change, which will seriously affect the accelerator operation and reduce the extraction beam intensity. The Institute of Modern Physics' future project, called High Intensity heavy ion Accelerator Facility (HIAF), will be built in Huizhou city, Guangdong Province, China. The Booster Ring (BRing) will provide 2×11 ppp 238U35+ for nuclear physics experiments. This article studies the track of particle U36+ before impacting on the wall, which is the reference particle U35+ losing one electron, and gets the U36+ loss distribution along the BRing. The simulation result shows that U36+ will be influenced seriously by dispersion elements, and will be lost in the drift sections after the dipoles. Collimators made out of materials with low desorption will be installed in the particles lost positions. The collimator efficiency after optimization can be larger than 95%. It also shows BRing average pressure change and beam intensity change between collimators on and off. The result points out that the BRing average pressure change will be less than 10% with collimators on, which makes BRing operate stably.
在强流重离子加速器运行中，带电粒子与真空管道中的残余气体分子相互作用发生的电荷交换反应是影响重离子束流寿命的关键因素。这种电荷交换过程导致的束流损失将解吸出真空管壁上吸附的气体分子，进而引起真空压力的动态变化，将严重影响加速器的稳定运行和最终束流引出流强。中国科学院近代物理研究所将在广东省惠州市建造的强流重离子加速器装置（High Intensity heavy-ion AcceleratorFacility，简称HIAF）利用增强器（Booster Ring，简称BRing）提供束流流强高达2×1011 ppp的238U35+用于核物理及原子物理等实验研究。对强流重离子加速器BRing中238U35+束流发生电荷交换反应，损失一个电子成为238U36+的过程进行了追踪模拟，计算得到了U36+损失前的运动径迹和全环粒子损失位置分布，模拟结果显示U36+受到色散元件的影响，将集中损失在位于二极磁铁后的漂移节区域中。基于模拟结果，在束流损失位置处设计安装由低解吸率材料制作的准直器，优化设计后的准直效率高达95%以上；并模拟计算了有无准直器时真空压力和束流流强的变化，安装准直器后BRing的平均真空度变化小于10%，将确保BRing加速器的稳定运行。
During heavy ion accelerator operation, the charge exchange effect between ions and residual gas molecules is the key factor to influence beam lifetime. The charge exchange process has ions lost on the wall and leads to a dynamical vacuum change, which will seriously affect the accelerator operation and reduce the extraction beam intensity. The Institute of Modern Physics' future project, called High Intensity heavy ion Accelerator Facility (HIAF), will be built in Huizhou city, Guangdong Province, China. The Booster Ring (BRing) will provide 2×11 ppp 238U35+ for nuclear physics experiments. This article studies the track of particle U36+ before impacting on the wall, which is the reference particle U35+ losing one electron, and gets the U36+ loss distribution along the BRing. The simulation result shows that U36+ will be influenced seriously by dispersion elements, and will be lost in the drift sections after the dipoles. Collimators made out of materials with low desorption will be installed in the particles lost positions. The collimator efficiency after optimization can be larger than 95%. It also shows BRing average pressure change and beam intensity change between collimators on and off. The result points out that the BRing average pressure change will be less than 10% with collimators on, which makes BRing operate stably.
2019, 36(1): 55-61.
doi: 10.11804/NuclPhysRev.36.01.055
摘要:
重离子治疗对病灶周围健康组织损伤最小，对癌细胞杀伤效果最佳，是当代公认的先进有效的放疗方法。重离子Bragg峰与束流能量的关系要求重离子束能够在不同的能量间切换，需要加速器实现变能量加速。变能量加速的关键系统是同步加速器高频计算机控制系统；要求该系统能够根据光触发事例自动更换加速波形文件。该系统主要由三块基于PXI总线的FPGA板卡组成，采用了SOPC、DSP等技术，实现了波形文件的接收、插值及输出等功能。目前，控制系统经过长期稳定性试验，指标完全满足重离子治疗要求。
Heavy ion therapy is the most advanced and effective method of radiotherapy. Because it has the advantage that it has minimal damage to surrounding healthy tissue and the greatest cancer celling killing effect. The relationship between heavy ion Bragg peak and beam energy requires the accelerator to switch the beam between different energy. The PXI RF control system plays an important role in Heavy Ion Medical Machine(HIMM). It can automatically change the waveform files according to the optical event. The system is mainly consisted by three FPGA cards, based on PXI bus, and mainly use the technology such as SOPC, DSP and so on. The PXI RF control system for HIMM has been tested through a long-term stability experiments, the system meets the proposed requirements.
重离子治疗对病灶周围健康组织损伤最小，对癌细胞杀伤效果最佳，是当代公认的先进有效的放疗方法。重离子Bragg峰与束流能量的关系要求重离子束能够在不同的能量间切换，需要加速器实现变能量加速。变能量加速的关键系统是同步加速器高频计算机控制系统；要求该系统能够根据光触发事例自动更换加速波形文件。该系统主要由三块基于PXI总线的FPGA板卡组成，采用了SOPC、DSP等技术，实现了波形文件的接收、插值及输出等功能。目前，控制系统经过长期稳定性试验，指标完全满足重离子治疗要求。
Heavy ion therapy is the most advanced and effective method of radiotherapy. Because it has the advantage that it has minimal damage to surrounding healthy tissue and the greatest cancer celling killing effect. The relationship between heavy ion Bragg peak and beam energy requires the accelerator to switch the beam between different energy. The PXI RF control system plays an important role in Heavy Ion Medical Machine(HIMM). It can automatically change the waveform files according to the optical event. The system is mainly consisted by three FPGA cards, based on PXI bus, and mainly use the technology such as SOPC, DSP and so on. The PXI RF control system for HIMM has been tested through a long-term stability experiments, the system meets the proposed requirements.
2019, 36(1): 62-70.
doi: 10.11804/NuclPhysRev.36.01.062
摘要:
加速器驱动次临界装置（ADS）对加速器运行稳定性和失束指标提出了前所未有的要求。对于超导直线加速器的研究发现，超导腔失效是失束的一个较大的来源，故针对超导腔的失效情况，本文提出分段补偿新方法，以提高高功率超导直线加速器的运行稳定性。提出的分段补偿方法与已有的全局补偿和局部补偿的方法相比，在保证加速器出口束流品质与无束损束流传输的同时，分段补偿束流能量，优化了参与能量补偿的超导腔数量，降低超导腔的备份功率源需求。论文最后针对CiADS的超导直线加速器的物理设计，做了分段补偿的多粒子模拟。结果表明，采用了分段补偿方法实现超导腔失效补偿的前提下，参与补偿过程中改变腔压的超导腔数量比例为48%，对功率源总的功率备份冗余需求小于20%。
The accelerator driven subcritical system (ADS) has put forward unprecedented demands on the stability and beam trip of the accelerator operation. Depending on analysis, failure of the superconducting cavities is a major cause for beam trip of the superconducting cavity. Therefore, a new method of piecewise compensation is proposed to improve the stability of high power superconductivity linac. The piecewise compensation scheme proposed in this paper is compared with the existing global compensation and local compensation technology. While guaranteeing the beam quality of the accelerator and without beam loss transmission, the piecewise compensation method can optimize the number of superconducting cavities involved in energy compensation and reduce the demand for the backup redundancy of power sources of the superconducting cavities. At the end of the paper, the multi-particle simulation of piecewise compensation aims at the physical design of CiADS superconducting linac. The result shows that 48% of superconducting cavities modify the cavity's Epeak during the compensation process and the demanded redundancy of total power sources is less than 20% under the premise of successful compensation for the failure of superconducting cavities through the piecewise compensation method.
加速器驱动次临界装置（ADS）对加速器运行稳定性和失束指标提出了前所未有的要求。对于超导直线加速器的研究发现，超导腔失效是失束的一个较大的来源，故针对超导腔的失效情况，本文提出分段补偿新方法，以提高高功率超导直线加速器的运行稳定性。提出的分段补偿方法与已有的全局补偿和局部补偿的方法相比，在保证加速器出口束流品质与无束损束流传输的同时，分段补偿束流能量，优化了参与能量补偿的超导腔数量，降低超导腔的备份功率源需求。论文最后针对CiADS的超导直线加速器的物理设计，做了分段补偿的多粒子模拟。结果表明，采用了分段补偿方法实现超导腔失效补偿的前提下，参与补偿过程中改变腔压的超导腔数量比例为48%，对功率源总的功率备份冗余需求小于20%。
The accelerator driven subcritical system (ADS) has put forward unprecedented demands on the stability and beam trip of the accelerator operation. Depending on analysis, failure of the superconducting cavities is a major cause for beam trip of the superconducting cavity. Therefore, a new method of piecewise compensation is proposed to improve the stability of high power superconductivity linac. The piecewise compensation scheme proposed in this paper is compared with the existing global compensation and local compensation technology. While guaranteeing the beam quality of the accelerator and without beam loss transmission, the piecewise compensation method can optimize the number of superconducting cavities involved in energy compensation and reduce the demand for the backup redundancy of power sources of the superconducting cavities. At the end of the paper, the multi-particle simulation of piecewise compensation aims at the physical design of CiADS superconducting linac. The result shows that 48% of superconducting cavities modify the cavity's Epeak during the compensation process and the demanded redundancy of total power sources is less than 20% under the premise of successful compensation for the failure of superconducting cavities through the piecewise compensation method.
2019, 36(1): 71-77.
doi: 10.11804/NuclPhysRev.36.01.071
摘要:
随着国内高通量中子源及中子散射谱仪的快速发展，对高探测效率、高位置分辨、低伽玛灵敏度的位置灵敏型热中子探测器需求日益迫切。目前国际上中子散射谱仪大多数采用了基于3He的热中子探测器，由于当前3He价格昂贵，寻求3He替代型热中子探测器的相关研究任务紧迫。提出了一种基于10B4C转换体的多层多丝正比室新型二维位置灵敏型热中子探测器，并利用蒙特卡罗模拟软件Geant4和Garfield++对其探测效率、位置分辨、n/γ抑制比等性能展开了详细的模拟研究。结果表明，当多丝正比室单元为40层，阈值为200 keV时，热中子（E=0.025 eV）探测效率可达到~54%，位置分辨为2.6 mm （FWHM），n/γ抑制比为~107，可以满足大多数中子散射谱仪的需求，为此类探测器设计及实验研究提供了理论依据。
As the development of high flux neutron sources and neutron scattering spectrometers in China, more and more neutron detectors with high detection efficiency, high position resolution, high time resolution and low gamma sensitivity are need ungently. 3He based neutron detector is one of the best options. Recently, because of the 3He gas shortage and its expensive price, we must find a new replacement of 3He. A two-dimensional position sensitive neutron detector based on multi-layer Multi Wires Proportional Chambers (mMWPC) with 10B4C converter was proposed in this paper. The neutron detection efficiency, position resolution and γ compression were simulated with Geant4 and Garfield++. The results show that with 40 layers of neutron convertor, high themal neutron (E=0.025 eV) detection of~54%, best position resolution of 2.6 mm (FWHM) and high n/γ rejection ratio of~107 with the threshold of 200 keV can be achieved, which can meet the requirements of most spectrometers. This simulation results lay a good foundation for the next step of detector construction and test.
随着国内高通量中子源及中子散射谱仪的快速发展，对高探测效率、高位置分辨、低伽玛灵敏度的位置灵敏型热中子探测器需求日益迫切。目前国际上中子散射谱仪大多数采用了基于3He的热中子探测器，由于当前3He价格昂贵，寻求3He替代型热中子探测器的相关研究任务紧迫。提出了一种基于10B4C转换体的多层多丝正比室新型二维位置灵敏型热中子探测器，并利用蒙特卡罗模拟软件Geant4和Garfield++对其探测效率、位置分辨、n/γ抑制比等性能展开了详细的模拟研究。结果表明，当多丝正比室单元为40层，阈值为200 keV时，热中子（E=0.025 eV）探测效率可达到~54%，位置分辨为2.6 mm （FWHM），n/γ抑制比为~107，可以满足大多数中子散射谱仪的需求，为此类探测器设计及实验研究提供了理论依据。
As the development of high flux neutron sources and neutron scattering spectrometers in China, more and more neutron detectors with high detection efficiency, high position resolution, high time resolution and low gamma sensitivity are need ungently. 3He based neutron detector is one of the best options. Recently, because of the 3He gas shortage and its expensive price, we must find a new replacement of 3He. A two-dimensional position sensitive neutron detector based on multi-layer Multi Wires Proportional Chambers (mMWPC) with 10B4C converter was proposed in this paper. The neutron detection efficiency, position resolution and γ compression were simulated with Geant4 and Garfield++. The results show that with 40 layers of neutron convertor, high themal neutron (E=0.025 eV) detection of~54%, best position resolution of 2.6 mm (FWHM) and high n/γ rejection ratio of~107 with the threshold of 200 keV can be achieved, which can meet the requirements of most spectrometers. This simulation results lay a good foundation for the next step of detector construction and test.
2019, 36(1): 78-84.
doi: 10.11804/NuclPhysRev.36.01.078
摘要:
闪烁体探测器被广泛应用于当今粒子物理与原子核物理实验中。研究闪烁探测器的光衰减规律（LASD）对时间和能量的准确测量都十分重要，这一点对条形闪烁探测器尤为如此。本文以圆柱闪烁探测器为例，对各向同性的闪烁光进行立体角积分，进而研究不同立体角下光程差异对结果的影响。在数值计算的基础上，导出了描述LASD的通用公式。在一定条件下，公式可以约化为双指数衰减形式。对于DAMPE上PSD的实验数据，该公式能使闪烁体远端的拟合偏差从大约10%降低至2%以下。同时，模型也能够很好地描述Kaiser实验、Gierlik实验和Platino实验的实验数据。
Scintillator detectors are widely used in modern nuclear and particle physics experiments. Studying the light attenuation of scintillator detector (LASD) is vitally important for extracting proper measurements of energy and time. In this paper, we integrate the isotropic fluorescence over solid angle to study the influence on overall light-intensity from varying optical path at different angle. Based on numerical results, a universal formula for describing LASD is derived. Under certain condition, our formula can be written as a form of widely-used double-exponential function. The universal formula describes the experimental data of PSD at DAMPE, reducing the maximum deviation at far-side of the scintillator from~10% to less than 2%. Moreover, our model also deciphers Kaiser's experiment, Gierlik's experiment and Platino's experiment successfully.
闪烁体探测器被广泛应用于当今粒子物理与原子核物理实验中。研究闪烁探测器的光衰减规律（LASD）对时间和能量的准确测量都十分重要，这一点对条形闪烁探测器尤为如此。本文以圆柱闪烁探测器为例，对各向同性的闪烁光进行立体角积分，进而研究不同立体角下光程差异对结果的影响。在数值计算的基础上，导出了描述LASD的通用公式。在一定条件下，公式可以约化为双指数衰减形式。对于DAMPE上PSD的实验数据，该公式能使闪烁体远端的拟合偏差从大约10%降低至2%以下。同时，模型也能够很好地描述Kaiser实验、Gierlik实验和Platino实验的实验数据。
Scintillator detectors are widely used in modern nuclear and particle physics experiments. Studying the light attenuation of scintillator detector (LASD) is vitally important for extracting proper measurements of energy and time. In this paper, we integrate the isotropic fluorescence over solid angle to study the influence on overall light-intensity from varying optical path at different angle. Based on numerical results, a universal formula for describing LASD is derived. Under certain condition, our formula can be written as a form of widely-used double-exponential function. The universal formula describes the experimental data of PSD at DAMPE, reducing the maximum deviation at far-side of the scintillator from~10% to less than 2%. Moreover, our model also deciphers Kaiser's experiment, Gierlik's experiment and Platino's experiment successfully.
2019, 36(1): 85-90.
doi: 10.11804/NuclPhysRev.36.01.085
摘要:
新型多层厚型气体电子倍增器（Multi-layers THick Gas Electron Multiplier，M-THGEM）和传统THGEM （厚型气体电子倍增器）相比，具有连续的雪崩区，能够在低气压和低电压下都有较高增益，结构更紧凑，易于大面积制作等优势。对M-THGEM探测器的工作原理及性能进行了模拟研究，首先通过有限元（ANSYS）软件对二层与三层结构的M-THGEM进行了建模，对电场和电势分布分别进行了模拟计算；再利用Garfield++程序包对M-THGEM探测器在不同低气压和不同工作电压下的增益、感生信号、正离子反馈率等性能进行了研究。模拟结果表明，三层结构M-THGEM在低气压（200 Torr）、纯He气体条件下，能够获得较稳定的增益（105），输出信号的宽度在12 ns左右；同时，为降低正离子反馈率，本工作提出并研究了一种非对称的电压施加方式，结果表明，这种施加方式能有效降低正离子的反馈率。
Compared to THGEM (Thick Gas Electron Multiplier), the novel Multilayer Thick Gaseous Electron Multiplier (M-THGEM) has many advantages, such as continuous avalanche zone, more compact structure, high gain at low pressure and low operating voltage, and easy to make large-area production. In the presented work, two types of the M-THGEM detector (two or three layers) were modeled, and their main principle and performances were also studied by simulation. Two types of the detector were molded and simulated by using the finite element software (ANSYS), and the electric field distribution and nodes information lists were figured out. The effective gain and induced signal from M-THGEM detector at different gas pressures and operating voltages were studied with the Garfield++ package. The simulation results shown that M-THGEM can obtain a stable higher gain around 105 in an environment where has a low pressure even in 200 Torr and within a pure inertia gas such as He. At this condition, the width of the induced signal from the three-layers structure is around 120 ns. Additionally, an asymmetric way of the applied voltage was studied and aim to reduce the efficiency of ion feedback, and our results show that this method is effective.
新型多层厚型气体电子倍增器（Multi-layers THick Gas Electron Multiplier，M-THGEM）和传统THGEM （厚型气体电子倍增器）相比，具有连续的雪崩区，能够在低气压和低电压下都有较高增益，结构更紧凑，易于大面积制作等优势。对M-THGEM探测器的工作原理及性能进行了模拟研究，首先通过有限元（ANSYS）软件对二层与三层结构的M-THGEM进行了建模，对电场和电势分布分别进行了模拟计算；再利用Garfield++程序包对M-THGEM探测器在不同低气压和不同工作电压下的增益、感生信号、正离子反馈率等性能进行了研究。模拟结果表明，三层结构M-THGEM在低气压（200 Torr）、纯He气体条件下，能够获得较稳定的增益（105），输出信号的宽度在12 ns左右；同时，为降低正离子反馈率，本工作提出并研究了一种非对称的电压施加方式，结果表明，这种施加方式能有效降低正离子的反馈率。
Compared to THGEM (Thick Gas Electron Multiplier), the novel Multilayer Thick Gaseous Electron Multiplier (M-THGEM) has many advantages, such as continuous avalanche zone, more compact structure, high gain at low pressure and low operating voltage, and easy to make large-area production. In the presented work, two types of the M-THGEM detector (two or three layers) were modeled, and their main principle and performances were also studied by simulation. Two types of the detector were molded and simulated by using the finite element software (ANSYS), and the electric field distribution and nodes information lists were figured out. The effective gain and induced signal from M-THGEM detector at different gas pressures and operating voltages were studied with the Garfield++ package. The simulation results shown that M-THGEM can obtain a stable higher gain around 105 in an environment where has a low pressure even in 200 Torr and within a pure inertia gas such as He. At this condition, the width of the induced signal from the three-layers structure is around 120 ns. Additionally, an asymmetric way of the applied voltage was studied and aim to reduce the efficiency of ion feedback, and our results show that this method is effective.
2019, 36(1): 91-95.
doi: 10.11804/NuclPhysRev.36.01.091
摘要:
金属纳米线是未来纳米电子器件中的重要组成部分，因此研究单根金属纳米线的电学性质具有重要的意义。相对于单根纳米线电学性质的移位测量，原位测量精确度更高，结果更可靠。目前，国际上用于原位电学性质测量的单根纳米线的最小直径为80 nm，更小直径的纳米线很难在纳米孔道中生长，其电化学生长动力学过程还不清楚，电阻率数据缺失。本文在单个蚀刻离子径迹孔道中利用电化学沉积技术成功生长了单根Cu纳米线，其直径仅为64 nm，为目前同方法最细。在此基础上，首次测量了该纳米线的电输运性质并获得了其电阻率数值。研究结果表明，利用电导法可以监测模板中单个孔道的形成和扩孔的动力学过程以及最终的孔径大小。电化学沉积时，沉积电流与沉积时间曲线清晰地揭示了纳米线的沉积动力学过程。I-V曲线研究显示Cu纳米线具有典型的金属特性。其电阻率为3.46 μΩ·cm，约是Cu块体材料电阻率的两倍。电阻率增大可能与电子在晶界和表面处的散射有关。
Metal nanowires, as one of the most crucial components of nanoelectronic devices in the future, have attracted enormous attention. Therefore, it is of great significance to investigate the electrical properties of single metal nanowires. Herein, the single Cu nanowire with diameter of 64 nm was successfully prepared by using single-ion track template method combined with electrochemical deposition approach, and its I-V curve was measured. Such a diameter represents the thinnest one as comparing the reported ones obtained by the same method. The results illustrated that the process of formation and growth, as well as the final diameter of single nanochannel in template can be monitored and measured by conductance method. During the electrochemical deposition, the dynamic evolution of the deposition of nanowire can be clearly reflected through the deposition current and deposition time. At the same time, I-V measurements reveal that the Cu nanowire has typical metallic characteristic. For the first time, the resistivity of such a thin nanowire is obtained and its resistivity is 3.46 μΩ·cm which is around twice that of Cu bulk materials. The increase of resistivity is believed coming from finite size effects and may be related to the electrons scattering at the grain boundaries and surfaces.
金属纳米线是未来纳米电子器件中的重要组成部分，因此研究单根金属纳米线的电学性质具有重要的意义。相对于单根纳米线电学性质的移位测量，原位测量精确度更高，结果更可靠。目前，国际上用于原位电学性质测量的单根纳米线的最小直径为80 nm，更小直径的纳米线很难在纳米孔道中生长，其电化学生长动力学过程还不清楚，电阻率数据缺失。本文在单个蚀刻离子径迹孔道中利用电化学沉积技术成功生长了单根Cu纳米线，其直径仅为64 nm，为目前同方法最细。在此基础上，首次测量了该纳米线的电输运性质并获得了其电阻率数值。研究结果表明，利用电导法可以监测模板中单个孔道的形成和扩孔的动力学过程以及最终的孔径大小。电化学沉积时，沉积电流与沉积时间曲线清晰地揭示了纳米线的沉积动力学过程。I-V曲线研究显示Cu纳米线具有典型的金属特性。其电阻率为3.46 μΩ·cm，约是Cu块体材料电阻率的两倍。电阻率增大可能与电子在晶界和表面处的散射有关。
Metal nanowires, as one of the most crucial components of nanoelectronic devices in the future, have attracted enormous attention. Therefore, it is of great significance to investigate the electrical properties of single metal nanowires. Herein, the single Cu nanowire with diameter of 64 nm was successfully prepared by using single-ion track template method combined with electrochemical deposition approach, and its I-V curve was measured. Such a diameter represents the thinnest one as comparing the reported ones obtained by the same method. The results illustrated that the process of formation and growth, as well as the final diameter of single nanochannel in template can be monitored and measured by conductance method. During the electrochemical deposition, the dynamic evolution of the deposition of nanowire can be clearly reflected through the deposition current and deposition time. At the same time, I-V measurements reveal that the Cu nanowire has typical metallic characteristic. For the first time, the resistivity of such a thin nanowire is obtained and its resistivity is 3.46 μΩ·cm which is around twice that of Cu bulk materials. The increase of resistivity is believed coming from finite size effects and may be related to the electrons scattering at the grain boundaries and surfaces.
2019, 36(1): 96-103.
doi: 10.11804/NuclPhysRev.36.01.096
摘要:
开发一种基于图形处理器（GPU）加速的质子调强放疗鲁棒优化器，用于减小质子束射程不确定性和靶区定位偏差对质子放疗的影响。建立的鲁棒优化模型使用的目标函数包括9种边界剂量目标，分别是：无偏差情况、2种射程偏差（偏长与偏短）、6种摆位不确定性（前后、侧向、上下入射方向各2种正负偏差）。首先靶区和危及器官的剂量贡献矩阵使用笔形束算法计算得到，然后使用共轭梯度法优化目标函数让其满足约束条件，这两部分均采用GPU加速。头颈部、肺部和前列腺三个临床病例被用来检测本优化器的性能表现。与传统基于计划靶区（PTV）的质子调强放疗计划相比，鲁棒优化器能够优化出对射程不确定性和摆位误差更加不敏感的治疗计划，让靶区实现了高剂量均匀性的同时危及器官（OARs）也得到了更好的保护。经过100次迭代，三个病例的优化时间均在10 s左右。该结果证明了基于GPU加速的质子调强放疗鲁棒优化器能够在短时间内设计出高鲁棒性的质子治疗计划，从而提高质子放射治疗的可靠性。
This paper describes the development of a fast robust optimization tool that takes advantage of the GPU technologies. The objective function of the robust optimization model considered nine boundary dose distributions——two for ±range uncertainties, six for ±set-up uncertainties along anteroposterior (A-P), lateral (R-L) and superior{inferior (S-I) directions, and one for nominal situation. The nine boundary influence matrices were calculated using an in-house dose engine for proton pencil beams of a finite size, while the conjugate gradient method was applied to minimize the objective function. The GPU platform was adopted to accelerate both the proton dose calculation algorithm and the conjugate gradient method. Three clinical cases-one head and neck cancer case, one lung cancer case and one prostate cancer case-were investigated to demonstrate the clinical significance of the proposed robust optimizer. Compared with conventional planning target volume (PTV) based IMPT plans, the proposed method was found to be conducive in designing robust treatment plans that were less sensitive to range and setup uncertainties. The three cases showed that targets could achieve high dose uniformity while organs at risks (OARs) were under better protection against setup and range errors. The run times for the three cases were around 10 s for 100 iterations. The GPU-based fast robust optimizer developed in this study can serve to improve the reliability of traditional proton treatment planning by achieving a high level of robustness in a much shorter time.
开发一种基于图形处理器（GPU）加速的质子调强放疗鲁棒优化器，用于减小质子束射程不确定性和靶区定位偏差对质子放疗的影响。建立的鲁棒优化模型使用的目标函数包括9种边界剂量目标，分别是：无偏差情况、2种射程偏差（偏长与偏短）、6种摆位不确定性（前后、侧向、上下入射方向各2种正负偏差）。首先靶区和危及器官的剂量贡献矩阵使用笔形束算法计算得到，然后使用共轭梯度法优化目标函数让其满足约束条件，这两部分均采用GPU加速。头颈部、肺部和前列腺三个临床病例被用来检测本优化器的性能表现。与传统基于计划靶区（PTV）的质子调强放疗计划相比，鲁棒优化器能够优化出对射程不确定性和摆位误差更加不敏感的治疗计划，让靶区实现了高剂量均匀性的同时危及器官（OARs）也得到了更好的保护。经过100次迭代，三个病例的优化时间均在10 s左右。该结果证明了基于GPU加速的质子调强放疗鲁棒优化器能够在短时间内设计出高鲁棒性的质子治疗计划，从而提高质子放射治疗的可靠性。
This paper describes the development of a fast robust optimization tool that takes advantage of the GPU technologies. The objective function of the robust optimization model considered nine boundary dose distributions——two for ±range uncertainties, six for ±set-up uncertainties along anteroposterior (A-P), lateral (R-L) and superior{inferior (S-I) directions, and one for nominal situation. The nine boundary influence matrices were calculated using an in-house dose engine for proton pencil beams of a finite size, while the conjugate gradient method was applied to minimize the objective function. The GPU platform was adopted to accelerate both the proton dose calculation algorithm and the conjugate gradient method. Three clinical cases-one head and neck cancer case, one lung cancer case and one prostate cancer case-were investigated to demonstrate the clinical significance of the proposed robust optimizer. Compared with conventional planning target volume (PTV) based IMPT plans, the proposed method was found to be conducive in designing robust treatment plans that were less sensitive to range and setup uncertainties. The three cases showed that targets could achieve high dose uniformity while organs at risks (OARs) were under better protection against setup and range errors. The run times for the three cases were around 10 s for 100 iterations. The GPU-based fast robust optimizer developed in this study can serve to improve the reliability of traditional proton treatment planning by achieving a high level of robustness in a much shorter time.
2019, 36(1): 104-110.
doi: 10.11804/NuclPhysRev.36.01.104
摘要:
研究了和厚朴酚（HNK）对非小细胞肺癌（NSCLC）细胞系A549和H1299对低线性能量转移（LET） X射线和高LET碳离子的辐射增敏效应。首先用CCK-8检测了HNK对A549和H1299细胞的生长抑制情况，发现20 μmol/L的HNK处理对细胞的生长抑制作用较弱。用该浓度HNK预处理细胞2 h后给予不同剂量X射线或碳离子的照射，克隆存活法检测细胞的辐射敏感性，Annexin-PI双染法检测细胞凋亡，γH2AX焦点法检测DNA的双链断裂（DSB）损伤。实验结果显示：与X射线相比，NSCLC细胞对碳离子更敏感，HNK预处理仅对碳离子照射有辐射增敏作用；与碳离子单独照射相比，HNK预处理联合碳离子照射诱导了更明显的细胞凋亡；在照射后24 h，HNK预处理联合碳离子照射引起的细胞γH2AX焦点阳性率维持在较高水平，而X射线照射没有这些效应。实验结果表明，HNK预处理抑制了NSCLC细胞DNA的DSB修复，诱导了细胞凋亡的发生，从而提高了细胞对碳离子的辐射敏感性。
The radiosensitizing effect of Honokiol (HNK) on non-small cell lung carcinoma (NSCLC) cell lines A549 and H1299 to low-linear energy transfer (LET) X-rays and high-LET carbon ions was investigated in this study. First, the inhibitory effects of HNK on the growth of A549 and H1299 cells were detected by CCK-8 assay, and 20 μmol/L HNK treatment was found to induce a growth inhibitory effect slightly in these two cell lines. Cells were pre-treated with HNK and then irradiated with X-rays and carbon ions of different doses. Cellular radiosensitivity, apoptosis and DNA damage were analyzed by clonogenic survival, Annexin-PI staining and γH2AX foci, respectively. The results showed the cells were more sensitive to carbon ion irradiation compared to X-rays and the radiosensitization of HNK was only observed after carbon ion irradiation. Furthermore, the co-treatment led to higher apoptosis rate 48 h after irradiation and increased the positive rate of γH2AX foci 24 h after irradiation in A549 and H1299 cells compared with those in the groups treated with carbon ion irradiation alone. These phenomena were not observed after X-ray irradiation. Our data suggest that the pre-treatment with HNK inhibited DNA DSB repair, induced apoptosis and then enhanced the cellular radiosensitivity to carbon ions in NSCLC cells.
研究了和厚朴酚（HNK）对非小细胞肺癌（NSCLC）细胞系A549和H1299对低线性能量转移（LET） X射线和高LET碳离子的辐射增敏效应。首先用CCK-8检测了HNK对A549和H1299细胞的生长抑制情况，发现20 μmol/L的HNK处理对细胞的生长抑制作用较弱。用该浓度HNK预处理细胞2 h后给予不同剂量X射线或碳离子的照射，克隆存活法检测细胞的辐射敏感性，Annexin-PI双染法检测细胞凋亡，γH2AX焦点法检测DNA的双链断裂（DSB）损伤。实验结果显示：与X射线相比，NSCLC细胞对碳离子更敏感，HNK预处理仅对碳离子照射有辐射增敏作用；与碳离子单独照射相比，HNK预处理联合碳离子照射诱导了更明显的细胞凋亡；在照射后24 h，HNK预处理联合碳离子照射引起的细胞γH2AX焦点阳性率维持在较高水平，而X射线照射没有这些效应。实验结果表明，HNK预处理抑制了NSCLC细胞DNA的DSB修复，诱导了细胞凋亡的发生，从而提高了细胞对碳离子的辐射敏感性。
The radiosensitizing effect of Honokiol (HNK) on non-small cell lung carcinoma (NSCLC) cell lines A549 and H1299 to low-linear energy transfer (LET) X-rays and high-LET carbon ions was investigated in this study. First, the inhibitory effects of HNK on the growth of A549 and H1299 cells were detected by CCK-8 assay, and 20 μmol/L HNK treatment was found to induce a growth inhibitory effect slightly in these two cell lines. Cells were pre-treated with HNK and then irradiated with X-rays and carbon ions of different doses. Cellular radiosensitivity, apoptosis and DNA damage were analyzed by clonogenic survival, Annexin-PI staining and γH2AX foci, respectively. The results showed the cells were more sensitive to carbon ion irradiation compared to X-rays and the radiosensitization of HNK was only observed after carbon ion irradiation. Furthermore, the co-treatment led to higher apoptosis rate 48 h after irradiation and increased the positive rate of γH2AX foci 24 h after irradiation in A549 and H1299 cells compared with those in the groups treated with carbon ion irradiation alone. These phenomena were not observed after X-ray irradiation. Our data suggest that the pre-treatment with HNK inhibited DNA DSB repair, induced apoptosis and then enhanced the cellular radiosensitivity to carbon ions in NSCLC cells.
2019, 36(1): 111-117.
doi: 10.11804/NuclPhysRev.36.01.111
摘要:
使用基于Dirac-Hartree-Fock方法的Grasp2K程序包，计算了Am原子及离子的K，L，M-X射线的跃迁能和跃迁速率。在计算中，包括了Breit相互作用、真空极化和自能等重要效应。目前研究结果与已有的其他实验和理论结果相对误差约为0.04%。此外，我们还首次计算了从Am1+到Am6+离子的K，L，M-X射线的跃迁能和跃迁速率。相对于中性原子，来自低离化态的跃迁能相对于中性的相应跃迁线的能量仅有轻微的偏移，这反映出外层电子几乎不影响内壳层的跃迁性质。
Transition energies and rates of K, L, and M X-ray lines from electric-dipole transition of americium have been calculated using GRASP2K code based on the Dirac-Hartee-Fock method. The effects of the Breit interaction, vacuum polarization and self energy were taken into account. It is found that the present results agree within 0.04% with other experimental and theoretical values. Furthermore, we also calculated transition energies and rates of the K-, L-, and M-shell hole states of americium ions with charge states Am1+-Am6+ for the first time. It is found that the transition energies and rates change slightly relative to the corresponding results of americium atoms, which indicates that the outermost electrons can hardly affect inner-shell transition properties.
使用基于Dirac-Hartree-Fock方法的Grasp2K程序包，计算了Am原子及离子的K，L，M-X射线的跃迁能和跃迁速率。在计算中，包括了Breit相互作用、真空极化和自能等重要效应。目前研究结果与已有的其他实验和理论结果相对误差约为0.04%。此外，我们还首次计算了从Am1+到Am6+离子的K，L，M-X射线的跃迁能和跃迁速率。相对于中性原子，来自低离化态的跃迁能相对于中性的相应跃迁线的能量仅有轻微的偏移，这反映出外层电子几乎不影响内壳层的跃迁性质。
Transition energies and rates of K, L, and M X-ray lines from electric-dipole transition of americium have been calculated using GRASP2K code based on the Dirac-Hartee-Fock method. The effects of the Breit interaction, vacuum polarization and self energy were taken into account. It is found that the present results agree within 0.04% with other experimental and theoretical values. Furthermore, we also calculated transition energies and rates of the K-, L-, and M-shell hole states of americium ions with charge states Am1+-Am6+ for the first time. It is found that the transition energies and rates change slightly relative to the corresponding results of americium atoms, which indicates that the outermost electrons can hardly affect inner-shell transition properties.
2019, 36(1): 118-123.
doi: 10.11804/NuclPhysRev.36.01.118
摘要:
散裂反应产生的中子能谱等数据是ADS系统设计中的关键参数。由于涉及到的能量范围大、反应道复杂，目前没有完善的评价核数据库可供使用，需要使用合适的核理论模型来进行计算。CiADS （Chinainitiative Accelerator Driven System）即将开始建设，在第一阶段将使用能量约为250 MeV的质子束。利用FLUKA及GEANT4中的BERT_HP、BIC_HP和INCLXX_HP等物理模型列表分别计算了256 MeV质子轰击薄的铝、铁、铅和铀靶后，在7.5°，30°，60°和150°等方向出射的中子双微分截面及轰击厚的铝、铁和铀靶后，在30°，60°，120°和150°等方向出射的中子双微分产额，并与已有的实验数据进行对比。结果表明，FLUKA和INCLXX_HP的计算结果整体上能够更好地符合实验数据。BIC_HP计算的薄靶结果，除铝靶的150°和铅靶的30°外，在5~30 MeV能量范围内要明显高于实验结果，能够达到实验结果的2倍以上。BIC_HP计算的厚铀靶结果在30°和60°方向的5~30 MeV能量范围内要比实验结果高出70%以上，在120°和150°方向的5 MeV以上要高于实验结果的2倍。BERT_HP计算的7.5°和30°方向上铝、铁和铅靶结果在20s100 MeV要比实验结果低40%以上，计算的铀靶结果在20 MeV以下能够达到实验结果的2倍以上。
Neutron spectra produced through spallation reaction are key parameters in the design of Accelerator Driven Subcritical Systems. Since the energy span is large and reaction channels are complicated, no complete evaluated nuclear data library is ready for use. Suitable theoretical models are required to calculate the data. The CiADS (China initiative Accelerator Driven System) is going to be constructed in China. At the first stage, the adopted proton energy is about 250 MeV. FLUKA and GEANT4 are used to calculate the double differential cross sections at 7.5°, 30°, 60° and 150° induced by 256 MeV protons bombarding on thin aluminum, iron, lead and uranium targets, respectively. The double differential neutron yields at 30°, 60°, 120° and 150° are also calculated for 256 MeV protons bombarding on thick aluminum, iron and uranium targets, respectively. Three model lists INCLXX_HP, BIC_HP and BERT_HP implemented in GEANT4 are used separately. The calculation results are compared with corresponding experimental data. It is shown that results calculated with FLUKA and INCLXX_HP in GEANT4 fit the corresponding experimental data much better. The calculation results with BIC_HP overestimate the experimental data for thin targets in 5~30 MeV for more than 100%, except for aluminum at 150° and lead at 30°. For uranium target, the results calculated with BIC_HP is greater than the experimental results by more than 70% in the energy range 5~30 MeV at 30° and 60° and by more than 100% in the energy range above 5 MeV at 120° and 150°. In 20~100 MeV for aluminum, iron and lead targets, calculation results at 7.5° and 30° with BERT_HP underestimate the experimental data by more than 40%. And for uranium target, the experimental data up to 20 MeV are overestimated by more than 100%.
散裂反应产生的中子能谱等数据是ADS系统设计中的关键参数。由于涉及到的能量范围大、反应道复杂，目前没有完善的评价核数据库可供使用，需要使用合适的核理论模型来进行计算。CiADS （Chinainitiative Accelerator Driven System）即将开始建设，在第一阶段将使用能量约为250 MeV的质子束。利用FLUKA及GEANT4中的BERT_HP、BIC_HP和INCLXX_HP等物理模型列表分别计算了256 MeV质子轰击薄的铝、铁、铅和铀靶后，在7.5°，30°，60°和150°等方向出射的中子双微分截面及轰击厚的铝、铁和铀靶后，在30°，60°，120°和150°等方向出射的中子双微分产额，并与已有的实验数据进行对比。结果表明，FLUKA和INCLXX_HP的计算结果整体上能够更好地符合实验数据。BIC_HP计算的薄靶结果，除铝靶的150°和铅靶的30°外，在5~30 MeV能量范围内要明显高于实验结果，能够达到实验结果的2倍以上。BIC_HP计算的厚铀靶结果在30°和60°方向的5~30 MeV能量范围内要比实验结果高出70%以上，在120°和150°方向的5 MeV以上要高于实验结果的2倍。BERT_HP计算的7.5°和30°方向上铝、铁和铅靶结果在20s100 MeV要比实验结果低40%以上，计算的铀靶结果在20 MeV以下能够达到实验结果的2倍以上。
Neutron spectra produced through spallation reaction are key parameters in the design of Accelerator Driven Subcritical Systems. Since the energy span is large and reaction channels are complicated, no complete evaluated nuclear data library is ready for use. Suitable theoretical models are required to calculate the data. The CiADS (China initiative Accelerator Driven System) is going to be constructed in China. At the first stage, the adopted proton energy is about 250 MeV. FLUKA and GEANT4 are used to calculate the double differential cross sections at 7.5°, 30°, 60° and 150° induced by 256 MeV protons bombarding on thin aluminum, iron, lead and uranium targets, respectively. The double differential neutron yields at 30°, 60°, 120° and 150° are also calculated for 256 MeV protons bombarding on thick aluminum, iron and uranium targets, respectively. Three model lists INCLXX_HP, BIC_HP and BERT_HP implemented in GEANT4 are used separately. The calculation results are compared with corresponding experimental data. It is shown that results calculated with FLUKA and INCLXX_HP in GEANT4 fit the corresponding experimental data much better. The calculation results with BIC_HP overestimate the experimental data for thin targets in 5~30 MeV for more than 100%, except for aluminum at 150° and lead at 30°. For uranium target, the results calculated with BIC_HP is greater than the experimental results by more than 70% in the energy range 5~30 MeV at 30° and 60° and by more than 100% in the energy range above 5 MeV at 120° and 150°. In 20~100 MeV for aluminum, iron and lead targets, calculation results at 7.5° and 30° with BERT_HP underestimate the experimental data by more than 40%. And for uranium target, the experimental data up to 20 MeV are overestimated by more than 100%.
甘公网安备 62010202000723号